summaryrefslogtreecommitdiffstats
path: root/Documentation/media/uapi/v4l/extended-controls.rst
blob: 7725c33d8b69c2feadf301bb6ee1bf8b4ead8cba (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
2482
2483
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
2498
2499
2500
2501
2502
2503
2504
2505
2506
2507
2508
2509
2510
2511
2512
2513
2514
2515
2516
2517
2518
2519
2520
2521
2522
2523
2524
2525
2526
2527
2528
2529
2530
2531
2532
2533
2534
2535
2536
2537
2538
2539
2540
2541
2542
2543
2544
2545
2546
2547
2548
2549
2550
2551
2552
2553
2554
2555
2556
2557
2558
2559
2560
2561
2562
2563
2564
2565
2566
2567
2568
2569
2570
2571
2572
2573
2574
2575
2576
2577
2578
2579
2580
2581
2582
2583
2584
2585
2586
2587
2588
2589
2590
2591
2592
2593
2594
2595
2596
2597
2598
2599
2600
2601
2602
2603
2604
2605
2606
2607
2608
2609
2610
2611
2612
2613
2614
2615
2616
2617
2618
2619
2620
2621
2622
2623
2624
2625
2626
2627
2628
2629
2630
2631
2632
2633
2634
2635
2636
2637
2638
2639
2640
2641
2642
2643
2644
2645
2646
2647
2648
2649
2650
2651
2652
2653
2654
2655
2656
2657
2658
2659
2660
2661
2662
2663
2664
2665
2666
2667
2668
2669
2670
2671
2672
2673
2674
2675
2676
2677
2678
2679
2680
2681
2682
2683
2684
2685
2686
2687
2688
2689
2690
2691
2692
2693
2694
2695
2696
2697
2698
2699
2700
2701
2702
2703
2704
2705
2706
2707
2708
2709
2710
2711
2712
2713
2714
2715
2716
2717
2718
2719
2720
2721
2722
2723
2724
2725
2726
2727
2728
2729
2730
2731
2732
2733
2734
2735
2736
2737
2738
2739
2740
2741
2742
2743
2744
2745
2746
2747
2748
2749
2750
2751
2752
2753
2754
2755
2756
2757
2758
2759
2760
2761
2762
2763
2764
2765
2766
2767
2768
2769
2770
2771
2772
2773
2774
2775
2776
2777
2778
2779
2780
2781
2782
2783
2784
2785
2786
2787
2788
2789
2790
2791
2792
2793
2794
2795
2796
2797
2798
2799
2800
2801
2802
2803
2804
2805
2806
2807
2808
2809
2810
2811
2812
2813
2814
2815
2816
2817
2818
2819
2820
2821
2822
2823
2824
2825
2826
2827
2828
2829
2830
2831
2832
2833
2834
2835
2836
2837
2838
2839
2840
2841
2842
2843
2844
2845
2846
2847
2848
2849
2850
2851
2852
2853
2854
2855
2856
2857
2858
2859
2860
2861
2862
2863
2864
2865
2866
2867
2868
2869
2870
2871
2872
2873
2874
2875
2876
2877
2878
2879
2880
2881
2882
2883
2884
2885
2886
2887
2888
2889
2890
2891
2892
2893
2894
2895
2896
2897
2898
2899
2900
2901
2902
2903
2904
2905
2906
2907
2908
2909
2910
2911
2912
2913
2914
2915
2916
2917
2918
2919
2920
2921
2922
2923
2924
2925
2926
2927
2928
2929
2930
2931
2932
2933
2934
2935
2936
2937
2938
2939
2940
2941
2942
2943
2944
2945
2946
2947
2948
2949
2950
2951
2952
2953
2954
2955
2956
2957
2958
2959
2960
2961
2962
2963
2964
2965
2966
2967
2968
2969
2970
2971
2972
2973
2974
2975
2976
2977
2978
2979
2980
2981
2982
2983
2984
2985
2986
2987
2988
2989
2990
2991
2992
2993
2994
2995
2996
2997
2998
2999
3000
3001
3002
3003
3004
3005
3006
3007
3008
3009
3010
3011
3012
3013
3014
3015
3016
3017
3018
3019
3020
3021
3022
3023
3024
3025
3026
3027
3028
3029
3030
3031
3032
3033
3034
3035
3036
3037
3038
3039
3040
3041
3042
3043
3044
3045
3046
3047
3048
3049
3050
3051
3052
3053
3054
3055
3056
3057
3058
3059
3060
3061
3062
3063
3064
3065
3066
3067
3068
3069
3070
3071
3072
3073
3074
3075
3076
3077
3078
3079
3080
3081
3082
3083
3084
3085
3086
3087
3088
3089
3090
3091
3092
3093
3094
3095
3096
3097
3098
3099
3100
3101
3102
3103
3104
3105
3106
3107
3108
3109
3110
3111
3112
3113
3114
3115
3116
3117
3118
3119
3120
3121
3122
3123
3124
3125
3126
3127
3128
3129
3130
3131
3132
3133
3134
3135
3136
3137
3138
3139
3140
3141
3142
3143
3144
3145
3146
3147
3148
3149
3150
3151
3152
3153
3154
3155
3156
3157
3158
3159
3160
3161
3162
3163
3164
3165
3166
3167
3168
3169
3170
3171
3172
3173
3174
3175
3176
3177
3178
3179
3180
3181
3182
3183
3184
3185
3186
3187
3188
3189
3190
3191
3192
3193
3194
3195
3196
3197
3198
3199
3200
3201
3202
3203
3204
3205
3206
3207
3208
3209
3210
3211
3212
3213
3214
3215
3216
3217
3218
3219
3220
3221
3222
3223
3224
3225
3226
3227
3228
3229
3230
3231
3232
3233
3234
3235
3236
3237
3238
3239
3240
3241
3242
3243
3244
3245
3246
3247
3248
3249
3250
3251
3252
3253
3254
3255
3256
3257
3258
3259
3260
3261
3262
3263
3264
3265
3266
3267
3268
3269
3270
3271
3272
3273
3274
3275
3276
3277
3278
3279
3280
3281
3282
3283
3284
3285
3286
3287
3288
3289
3290
3291
3292
3293
3294
3295
3296
3297
3298
3299
3300
3301
3302
3303
3304
3305
3306
3307
3308
3309
3310
3311
3312
3313
3314
3315
3316
3317
3318
3319
3320
3321
3322
3323
3324
3325
3326
3327
3328
3329
3330
3331
3332
3333
3334
3335
3336
3337
3338
3339
3340
3341
3342
3343
3344
3345
3346
3347
3348
3349
3350
3351
3352
3353
3354
3355
3356
3357
3358
3359
3360
3361
3362
3363
3364
3365
3366
3367
3368
3369
3370
3371
3372
3373
3374
3375
3376
3377
3378
3379
3380
3381
3382
3383
3384
3385
3386
3387
3388
3389
3390
3391
3392
3393
3394
3395
3396
3397
3398
3399
3400
3401
3402
3403
3404
3405
3406
3407
3408
3409
3410
3411
3412
3413
3414
3415
3416
3417
3418
3419
3420
.. -*- coding: utf-8; mode: rst -*-

.. _extended-controls:

*****************
Extended Controls
*****************


Introduction
============

The control mechanism as originally designed was meant to be used for
user settings (brightness, saturation, etc). However, it turned out to
be a very useful model for implementing more complicated driver APIs
where each driver implements only a subset of a larger API.

The MPEG encoding API was the driving force behind designing and
implementing this extended control mechanism: the MPEG standard is quite
large and the currently supported hardware MPEG encoders each only
implement a subset of this standard. Further more, many parameters
relating to how the video is encoded into an MPEG stream are specific to
the MPEG encoding chip since the MPEG standard only defines the format
of the resulting MPEG stream, not how the video is actually encoded into
that format.

Unfortunately, the original control API lacked some features needed for
these new uses and so it was extended into the (not terribly originally
named) extended control API.

Even though the MPEG encoding API was the first effort to use the
Extended Control API, nowadays there are also other classes of Extended
Controls, such as Camera Controls and FM Transmitter Controls. The
Extended Controls API as well as all Extended Controls classes are
described in the following text.


The Extended Control API
========================

Three new ioctls are available:
:ref:`VIDIOC_G_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>`,
:ref:`VIDIOC_S_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>` and
:ref:`VIDIOC_TRY_EXT_CTRLS <VIDIOC_G_EXT_CTRLS>`. These ioctls act
on arrays of controls (as opposed to the
:ref:`VIDIOC_G_CTRL <VIDIOC_G_CTRL>` and
:ref:`VIDIOC_S_CTRL <VIDIOC_G_CTRL>` ioctls that act on a single
control). This is needed since it is often required to atomically change
several controls at once.

Each of the new ioctls expects a pointer to a struct
:c:type:`v4l2_ext_controls`. This structure
contains a pointer to the control array, a count of the number of
controls in that array and a control class. Control classes are used to
group similar controls into a single class. For example, control class
``V4L2_CTRL_CLASS_USER`` contains all user controls (i. e. all controls
that can also be set using the old :ref:`VIDIOC_S_CTRL <VIDIOC_G_CTRL>`
ioctl). Control class ``V4L2_CTRL_CLASS_MPEG`` contains all controls
relating to MPEG encoding, etc.

All controls in the control array must belong to the specified control
class. An error is returned if this is not the case.

It is also possible to use an empty control array (``count`` == 0) to check
whether the specified control class is supported.

The control array is a struct
:c:type:`v4l2_ext_control` array. The
struct :c:type:`v4l2_ext_control` is very similar to
struct :c:type:`v4l2_control`, except for the fact that
it also allows for 64-bit values and pointers to be passed.

Since the struct :c:type:`v4l2_ext_control` supports
pointers it is now also possible to have controls with compound types
such as N-dimensional arrays and/or structures. You need to specify the
``V4L2_CTRL_FLAG_NEXT_COMPOUND`` when enumerating controls to actually
be able to see such compound controls. In other words, these controls
with compound types should only be used programmatically.

Since such compound controls need to expose more information about
themselves than is possible with
:ref:`VIDIOC_QUERYCTRL` the
:ref:`VIDIOC_QUERY_EXT_CTRL <VIDIOC_QUERYCTRL>` ioctl was added. In
particular, this ioctl gives the dimensions of the N-dimensional array
if this control consists of more than one element.

.. note::

   #. It is important to realize that due to the flexibility of controls it is
      necessary to check whether the control you want to set actually is
      supported in the driver and what the valid range of values is. So use
      the :ref:`VIDIOC_QUERYCTRL` (or :ref:`VIDIOC_QUERY_EXT_CTRL
      <VIDIOC_QUERYCTRL>`) and :ref:`VIDIOC_QUERYMENU <VIDIOC_QUERYCTRL>`
      ioctls to check this.

   #. It is possible that some of the menu indices in a control of
      type ``V4L2_CTRL_TYPE_MENU`` may not be supported (``VIDIOC_QUERYMENU``
      will return an error). A good example is the list of supported MPEG
      audio bitrates. Some drivers only support one or two bitrates, others
      support a wider range.

All controls use machine endianness.


Enumerating Extended Controls
=============================

The recommended way to enumerate over the extended controls is by using
:ref:`VIDIOC_QUERYCTRL` in combination with the
``V4L2_CTRL_FLAG_NEXT_CTRL`` flag:


.. code-block:: c

    struct v4l2_queryctrl qctrl;

    qctrl.id = V4L2_CTRL_FLAG_NEXT_CTRL;
    while (0 == ioctl (fd, VIDIOC_QUERYCTRL, &qctrl)) {
	/* ... */
	qctrl.id |= V4L2_CTRL_FLAG_NEXT_CTRL;
    }

The initial control ID is set to 0 ORed with the
``V4L2_CTRL_FLAG_NEXT_CTRL`` flag. The ``VIDIOC_QUERYCTRL`` ioctl will
return the first control with a higher ID than the specified one. When
no such controls are found an error is returned.

If you want to get all controls within a specific control class, then
you can set the initial ``qctrl.id`` value to the control class and add
an extra check to break out of the loop when a control of another
control class is found:


.. code-block:: c

    qctrl.id = V4L2_CTRL_CLASS_MPEG | V4L2_CTRL_FLAG_NEXT_CTRL;
    while (0 == ioctl(fd, VIDIOC_QUERYCTRL, &qctrl)) {
	if (V4L2_CTRL_ID2CLASS(qctrl.id) != V4L2_CTRL_CLASS_MPEG)
	    break;
	    /* ... */
	qctrl.id |= V4L2_CTRL_FLAG_NEXT_CTRL;
    }

The 32-bit ``qctrl.id`` value is subdivided into three bit ranges: the
top 4 bits are reserved for flags (e. g. ``V4L2_CTRL_FLAG_NEXT_CTRL``)
and are not actually part of the ID. The remaining 28 bits form the
control ID, of which the most significant 12 bits define the control
class and the least significant 16 bits identify the control within the
control class. It is guaranteed that these last 16 bits are always
non-zero for controls. The range of 0x1000 and up are reserved for
driver-specific controls. The macro ``V4L2_CTRL_ID2CLASS(id)`` returns
the control class ID based on a control ID.

If the driver does not support extended controls, then
``VIDIOC_QUERYCTRL`` will fail when used in combination with
``V4L2_CTRL_FLAG_NEXT_CTRL``. In that case the old method of enumerating
control should be used (see :ref:`enum_all_controls`). But if it is
supported, then it is guaranteed to enumerate over all controls,
including driver-private controls.


Creating Control Panels
=======================

It is possible to create control panels for a graphical user interface
where the user can select the various controls. Basically you will have
to iterate over all controls using the method described above. Each
control class starts with a control of type
``V4L2_CTRL_TYPE_CTRL_CLASS``. ``VIDIOC_QUERYCTRL`` will return the name
of this control class which can be used as the title of a tab page
within a control panel.

The flags field of struct :ref:`v4l2_queryctrl <v4l2-queryctrl>` also
contains hints on the behavior of the control. See the
:ref:`VIDIOC_QUERYCTRL` documentation for more
details.


.. _mpeg-controls:

Codec Control Reference
=======================

Below all controls within the Codec control class are described. First
the generic controls, then controls specific for certain hardware.

.. note::

   These controls are applicable to all codecs and not just MPEG. The
   defines are prefixed with V4L2_CID_MPEG/V4L2_MPEG as the controls
   were originally made for MPEG codecs and later extended to cover all
   encoding formats.


Generic Codec Controls
----------------------


.. _mpeg-control-id:

Codec Control IDs
^^^^^^^^^^^^^^^^^

``V4L2_CID_MPEG_CLASS (class)``
    The Codec class descriptor. Calling
    :ref:`VIDIOC_QUERYCTRL` for this control will
    return a description of this control class. This description can be
    used as the caption of a Tab page in a GUI, for example.

