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| author | Jammy Huang <jammy_huang@aspeedtech.com> | 2022-10-28 10:35:50 +0800 |
|---|---|---|
| committer | Hans Verkuil <hverkuil-cisco@xs4all.nl> | 2022-11-04 16:56:39 +0100 |
| commit | 7a4b3770d635d05f1d8a4a17ae4acab5b3d2bad1 (patch) | |
| tree | 7a93963503b9925bca31b4fc97086ee35fdee2b4 /Documentation/userspace-api | |
| parent | c4d344163c3a7f90712525f931a6c016bbb35e18 (diff) | |
| download | linux-7a4b3770d635d05f1d8a4a17ae4acab5b3d2bad1.tar.bz2 | |
media: v4l: Add definition for the Aspeed JPEG format
This introduces support for the Aspeed JPEG format, where the new frame
can refer to previous frame to reduce the amount of compressed data.
The concept is similar to I/P frame of video compression. It will
compare the new frame with previous one to decide which macroblock's
data is changed, and only the changed macroblocks will be compressed.
This Aspeed JPEG format is used by the video engine on Aspeed platforms,
which is generally adapted for remote KVM.
Signed-off-by: Jammy Huang <jammy_huang@aspeedtech.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Diffstat (limited to 'Documentation/userspace-api')
| -rw-r--r-- | Documentation/userspace-api/media/v4l/pixfmt-reserved.rst | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/Documentation/userspace-api/media/v4l/pixfmt-reserved.rst b/Documentation/userspace-api/media/v4l/pixfmt-reserved.rst index 0ff68cd8cf62..73cd99828010 100644 --- a/Documentation/userspace-api/media/v4l/pixfmt-reserved.rst +++ b/Documentation/userspace-api/media/v4l/pixfmt-reserved.rst @@ -258,6 +258,23 @@ please make a proposal on the linux-media mailing list. and it is used by various multimedia hardware blocks like GPU, display controllers, ISP and video accelerators. It contains four planes for progressive video. + * .. _V4L2-PIX-FMT-AJPG: + + - ``V4L2_PIX_FMT_AJPG`` + - 'AJPG' + - ASPEED JPEG format used by the aspeed-video driver on Aspeed platforms, + which is generally adapted for remote KVM. + On each frame compression, I will compare the new frame with previous + one to decide which macroblock's data is changed, and only the changed + macroblocks will be compressed. + + The implementation is based on AST2600 A3 datasheet, revision 0.9, which + is not publicly available. Or you can reference Video stream data format + – ASPEED mode compression of SDK_User_Guide which available on + AspeedTech-BMC/openbmc/releases. + + Decoder's implementation can be found here, + `aspeed_codec <https://github.com/AspeedTech-BMC/aspeed_codec/>`__ .. raw:: latex \normalsize |