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| author | Nicolas Dufresne <nicolas.dufresne@collabora.com> | 2021-02-09 18:22:33 +0100 |
|---|---|---|
| committer | Mauro Carvalho Chehab <mchehab+huawei@kernel.org> | 2021-03-11 11:59:42 +0100 |
| commit | 21ea3defde62fb9441049d1cea282807b7d773d4 (patch) | |
| tree | c64b18efb0d4a238e17f10304195d136cd30f09e /Documentation/userspace-api | |
| parent | 6a49401e15b5ea41503a6905f99f3b32f0a534fb (diff) | |
| download | linux-21ea3defde62fb9441049d1cea282807b7d773d4.tar.gz linux-21ea3defde62fb9441049d1cea282807b7d773d4.tar.xz | |
media: doc: h264/hevc: Clarify _START_CODE_NONE meaning
As some hardware have a knob to enable or disable emulation prevention
bytes removal, driver writers ended up wondering what exactly the
START_CODE_NONE modes meant in this regards. This patch clarify what is
expected with a reference to the specification.
Reported-by: John Cox <jc@kynesim.co.uk>
Signed-off-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Diffstat (limited to 'Documentation/userspace-api')
| -rw-r--r-- | Documentation/userspace-api/media/v4l/ext-ctrls-codec-stateless.rst | 4 | ||||
| -rw-r--r-- | Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst | 4 |
2 files changed, 6 insertions, 2 deletions
diff --git a/Documentation/userspace-api/media/v4l/ext-ctrls-codec-stateless.rst b/Documentation/userspace-api/media/v4l/ext-ctrls-codec-stateless.rst index 681f59e0a8f5..90c0e1d57544 100644 --- a/Documentation/userspace-api/media/v4l/ext-ctrls-codec-stateless.rst +++ b/Documentation/userspace-api/media/v4l/ext-ctrls-codec-stateless.rst @@ -769,7 +769,9 @@ Stateless Codec Control ID * - ``V4L2_STATELESS_H264_START_CODE_NONE`` - 0 - Selecting this value specifies that H264 slices are passed - to the driver without any start code. + to the driver without any start code. The bitstream data should be + according to :ref:`h264` 7.3.1 NAL unit syntax, hence contains + emulation prevention bytes when required. * - ``V4L2_STATELESS_H264_START_CODE_ANNEX_B`` - 1 - Selecting this value specifies that H264 slices are expected diff --git a/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst b/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst index 76ebf86b9d0b..7ee8ae073b91 100644 --- a/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst +++ b/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst @@ -3719,7 +3719,9 @@ enum v4l2_mpeg_video_hevc_size_of_length_field - * - ``V4L2_MPEG_VIDEO_HEVC_START_CODE_NONE`` - 0 - Selecting this value specifies that HEVC slices are passed - to the driver without any start code. + to the driver without any start code. The bitstream data should be + according to :ref:`hevc` 7.3.1.1 General NAL unit syntax, hence + contains emulation prevention bytes when required. * - ``V4L2_MPEG_VIDEO_HEVC_START_CODE_ANNEX_B`` - 1 - Selecting this value specifies that HEVC slices are expected |