.. _v4l2-mpeg-stream-type:

``V4L2_CID_MPEG_STREAM_TYPE``
    (enum)

enum v4l2_mpeg_stream_type -
    The MPEG-1, -2 or -4 output stream type. One cannot assume anything
    here. Each hardware MPEG encoder tends to support different subsets
    of the available MPEG stream types. This control is specific to
    multiplexed MPEG streams. The currently defined stream types are:



.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_MPEG_STREAM_TYPE_MPEG2_PS``
      - MPEG-2 program stream
    * - ``V4L2_MPEG_STREAM_TYPE_MPEG2_TS``
      - MPEG-2 transport stream
    * - ``V4L2_MPEG_STREAM_TYPE_MPEG1_SS``
      - MPEG-1 system stream
    * - ``V4L2_MPEG_STREAM_TYPE_MPEG2_DVD``
      - MPEG-2 DVD-compatible stream
    * - ``V4L2_MPEG_STREAM_TYPE_MPEG1_VCD``
      - MPEG-1 VCD-compatible stream
    * - ``V4L2_MPEG_STREAM_TYPE_MPEG2_SVCD``
      - MPEG-2 SVCD-compatible stream



``V4L2_CID_MPEG_STREAM_PID_PMT (integer)``
    Program Map Table Packet ID for the MPEG transport stream (default
    16)

``V4L2_CID_MPEG_STREAM_PID_AUDIO (integer)``
    Audio Packet ID for the MPEG transport stream (default 256)

``V4L2_CID_MPEG_STREAM_PID_VIDEO (integer)``
    Video Packet ID for the MPEG transport stream (default 260)

``V4L2_CID_MPEG_STREAM_PID_PCR (integer)``
    Packet ID for the MPEG transport stream carrying PCR fields (default
    259)

``V4L2_CID_MPEG_STREAM_PES_ID_AUDIO (integer)``
    Audio ID for MPEG PES

``V4L2_CID_MPEG_STREAM_PES_ID_VIDEO (integer)``
    Video ID for MPEG PES

.. _v4l2-mpeg-stream-vbi-fmt:

``V4L2_CID_MPEG_STREAM_VBI_FMT``
    (enum)

enum v4l2_mpeg_stream_vbi_fmt -
    Some cards can embed VBI data (e. g. Closed Caption, Teletext) into
    the MPEG stream. This control selects whether VBI data should be
    embedded, and if so, what embedding method should be used. The list
    of possible VBI formats depends on the driver. The currently defined
    VBI format types are:



.. tabularcolumns:: |p{6 cm}|p{11.5cm}|

.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_MPEG_STREAM_VBI_FMT_NONE``
      - No VBI in the MPEG stream
    * - ``V4L2_MPEG_STREAM_VBI_FMT_IVTV``
      - VBI in private packets, IVTV format (documented in the kernel
	sources in the file
	``Documentation/video4linux/cx2341x/README.vbi``)



.. _v4l2-mpeg-audio-sampling-freq:

``V4L2_CID_MPEG_AUDIO_SAMPLING_FREQ``
    (enum)

enum v4l2_mpeg_audio_sampling_freq -
    MPEG Audio sampling frequency. Possible values are:



.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_MPEG_AUDIO_SAMPLING_FREQ_44100``
      - 44.1 kHz
    * - ``V4L2_MPEG_AUDIO_SAMPLING_FREQ_48000``
      - 48 kHz
    * - ``V4L2_MPEG_AUDIO_SAMPLING_FREQ_32000``
      - 32 kHz



.. _v4l2-mpeg-audio-encoding:

``V4L2_CID_MPEG_AUDIO_ENCODING``
    (enum)

enum v4l2_mpeg_audio_encoding -
    MPEG Audio encoding. This control is specific to multiplexed MPEG
    streams. Possible values are:



.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_MPEG_AUDIO_ENCODING_LAYER_1``
      - MPEG-1/2 Layer I encoding
    * - ``V4L2_MPEG_AUDIO_ENCODING_LAYER_2``
      - MPEG-1/2 Layer II encoding
    * - ``V4L2_MPEG_AUDIO_ENCODING_LAYER_3``
      - MPEG-1/2 Layer III encoding
    * - ``V4L2_MPEG_AUDIO_ENCODING_AAC``
      - MPEG-2/4 AAC (Advanced Audio Coding)
    * - ``V4L2_MPEG_AUDIO_ENCODING_AC3``
      - AC-3 aka ATSC A/52 encoding



.. _v4l2-mpeg-audio-l1-bitrate:

``V4L2_CID_MPEG_AUDIO_L1_BITRATE``
    (enum)

enum v4l2_mpeg_audio_l1_bitrate -
    MPEG-1/2 Layer I bitrate. Possible values are:



.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_MPEG_AUDIO_L1_BITRATE_32K``
      - 32 kbit/s
    * - ``V4L2_MPEG_AUDIO_L1_BITRATE_64K``
      - 64 kbit/s
    * - ``V4L2_MPEG_AUDIO_L1_BITRATE_96K``
      - 96 kbit/s
    * - ``V4L2_MPEG_AUDIO_L1_BITRATE_128K``
      - 128 kbit/s
    * - ``V4L2_MPEG_AUDIO_L1_BITRATE_160K``
      - 160 kbit/s
    * - ``V4L2_MPEG_AUDIO_L1_BITRATE_192K``
      - 192 kbit/s
    * - ``V4L2_MPEG_AUDIO_L1_BITRATE_224K``
      - 224 kbit/s
    * - ``V4L2_MPEG_AUDIO_L1_BITRATE_256K``
      - 256 kbit/s
    * - ``V4L2_MPEG_AUDIO_L1_BITRATE_288K``
      - 288 kbit/s
    * - ``V4L2_MPEG_AUDIO_L1_BITRATE_320K``
      - 320 kbit/s
    * - ``V4L2_MPEG_AUDIO_L1_BITRATE_352K``
      - 352 kbit/s
    * - ``V4L2_MPEG_AUDIO_L1_BITRATE_384K``
      - 384 kbit/s
    * - ``V4L2_MPEG_AUDIO_L1_BITRATE_416K``
      - 416 kbit/s
    * - ``V4L2_MPEG_AUDIO_L1_BITRATE_448K``
      - 448 kbit/s



.. _v4l2-mpeg-audio-l2-bitrate:

``V4L2_CID_MPEG_AUDIO_L2_BITRATE``
    (enum)

enum v4l2_mpeg_audio_l2_bitrate -
    MPEG-1/2 Layer II bitrate. Possible values are:



.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_MPEG_AUDIO_L2_BITRATE_32K``
      - 32 kbit/s
    * - ``V4L2_MPEG_AUDIO_L2_BITRATE_48K``
      - 48 kbit/s
    * - ``V4L2_MPEG_AUDIO_L2_BITRATE_56K``
      - 56 kbit/s
    * - ``V4L2_MPEG_AUDIO_L2_BITRATE_64K``
      - 64 kbit/s
    * - ``V4L2_MPEG_AUDIO_L2_BITRATE_80K``
      - 80 kbit/s
    * - ``V4L2_MPEG_AUDIO_L2_BITRATE_96K``
      - 96 kbit/s
    * - ``V4L2_MPEG_AUDIO_L2_BITRATE_112K``
      - 112 kbit/s
    * - ``V4L2_MPEG_AUDIO_L2_BITRATE_128K``
      - 128 kbit/s
    * - ``V4L2_MPEG_AUDIO_L2_BITRATE_160K``
      - 160 kbit/s
    * - ``V4L2_MPEG_AUDIO_L2_BITRATE_192K``
      - 192 kbit/s
    * - ``V4L2_MPEG_AUDIO_L2_BITRATE_224K``
      - 224 kbit/s
    * - ``V4L2_MPEG_AUDIO_L2_BITRATE_256K``
      - 256 kbit/s
    * - ``V4L2_MPEG_AUDIO_L2_BITRATE_320K``
      - 320 kbit/s
    * - ``V4L2_MPEG_AUDIO_L2_BITRATE_384K``
      - 384 kbit/s



.. _v4l2-mpeg-audio-l3-bitrate:

``V4L2_CID_MPEG_AUDIO_L3_BITRATE``
    (enum)

enum v4l2_mpeg_audio_l3_bitrate -
    MPEG-1/2 Layer III bitrate. Possible values are:



.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_MPEG_AUDIO_L3_BITRATE_32K``
      - 32 kbit/s
    * - ``V4L2_MPEG_AUDIO_L3_BITRATE_40K``
      - 40 kbit/s
    * - ``V4L2_MPEG_AUDIO_L3_BITRATE_48K``
      - 48 kbit/s
    * - ``V4L2_MPEG_AUDIO_L3_BITRATE_56K``
      - 56 kbit/s
    * - ``V4L2_MPEG_AUDIO_L3_BITRATE_64K``
      - 64 kbit/s
    * - ``V4L2_MPEG_AUDIO_L3_BITRATE_80K``
      - 80 kbit/s
    * - ``V4L2_MPEG_AUDIO_L3_BITRATE_96K``
      - 96 kbit/s
    * - ``V4L2_MPEG_AUDIO_L3_BITRATE_112K``
      - 112 kbit/s
    * - ``V4L2_MPEG_AUDIO_L3_BITRATE_128K``
      - 128 kbit/s
    * - ``V4L2_MPEG_AUDIO_L3_BITRATE_160K``
      - 160 kbit/s
    * - ``V4L2_MPEG_AUDIO_L3_BITRATE_192K``
      - 192 kbit/s
    * - ``V4L2_MPEG_AUDIO_L3_BITRATE_224K``
      - 224 kbit/s
    * - ``V4L2_MPEG_AUDIO_L3_BITRATE_256K``
      - 256 kbit/s
    * - ``V4L2_MPEG_AUDIO_L3_BITRATE_320K``
      - 320 kbit/s



``V4L2_CID_MPEG_AUDIO_AAC_BITRATE (integer)``
    AAC bitrate in bits per second.

.. _v4l2-mpeg-audio-ac3-bitrate:

``V4L2_CID_MPEG_AUDIO_AC3_BITRATE``
    (enum)

enum v4l2_mpeg_audio_ac3_bitrate -
    AC-3 bitrate. Possible values are:



.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_32K``
      - 32 kbit/s
    * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_40K``
      - 40 kbit/s
    * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_48K``
      - 48 kbit/s
    * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_56K``
      - 56 kbit/s
    * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_64K``
      - 64 kbit/s
    * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_80K``
      - 80 kbit/s
    * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_96K``
      - 96 kbit/s
    * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_112K``
      - 112 kbit/s
    * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_128K``
      - 128 kbit/s
    * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_160K``
      - 160 kbit/s
    * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_192K``
      - 192 kbit/s
    * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_224K``
      - 224 kbit/s
    * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_256K``
      - 256 kbit/s
    * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_320K``
      - 320 kbit/s
    * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_384K``
      - 384 kbit/s
    * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_448K``
      - 448 kbit/s
    * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_512K``
      - 512 kbit/s
    * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_576K``
      - 576 kbit/s
    * - ``V4L2_MPEG_AUDIO_AC3_BITRATE_640K``
      - 640 kbit/s



.. _v4l2-mpeg-audio-mode:

``V4L2_CID_MPEG_AUDIO_MODE``
    (enum)

enum v4l2_mpeg_audio_mode -
    MPEG Audio mode. Possible values are:



.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_MPEG_AUDIO_MODE_STEREO``
      - Stereo
    * - ``V4L2_MPEG_AUDIO_MODE_JOINT_STEREO``
      - Joint Stereo
    * - ``V4L2_MPEG_AUDIO_MODE_DUAL``
      - Bilingual
    * - ``V4L2_MPEG_AUDIO_MODE_MONO``
      - Mono



.. _v4l2-mpeg-audio-mode-extension:

``V4L2_CID_MPEG_AUDIO_MODE_EXTENSION``
    (enum)

enum v4l2_mpeg_audio_mode_extension -
    Joint Stereo audio mode extension. In Layer I and II they indicate
    which subbands are in intensity stereo. All other subbands are coded
    in stereo. Layer III is not (yet) supported. Possible values are:



.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_MPEG_AUDIO_MODE_EXTENSION_BOUND_4``
      - Subbands 4-31 in intensity stereo
    * - ``V4L2_MPEG_AUDIO_MODE_EXTENSION_BOUND_8``
      - Subbands 8-31 in intensity stereo
    * - ``V4L2_MPEG_AUDIO_MODE_EXTENSION_BOUND_12``
      - Subbands 12-31 in intensity stereo
    * - ``V4L2_MPEG_AUDIO_MODE_EXTENSION_BOUND_16``
      - Subbands 16-31 in intensity stereo



.. _v4l2-mpeg-audio-emphasis:

``V4L2_CID_MPEG_AUDIO_EMPHASIS``
    (enum)

enum v4l2_mpeg_audio_emphasis -
    Audio Emphasis. Possible values are:



.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_MPEG_AUDIO_EMPHASIS_NONE``
      - None
    * - ``V4L2_MPEG_AUDIO_EMPHASIS_50_DIV_15_uS``
      - 50/15 microsecond emphasis
    * - ``V4L2_MPEG_AUDIO_EMPHASIS_CCITT_J17``
      - CCITT J.17



.. _v4l2-mpeg-audio-crc:

``V4L2_CID_MPEG_AUDIO_CRC``
    (enum)

enum v4l2_mpeg_audio_crc -
    CRC method. Possible values are:



.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_MPEG_AUDIO_CRC_NONE``
      - None
    * - ``V4L2_MPEG_AUDIO_CRC_CRC16``
      - 16 bit parity check



``V4L2_CID_MPEG_AUDIO_MUTE (boolean)``
    Mutes the audio when capturing. This is not done by muting audio
    hardware, which can still produce a slight hiss, but in the encoder
    itself, guaranteeing a fixed and reproducible audio bitstream. 0 =
    unmuted, 1 = muted.

.. _v4l2-mpeg-audio-dec-playback:

``V4L2_CID_MPEG_AUDIO_DEC_PLAYBACK``
    (enum)

enum v4l2_mpeg_audio_dec_playback -
    Determines how monolingual audio should be played back. Possible
    values are:



.. tabularcolumns:: |p{9.0cm}|p{8.5cm}|

.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_MPEG_AUDIO_DEC_PLAYBACK_AUTO``
      - Automatically determines the best playback mode.
    * - ``V4L2_MPEG_AUDIO_DEC_PLAYBACK_STEREO``
      - Stereo playback.
    * - ``V4L2_MPEG_AUDIO_DEC_PLAYBACK_LEFT``
      - Left channel playback.
    * - ``V4L2_MPEG_AUDIO_DEC_PLAYBACK_RIGHT``
      - Right channel playback.
    * - ``V4L2_MPEG_AUDIO_DEC_PLAYBACK_MONO``
      - Mono playback.
    * - ``V4L2_MPEG_AUDIO_DEC_PLAYBACK_SWAPPED_STEREO``
      - Stereo playback with swapped left and right channels.



.. _v4l2-mpeg-audio-dec-multilingual-playback:

``V4L2_CID_MPEG_AUDIO_DEC_MULTILINGUAL_PLAYBACK``
    (enum)

enum v4l2_mpeg_audio_dec_playback -
    Determines how multilingual audio should be played back.

.. _v4l2-mpeg-video-encoding:

``V4L2_CID_MPEG_VIDEO_ENCODING``
    (enum)

enum v4l2_mpeg_video_encoding -
    MPEG Video encoding method. This control is specific to multiplexed
    MPEG streams. Possible values are:



.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_MPEG_VIDEO_ENCODING_MPEG_1``
      - MPEG-1 Video encoding
    * - ``V4L2_MPEG_VIDEO_ENCODING_MPEG_2``
      - MPEG-2 Video encoding
    * - ``V4L2_MPEG_VIDEO_ENCODING_MPEG_4_AVC``
      - MPEG-4 AVC (H.264) Video encoding



.. _v4l2-mpeg-video-aspect:

``V4L2_CID_MPEG_VIDEO_ASPECT``
    (enum)

enum v4l2_mpeg_video_aspect -
    Video aspect. Possible values are:



.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_MPEG_VIDEO_ASPECT_1x1``
    * - ``V4L2_MPEG_VIDEO_ASPECT_4x3``
    * - ``V4L2_MPEG_VIDEO_ASPECT_16x9``
    * - ``V4L2_MPEG_VIDEO_ASPECT_221x100``



``V4L2_CID_MPEG_VIDEO_B_FRAMES (integer)``
    Number of B-Frames (default 2)

``V4L2_CID_MPEG_VIDEO_GOP_SIZE (integer)``
    GOP size (default 12)

``V4L2_CID_MPEG_VIDEO_GOP_CLOSURE (boolean)``
    GOP closure (default 1)

``V4L2_CID_MPEG_VIDEO_PULLDOWN (boolean)``
    Enable 3:2 pulldown (default 0)

.. _v4l2-mpeg-video-bitrate-mode:

``V4L2_CID_MPEG_VIDEO_BITRATE_MODE``
    (enum)

enum v4l2_mpeg_video_bitrate_mode -
    Video bitrate mode. Possible values are:



.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_MPEG_VIDEO_BITRATE_MODE_VBR``
      - Variable bitrate
    * - ``V4L2_MPEG_VIDEO_BITRATE_MODE_CBR``
      - Constant bitrate



``V4L2_CID_MPEG_VIDEO_BITRATE (integer)``
    Video bitrate in bits per second.

``V4L2_CID_MPEG_VIDEO_BITRATE_PEAK (integer)``
    Peak video bitrate in bits per second. Must be larger or equal to
    the average video bitrate. It is ignored if the video bitrate mode
    is set to constant bitrate.

``V4L2_CID_MPEG_VIDEO_TEMPORAL_DECIMATION (integer)``
    For every captured frame, skip this many subsequent frames (default
    0).

``V4L2_CID_MPEG_VIDEO_MUTE (boolean)``
    "Mutes" the video to a fixed color when capturing. This is useful
    for testing, to produce a fixed video bitstream. 0 = unmuted, 1 =
    muted.

``V4L2_CID_MPEG_VIDEO_MUTE_YUV (integer)``
    Sets the "mute" color of the video. The supplied 32-bit integer is
    interpreted as follows (bit 0 = least significant bit):



.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - Bit 0:7
      - V chrominance information
    * - Bit 8:15
      - U chrominance information
    * - Bit 16:23
      - Y luminance information
    * - Bit 24:31
      - Must be zero.



