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| author | Nicolas Dufresne <nicolas.dufresne@collabora.com> | 2022-04-26 14:57:27 +0200 |
|---|---|---|
| committer | Mauro Carvalho Chehab <mchehab@kernel.org> | 2022-05-13 14:58:29 +0200 |
| commit | 804e192a81149ef43ccaf09ac65b264813ad511b (patch) | |
| tree | 928d3ab69b10ac044115a9a1d094b78463d56d75 /Documentation | |
| parent | 397edc703a10f670a2692e492a245f6be1fe279a (diff) | |
| download | linux-804e192a81149ef43ccaf09ac65b264813ad511b.tar.bz2 | |
media: doc: Document dual use of H.264 pic_num/frame_num
These two fields need documentation as they have dual meaning. It is also
confusing since pic_num is a derived value from frame_num, so this should
help application developers. If we ever need to make a V2 of this API, I
would suggest to remove pic_num entirely.
Signed-off-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Reviewed-by: Sebastian Fricke <sebastian.fricke@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/userspace-api/media/v4l/ext-ctrls-codec-stateless.rst | 10 |
1 files changed, 8 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 6541e4c32b26..bee73065e993 100644 --- a/Documentation/userspace-api/media/v4l/ext-ctrls-codec-stateless.rst +++ b/Documentation/userspace-api/media/v4l/ext-ctrls-codec-stateless.rst @@ -649,10 +649,16 @@ Stateless Codec Control ID :c:type:`timeval` in struct :c:type:`v4l2_buffer` to a __u64. * - __u32 - ``pic_num`` - - + - For short term references, this must match the derived value PicNum + (8-28) and for long term references it must match the derived value + LongTermPicNum (8-29). When decoding frames (as opposed to fields) + pic_num is the same as FrameNumWrap. * - __u16 - ``frame_num`` - - + - For short term references, this must match the frame_num value from + the slice header syntax (the driver will wrap the value if needed). For + long term references, this must be set to the value of + long_term_frame_idx described in the dec_ref_pic_marking() syntax. * - __u8 - ``fields`` - Specifies how the DPB entry is referenced. See :ref:`Reference Fields <h264_ref_fields>` |