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Diffstat (limited to 'target/linux/bcm27xx/patches-6.6/950-1151-media-uapi-Document-PiSP-Compressed-RAW-Bayer-format.patch')
| -rw-r--r-- | target/linux/bcm27xx/patches-6.6/950-1151-media-uapi-Document-PiSP-Compressed-RAW-Bayer-format.patch | 106 |
1 files changed, 106 insertions, 0 deletions
diff --git a/target/linux/bcm27xx/patches-6.6/950-1151-media-uapi-Document-PiSP-Compressed-RAW-Bayer-format.patch b/target/linux/bcm27xx/patches-6.6/950-1151-media-uapi-Document-PiSP-Compressed-RAW-Bayer-format.patch new file mode 100644 index 0000000000..aa4b003e5b --- /dev/null +++ b/target/linux/bcm27xx/patches-6.6/950-1151-media-uapi-Document-PiSP-Compressed-RAW-Bayer-format.patch @@ -0,0 +1,106 @@ +From 5d6318f242cce5f9b5677baedde736a2b81061df Mon Sep 17 00:00:00 2001 +From: Jacopo Mondi <jacopo.mondi@ideasonboard.com> +Date: Wed, 17 Jan 2024 11:21:50 +0200 +Subject: [PATCH 1151/1215] media: uapi: Document PiSP Compressed RAW Bayer + formats + +Document the Raspberry Pi compressed RAW Bayer formats. + +The compression algorithm description is provided by Nick Hollinghurst +<nick.hollinghurst@raspberrypi.com> from Raspberry Pi. + +Signed-off-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com> +Reviewed-by: Naushir Patuck <naush@raspberrypi.com> +--- + .../userspace-api/media/v4l/pixfmt-bayer.rst | 1 + + .../media/v4l/pixfmt-srggb8-pisp-comp.rst | 74 +++++++++++++++++++ + 2 files changed, 75 insertions(+) + create mode 100644 Documentation/userspace-api/media/v4l/pixfmt-srggb8-pisp-comp.rst + +--- a/Documentation/userspace-api/media/v4l/pixfmt-bayer.rst ++++ b/Documentation/userspace-api/media/v4l/pixfmt-bayer.rst +@@ -20,6 +20,7 @@ orders. See also `the Wikipedia article + :maxdepth: 1 + + pixfmt-srggb8 ++ pixfmt-srggb8-pisp-comp + pixfmt-srggb10 + pixfmt-srggb10p + pixfmt-srggb10alaw8 +--- /dev/null ++++ b/Documentation/userspace-api/media/v4l/pixfmt-srggb8-pisp-comp.rst +@@ -0,0 +1,74 @@ ++.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later ++ ++.. _v4l2-pix-fmt-pisp-comp1-rggb: ++.. _v4l2-pix-fmt-pisp-comp1-grbg: ++.. _v4l2-pix-fmt-pisp-comp1-gbrg: ++.. _v4l2-pix-fmt-pisp-comp1-bggr: ++.. _v4l2-pix-fmt-pisp-comp1-mono: ++.. _v4l2-pix-fmt-pisp-comp2-rggb: ++.. _v4l2-pix-fmt-pisp-comp2-grbg: ++.. _v4l2-pix-fmt-pisp-comp2-gbrg: ++.. _v4l2-pix-fmt-pisp-comp2-bggr: ++.. _v4l2-pix-fmt-pisp-comp2-mono: ++ ++************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************** ++V4L2_PIX_FMT_PISP_COMP1_RGGB ('PC1R'), V4L2_PIX_FMT_PISP_COMP1_GRBG ('PC1G'), V4L2_PIX_FMT_PISP_COMP1_GBRG ('PC1g'), V4L2_PIX_FMT_PISP_COMP1_BGGR ('PC1B), V4L2_PIX_FMT_PISP_COMP1_MONO ('PC1M'), V4L2_PIX_FMT_PISP_COMP2_RGGB ('PC2R'), V4L2_PIX_FMT_PISP_COMP2_GRBG ('PC2G'), V4L2_PIX_FMT_PISP_COMP2_GBRG ('PC2g'), V4L2_PIX_FMT_PISP_COMP2_BGGR ('PC2B), V4L2_PIX_FMT_PISP_COMP2_MONO ('PC2M') ++************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************************** ++ ++================================================ ++Raspberry Pi PiSP compressed 8-bit Bayer formats ++================================================ ++ ++Description ++=========== ++ ++The Raspberry Pi ISP (PiSP) uses a family of three fixed-rate compressed Bayer ++formats. A black-level offset may be subtracted to improve compression ++efficiency; the nominal black level and amount of offset must be signalled out ++of band. Each scanline is padded to a multiple of 8 pixels wide, and each block ++of 8 horizontally-contiguous pixels is coded using 8 bytes. ++ ++Mode 1 uses a quantization and delta-based coding scheme which preserves up to ++12 significant bits. Mode 2 is a simple sqrt-like companding scheme with 6 PWL ++chords, preserving up to 12 significant bits. Mode 3 combines both companding ++(with 4 chords) and the delta scheme, preserving up to 14 significant bits. ++ ++The remainder of this description applies to Modes 1 and 3. ++ ++Each block of 8 pixels is separated into even and odd phases of 4 pixels, ++coded independently by 32-bit words at successive locations in memory. ++The two LS bits of each 32-bit word give its "quantization mode". ++ ++In quantization mode 0, the lowest 321 quantization levels are multiples of ++FSD/4096 and the remaining levels are successive multiples of FSD/2048. ++Quantization modes 1 and 2 use linear quantization with step sizes of ++FSD/1024 and FSD/512 respectively. Each of the four pixels is quantized ++independently, with rounding to the nearest level. ++In quantization mode 2 where the middle two samples have quantized values ++(q1,q2) both in the range [384..511], they are coded using 9 bits for q1 ++followed by 7 bits for (q2 & 127). Otherwise, for quantization modes ++0, 1 and 2: a 9-bit field encodes MIN(q1,q2) which must be in the range ++[0..511] and a 7-bit field encodes (q2-q1+64) which must be in [0..127]. ++ ++Each of the outer samples (q0,q3) is encoded using a 7-bit field based ++on its inner neighbour q1 or q2. In quantization mode 2 where the inner ++sample has a quantized value in the range [448..511], the field value is ++(q0-384). Otherwise for quantization modes 0, 1 and 2: The outer sample ++is encoded as (q0-MAX(0,q1-64)). q3 is likewise coded based on q2. ++Each of these values must be in the range [0..127]. All these fields ++of 2, 9, 7, 7, 7 bits respectively are packed in little-endian order ++to give a 32-bit word with LE byte order. ++ ++Quantization mode 3 has a "7.5-bit" escape, used when none of the above ++encodings will fit. Each pixel value is quantized to the nearest of 176 ++levels, where the lowest 95 levels are multiples of FSD/256 and the ++remaining levels are multiples of FSD/128 (level 175 represents values ++very close to FSD and may require saturating arithmetic to decode). ++ ++Each pair of quantized pixels (q0,q1) or (q2,q3) is jointly coded ++by a 15-bit field: 2816*(q0>>4) + 16*q1 + (q0&15). ++Three fields of 2, 15, 15 bits are packed in LE order {15,15,2}. ++ ++An implementation of a software decoder of compressed formats is available ++in `Raspberry Pi camera applications code base ++<https://github.com/raspberrypi/rpicam-apps/blob/main/image/dng.cpp>`_. |