.. _v4l2-mpeg-video-dec-pts:

``V4L2_CID_MPEG_VIDEO_DEC_PTS (integer64)``
    This read-only control returns the 33-bit video Presentation Time
    Stamp as defined in ITU T-REC-H.222.0 and ISO/IEC 13818-1 of the
    currently displayed frame. This is the same PTS as is used in
    :ref:`VIDIOC_DECODER_CMD`.

.. _v4l2-mpeg-video-dec-frame:

``V4L2_CID_MPEG_VIDEO_DEC_FRAME (integer64)``
    This read-only control returns the frame counter of the frame that
    is currently displayed (decoded). This value is reset to 0 whenever
    the decoder is started.

``V4L2_CID_MPEG_VIDEO_DECODER_SLICE_INTERFACE (boolean)``
    If enabled the decoder expects to receive a single slice per buffer,
    otherwise the decoder expects a single frame in per buffer.
    Applicable to the decoder, all codecs.

``V4L2_CID_MPEG_VIDEO_H264_VUI_SAR_ENABLE (boolean)``
    Enable writing sample aspect ratio in the Video Usability
    Information. Applicable to the H264 encoder.

.. _v4l2-mpeg-video-h264-vui-sar-idc:

``V4L2_CID_MPEG_VIDEO_H264_VUI_SAR_IDC``
    (enum)

enum v4l2_mpeg_video_h264_vui_sar_idc -
    VUI sample aspect ratio indicator for H.264 encoding. The value is
    defined in the table E-1 in the standard. Applicable to the H264
    encoder.



.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_UNSPECIFIED``
      - Unspecified
    * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_1x1``
      - 1x1
    * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_12x11``
      - 12x11
    * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_10x11``
      - 10x11
    * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_16x11``
      - 16x11
    * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_40x33``
      - 40x33
    * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_24x11``
      - 24x11
    * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_20x11``
      - 20x11
    * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_32x11``
      - 32x11
    * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_80x33``
      - 80x33
    * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_18x11``
      - 18x11
    * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_15x11``
      - 15x11
    * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_64x33``
      - 64x33
    * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_160x99``
      - 160x99
    * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_4x3``
      - 4x3
    * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_3x2``
      - 3x2
    * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_2x1``
      - 2x1
    * - ``V4L2_MPEG_VIDEO_H264_VUI_SAR_IDC_EXTENDED``
      - Extended SAR



``V4L2_CID_MPEG_VIDEO_H264_VUI_EXT_SAR_WIDTH (integer)``
    Extended sample aspect ratio width for H.264 VUI encoding.
    Applicable to the H264 encoder.

``V4L2_CID_MPEG_VIDEO_H264_VUI_EXT_SAR_HEIGHT (integer)``
    Extended sample aspect ratio height for H.264 VUI encoding.
    Applicable to the H264 encoder.

.. _v4l2-mpeg-video-h264-level:

``V4L2_CID_MPEG_VIDEO_H264_LEVEL``
    (enum)

enum v4l2_mpeg_video_h264_level -
    The level information for the H264 video elementary stream.
    Applicable to the H264 encoder. Possible values are:



.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_MPEG_VIDEO_H264_LEVEL_1_0``
      - Level 1.0
    * - ``V4L2_MPEG_VIDEO_H264_LEVEL_1B``
      - Level 1B
    * - ``V4L2_MPEG_VIDEO_H264_LEVEL_1_1``
      - Level 1.1
    * - ``V4L2_MPEG_VIDEO_H264_LEVEL_1_2``
      - Level 1.2
    * - ``V4L2_MPEG_VIDEO_H264_LEVEL_1_3``
      - Level 1.3
    * - ``V4L2_MPEG_VIDEO_H264_LEVEL_2_0``
      - Level 2.0
    * - ``V4L2_MPEG_VIDEO_H264_LEVEL_2_1``
      - Level 2.1
    * - ``V4L2_MPEG_VIDEO_H264_LEVEL_2_2``
      - Level 2.2
    * - ``V4L2_MPEG_VIDEO_H264_LEVEL_3_0``
      - Level 3.0
    * - ``V4L2_MPEG_VIDEO_H264_LEVEL_3_1``
      - Level 3.1
    * - ``V4L2_MPEG_VIDEO_H264_LEVEL_3_2``
      - Level 3.2
    * - ``V4L2_MPEG_VIDEO_H264_LEVEL_4_0``
      - Level 4.0
    * - ``V4L2_MPEG_VIDEO_H264_LEVEL_4_1``
      - Level 4.1
    * - ``V4L2_MPEG_VIDEO_H264_LEVEL_4_2``
      - Level 4.2
    * - ``V4L2_MPEG_VIDEO_H264_LEVEL_5_0``
      - Level 5.0
    * - ``V4L2_MPEG_VIDEO_H264_LEVEL_5_1``
      - Level 5.1



.. _v4l2-mpeg-video-mpeg4-level:

``V4L2_CID_MPEG_VIDEO_MPEG4_LEVEL``
    (enum)

enum v4l2_mpeg_video_mpeg4_level -
    The level information for the MPEG4 elementary stream. Applicable to
    the MPEG4 encoder. Possible values are:



.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_MPEG_VIDEO_LEVEL_0``
      - Level 0
    * - ``V4L2_MPEG_VIDEO_LEVEL_0B``
      - Level 0b
    * - ``V4L2_MPEG_VIDEO_LEVEL_1``
      - Level 1
    * - ``V4L2_MPEG_VIDEO_LEVEL_2``
      - Level 2
    * - ``V4L2_MPEG_VIDEO_LEVEL_3``
      - Level 3
    * - ``V4L2_MPEG_VIDEO_LEVEL_3B``
      - Level 3b
    * - ``V4L2_MPEG_VIDEO_LEVEL_4``
      - Level 4
    * - ``V4L2_MPEG_VIDEO_LEVEL_5``
      - Level 5



.. _v4l2-mpeg-video-h264-profile:

``V4L2_CID_MPEG_VIDEO_H264_PROFILE``
    (enum)

enum v4l2_mpeg_video_h264_profile -
    The profile information for H264. Applicable to the H264 encoder.
    Possible values are:



.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_MPEG_VIDEO_H264_PROFILE_BASELINE``
      - Baseline profile
    * - ``V4L2_MPEG_VIDEO_H264_PROFILE_CONSTRAINED_BASELINE``
      - Constrained Baseline profile
    * - ``V4L2_MPEG_VIDEO_H264_PROFILE_MAIN``
      - Main profile
    * - ``V4L2_MPEG_VIDEO_H264_PROFILE_EXTENDED``
      - Extended profile
    * - ``V4L2_MPEG_VIDEO_H264_PROFILE_HIGH``
      - High profile
    * - ``V4L2_MPEG_VIDEO_H264_PROFILE_HIGH_10``
      - High 10 profile
    * - ``V4L2_MPEG_VIDEO_H264_PROFILE_HIGH_422``
      - High 422 profile
    * - ``V4L2_MPEG_VIDEO_H264_PROFILE_HIGH_444_PREDICTIVE``
      - High 444 Predictive profile
    * - ``V4L2_MPEG_VIDEO_H264_PROFILE_HIGH_10_INTRA``
      - High 10 Intra profile
    * - ``V4L2_MPEG_VIDEO_H264_PROFILE_HIGH_422_INTRA``
      - High 422 Intra profile
    * - ``V4L2_MPEG_VIDEO_H264_PROFILE_HIGH_444_INTRA``
      - High 444 Intra profile
    * - ``V4L2_MPEG_VIDEO_H264_PROFILE_CAVLC_444_INTRA``
      - CAVLC 444 Intra profile
    * - ``V4L2_MPEG_VIDEO_H264_PROFILE_SCALABLE_BASELINE``
      - Scalable Baseline profile
    * - ``V4L2_MPEG_VIDEO_H264_PROFILE_SCALABLE_HIGH``
      - Scalable High profile
    * - ``V4L2_MPEG_VIDEO_H264_PROFILE_SCALABLE_HIGH_INTRA``
      - Scalable High Intra profile
    * - ``V4L2_MPEG_VIDEO_H264_PROFILE_STEREO_HIGH``
      - Stereo High profile
    * - ``V4L2_MPEG_VIDEO_H264_PROFILE_MULTIVIEW_HIGH``
      - Multiview High profile



.. _v4l2-mpeg-video-mpeg4-profile:

``V4L2_CID_MPEG_VIDEO_MPEG4_PROFILE``
    (enum)

enum v4l2_mpeg_video_mpeg4_profile -
    The profile information for MPEG4. Applicable to the MPEG4 encoder.
    Possible values are:



.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_MPEG_VIDEO_PROFILE_SIMPLE``
      - Simple profile
    * - ``V4L2_MPEG_VIDEO_PROFILE_ADVANCED_SIMPLE``
      - Advanced Simple profile
    * - ``V4L2_MPEG_VIDEO_PROFILE_CORE``
      - Core profile
    * - ``V4L2_MPEG_VIDEO_PROFILE_SIMPLE_SCALABLE``
      - Simple Scalable profile
    * - ``V4L2_MPEG_VIDEO_PROFILE_ADVANCED_CODING_EFFICIENCY``
      -



``V4L2_CID_MPEG_VIDEO_MAX_REF_PIC (integer)``
    The maximum number of reference pictures used for encoding.
    Applicable to the encoder.

.. _v4l2-mpeg-video-multi-slice-mode:

``V4L2_CID_MPEG_VIDEO_MULTI_SLICE_MODE``
    (enum)

enum v4l2_mpeg_video_multi_slice_mode -
    Determines how the encoder should handle division of frame into
    slices. Applicable to the encoder. Possible values are:



.. tabularcolumns:: |p{8.7cm}|p{8.8cm}|

.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_MPEG_VIDEO_MULTI_SLICE_MODE_SINGLE``
      - Single slice per frame.
    * - ``V4L2_MPEG_VIDEO_MULTI_SLICE_MODE_MAX_MB``
      - Multiple slices with set maximum number of macroblocks per slice.
    * - ``V4L2_MPEG_VIDEO_MULTI_SLICE_MODE_MAX_BYTES``
      - Multiple slice with set maximum size in bytes per slice.



``V4L2_CID_MPEG_VIDEO_MULTI_SLICE_MAX_MB (integer)``
    The maximum number of macroblocks in a slice. Used when
    ``V4L2_CID_MPEG_VIDEO_MULTI_SLICE_MODE`` is set to
    ``V4L2_MPEG_VIDEO_MULTI_SLICE_MODE_MAX_MB``. Applicable to the
    encoder.

``V4L2_CID_MPEG_VIDEO_MULTI_SLICE_MAX_BYTES (integer)``
    The maximum size of a slice in bytes. Used when
    ``V4L2_CID_MPEG_VIDEO_MULTI_SLICE_MODE`` is set to
    ``V4L2_MPEG_VIDEO_MULTI_SLICE_MODE_MAX_BYTES``. Applicable to the
    encoder.

.. _v4l2-mpeg-video-h264-loop-filter-mode:

``V4L2_CID_MPEG_VIDEO_H264_LOOP_FILTER_MODE``
    (enum)

enum v4l2_mpeg_video_h264_loop_filter_mode -
    Loop filter mode for H264 encoder. Possible values are:



.. tabularcolumns:: |p{14.0cm}|p{3.5cm}|

.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_MPEG_VIDEO_H264_LOOP_FILTER_MODE_ENABLED``
      - Loop filter is enabled.
    * - ``V4L2_MPEG_VIDEO_H264_LOOP_FILTER_MODE_DISABLED``
      - Loop filter is disabled.
    * - ``V4L2_MPEG_VIDEO_H264_LOOP_FILTER_MODE_DISABLED_AT_SLICE_BOUNDARY``
      - Loop filter is disabled at the slice boundary.



``V4L2_CID_MPEG_VIDEO_H264_LOOP_FILTER_ALPHA (integer)``
    Loop filter alpha coefficient, defined in the H264 standard.
    Applicable to the H264 encoder.

``V4L2_CID_MPEG_VIDEO_H264_LOOP_FILTER_BETA (integer)``
    Loop filter beta coefficient, defined in the H264 standard.
    Applicable to the H264 encoder.

.. _v4l2-mpeg-video-h264-entropy-mode:

``V4L2_CID_MPEG_VIDEO_H264_ENTROPY_MODE``
    (enum)

enum v4l2_mpeg_video_h264_entropy_mode -
    Entropy coding mode for H264 - CABAC/CAVALC. Applicable to the H264
    encoder. Possible values are:



.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_MPEG_VIDEO_H264_ENTROPY_MODE_CAVLC``
      - Use CAVLC entropy coding.
    * - ``V4L2_MPEG_VIDEO_H264_ENTROPY_MODE_CABAC``
      - Use CABAC entropy coding.



``V4L2_CID_MPEG_VIDEO_H264_8X8_TRANSFORM (boolean)``
    Enable 8X8 transform for H264. Applicable to the H264 encoder.

``V4L2_CID_MPEG_VIDEO_CYCLIC_INTRA_REFRESH_MB (integer)``
    Cyclic intra macroblock refresh. This is the number of continuous
    macroblocks refreshed every frame. Each frame a successive set of
    macroblocks is refreshed until the cycle completes and starts from
    the top of the frame. Applicable to H264, H263 and MPEG4 encoder.

``V4L2_CID_MPEG_VIDEO_FRAME_RC_ENABLE (boolean)``
    Frame level rate control enable. If this control is disabled then
    the quantization parameter for each frame type is constant and set
    with appropriate controls (e.g.
    ``V4L2_CID_MPEG_VIDEO_H263_I_FRAME_QP``). If frame rate control is
    enabled then quantization parameter is adjusted to meet the chosen
    bitrate. Minimum and maximum value for the quantization parameter
    can be set with appropriate controls (e.g.
    ``V4L2_CID_MPEG_VIDEO_H263_MIN_QP``). Applicable to encoders.

``V4L2_CID_MPEG_VIDEO_MB_RC_ENABLE (boolean)``
    Macroblock level rate control enable. Applicable to the MPEG4 and
    H264 encoders.

``V4L2_CID_MPEG_VIDEO_MPEG4_QPEL (boolean)``
    Quarter pixel motion estimation for MPEG4. Applicable to the MPEG4
    encoder.

``V4L2_CID_MPEG_VIDEO_H263_I_FRAME_QP (integer)``
    Quantization parameter for an I frame for H263. Valid range: from 1
    to 31.

``V4L2_CID_MPEG_VIDEO_H263_MIN_QP (integer)``
    Minimum quantization parameter for H263. Valid range: from 1 to 31.

``V4L2_CID_MPEG_VIDEO_H263_MAX_QP (integer)``
    Maximum quantization parameter for H263. Valid range: from 1 to 31.

``V4L2_CID_MPEG_VIDEO_H263_P_FRAME_QP (integer)``
    Quantization parameter for an P frame for H263. Valid range: from 1
    to 31.

``V4L2_CID_MPEG_VIDEO_H263_B_FRAME_QP (integer)``
    Quantization parameter for an B frame for H263. Valid range: from 1
    to 31.

``V4L2_CID_MPEG_VIDEO_H264_I_FRAME_QP (integer)``
    Quantization parameter for an I frame for H264. Valid range: from 0
    to 51.

``V4L2_CID_MPEG_VIDEO_H264_MIN_QP (integer)``
    Minimum quantization parameter for H264. Valid range: from 0 to 51.

``V4L2_CID_MPEG_VIDEO_H264_MAX_QP (integer)``
    Maximum quantization parameter for H264. Valid range: from 0 to 51.

``V4L2_CID_MPEG_VIDEO_H264_P_FRAME_QP (integer)``
    Quantization parameter for an P frame for H264. Valid range: from 0
    to 51.

``V4L2_CID_MPEG_VIDEO_H264_B_FRAME_QP (integer)``
    Quantization parameter for an B frame for H264. Valid range: from 0
    to 51.

``V4L2_CID_MPEG_VIDEO_MPEG4_I_FRAME_QP (integer)``
    Quantization parameter for an I frame for MPEG4. Valid range: from 1
    to 31.

``V4L2_CID_MPEG_VIDEO_MPEG4_MIN_QP (integer)``
    Minimum quantization parameter for MPEG4. Valid range: from 1 to 31.

``V4L2_CID_MPEG_VIDEO_MPEG4_MAX_QP (integer)``
    Maximum quantization parameter for MPEG4. Valid range: from 1 to 31.

``V4L2_CID_MPEG_VIDEO_MPEG4_P_FRAME_QP (integer)``
    Quantization parameter for an P frame for MPEG4. Valid range: from 1
    to 31.

``V4L2_CID_MPEG_VIDEO_MPEG4_B_FRAME_QP (integer)``
    Quantization parameter for an B frame for MPEG4. Valid range: from 1
    to 31.

