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| author | Hans Verkuil <hverkuil-cisco@xs4all.nl> | 2019-08-15 17:44:52 +0300 |
|---|---|---|
| committer | Mauro Carvalho Chehab <mchehab+samsung@kernel.org> | 2019-08-19 21:00:54 +0300 |
| commit | d4e0f82ac840bf3d16b25d60f261b429603138a9 (patch) | |
| tree | d0667d77783af2014e3253f060cf8f13a8f18aff /Documentation/media/uapi/v4l | |
| parent | 051f8d2d86f848cd29632908f56d277ac5800a50 (diff) | |
| download | linux-d4e0f82ac840bf3d16b25d60f261b429603138a9.tar.xz | |
media: pixfmt-compressed.rst: improve H264/HEVC/MPEG1+2/VP8+9 documentation
The existing documentation was incorrect and did not correspond
to how actual codec drivers implemented this.
Update the documentation to explicitly specify what is actually
expected.
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Diffstat (limited to 'Documentation/media/uapi/v4l')
| -rw-r--r-- | Documentation/media/uapi/v4l/pixfmt-compressed.rst | 36 |
1 files changed, 30 insertions, 6 deletions
diff --git a/Documentation/media/uapi/v4l/pixfmt-compressed.rst b/Documentation/media/uapi/v4l/pixfmt-compressed.rst index 493b6020107d..292fdc116c77 100644 --- a/Documentation/media/uapi/v4l/pixfmt-compressed.rst +++ b/Documentation/media/uapi/v4l/pixfmt-compressed.rst @@ -41,7 +41,12 @@ Compressed Formats - ``V4L2_PIX_FMT_H264`` - 'H264' - - H264 video elementary stream with start codes. + - H264 Access Unit. + The decoder expects one Access Unit per buffer. + The encoder generates one Access Unit per buffer. + If :ref:`VIDIOC_ENUM_FMT` reports ``V4L2_FMT_FLAG_CONTINUOUS_BYTESTREAM`` + then the decoder has no requirements since it can parse all the + information from the raw bytestream. * .. _V4L2-PIX-FMT-H264-NO-SC: - ``V4L2_PIX_FMT_H264_NO_SC`` @@ -89,12 +94,20 @@ Compressed Formats - ``V4L2_PIX_FMT_MPEG1`` - 'MPG1' - - MPEG1 video elementary stream. + - MPEG1 Picture. Each buffer starts with a Picture header, followed + by other headers as needed and ending with the Picture data. + If :ref:`VIDIOC_ENUM_FMT` reports ``V4L2_FMT_FLAG_CONTINUOUS_BYTESTREAM`` + then the decoder has no requirements since it can parse all the + information from the raw bytestream. * .. _V4L2-PIX-FMT-MPEG2: - ``V4L2_PIX_FMT_MPEG2`` - 'MPG2' - - MPEG2 video elementary stream. + - MPEG2 Picture. Each buffer starts with a Picture header, followed + by other headers as needed and ending with the Picture data. + If :ref:`VIDIOC_ENUM_FMT` reports ``V4L2_FMT_FLAG_CONTINUOUS_BYTESTREAM`` + then the decoder has no requirements since it can parse all the + information from the raw bytestream. * .. _V4L2-PIX-FMT-MPEG2-SLICE: - ``V4L2_PIX_FMT_MPEG2_SLICE`` @@ -135,7 +148,9 @@ Compressed Formats - ``V4L2_PIX_FMT_VP8`` - 'VP80' - - VP8 video elementary stream. + - VP8 compressed video frame. The encoder generates one + compressed frame per buffer, and the decoder requires one + compressed frame per buffer. * .. _V4L2-PIX-FMT-VP8-FRAME: - ``V4L2_PIX_FMT_VP8_FRAME`` @@ -160,12 +175,19 @@ Compressed Formats - ``V4L2_PIX_FMT_VP9`` - 'VP90' - - VP9 video elementary stream. + - VP9 compressed video frame. The encoder generates one + compressed frame per buffer, and the decoder requires one + compressed frame per buffer. * .. _V4L2-PIX-FMT-HEVC: - ``V4L2_PIX_FMT_HEVC`` - 'HEVC' - - HEVC/H.265 video elementary stream. + - HEVC/H.265 Access Unit. + The decoder expects one Access Unit per buffer. + The encoder generates one Access Unit per buffer. + If :ref:`VIDIOC_ENUM_FMT` reports ``V4L2_FMT_FLAG_CONTINUOUS_BYTESTREAM`` + then the decoder has no requirements since it can parse all the + information from the raw bytestream. * .. _V4L2-PIX-FMT-FWHT: - ``V4L2_PIX_FMT_FWHT`` @@ -173,6 +195,8 @@ Compressed Formats - Video elementary stream using a codec based on the Fast Walsh Hadamard Transform. This codec is implemented by the vicodec ('Virtual Codec') driver. See the codec-fwht.h header for more details. + :ref:`VIDIOC_ENUM_FMT` reports ``V4L2_FMT_FLAG_CONTINUOUS_BYTESTREAM`` + since the decoder can parse all the information from the raw bytestream. * .. _V4L2-PIX-FMT-FWHT-STATELESS: - ``V4L2_PIX_FMT_FWHT_STATELESS`` |