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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>
This commit is contained in:
Hans Verkuil 2019-08-15 11:44:52 -03:00 committed by Mauro Carvalho Chehab
parent 051f8d2d86
commit d4e0f82ac8
1 changed files with 30 additions and 6 deletions
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36
Documentation/media/uapi/v4l/pixfmt-compressed.rst
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@ -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``