``V4L2_CID_MPEG_VIDEO_VBV_SIZE (integer)``
    The Video Buffer Verifier size in kilobytes, it is used as a
    limitation of frame skip. The VBV is defined in the standard as a
    mean to verify that the produced stream will be successfully
    decoded. The standard describes it as "Part of a hypothetical
    decoder that is conceptually connected to the output of the encoder.
    Its purpose is to provide a constraint on the variability of the
    data rate that an encoder or editing process may produce.".
    Applicable to the MPEG1, MPEG2, MPEG4 encoders.

.. _v4l2-mpeg-video-vbv-delay:

``V4L2_CID_MPEG_VIDEO_VBV_DELAY (integer)``
    Sets the initial delay in milliseconds for VBV buffer control.

.. _v4l2-mpeg-video-hor-search-range:

``V4L2_CID_MPEG_VIDEO_MV_H_SEARCH_RANGE (integer)``
    Horizontal search range defines maximum horizontal search area in
    pixels to search and match for the present Macroblock (MB) in the
    reference picture. This V4L2 control macro is used to set horizontal
    search range for motion estimation module in video encoder.

.. _v4l2-mpeg-video-vert-search-range:

``V4L2_CID_MPEG_VIDEO_MV_V_SEARCH_RANGE (integer)``
    Vertical search range defines maximum vertical search area in pixels
    to search and match for the present Macroblock (MB) in the reference
    picture. This V4L2 control macro is used to set vertical search
    range for motion estimation module in video encoder.

.. _v4l2-mpeg-video-force-key-frame:

``V4L2_CID_MPEG_VIDEO_FORCE_KEY_FRAME (button)``
    Force a key frame for the next queued buffer. Applicable to
    encoders. This is a general, codec-agnostic keyframe control.

``V4L2_CID_MPEG_VIDEO_H264_CPB_SIZE (integer)``
    The Coded Picture Buffer size in kilobytes, it is used as a
    limitation of frame skip. The CPB is defined in the H264 standard as
    a mean to verify that the produced stream will be successfully
    decoded. Applicable to the H264 encoder.

``V4L2_CID_MPEG_VIDEO_H264_I_PERIOD (integer)``
    Period between I-frames in the open GOP for H264. In case of an open
    GOP this is the period between two I-frames. The period between IDR
    (Instantaneous Decoding Refresh) frames is taken from the GOP_SIZE
    control. An IDR frame, which stands for Instantaneous Decoding
    Refresh is an I-frame after which no prior frames are referenced.
    This means that a stream can be restarted from an IDR frame without
    the need to store or decode any previous frames. Applicable to the
    H264 encoder.

.. _v4l2-mpeg-video-header-mode:

``V4L2_CID_MPEG_VIDEO_HEADER_MODE``
    (enum)

enum v4l2_mpeg_video_header_mode -
    Determines whether the header is returned as the first buffer or is
    it returned together with the first frame. Applicable to encoders.
    Possible values are:



.. tabularcolumns:: |p{10.3cm}|p{7.2cm}|

.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_MPEG_VIDEO_HEADER_MODE_SEPARATE``
      - The stream header is returned separately in the first buffer.
    * - ``V4L2_MPEG_VIDEO_HEADER_MODE_JOINED_WITH_1ST_FRAME``
      - The stream header is returned together with the first encoded
	frame.



``V4L2_CID_MPEG_VIDEO_REPEAT_SEQ_HEADER (boolean)``
    Repeat the video sequence headers. Repeating these headers makes
    random access to the video stream easier. Applicable to the MPEG1, 2
    and 4 encoder.

``V4L2_CID_MPEG_VIDEO_DECODER_MPEG4_DEBLOCK_FILTER (boolean)``
    Enabled the deblocking post processing filter for MPEG4 decoder.
    Applicable to the MPEG4 decoder.

``V4L2_CID_MPEG_VIDEO_MPEG4_VOP_TIME_RES (integer)``
    vop_time_increment_resolution value for MPEG4. Applicable to the
    MPEG4 encoder.

``V4L2_CID_MPEG_VIDEO_MPEG4_VOP_TIME_INC (integer)``
    vop_time_increment value for MPEG4. Applicable to the MPEG4
    encoder.

``V4L2_CID_MPEG_VIDEO_H264_SEI_FRAME_PACKING (boolean)``
    Enable generation of frame packing supplemental enhancement
    information in the encoded bitstream. The frame packing SEI message
    contains the arrangement of L and R planes for 3D viewing.
    Applicable to the H264 encoder.

``V4L2_CID_MPEG_VIDEO_H264_SEI_FP_CURRENT_FRAME_0 (boolean)``
    Sets current frame as frame0 in frame packing SEI. Applicable to the
    H264 encoder.

.. _v4l2-mpeg-video-h264-sei-fp-arrangement-type:

``V4L2_CID_MPEG_VIDEO_H264_SEI_FP_ARRANGEMENT_TYPE``
    (enum)

enum v4l2_mpeg_video_h264_sei_fp_arrangement_type -
    Frame packing arrangement type for H264 SEI. Applicable to the H264
    encoder. Possible values are:

.. tabularcolumns:: |p{12cm}|p{5.5cm}|

.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_MPEG_VIDEO_H264_SEI_FP_ARRANGEMENT_TYPE_CHEKERBOARD``
      - Pixels are alternatively from L and R.
    * - ``V4L2_MPEG_VIDEO_H264_SEI_FP_ARRANGEMENT_TYPE_COLUMN``
      - L and R are interlaced by column.
    * - ``V4L2_MPEG_VIDEO_H264_SEI_FP_ARRANGEMENT_TYPE_ROW``
      - L and R are interlaced by row.
    * - ``V4L2_MPEG_VIDEO_H264_SEI_FP_ARRANGEMENT_TYPE_SIDE_BY_SIDE``
      - L is on the left, R on the right.
    * - ``V4L2_MPEG_VIDEO_H264_SEI_FP_ARRANGEMENT_TYPE_TOP_BOTTOM``
      - L is on top, R on bottom.
    * - ``V4L2_MPEG_VIDEO_H264_SEI_FP_ARRANGEMENT_TYPE_TEMPORAL``
      - One view per frame.



``V4L2_CID_MPEG_VIDEO_H264_FMO (boolean)``
    Enables flexible macroblock ordering in the encoded bitstream. It is
    a technique used for restructuring the ordering of macroblocks in
    pictures. Applicable to the H264 encoder.

.. _v4l2-mpeg-video-h264-fmo-map-type:

``V4L2_CID_MPEG_VIDEO_H264_FMO_MAP_TYPE``
   (enum)

enum v4l2_mpeg_video_h264_fmo_map_type -
    When using FMO, the map type divides the image in different scan
    patterns of macroblocks. Applicable to the H264 encoder. Possible
    values are:

.. tabularcolumns:: |p{12.5cm}|p{5.0cm}|

.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_MPEG_VIDEO_H264_FMO_MAP_TYPE_INTERLEAVED_SLICES``
      - Slices are interleaved one after other with macroblocks in run
	length order.
    * - ``V4L2_MPEG_VIDEO_H264_FMO_MAP_TYPE_SCATTERED_SLICES``
      - Scatters the macroblocks based on a mathematical function known to
	both encoder and decoder.
    * - ``V4L2_MPEG_VIDEO_H264_FMO_MAP_TYPE_FOREGROUND_WITH_LEFT_OVER``
      - Macroblocks arranged in rectangular areas or regions of interest.
    * - ``V4L2_MPEG_VIDEO_H264_FMO_MAP_TYPE_BOX_OUT``
      - Slice groups grow in a cyclic way from centre to outwards.
    * - ``V4L2_MPEG_VIDEO_H264_FMO_MAP_TYPE_RASTER_SCAN``
      - Slice groups grow in raster scan pattern from left to right.
    * - ``V4L2_MPEG_VIDEO_H264_FMO_MAP_TYPE_WIPE_SCAN``
      - Slice groups grow in wipe scan pattern from top to bottom.
    * - ``V4L2_MPEG_VIDEO_H264_FMO_MAP_TYPE_EXPLICIT``
      - User defined map type.



``V4L2_CID_MPEG_VIDEO_H264_FMO_SLICE_GROUP (integer)``
    Number of slice groups in FMO. Applicable to the H264 encoder.

.. _v4l2-mpeg-video-h264-fmo-change-direction:

``V4L2_CID_MPEG_VIDEO_H264_FMO_CHANGE_DIRECTION``
    (enum)

enum v4l2_mpeg_video_h264_fmo_change_dir -
    Specifies a direction of the slice group change for raster and wipe
    maps. Applicable to the H264 encoder. Possible values are:



.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_MPEG_VIDEO_H264_FMO_CHANGE_DIR_RIGHT``
      - Raster scan or wipe right.
    * - ``V4L2_MPEG_VIDEO_H264_FMO_CHANGE_DIR_LEFT``
      - Reverse raster scan or wipe left.



``V4L2_CID_MPEG_VIDEO_H264_FMO_CHANGE_RATE (integer)``
    Specifies the size of the first slice group for raster and wipe map.
    Applicable to the H264 encoder.

``V4L2_CID_MPEG_VIDEO_H264_FMO_RUN_LENGTH (integer)``
    Specifies the number of consecutive macroblocks for the interleaved
    map. Applicable to the H264 encoder.

``V4L2_CID_MPEG_VIDEO_H264_ASO (boolean)``
    Enables arbitrary slice ordering in encoded bitstream. Applicable to
    the H264 encoder.

``V4L2_CID_MPEG_VIDEO_H264_ASO_SLICE_ORDER (integer)``
    Specifies the slice order in ASO. Applicable to the H264 encoder.
    The supplied 32-bit integer is interpreted as follows (bit 0 = least
    significant bit):



.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - Bit 0:15
      - Slice ID
    * - Bit 16:32
      - Slice position or order



``V4L2_CID_MPEG_VIDEO_H264_HIERARCHICAL_CODING (boolean)``
    Enables H264 hierarchical coding. Applicable to the H264 encoder.

.. _v4l2-mpeg-video-h264-hierarchical-coding-type:

``V4L2_CID_MPEG_VIDEO_H264_HIERARCHICAL_CODING_TYPE``
    (enum)

enum v4l2_mpeg_video_h264_hierarchical_coding_type -
    Specifies the hierarchical coding type. Applicable to the H264
    encoder. Possible values are:



.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_MPEG_VIDEO_H264_HIERARCHICAL_CODING_B``
      - Hierarchical B coding.
    * - ``V4L2_MPEG_VIDEO_H264_HIERARCHICAL_CODING_P``
      - Hierarchical P coding.



``V4L2_CID_MPEG_VIDEO_H264_HIERARCHICAL_CODING_LAYER (integer)``
    Specifies the number of hierarchical coding layers. Applicable to
    the H264 encoder.

``V4L2_CID_MPEG_VIDEO_H264_HIERARCHICAL_CODING_LAYER_QP (integer)``
    Specifies a user defined QP for each layer. Applicable to the H264
    encoder. The supplied 32-bit integer is interpreted as follows (bit
    0 = least significant bit):



.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - Bit 0:15
      - QP value
    * - Bit 16:32
      - Layer number




MFC 5.1 MPEG Controls
---------------------

The following MPEG class controls deal with MPEG decoding and encoding
settings that are specific to the Multi Format Codec 5.1 device present
in the S5P family of SoCs by Samsung.


.. _mfc51-control-id:

MFC 5.1 Control IDs
^^^^^^^^^^^^^^^^^^^

``V4L2_CID_MPEG_MFC51_VIDEO_DECODER_H264_DISPLAY_DELAY_ENABLE (boolean)``
    If the display delay is enabled then the decoder is forced to return
    a CAPTURE buffer (decoded frame) after processing a certain number
    of OUTPUT buffers. The delay can be set through
    ``V4L2_CID_MPEG_MFC51_VIDEO_DECODER_H264_DISPLAY_DELAY``. This
    feature can be used for example for generating thumbnails of videos.
    Applicable to the H264 decoder.

``V4L2_CID_MPEG_MFC51_VIDEO_DECODER_H264_DISPLAY_DELAY (integer)``
    Display delay value for H264 decoder. The decoder is forced to
    return a decoded frame after the set 'display delay' number of
    frames. If this number is low it may result in frames returned out
    of dispaly order, in addition the hardware may still be using the
    returned buffer as a reference picture for subsequent frames.

``V4L2_CID_MPEG_MFC51_VIDEO_H264_NUM_REF_PIC_FOR_P (integer)``
    The number of reference pictures used for encoding a P picture.
    Applicable to the H264 encoder.

``V4L2_CID_MPEG_MFC51_VIDEO_PADDING (boolean)``
    Padding enable in the encoder - use a color instead of repeating
    border pixels. Applicable to encoders.

``V4L2_CID_MPEG_MFC51_VIDEO_PADDING_YUV (integer)``
    Padding color in the encoder. Applicable to encoders. The supplied
    32-bit integer is interpreted as follows (bit 0 = least significant
    bit):



.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - Bit 0:7
      - V chrominance information
    * - Bit 8:15
      - U chrominance information
    * - Bit 16:23
      - Y luminance information
    * - Bit 24:31
      - Must be zero.



``V4L2_CID_MPEG_MFC51_VIDEO_RC_REACTION_COEFF (integer)``
    Reaction coefficient for MFC rate control. Applicable to encoders.

    .. note::

       #. Valid only when the frame level RC is enabled.

       #. For tight CBR, this field must be small (ex. 2 ~ 10). For
	  VBR, this field must be large (ex. 100 ~ 1000).

       #. It is not recommended to use the greater number than
	  FRAME_RATE * (10^9 / BIT_RATE).

``V4L2_CID_MPEG_MFC51_VIDEO_H264_ADAPTIVE_RC_DARK (boolean)``
    Adaptive rate control for dark region. Valid only when H.264 and
    macroblock level RC is enabled
    (``V4L2_CID_MPEG_VIDEO_MB_RC_ENABLE``). Applicable to the H264
    encoder.

``V4L2_CID_MPEG_MFC51_VIDEO_H264_ADAPTIVE_RC_SMOOTH (boolean)``
    Adaptive rate control for smooth region. Valid only when H.264 and
    macroblock level RC is enabled
    (``V4L2_CID_MPEG_VIDEO_MB_RC_ENABLE``). Applicable to the H264
    encoder.

``V4L2_CID_MPEG_MFC51_VIDEO_H264_ADAPTIVE_RC_STATIC (boolean)``
    Adaptive rate control for static region. Valid only when H.264 and
    macroblock level RC is enabled
    (``V4L2_CID_MPEG_VIDEO_MB_RC_ENABLE``). Applicable to the H264
    encoder.

``V4L2_CID_MPEG_MFC51_VIDEO_H264_ADAPTIVE_RC_ACTIVITY (boolean)``
    Adaptive rate control for activity region. Valid only when H.264 and
    macroblock level RC is enabled
    (``V4L2_CID_MPEG_VIDEO_MB_RC_ENABLE``). Applicable to the H264
    encoder.

.. _v4l2-mpeg-mfc51-video-frame-skip-mode:

``V4L2_CID_MPEG_MFC51_VIDEO_FRAME_SKIP_MODE``
    (enum)

enum v4l2_mpeg_mfc51_video_frame_skip_mode -
    Indicates in what conditions the encoder should skip frames. If
    encoding a frame would cause the encoded stream to be larger then a
    chosen data limit then the frame will be skipped. Possible values
    are:


.. tabularcolumns:: |p{9.0cm}|p{8.5cm}|

.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_MPEG_MFC51_FRAME_SKIP_MODE_DISABLED``
      - Frame skip mode is disabled.
    * - ``V4L2_MPEG_MFC51_FRAME_SKIP_MODE_LEVEL_LIMIT``
      - Frame skip mode enabled and buffer limit is set by the chosen
	level and is defined by the standard.
    * - ``V4L2_MPEG_MFC51_FRAME_SKIP_MODE_BUF_LIMIT``
      - Frame skip mode enabled and buffer limit is set by the VBV
	(MPEG1/2/4) or CPB (H264) buffer size control.



``V4L2_CID_MPEG_MFC51_VIDEO_RC_FIXED_TARGET_BIT (integer)``
    Enable rate-control with fixed target bit. If this setting is
    enabled, then the rate control logic of the encoder will calculate
    the average bitrate for a GOP and keep it below or equal the set
    bitrate target. Otherwise the rate control logic calculates the
    overall average bitrate for the stream and keeps it below or equal
    to the set bitrate. In the first case the average bitrate for the
    whole stream will be smaller then the set bitrate. This is caused
    because the average is calculated for smaller number of frames, on
    the other hand enabling this setting will ensure that the stream
    will meet tight bandwidth constraints. Applicable to encoders.

.. _v4l2-mpeg-mfc51-video-force-frame-type:

``V4L2_CID_MPEG_MFC51_VIDEO_FORCE_FRAME_TYPE``
    (enum)

enum v4l2_mpeg_mfc51_video_force_frame_type -
    Force a frame type for the next queued buffer. Applicable to
    encoders. Possible values are:



.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_MPEG_MFC51_FORCE_FRAME_TYPE_DISABLED``
      - Forcing a specific frame type disabled.
    * - ``V4L2_MPEG_MFC51_FORCE_FRAME_TYPE_I_FRAME``
      - Force an I-frame.
    * - ``V4L2_MPEG_MFC51_FORCE_FRAME_TYPE_NOT_CODED``
      - Force a non-coded frame.




CX2341x MPEG Controls
---------------------

The following MPEG class controls deal with MPEG encoding settings that
are specific to the Conexant CX23415 and CX23416 MPEG encoding chips.


.. _cx2341x-control-id:

CX2341x Control IDs
^^^^^^^^^^^^^^^^^^^

.. _v4l2-mpeg-cx2341x-video-spatial-filter-mode:

``V4L2_CID_MPEG_CX2341X_VIDEO_SPATIAL_FILTER_MODE``
    (enum)

enum v4l2_mpeg_cx2341x_video_spatial_filter_mode -
    Sets the Spatial Filter mode (default ``MANUAL``). Possible values
    are:



.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_MPEG_CX2341X_VIDEO_SPATIAL_FILTER_MODE_MANUAL``
      - Choose the filter manually
    * - ``V4L2_MPEG_CX2341X_VIDEO_SPATIAL_FILTER_MODE_AUTO``
      - Choose the filter automatically



``V4L2_CID_MPEG_CX2341X_VIDEO_SPATIAL_FILTER (integer (0-15))``
    The setting for the Spatial Filter. 0 = off, 15 = maximum. (Default
    is 0.)

.. _luma-spatial-filter-type:

``V4L2_CID_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE``
    (enum)

enum v4l2_mpeg_cx2341x_video_luma_spatial_filter_type -
    Select the algorithm to use for the Luma Spatial Filter (default
    ``1D_HOR``). Possible values:



.. tabularcolumns:: |p{14.5cm}|p{3.0cm}|

.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_OFF``
      - No filter
    * - ``V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_1D_HOR``
      - One-dimensional horizontal
    * - ``V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_1D_VERT``
      - One-dimensional vertical
    * - ``V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_2D_HV_SEPARABLE``
      - Two-dimensional separable
    * - ``V4L2_MPEG_CX2341X_VIDEO_LUMA_SPATIAL_FILTER_TYPE_2D_SYM_NON_SEPARABLE``
      - Two-dimensional symmetrical non-separable



.. _chroma-spatial-filter-type:

``V4L2_CID_MPEG_CX2341X_VIDEO_CHROMA_SPATIAL_FILTER_TYPE``
    (enum)

enum v4l2_mpeg_cx2341x_video_chroma_spatial_filter_type -
    Select the algorithm for the Chroma Spatial Filter (default
    ``1D_HOR``). Possible values are:



.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_MPEG_CX2341X_VIDEO_CHROMA_SPATIAL_FILTER_TYPE_OFF``
      - No filter
    * - ``V4L2_MPEG_CX2341X_VIDEO_CHROMA_SPATIAL_FILTER_TYPE_1D_HOR``
      - One-dimensional horizontal



.. _v4l2-mpeg-cx2341x-video-temporal-filter-mode:

``V4L2_CID_MPEG_CX2341X_VIDEO_TEMPORAL_FILTER_MODE``
    (enum)

enum v4l2_mpeg_cx2341x_video_temporal_filter_mode -
    Sets the Temporal Filter mode (default ``MANUAL``). Possible values
    are:



.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_MPEG_CX2341X_VIDEO_TEMPORAL_FILTER_MODE_MANUAL``
      - Choose the filter manually
    * - ``V4L2_MPEG_CX2341X_VIDEO_TEMPORAL_FILTER_MODE_AUTO``
      - Choose the filter automatically



``V4L2_CID_MPEG_CX2341X_VIDEO_TEMPORAL_FILTER (integer (0-31))``
    The setting for the Temporal Filter. 0 = off, 31 = maximum. (Default
    is 8 for full-scale capturing and 0 for scaled capturing.)

.. _v4l2-mpeg-cx2341x-video-median-filter-type:

``V4L2_CID_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE``
    (enum)

enum v4l2_mpeg_cx2341x_video_median_filter_type -
    Median Filter Type (default ``OFF``). Possible values are:



.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_OFF``
      - No filter
    * - ``V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_HOR``
      - Horizontal filter
    * - ``V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_VERT``
      - Vertical filter
    * - ``V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_HOR_VERT``
      - Horizontal and vertical filter
    * - ``V4L2_MPEG_CX2341X_VIDEO_MEDIAN_FILTER_TYPE_DIAG``
      - Diagonal filter



``V4L2_CID_MPEG_CX2341X_VIDEO_LUMA_MEDIAN_FILTER_BOTTOM (integer (0-255))``
    Threshold above which the luminance median filter is enabled
    (default 0)

``V4L2_CID_MPEG_CX2341X_VIDEO_LUMA_MEDIAN_FILTER_TOP (integer (0-255))``
    Threshold below which the luminance median filter is enabled
    (default 255)

``V4L2_CID_MPEG_CX2341X_VIDEO_CHROMA_MEDIAN_FILTER_BOTTOM (integer (0-255))``
    Threshold above which the chroma median filter is enabled (default
    0)

``V4L2_CID_MPEG_CX2341X_VIDEO_CHROMA_MEDIAN_FILTER_TOP (integer (0-255))``
    Threshold below which the chroma median filter is enabled (default
    255)

``V4L2_CID_MPEG_CX2341X_STREAM_INSERT_NAV_PACKETS (boolean)``
    The CX2341X MPEG encoder can insert one empty MPEG-2 PES packet into
    the stream between every four video frames. The packet size is 2048
    bytes, including the packet_start_code_prefix and stream_id
    fields. The stream_id is 0xBF (private stream 2). The payload
    consists of 0x00 bytes, to be filled in by the application. 0 = do
    not insert, 1 = insert packets.


VPX Control Reference
---------------------

The VPX controls include controls for encoding parameters of VPx video
codec.


.. _vpx-control-id:

VPX Control IDs
^^^^^^^^^^^^^^^

.. _v4l2-vpx-num-partitions:

``V4L2_CID_MPEG_VIDEO_VPX_NUM_PARTITIONS``
    (enum)

enum v4l2_vp8_num_partitions -
    The number of token partitions to use in VP8 encoder. Possible
    values are:



.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_CID_MPEG_VIDEO_VPX_1_PARTITION``
      - 1 coefficient partition
    * - ``V4L2_CID_MPEG_VIDEO_VPX_2_PARTITIONS``
      - 2 coefficient partitions
    * - ``V4L2_CID_MPEG_VIDEO_VPX_4_PARTITIONS``
      - 4 coefficient partitions
    * - ``V4L2_CID_MPEG_VIDEO_VPX_8_PARTITIONS``
      - 8 coefficient partitions



``V4L2_CID_MPEG_VIDEO_VPX_IMD_DISABLE_4X4 (boolean)``
    Setting this prevents intra 4x4 mode in the intra mode decision.

.. _v4l2-vpx-num-ref-frames:

``V4L2_CID_MPEG_VIDEO_VPX_NUM_REF_FRAMES``
    (enum)

enum v4l2_vp8_num_ref_frames -
    The number of reference pictures for encoding P frames. Possible
    values are:

.. tabularcolumns:: |p{7.9cm}|p{9.6cm}|

.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_CID_MPEG_VIDEO_VPX_1_REF_FRAME``
      - Last encoded frame will be searched
    * - ``V4L2_CID_MPEG_VIDEO_VPX_2_REF_FRAME``
      - Two frames will be searched among the last encoded frame, the
	golden frame and the alternate reference (altref) frame. The
	encoder implementation will decide which two are chosen.
    * - ``V4L2_CID_MPEG_VIDEO_VPX_3_REF_FRAME``
      - The last encoded frame, the golden frame and the altref frame will
	be searched.



``V4L2_CID_MPEG_VIDEO_VPX_FILTER_LEVEL (integer)``
    Indicates the loop filter level. The adjustment of the loop filter
    level is done via a delta value against a baseline loop filter
    value.

``V4L2_CID_MPEG_VIDEO_VPX_FILTER_SHARPNESS (integer)``
    This parameter affects the loop filter. Anything above zero weakens
    the deblocking effect on the loop filter.

``V4L2_CID_MPEG_VIDEO_VPX_GOLDEN_FRAME_REF_PERIOD (integer)``
    Sets the refresh period for the golden frame. The period is defined
    in number of frames. For a value of 'n', every nth frame starting
    from the first key frame will be taken as a golden frame. For eg.
    for encoding sequence of 0, 1, 2, 3, 4, 5, 6, 7 where the golden
    frame refresh period is set as 4, the frames 0, 4, 8 etc will be
    taken as the golden frames as frame 0 is always a key frame.

.. _v4l2-vpx-golden-frame-sel:

``V4L2_CID_MPEG_VIDEO_VPX_GOLDEN_FRAME_SEL``
    (enum)

enum v4l2_vp8_golden_frame_sel -
    Selects the golden frame for encoding. Possible values are:

.. raw:: latex

    \begin{adjustbox}{width=\columnwidth}

.. tabularcolumns:: |p{11.0cm}|p{10.0cm}|

.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_CID_MPEG_VIDEO_VPX_GOLDEN_FRAME_USE_PREV``
      - Use the (n-2)th frame as a golden frame, current frame index being
	'n'.
    * - ``V4L2_CID_MPEG_VIDEO_VPX_GOLDEN_FRAME_USE_REF_PERIOD``
      - Use the previous specific frame indicated by
	``V4L2_CID_MPEG_VIDEO_VPX_GOLDEN_FRAME_REF_PERIOD`` as a
	golden frame.

.. raw:: latex

    \end{adjustbox}


``V4L2_CID_MPEG_VIDEO_VPX_MIN_QP (integer)``
    Minimum quantization parameter for VP8.

``V4L2_CID_MPEG_VIDEO_VPX_MAX_QP (integer)``
    Maximum quantization parameter for VP8.

``V4L2_CID_MPEG_VIDEO_VPX_I_FRAME_QP (integer)``
    Quantization parameter for an I frame for VP8.

``V4L2_CID_MPEG_VIDEO_VPX_P_FRAME_QP (integer)``
    Quantization parameter for a P frame for VP8.

``V4L2_CID_MPEG_VIDEO_VPX_PROFILE (integer)``
    Select the desired profile for VPx encoder. Acceptable values are 0,
    1, 2 and 3 corresponding to encoder profiles 0, 1, 2 and 3.


.. _camera-controls:

Camera Control Reference
========================

The Camera class includes controls for mechanical (or equivalent
digital) features of a device such as controllable lenses or sensors.


.. _camera-control-id:

Camera Control IDs
------------------

``V4L2_CID_CAMERA_CLASS (class)``
    The Camera class descriptor. Calling
    :ref:`VIDIOC_QUERYCTRL` for this control will
    return a description of this control class.

.. _v4l2-exposure-auto-type:

``V4L2_CID_EXPOSURE_AUTO``
    (enum)

enum v4l2_exposure_auto_type -
    Enables automatic adjustments of the exposure time and/or iris
    aperture. The effect of manual changes of the exposure time or iris
    aperture while these features are enabled is undefined, drivers
    should ignore such requests. Possible values are:



.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_EXPOSURE_AUTO``
      - Automatic exposure time, automatic iris aperture.
    * - ``V4L2_EXPOSURE_MANUAL``
      - Manual exposure time, manual iris.
    * - ``V4L2_EXPOSURE_SHUTTER_PRIORITY``
      - Manual exposure time, auto iris.
    * - ``V4L2_EXPOSURE_APERTURE_PRIORITY``
      - Auto exposure time, manual iris.



``V4L2_CID_EXPOSURE_ABSOLUTE (integer)``
    Determines the exposure time of the camera sensor. The exposure time
    is limited by the frame interval. Drivers should interpret the
    values as 100 µs units, where the value 1 stands for 1/10000th of a
    second, 10000 for 1 second and 100000 for 10 seconds.

``V4L2_CID_EXPOSURE_AUTO_PRIORITY (boolean)``
    When ``V4L2_CID_EXPOSURE_AUTO`` is set to ``AUTO`` or
    ``APERTURE_PRIORITY``, this control determines if the device may
    dynamically vary the frame rate. By default this feature is disabled
    (0) and the frame rate must remain constant.

``V4L2_CID_EXPOSURE_BIAS (integer menu)``
    Determines the automatic exposure compensation, it is effective only
    when ``V4L2_CID_EXPOSURE_AUTO`` control is set to ``AUTO``,
    ``SHUTTER_PRIORITY`` or ``APERTURE_PRIORITY``. It is expressed in
    terms of EV, drivers should interpret the values as 0.001 EV units,
    where the value 1000 stands for +1 EV.

    Increasing the exposure compensation value is equivalent to
    decreasing the exposure value (EV) and will increase the amount of
    light at the image sensor. The camera performs the exposure
    compensation by adjusting absolute exposure time and/or aperture.

.. _v4l2-exposure-metering:

``V4L2_CID_EXPOSURE_METERING``
    (enum)

enum v4l2_exposure_metering -
    Determines how the camera measures the amount of light available for
    the frame exposure. Possible values are:

.. tabularcolumns:: |p{8.5cm}|p{9.0cm}|

.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_EXPOSURE_METERING_AVERAGE``
      - Use the light information coming from the entire frame and average
	giving no weighting to any particular portion of the metered area.
    * - ``V4L2_EXPOSURE_METERING_CENTER_WEIGHTED``
      - Average the light information coming from the entire frame giving
	priority to the center of the metered area.
    * - ``V4L2_EXPOSURE_METERING_SPOT``
      - Measure only very small area at the center of the frame.
    * - ``V4L2_EXPOSURE_METERING_MATRIX``
      - A multi-zone metering. The light intensity is measured in several
	points of the frame and the results are combined. The algorithm of
	the zones selection and their significance in calculating the
	final value is device dependent.



``V4L2_CID_PAN_RELATIVE (integer)``
    This control turns the camera horizontally by the specified amount.
    The unit is undefined. A positive value moves the camera to the
    right (clockwise when viewed from above), a negative value to the
    left. A value of zero does not cause motion. This is a write-only
    control.

``V4L2_CID_TILT_RELATIVE (integer)``
    This control turns the camera vertically by the specified amount.
    The unit is undefined. A positive value moves the camera up, a
    negative value down. A value of zero does not cause motion. This is
    a write-only control.

``V4L2_CID_PAN_RESET (button)``
    When this control is set, the camera moves horizontally to the
    default position.

``V4L2_CID_TILT_RESET (button)``
    When this control is set, the camera moves vertically to the default
    position.

``V4L2_CID_PAN_ABSOLUTE (integer)``
    This control turns the camera horizontally to the specified
    position. Positive values move the camera to the right (clockwise
    when viewed from above), negative values to the left. Drivers should
    interpret the values as arc seconds, with valid values between -180
    * 3600 and +180 * 3600 inclusive.

``V4L2_CID_TILT_ABSOLUTE (integer)``
    This control turns the camera vertically to the specified position.
    Positive values move the camera up, negative values down. Drivers
    should interpret the values as arc seconds, with valid values
    between -180 * 3600 and +180 * 3600 inclusive.

``V4L2_CID_FOCUS_ABSOLUTE (integer)``
    This control sets the focal point of the camera to the specified
    position. The unit is undefined. Positive values set the focus
    closer to the camera, negative values towards infinity.

``V4L2_CID_FOCUS_RELATIVE (integer)``
    This control moves the focal point of the camera by the specified
    amount. The unit is undefined. Positive values move the focus closer
    to the camera, negative values towards infinity. This is a
    write-only control.

``V4L2_CID_FOCUS_AUTO (boolean)``
    Enables continuous automatic focus adjustments. The effect of manual
    focus adjustments while this feature is enabled is undefined,
    drivers should ignore such requests.

``V4L2_CID_AUTO_FOCUS_START (button)``
    Starts single auto focus process. The effect of setting this control
    when ``V4L2_CID_FOCUS_AUTO`` is set to ``TRUE`` (1) is undefined,
    drivers should ignore such requests.

``V4L2_CID_AUTO_FOCUS_STOP (button)``
    Aborts automatic focusing started with ``V4L2_CID_AUTO_FOCUS_START``
    control. It is effective only when the continuous autofocus is
    disabled, that is when ``V4L2_CID_FOCUS_AUTO`` control is set to
    ``FALSE`` (0).

.. _v4l2-auto-focus-status:

``V4L2_CID_AUTO_FOCUS_STATUS (bitmask)``
    The automatic focus status. This is a read-only control.

    Setting ``V4L2_LOCK_FOCUS`` lock bit of the ``V4L2_CID_3A_LOCK``
    control may stop updates of the ``V4L2_CID_AUTO_FOCUS_STATUS``
    control value.

.. tabularcolumns:: |p{6.5cm}|p{11.0cm}|

.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_AUTO_FOCUS_STATUS_IDLE``
      - Automatic focus is not active.
    * - ``V4L2_AUTO_FOCUS_STATUS_BUSY``
      - Automatic focusing is in progress.
    * - ``V4L2_AUTO_FOCUS_STATUS_REACHED``
      - Focus has been reached.
    * - ``V4L2_AUTO_FOCUS_STATUS_FAILED``
      - Automatic focus has failed, the driver will not transition from
	this state until another action is performed by an application.



.. _v4l2-auto-focus-range:

``V4L2_CID_AUTO_FOCUS_RANGE``
    (enum)

enum v4l2_auto_focus_range -
    Determines auto focus distance range for which lens may be adjusted.

.. tabularcolumns:: |p{6.5cm}|p{11.0cm}|

.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_AUTO_FOCUS_RANGE_AUTO``
      - The camera automatically selects the focus range.
    * - ``V4L2_AUTO_FOCUS_RANGE_NORMAL``
      - Normal distance range, limited for best automatic focus
	performance.
    * - ``V4L2_AUTO_FOCUS_RANGE_MACRO``
      - Macro (close-up) auto focus. The camera will use its minimum
	possible distance for auto focus.
    * - ``V4L2_AUTO_FOCUS_RANGE_INFINITY``
      - The lens is set to focus on an object at infinite distance.



``V4L2_CID_ZOOM_ABSOLUTE (integer)``
    Specify the objective lens focal length as an absolute value. The
    zoom unit is driver-specific and its value should be a positive
    integer.

``V4L2_CID_ZOOM_RELATIVE (integer)``
    Specify the objective lens focal length relatively to the current
    value. Positive values move the zoom lens group towards the
    telephoto direction, negative values towards the wide-angle
    direction. The zoom unit is driver-specific. This is a write-only
    control.

``V4L2_CID_ZOOM_CONTINUOUS (integer)``
    Move the objective lens group at the specified speed until it
    reaches physical device limits or until an explicit request to stop
    the movement. A positive value moves the zoom lens group towards the
    telephoto direction. A value of zero stops the zoom lens group
    movement. A negative value moves the zoom lens group towards the
    wide-angle direction. The zoom speed unit is driver-specific.

``V4L2_CID_IRIS_ABSOLUTE (integer)``
    This control sets the camera's aperture to the specified value. The
    unit is undefined. Larger values open the iris wider, smaller values
    close it.

``V4L2_CID_IRIS_RELATIVE (integer)``
    This control modifies the camera's aperture by the specified amount.
    The unit is undefined. Positive values open the iris one step
    further, negative values close it one step further. This is a
    write-only control.

``V4L2_CID_PRIVACY (boolean)``
    Prevent video from being acquired by the camera. When this control
    is set to ``TRUE`` (1), no image can be captured by the camera.
    Common means to enforce privacy are mechanical obturation of the
    sensor and firmware image processing, but the device is not
    restricted to these methods. Devices that implement the privacy
    control must support read access and may support write access.

``V4L2_CID_BAND_STOP_FILTER (integer)``
    Switch the band-stop filter of a camera sensor on or off, or specify
    its strength. Such band-stop filters can be used, for example, to
    filter out the fluorescent light component.

.. _v4l2-auto-n-preset-white-balance:

``V4L2_CID_AUTO_N_PRESET_WHITE_BALANCE``
    (enum)

enum v4l2_auto_n_preset_white_balance -
    Sets white balance to automatic, manual or a preset. The presets
    determine color temperature of the light as a hint to the camera for
    white balance adjustments resulting in most accurate color
    representation. The following white balance presets are listed in
    order of increasing color temperature.

.. tabularcolumns:: |p{7.0 cm}|p{10.5cm}|

.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_WHITE_BALANCE_MANUAL``
      - Manual white balance.
    * - ``V4L2_WHITE_BALANCE_AUTO``
      - Automatic white balance adjustments.
    * - ``V4L2_WHITE_BALANCE_INCANDESCENT``
      - White balance setting for incandescent (tungsten) lighting. It
	generally cools down the colors and corresponds approximately to
	2500...3500 K color temperature range.
    * - ``V4L2_WHITE_BALANCE_FLUORESCENT``
      - White balance preset for fluorescent lighting. It corresponds
	approximately to 4000...5000 K color temperature.
    * - ``V4L2_WHITE_BALANCE_FLUORESCENT_H``
      - With this setting the camera will compensate for fluorescent H
	lighting.
    * - ``V4L2_WHITE_BALANCE_HORIZON``
      - White balance setting for horizon daylight. It corresponds
	approximately to 5000 K color temperature.
    * - ``V4L2_WHITE_BALANCE_DAYLIGHT``
      - White balance preset for daylight (with clear sky). It corresponds
	approximately to 5000...6500 K color temperature.
    * - ``V4L2_WHITE_BALANCE_FLASH``
      - With this setting the camera will compensate for the flash light.
	It slightly warms up the colors and corresponds roughly to
	5000...5500 K color temperature.
    * - ``V4L2_WHITE_BALANCE_CLOUDY``
      - White balance preset for moderately overcast sky. This option
	corresponds approximately to 6500...8000 K color temperature
	range.
    * - ``V4L2_WHITE_BALANCE_SHADE``
      - White balance preset for shade or heavily overcast sky. It
	corresponds approximately to 9000...10000 K color temperature.



.. _v4l2-wide-dynamic-range:

``V4L2_CID_WIDE_DYNAMIC_RANGE (boolean)``
    Enables or disables the camera's wide dynamic range feature. This
    feature allows to obtain clear images in situations where intensity
    of the illumination varies significantly throughout the scene, i.e.
    there are simultaneously very dark and very bright areas. It is most
    commonly realized in cameras by combining two subsequent frames with
    different exposure times.  [#f1]_

.. _v4l2-image-stabilization:

``V4L2_CID_IMAGE_STABILIZATION (boolean)``
    Enables or disables image stabilization.

``V4L2_CID_ISO_SENSITIVITY (integer menu)``
    Determines ISO equivalent of an image sensor indicating the sensor's
    sensitivity to light. The numbers are expressed in arithmetic scale,
    as per :ref:`iso12232` standard, where doubling the sensor
    sensitivity is represented by doubling the numerical ISO value.
    Applications should interpret the values as standard ISO values
    multiplied by 1000, e.g. control value 800 stands for ISO 0.8.
    Drivers will usually support only a subset of standard ISO values.
    The effect of setting this control while the
    ``V4L2_CID_ISO_SENSITIVITY_AUTO`` control is set to a value other
    than ``V4L2_CID_ISO_SENSITIVITY_MANUAL`` is undefined, drivers
    should ignore such requests.

.. _v4l2-iso-sensitivity-auto-type:

``V4L2_CID_ISO_SENSITIVITY_AUTO``
    (enum)

enum v4l2_iso_sensitivity_type -
    Enables or disables automatic ISO sensitivity adjustments.



.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_CID_ISO_SENSITIVITY_MANUAL``
      - Manual ISO sensitivity.
    * - ``V4L2_CID_ISO_SENSITIVITY_AUTO``
      - Automatic ISO sensitivity adjustments.



.. _v4l2-scene-mode:

``V4L2_CID_SCENE_MODE``
    (enum)

enum v4l2_scene_mode -
    This control allows to select scene programs as the camera automatic
    modes optimized for common shooting scenes. Within these modes the
    camera determines best exposure, aperture, focusing, light metering,
    white balance and equivalent sensitivity. The controls of those
    parameters are influenced by the scene mode control. An exact
    behavior in each mode is subject to the camera specification.

    When the scene mode feature is not used, this control should be set
    to ``V4L2_SCENE_MODE_NONE`` to make sure the other possibly related
    controls are accessible. The following scene programs are defined:

.. tabularcolumns:: |p{6.0cm}|p{11.5cm}|

.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_SCENE_MODE_NONE``
      - The scene mode feature is disabled.
    * - ``V4L2_SCENE_MODE_BACKLIGHT``
      - Backlight. Compensates for dark shadows when light is coming from
	behind a subject, also by automatically turning on the flash.
    * - ``V4L2_SCENE_MODE_BEACH_SNOW``
      - Beach and snow. This mode compensates for all-white or bright
	scenes, which tend to look gray and low contrast, when camera's
	automatic exposure is based on an average scene brightness. To
	compensate, this mode automatically slightly overexposes the
	frames. The white balance may also be adjusted to compensate for
	the fact that reflected snow looks bluish rather than white.
    * - ``V4L2_SCENE_MODE_CANDLELIGHT``
      - Candle light. The camera generally raises the ISO sensitivity and
	lowers the shutter speed. This mode compensates for relatively
	close subject in the scene. The flash is disabled in order to
	preserve the ambiance of the light.
    * - ``V4L2_SCENE_MODE_DAWN_DUSK``
      - Dawn and dusk. Preserves the colors seen in low natural light
	before dusk and after down. The camera may turn off the flash, and
	automatically focus at infinity. It will usually boost saturation
	and lower the shutter speed.
    * - ``V4L2_SCENE_MODE_FALL_COLORS``
      - Fall colors. Increases saturation and adjusts white balance for
	color enhancement. Pictures of autumn leaves get saturated reds
	and yellows.
    * - ``V4L2_SCENE_MODE_FIREWORKS``
      - Fireworks. Long exposure times are used to capture the expanding
	burst of light from a firework. The camera may invoke image
	stabilization.
    * - ``V4L2_SCENE_MODE_LANDSCAPE``
      - Landscape. The camera may choose a small aperture to provide deep
	depth of field and long exposure duration to help capture detail
	in dim light conditions. The focus is fixed at infinity. Suitable
	for distant and wide scenery.
    * - ``V4L2_SCENE_MODE_NIGHT``
      - Night, also known as Night Landscape. Designed for low light
	conditions, it preserves detail in the dark areas without blowing
	out bright objects. The camera generally sets itself to a
	medium-to-high ISO sensitivity, with a relatively long exposure
	time, and turns flash off. As such, there will be increased image
	noise and the possibility of blurred image.
    * - ``V4L2_SCENE_MODE_PARTY_INDOOR``
      - Party and indoor. Designed to capture indoor scenes that are lit
	by indoor background lighting as well as the flash. The camera
	usually increases ISO sensitivity, and adjusts exposure for the
	low light conditions.
    * - ``V4L2_SCENE_MODE_PORTRAIT``
      - Portrait. The camera adjusts the aperture so that the depth of
	field is reduced, which helps to isolate the subject against a
	smooth background. Most cameras recognize the presence of faces in
	the scene and focus on them. The color hue is adjusted to enhance
	skin tones. The intensity of the flash is often reduced.
    * - ``V4L2_SCENE_MODE_SPORTS``
      - Sports. Significantly increases ISO and uses a fast shutter speed
	to freeze motion of rapidly-moving subjects. Increased image noise
	may be seen in this mode.
    * - ``V4L2_SCENE_MODE_SUNSET``
      - Sunset. Preserves deep hues seen in sunsets and sunrises. It bumps
	up the saturation.
    * - ``V4L2_SCENE_MODE_TEXT``
      - Text. It applies extra contrast and sharpness, it is typically a
	black-and-white mode optimized for readability. Automatic focus
	may be switched to close-up mode and this setting may also involve
	some lens-distortion correction.



``V4L2_CID_3A_LOCK (bitmask)``
    This control locks or unlocks the automatic focus, exposure and
    white balance. The automatic adjustments can be paused independently
    by setting the corresponding lock bit to 1. The camera then retains
    the settings until the lock bit is cleared. The following lock bits
    are defined:

    When a given algorithm is not enabled, drivers should ignore
    requests to lock it and should return no error. An example might be
    an application setting bit ``V4L2_LOCK_WHITE_BALANCE`` when the
    ``V4L2_CID_AUTO_WHITE_BALANCE`` control is set to ``FALSE``. The
    value of this control may be changed by exposure, white balance or
    focus controls.



.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_LOCK_EXPOSURE``
      - Automatic exposure adjustments lock.
    * - ``V4L2_LOCK_WHITE_BALANCE``
      - Automatic white balance adjustments lock.
    * - ``V4L2_LOCK_FOCUS``
      - Automatic focus lock.



``V4L2_CID_PAN_SPEED (integer)``
    This control turns the camera horizontally at the specific speed.
    The unit is undefined. A positive value moves the camera to the
    right (clockwise when viewed from above), a negative value to the
    left. A value of zero stops the motion if one is in progress and has
    no effect otherwise.

``V4L2_CID_TILT_SPEED (integer)``
    This control turns the camera vertically at the specified speed. The
    unit is undefined. A positive value moves the camera up, a negative
    value down. A value of zero stops the motion if one is in progress
    and has no effect otherwise.


.. _fm-tx-controls:

FM Transmitter Control Reference
================================

The FM Transmitter (FM_TX) class includes controls for common features
of FM transmissions capable devices. Currently this class includes
parameters for audio compression, pilot tone generation, audio deviation
limiter, RDS transmission and tuning power features.


.. _fm-tx-control-id:

FM_TX Control IDs
-----------------

``V4L2_CID_FM_TX_CLASS (class)``
    The FM_TX class descriptor. Calling
    :ref:`VIDIOC_QUERYCTRL` for this control will
    return a description of this control class.

``V4L2_CID_RDS_TX_DEVIATION (integer)``
    Configures RDS signal frequency deviation level in Hz. The range and
    step are driver-specific.

``V4L2_CID_RDS_TX_PI (integer)``
    Sets the RDS Programme Identification field for transmission.

``V4L2_CID_RDS_TX_PTY (integer)``
    Sets the RDS Programme Type field for transmission. This encodes up
    to 31 pre-defined programme types.

``V4L2_CID_RDS_TX_PS_NAME (string)``
    Sets the Programme Service name (PS_NAME) for transmission. It is
    intended for static display on a receiver. It is the primary aid to
    listeners in programme service identification and selection. In
    Annex E of :ref:`iec62106`, the RDS specification, there is a full
    description of the correct character encoding for Programme Service
    name strings. Also from RDS specification, PS is usually a single
    eight character text. However, it is also possible to find receivers
    which can scroll strings sized as 8 x N characters. So, this control
    must be configured with steps of 8 characters. The result is it must
    always contain a string with size multiple of 8.

``V4L2_CID_RDS_TX_RADIO_TEXT (string)``
    Sets the Radio Text info for transmission. It is a textual
    description of what is being broadcasted. RDS Radio Text can be
    applied when broadcaster wishes to transmit longer PS names,
    programme-related information or any other text. In these cases,
    RadioText should be used in addition to ``V4L2_CID_RDS_TX_PS_NAME``.
    The encoding for Radio Text strings is also fully described in Annex
    E of :ref:`iec62106`. The length of Radio Text strings depends on
    which RDS Block is being used to transmit it, either 32 (2A block)
    or 64 (2B block). However, it is also possible to find receivers
    which can scroll strings sized as 32 x N or 64 x N characters. So,
    this control must be configured with steps of 32 or 64 characters.
    The result is it must always contain a string with size multiple of
    32 or 64.

``V4L2_CID_RDS_TX_MONO_STEREO (boolean)``
    Sets the Mono/Stereo bit of the Decoder Identification code. If set,
    then the audio was recorded as stereo.

``V4L2_CID_RDS_TX_ARTIFICIAL_HEAD (boolean)``
    Sets the
    `Artificial Head <http://en.wikipedia.org/wiki/Artificial_head>`__
    bit of the Decoder Identification code. If set, then the audio was
    recorded using an artificial head.

``V4L2_CID_RDS_TX_COMPRESSED (boolean)``
    Sets the Compressed bit of the Decoder Identification code. If set,
    then the audio is compressed.

``V4L2_CID_RDS_TX_DYNAMIC_PTY (boolean)``
    Sets the Dynamic PTY bit of the Decoder Identification code. If set,
    then the PTY code is dynamically switched.

``V4L2_CID_RDS_TX_TRAFFIC_ANNOUNCEMENT (boolean)``
    If set, then a traffic announcement is in progress.

``V4L2_CID_RDS_TX_TRAFFIC_PROGRAM (boolean)``
    If set, then the tuned programme carries traffic announcements.

``V4L2_CID_RDS_TX_MUSIC_SPEECH (boolean)``
    If set, then this channel broadcasts music. If cleared, then it
    broadcasts speech. If the transmitter doesn't make this distinction,
    then it should be set.

``V4L2_CID_RDS_TX_ALT_FREQS_ENABLE (boolean)``
    If set, then transmit alternate frequencies.

``V4L2_CID_RDS_TX_ALT_FREQS (__u32 array)``
    The alternate frequencies in kHz units. The RDS standard allows for
    up to 25 frequencies to be defined. Drivers may support fewer
    frequencies so check the array size.

``V4L2_CID_AUDIO_LIMITER_ENABLED (boolean)``
    Enables or disables the audio deviation limiter feature. The limiter
    is useful when trying to maximize the audio volume, minimize
    receiver-generated distortion and prevent overmodulation.

``V4L2_CID_AUDIO_LIMITER_RELEASE_TIME (integer)``
    Sets the audio deviation limiter feature release time. Unit is in
    useconds. Step and range are driver-specific.

``V4L2_CID_AUDIO_LIMITER_DEVIATION (integer)``
    Configures audio frequency deviation level in Hz. The range and step
    are driver-specific.

``V4L2_CID_AUDIO_COMPRESSION_ENABLED (boolean)``
    Enables or disables the audio compression feature. This feature
    amplifies signals below the threshold by a fixed gain and compresses
    audio signals above the threshold by the ratio of Threshold/(Gain +
    Threshold).

``V4L2_CID_AUDIO_COMPRESSION_GAIN (integer)``
    Sets the gain for audio compression feature. It is a dB value. The
    range and step are driver-specific.

``V4L2_CID_AUDIO_COMPRESSION_THRESHOLD (integer)``
    Sets the threshold level for audio compression freature. It is a dB
    value. The range and step are driver-specific.

``V4L2_CID_AUDIO_COMPRESSION_ATTACK_TIME (integer)``
    Sets the attack time for audio compression feature. It is a useconds
    value. The range and step are driver-specific.

``V4L2_CID_AUDIO_COMPRESSION_RELEASE_TIME (integer)``
    Sets the release time for audio compression feature. It is a
    useconds value. The range and step are driver-specific.

``V4L2_CID_PILOT_TONE_ENABLED (boolean)``
    Enables or disables the pilot tone generation feature.

``V4L2_CID_PILOT_TONE_DEVIATION (integer)``
    Configures pilot tone frequency deviation level. Unit is in Hz. The
    range and step are driver-specific.

``V4L2_CID_PILOT_TONE_FREQUENCY (integer)``
    Configures pilot tone frequency value. Unit is in Hz. The range and
    step are driver-specific.

``V4L2_CID_TUNE_PREEMPHASIS``
    (enum)

enum v4l2_preemphasis -
    Configures the pre-emphasis value for broadcasting. A pre-emphasis
    filter is applied to the broadcast to accentuate the high audio
    frequencies. Depending on the region, a time constant of either 50
    or 75 useconds is used. The enum v4l2_preemphasis defines possible
    values for pre-emphasis. Here they are:



.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_PREEMPHASIS_DISABLED``
      - No pre-emphasis is applied.
    * - ``V4L2_PREEMPHASIS_50_uS``
      - A pre-emphasis of 50 uS is used.
    * - ``V4L2_PREEMPHASIS_75_uS``
      - A pre-emphasis of 75 uS is used.



``V4L2_CID_TUNE_POWER_LEVEL (integer)``
    Sets the output power level for signal transmission. Unit is in
    dBuV. Range and step are driver-specific.

``V4L2_CID_TUNE_ANTENNA_CAPACITOR (integer)``
    This selects the value of antenna tuning capacitor manually or
    automatically if set to zero. Unit, range and step are
    driver-specific.

For more details about RDS specification, refer to :ref:`iec62106`
document, from CENELEC.


.. _flash-controls:

Flash Control Reference
=======================

The V4L2 flash controls are intended to provide generic access to flash
controller devices. Flash controller devices are typically used in
digital cameras.

The interface can support both LED and xenon flash devices. As of
writing this, there is no xenon flash driver using this interface.


.. _flash-controls-use-cases:

Supported use cases
-------------------


Unsynchronised LED flash (software strobe)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Unsynchronised LED flash is controlled directly by the host as the
sensor. The flash must be enabled by the host before the exposure of the
image starts and disabled once it ends. The host is fully responsible
for the timing of the flash.

Example of such device: Nokia N900.


Synchronised LED flash (hardware strobe)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

The synchronised LED flash is pre-programmed by the host (power and
timeout) but controlled by the sensor through a strobe signal from the
sensor to the flash.

The sensor controls the flash duration and timing. This information
typically must be made available to the sensor.


LED flash as torch
^^^^^^^^^^^^^^^^^^

LED flash may be used as torch in conjunction with another use case
involving camera or individually.


.. _flash-control-id:

Flash Control IDs
"""""""""""""""""

``V4L2_CID_FLASH_CLASS (class)``
    The FLASH class descriptor.

``V4L2_CID_FLASH_LED_MODE (menu)``
    Defines the mode of the flash LED, the high-power white LED attached
    to the flash controller. Setting this control may not be possible in
    presence of some faults. See V4L2_CID_FLASH_FAULT.



.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_FLASH_LED_MODE_NONE``
      - Off.
    * - ``V4L2_FLASH_LED_MODE_FLASH``
      - Flash mode.
    * - ``V4L2_FLASH_LED_MODE_TORCH``
      - Torch mode. See V4L2_CID_FLASH_TORCH_INTENSITY.



``V4L2_CID_FLASH_STROBE_SOURCE (menu)``
    Defines the source of the flash LED strobe.

.. tabularcolumns:: |p{7.0cm}|p{10.5cm}|

.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_FLASH_STROBE_SOURCE_SOFTWARE``
      - The flash strobe is triggered by using the
	V4L2_CID_FLASH_STROBE control.
    * - ``V4L2_FLASH_STROBE_SOURCE_EXTERNAL``
      - The flash strobe is triggered by an external source. Typically
	this is a sensor, which makes it possible to synchronises the
	flash strobe start to exposure start.



``V4L2_CID_FLASH_STROBE (button)``
    Strobe flash. Valid when V4L2_CID_FLASH_LED_MODE is set to
    V4L2_FLASH_LED_MODE_FLASH and V4L2_CID_FLASH_STROBE_SOURCE
    is set to V4L2_FLASH_STROBE_SOURCE_SOFTWARE. Setting this
    control may not be possible in presence of some faults. See
    V4L2_CID_FLASH_FAULT.

``V4L2_CID_FLASH_STROBE_STOP (button)``
    Stop flash strobe immediately.

``V4L2_CID_FLASH_STROBE_STATUS (boolean)``
    Strobe status: whether the flash is strobing at the moment or not.
    This is a read-only control.

``V4L2_CID_FLASH_TIMEOUT (integer)``
    Hardware timeout for flash. The flash strobe is stopped after this
    period of time has passed from the start of the strobe.

``V4L2_CID_FLASH_INTENSITY (integer)``
    Intensity of the flash strobe when the flash LED is in flash mode
    (V4L2_FLASH_LED_MODE_FLASH). The unit should be milliamps (mA)
    if possible.

``V4L2_CID_FLASH_TORCH_INTENSITY (integer)``
    Intensity of the flash LED in torch mode
    (V4L2_FLASH_LED_MODE_TORCH). The unit should be milliamps (mA)
    if possible. Setting this control may not be possible in presence of
    some faults. See V4L2_CID_FLASH_FAULT.

``V4L2_CID_FLASH_INDICATOR_INTENSITY (integer)``
    Intensity of the indicator LED. The indicator LED may be fully
    independent of the flash LED. The unit should be microamps (uA) if
    possible.

``V4L2_CID_FLASH_FAULT (bitmask)``
    Faults related to the flash. The faults tell about specific problems
    in the flash chip itself or the LEDs attached to it. Faults may
    prevent further use of some of the flash controls. In particular,
    V4L2_CID_FLASH_LED_MODE is set to V4L2_FLASH_LED_MODE_NONE
    if the fault affects the flash LED. Exactly which faults have such
    an effect is chip dependent. Reading the faults resets the control
    and returns the chip to a usable state if possible.

.. tabularcolumns:: |p{8.0cm}|p{9.5cm}|

.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_FLASH_FAULT_OVER_VOLTAGE``
      - Flash controller voltage to the flash LED has exceeded the limit
	specific to the flash controller.
    * - ``V4L2_FLASH_FAULT_TIMEOUT``
      - The flash strobe was still on when the timeout set by the user ---
	V4L2_CID_FLASH_TIMEOUT control --- has expired. Not all flash
	controllers may set this in all such conditions.
    * - ``V4L2_FLASH_FAULT_OVER_TEMPERATURE``
      - The flash controller has overheated.
    * - ``V4L2_FLASH_FAULT_SHORT_CIRCUIT``
      - The short circuit protection of the flash controller has been
	triggered.
    * - ``V4L2_FLASH_FAULT_OVER_CURRENT``
      - Current in the LED power supply has exceeded the limit specific to
	the flash controller.
    * - ``V4L2_FLASH_FAULT_INDICATOR``
      - The flash controller has detected a short or open circuit
	condition on the indicator LED.
    * - ``V4L2_FLASH_FAULT_UNDER_VOLTAGE``
      - Flash controller voltage to the flash LED has been below the
	minimum limit specific to the flash controller.
    * - ``V4L2_FLASH_FAULT_INPUT_VOLTAGE``
      - The input voltage of the flash controller is below the limit under
	which strobing the flash at full current will not be possible.The
	condition persists until this flag is no longer set.
    * - ``V4L2_FLASH_FAULT_LED_OVER_TEMPERATURE``
      - The temperature of the LED has exceeded its allowed upper limit.



``V4L2_CID_FLASH_CHARGE (boolean)``
    Enable or disable charging of the xenon flash capacitor.

``V4L2_CID_FLASH_READY (boolean)``
    Is the flash ready to strobe? Xenon flashes require their capacitors
    charged before strobing. LED flashes often require a cooldown period
    after strobe during which another strobe will not be possible. This
    is a read-only control.


.. _jpeg-controls:

JPEG Control Reference
======================

The JPEG class includes controls for common features of JPEG encoders
and decoders. Currently it includes features for codecs implementing
progressive baseline DCT compression process with Huffman entrophy
coding.


.. _jpeg-control-id:

JPEG Control IDs
----------------

``V4L2_CID_JPEG_CLASS (class)``
    The JPEG class descriptor. Calling
    :ref:`VIDIOC_QUERYCTRL` for this control will
    return a description of this control class.

``V4L2_CID_JPEG_CHROMA_SUBSAMPLING (menu)``
    The chroma subsampling factors describe how each component of an
    input image is sampled, in respect to maximum sample rate in each
    spatial dimension. See :ref:`itu-t81`, clause A.1.1. for more
    details. The ``V4L2_CID_JPEG_CHROMA_SUBSAMPLING`` control determines
    how Cb and Cr components are downsampled after coverting an input
    image from RGB to Y'CbCr color space.

.. tabularcolumns:: |p{7.0cm}|p{10.5cm}|

.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_JPEG_CHROMA_SUBSAMPLING_444``
      - No chroma subsampling, each pixel has Y, Cr and Cb values.
    * - ``V4L2_JPEG_CHROMA_SUBSAMPLING_422``
      - Horizontally subsample Cr, Cb components by a factor of 2.
    * - ``V4L2_JPEG_CHROMA_SUBSAMPLING_420``
      - Subsample Cr, Cb components horizontally and vertically by 2.
    * - ``V4L2_JPEG_CHROMA_SUBSAMPLING_411``
      - Horizontally subsample Cr, Cb components by a factor of 4.
    * - ``V4L2_JPEG_CHROMA_SUBSAMPLING_410``
      - Subsample Cr, Cb components horizontally by 4 and vertically by 2.
    * - ``V4L2_JPEG_CHROMA_SUBSAMPLING_GRAY``
      - Use only luminance component.



``V4L2_CID_JPEG_RESTART_INTERVAL (integer)``
    The restart interval determines an interval of inserting RSTm
    markers (m = 0..7). The purpose of these markers is to additionally
    reinitialize the encoder process, in order to process blocks of an
    image independently. For the lossy compression processes the restart
    interval unit is MCU (Minimum Coded Unit) and its value is contained
    in DRI (Define Restart Interval) marker. If
    ``V4L2_CID_JPEG_RESTART_INTERVAL`` control is set to 0, DRI and RSTm
    markers will not be inserted.

.. _jpeg-quality-control:

``V4L2_CID_JPEG_COMPRESSION_QUALITY (integer)``
    ``V4L2_CID_JPEG_COMPRESSION_QUALITY`` control determines trade-off
    between image quality and size. It provides simpler method for
    applications to control image quality, without a need for direct
    reconfiguration of luminance and chrominance quantization tables. In
    cases where a driver uses quantization tables configured directly by
    an application, using interfaces defined elsewhere,
    ``V4L2_CID_JPEG_COMPRESSION_QUALITY`` control should be set by
    driver to 0.

    The value range of this control is driver-specific. Only positive,
    non-zero values are meaningful. The recommended range is 1 - 100,
    where larger values correspond to better image quality.

.. _jpeg-active-marker-control:

``V4L2_CID_JPEG_ACTIVE_MARKER (bitmask)``
    Specify which JPEG markers are included in compressed stream. This
    control is valid only for encoders.



.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_JPEG_ACTIVE_MARKER_APP0``
      - Application data segment APP\ :sub:`0`.
    * - ``V4L2_JPEG_ACTIVE_MARKER_APP1``
      - Application data segment APP\ :sub:`1`.
    * - ``V4L2_JPEG_ACTIVE_MARKER_COM``
      - Comment segment.
    * - ``V4L2_JPEG_ACTIVE_MARKER_DQT``
      - Quantization tables segment.
    * - ``V4L2_JPEG_ACTIVE_MARKER_DHT``
      - Huffman tables segment.



For more details about JPEG specification, refer to :ref:`itu-t81`,
:ref:`jfif`, :ref:`w3c-jpeg-jfif`.


.. _image-source-controls:

Image Source Control Reference
==============================

The Image Source control class is intended for low-level control of
image source devices such as image sensors. The devices feature an
analogue to digital converter and a bus transmitter to transmit the
image data out of the device.


.. _image-source-control-id:

Image Source Control IDs
------------------------

``V4L2_CID_IMAGE_SOURCE_CLASS (class)``
    The IMAGE_SOURCE class descriptor.

``V4L2_CID_VBLANK (integer)``
    Vertical blanking. The idle period after every frame during which no
    image data is produced. The unit of vertical blanking is a line.
    Every line has length of the image width plus horizontal blanking at
    the pixel rate defined by ``V4L2_CID_PIXEL_RATE`` control in the
    same sub-device.

``V4L2_CID_HBLANK (integer)``
    Horizontal blanking. The idle period after every line of image data
    during which no image data is produced. The unit of horizontal
    blanking is pixels.

``V4L2_CID_ANALOGUE_GAIN (integer)``
    Analogue gain is gain affecting all colour components in the pixel
    matrix. The gain operation is performed in the analogue domain
    before A/D conversion.

``V4L2_CID_TEST_PATTERN_RED (integer)``
    Test pattern red colour component.

``V4L2_CID_TEST_PATTERN_GREENR (integer)``
    Test pattern green (next to red) colour component.

``V4L2_CID_TEST_PATTERN_BLUE (integer)``
    Test pattern blue colour component.

``V4L2_CID_TEST_PATTERN_GREENB (integer)``
    Test pattern green (next to blue) colour component.


.. _image-process-controls:

Image Process Control Reference
===============================

The Image Process control class is intended for low-level control of
image processing functions. Unlike ``V4L2_CID_IMAGE_SOURCE_CLASS``, the
controls in this class affect processing the image, and do not control
capturing of it.


.. _image-process-control-id:

Image Process Control IDs
-------------------------

``V4L2_CID_IMAGE_PROC_CLASS (class)``
    The IMAGE_PROC class descriptor.

``V4L2_CID_LINK_FREQ (integer menu)``
    Data bus frequency. Together with the media bus pixel code, bus type
    (clock cycles per sample), the data bus frequency defines the pixel
    rate (``V4L2_CID_PIXEL_RATE``) in the pixel array (or possibly
    elsewhere, if the device is not an image sensor). The frame rate can
    be calculated from the pixel clock, image width and height and
    horizontal and vertical blanking. While the pixel rate control may
    be defined elsewhere than in the subdev containing the pixel array,
    the frame rate cannot be obtained from that information. This is
    because only on the pixel array it can be assumed that the vertical
    and horizontal blanking information is exact: no other blanking is
    allowed in the pixel array. The selection of frame rate is performed
    by selecting the desired horizontal and vertical blanking. The unit
    of this control is Hz.

``V4L2_CID_PIXEL_RATE (64-bit integer)``
    Pixel rate in the source pads of the subdev. This control is
    read-only and its unit is pixels / second.

``V4L2_CID_TEST_PATTERN (menu)``
    Some capture/display/sensor devices have the capability to generate
    test pattern images. These hardware specific test patterns can be
    used to test if a device is working properly.


.. _dv-controls:

Digital Video Control Reference
===============================

The Digital Video control class is intended to control receivers and
transmitters for `VGA <http://en.wikipedia.org/wiki/Vga>`__,
`DVI <http://en.wikipedia.org/wiki/Digital_Visual_Interface>`__
(Digital Visual Interface), HDMI (:ref:`hdmi`) and DisplayPort
(:ref:`dp`). These controls are generally expected to be private to
the receiver or transmitter subdevice that implements them, so they are
only exposed on the ``/dev/v4l-subdev*`` device node.

.. note::

   Note that these devices can have multiple input or output pads which are
   hooked up to e.g. HDMI connectors. Even though the subdevice will
   receive or transmit video from/to only one of those pads, the other pads
   can still be active when it comes to EDID (Extended Display
   Identification Data, :ref:`vesaedid`) and HDCP (High-bandwidth Digital
   Content Protection System, :ref:`hdcp`) processing, allowing the
   device to do the fairly slow EDID/HDCP handling in advance. This allows
   for quick switching between connectors.

These pads appear in several of the controls in this section as
bitmasks, one bit for each pad. Bit 0 corresponds to pad 0, bit 1 to pad
1, etc. The maximum value of the control is the set of valid pads.


.. _dv-control-id:

Digital Video Control IDs
-------------------------

``V4L2_CID_DV_CLASS (class)``
    The Digital Video class descriptor.

``V4L2_CID_DV_TX_HOTPLUG (bitmask)``
    Many connectors have a hotplug pin which is high if EDID information
    is available from the source. This control shows the state of the
    hotplug pin as seen by the transmitter. Each bit corresponds to an
    output pad on the transmitter. If an output pad does not have an
    associated hotplug pin, then the bit for that pad will be 0. This
    read-only control is applicable to DVI-D, HDMI and DisplayPort
    connectors.

``V4L2_CID_DV_TX_RXSENSE (bitmask)``
    Rx Sense is the detection of pull-ups on the TMDS clock lines. This
    normally means that the sink has left/entered standby (i.e. the
    transmitter can sense that the receiver is ready to receive video).
    Each bit corresponds to an output pad on the transmitter. If an
    output pad does not have an associated Rx Sense, then the bit for
    that pad will be 0. This read-only control is applicable to DVI-D
    and HDMI devices.

``V4L2_CID_DV_TX_EDID_PRESENT (bitmask)``
    When the transmitter sees the hotplug signal from the receiver it
    will attempt to read the EDID. If set, then the transmitter has read
    at least the first block (= 128 bytes). Each bit corresponds to an
    output pad on the transmitter. If an output pad does not support
    EDIDs, then the bit for that pad will be 0. This read-only control
    is applicable to VGA, DVI-A/D, HDMI and DisplayPort connectors.

``V4L2_CID_DV_TX_MODE``
    (enum)

enum v4l2_dv_tx_mode -
    HDMI transmitters can transmit in DVI-D mode (just video) or in HDMI
    mode (video + audio + auxiliary data). This control selects which
    mode to use: V4L2_DV_TX_MODE_DVI_D or V4L2_DV_TX_MODE_HDMI.
    This control is applicable to HDMI connectors.

``V4L2_CID_DV_TX_RGB_RANGE``
    (enum)

enum v4l2_dv_rgb_range -
    Select the quantization range for RGB output. V4L2_DV_RANGE_AUTO
    follows the RGB quantization range specified in the standard for the
    video interface (ie. :ref:`cea861` for HDMI).
    V4L2_DV_RANGE_LIMITED and V4L2_DV_RANGE_FULL override the
    standard to be compatible with sinks that have not implemented the
    standard correctly (unfortunately quite common for HDMI and DVI-D).
    Full range allows all possible values to be used whereas limited
    range sets the range to (16 << (N-8)) - (235 << (N-8)) where N is
    the number of bits per component. This control is applicable to VGA,
    DVI-A/D, HDMI and DisplayPort connectors.

``V4L2_CID_DV_TX_IT_CONTENT_TYPE``
    (enum)

enum v4l2_dv_it_content_type -
    Configures the IT Content Type of the transmitted video. This
    information is sent over HDMI and DisplayPort connectors as part of
    the AVI InfoFrame. The term 'IT Content' is used for content that
    originates from a computer as opposed to content from a TV broadcast
    or an analog source. The enum v4l2_dv_it_content_type defines
    the possible content types:

.. tabularcolumns:: |p{7.0cm}|p{10.5cm}|

.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_DV_IT_CONTENT_TYPE_GRAPHICS``
      - Graphics content. Pixel data should be passed unfiltered and
	without analog reconstruction.
    * - ``V4L2_DV_IT_CONTENT_TYPE_PHOTO``
      - Photo content. The content is derived from digital still pictures.
	The content should be passed through with minimal scaling and
	picture enhancements.
    * - ``V4L2_DV_IT_CONTENT_TYPE_CINEMA``
      - Cinema content.
    * - ``V4L2_DV_IT_CONTENT_TYPE_GAME``
      - Game content. Audio and video latency should be minimized.
    * - ``V4L2_DV_IT_CONTENT_TYPE_NO_ITC``
      - No IT Content information is available and the ITC bit in the AVI
	InfoFrame is set to 0.



``V4L2_CID_DV_RX_POWER_PRESENT (bitmask)``
    Detects whether the receiver receives power from the source (e.g.
    HDMI carries 5V on one of the pins). This is often used to power an
    eeprom which contains EDID information, such that the source can
    read the EDID even if the sink is in standby/power off. Each bit
    corresponds to an input pad on the transmitter. If an input pad
    cannot detect whether power is present, then the bit for that pad
    will be 0. This read-only control is applicable to DVI-D, HDMI and
    DisplayPort connectors.

``V4L2_CID_DV_RX_RGB_RANGE``
    (enum)

enum v4l2_dv_rgb_range -
    Select the quantization range for RGB input. V4L2_DV_RANGE_AUTO
    follows the RGB quantization range specified in the standard for the
    video interface (ie. :ref:`cea861` for HDMI).
    V4L2_DV_RANGE_LIMITED and V4L2_DV_RANGE_FULL override the
    standard to be compatible with sources that have not implemented the
    standard correctly (unfortunately quite common for HDMI and DVI-D).
    Full range allows all possible values to be used whereas limited
    range sets the range to (16 << (N-8)) - (235 << (N-8)) where N is
    the number of bits per component. This control is applicable to VGA,
    DVI-A/D, HDMI and DisplayPort connectors.

``V4L2_CID_DV_RX_IT_CONTENT_TYPE``
    (enum)

enum v4l2_dv_it_content_type -
    Reads the IT Content Type of the received video. This information is
    sent over HDMI and DisplayPort connectors as part of the AVI
    InfoFrame. The term 'IT Content' is used for content that originates
    from a computer as opposed to content from a TV broadcast or an
    analog source. See ``V4L2_CID_DV_TX_IT_CONTENT_TYPE`` for the
    available content types.


.. _fm-rx-controls:

FM Receiver Control Reference
=============================

The FM Receiver (FM_RX) class includes controls for common features of
FM Reception capable devices.


.. _fm-rx-control-id:

FM_RX Control IDs
-----------------

``V4L2_CID_FM_RX_CLASS (class)``
    The FM_RX class descriptor. Calling
    :ref:`VIDIOC_QUERYCTRL` for this control will
    return a description of this control class.

``V4L2_CID_RDS_RECEPTION (boolean)``
    Enables/disables RDS reception by the radio tuner

``V4L2_CID_RDS_RX_PTY (integer)``
    Gets RDS Programme Type field. This encodes up to 31 pre-defined
    programme types.

``V4L2_CID_RDS_RX_PS_NAME (string)``
    Gets the Programme Service name (PS_NAME). It is intended for
    static display on a receiver. It is the primary aid to listeners in
    programme service identification and selection. In Annex E of
    :ref:`iec62106`, the RDS specification, there is a full
    description of the correct character encoding for Programme Service
    name strings. Also from RDS specification, PS is usually a single
    eight character text. However, it is also possible to find receivers
    which can scroll strings sized as 8 x N characters. So, this control
    must be configured with steps of 8 characters. The result is it must
    always contain a string with size multiple of 8.

``V4L2_CID_RDS_RX_RADIO_TEXT (string)``
    Gets the Radio Text info. It is a textual description of what is
    being broadcasted. RDS Radio Text can be applied when broadcaster
    wishes to transmit longer PS names, programme-related information or
    any other text. In these cases, RadioText can be used in addition to
    ``V4L2_CID_RDS_RX_PS_NAME``. The encoding for Radio Text strings is
    also fully described in Annex E of :ref:`iec62106`. The length of
    Radio Text strings depends on which RDS Block is being used to
    transmit it, either 32 (2A block) or 64 (2B block). However, it is
    also possible to find receivers which can scroll strings sized as 32
    x N or 64 x N characters. So, this control must be configured with
    steps of 32 or 64 characters. The result is it must always contain a
    string with size multiple of 32 or 64.

``V4L2_CID_RDS_RX_TRAFFIC_ANNOUNCEMENT (boolean)``
    If set, then a traffic announcement is in progress.

``V4L2_CID_RDS_RX_TRAFFIC_PROGRAM (boolean)``
    If set, then the tuned programme carries traffic announcements.

``V4L2_CID_RDS_RX_MUSIC_SPEECH (boolean)``
    If set, then this channel broadcasts music. If cleared, then it
    broadcasts speech. If the transmitter doesn't make this distinction,
    then it will be set.

``V4L2_CID_TUNE_DEEMPHASIS``
    (enum)

enum v4l2_deemphasis -
    Configures the de-emphasis value for reception. A de-emphasis filter
    is applied to the broadcast to accentuate the high audio
    frequencies. Depending on the region, a time constant of either 50
    or 75 useconds is used. The enum v4l2_deemphasis defines possible
    values for de-emphasis. Here they are:



.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_DEEMPHASIS_DISABLED``
      - No de-emphasis is applied.
    * - ``V4L2_DEEMPHASIS_50_uS``
      - A de-emphasis of 50 uS is used.
    * - ``V4L2_DEEMPHASIS_75_uS``
      - A de-emphasis of 75 uS is used.




.. _detect-controls:

Detect Control Reference
========================

The Detect class includes controls for common features of various motion
or object detection capable devices.


.. _detect-control-id:

Detect Control IDs
------------------

``V4L2_CID_DETECT_CLASS (class)``
    The Detect class descriptor. Calling
    :ref:`VIDIOC_QUERYCTRL` for this control will
    return a description of this control class.

``V4L2_CID_DETECT_MD_MODE (menu)``
    Sets the motion detection mode.

.. tabularcolumns:: |p{7.5cm}|p{10.0cm}|

.. flat-table::
    :header-rows:  0
    :stub-columns: 0

    * - ``V4L2_DETECT_MD_MODE_DISABLED``
      - Disable motion detection.
    * - ``V4L2_DETECT_MD_MODE_GLOBAL``
      - Use a single motion detection threshold.
    * - ``V4L2_DETECT_MD_MODE_THRESHOLD_GRID``
      - The image is divided into a grid, each cell with its own motion
	detection threshold. These thresholds are set through the
	``V4L2_CID_DETECT_MD_THRESHOLD_GRID`` matrix control.
    * - ``V4L2_DETECT_MD_MODE_REGION_GRID``
      - The image is divided into a grid, each cell with its own region
	value that specifies which per-region motion detection thresholds
	should be used. Each region has its own thresholds. How these
	per-region thresholds are set up is driver-specific. The region
	values for the grid are set through the
	``V4L2_CID_DETECT_MD_REGION_GRID`` matrix control.



``V4L2_CID_DETECT_MD_GLOBAL_THRESHOLD (integer)``
    Sets the global motion detection threshold to be used with the
    ``V4L2_DETECT_MD_MODE_GLOBAL`` motion detection mode.

``V4L2_CID_DETECT_MD_THRESHOLD_GRID (__u16 matrix)``
    Sets the motion detection thresholds for each cell in the grid. To
    be used with the ``V4L2_DETECT_MD_MODE_THRESHOLD_GRID`` motion
    detection mode. Matrix element (0, 0) represents the cell at the
    top-left of the grid.

``V4L2_CID_DETECT_MD_REGION_GRID (__u8 matrix)``
    Sets the motion detection region value for each cell in the grid. To
    be used with the ``V4L2_DETECT_MD_MODE_REGION_GRID`` motion
    detection mode. Matrix element (0, 0) represents the cell at the
    top-left of the grid.


.. _rf-tuner-controls:

RF Tuner Control Reference
==========================

The RF Tuner (RF_TUNER) class includes controls for common features of
devices having RF tuner.

In this context, RF tuner is radio receiver circuit between antenna and
demodulator. It receives radio frequency (RF) from the antenna and
converts that received signal to lower intermediate frequency (IF) or
baseband frequency (BB). Tuners that could do baseband output are often
called Zero-IF tuners. Older tuners were typically simple PLL tuners
inside a metal box, whilst newer ones are highly integrated chips
without a metal box "silicon tuners". These controls are mostly
applicable for new feature rich silicon tuners, just because older
tuners does not have much adjustable features.

For more information about RF tuners see
`Tuner (radio) <http://en.wikipedia.org/wiki/Tuner_%28radio%29>`__
and `RF front end <http://en.wikipedia.org/wiki/RF_front_end>`__
from Wikipedia.


.. _rf-tuner-control-id:

RF_TUNER Control IDs
--------------------

``V4L2_CID_RF_TUNER_CLASS (class)``
    The RF_TUNER class descriptor. Calling
    :ref:`VIDIOC_QUERYCTRL` for this control will
    return a description of this control class.

``V4L2_CID_RF_TUNER_BANDWIDTH_AUTO (boolean)``
    Enables/disables tuner radio channel bandwidth configuration. In
    automatic mode bandwidth configuration is performed by the driver.

``V4L2_CID_RF_TUNER_BANDWIDTH (integer)``
    Filter(s) on tuner signal path are used to filter signal according
    to receiving party needs. Driver configures filters to fulfill
    desired bandwidth requirement. Used when
    V4L2_CID_RF_TUNER_BANDWIDTH_AUTO is not set. Unit is in Hz. The
    range and step are driver-specific.

``V4L2_CID_RF_TUNER_LNA_GAIN_AUTO (boolean)``
    Enables/disables LNA automatic gain control (AGC)

``V4L2_CID_RF_TUNER_MIXER_GAIN_AUTO (boolean)``
    Enables/disables mixer automatic gain control (AGC)

``V4L2_CID_RF_TUNER_IF_GAIN_AUTO (boolean)``
    Enables/disables IF automatic gain control (AGC)

``V4L2_CID_RF_TUNER_RF_GAIN (integer)``
    The RF amplifier is the very first amplifier on the receiver signal
    path, just right after the antenna input. The difference between the
    LNA gain and the RF gain in this document is that the LNA gain is
    integrated in the tuner chip while the RF gain is a separate chip.
    There may be both RF and LNA gain controls in the same device. The
    range and step are driver-specific.

``V4L2_CID_RF_TUNER_LNA_GAIN (integer)``
    LNA (low noise amplifier) gain is first gain stage on the RF tuner
    signal path. It is located very close to tuner antenna input. Used
    when ``V4L2_CID_RF_TUNER_LNA_GAIN_AUTO`` is not set. See
    ``V4L2_CID_RF_TUNER_RF_GAIN`` to understand how RF gain and LNA gain
    differs from the each others. The range and step are
    driver-specific.

``V4L2_CID_RF_TUNER_MIXER_GAIN (integer)``
    Mixer gain is second gain stage on the RF tuner signal path. It is
    located inside mixer block, where RF signal is down-converted by the
    mixer. Used when ``V4L2_CID_RF_TUNER_MIXER_GAIN_AUTO`` is not set.
    The range and step are driver-specific.

``V4L2_CID_RF_TUNER_IF_GAIN (integer)``
    IF gain is last gain stage on the RF tuner signal path. It is
    located on output of RF tuner. It controls signal level of
    intermediate frequency output or baseband output. Used when
    ``V4L2_CID_RF_TUNER_IF_GAIN_AUTO`` is not set. The range and step
    are driver-specific.

``V4L2_CID_RF_TUNER_PLL_LOCK (boolean)``
    Is synthesizer PLL locked? RF tuner is receiving given frequency
    when that control is set. This is a read-only control.

.. [#f1]
   This control may be changed to a menu control in the future, if more
   options are required.