From 804e192a81149ef43ccaf09ac65b264813ad511b Mon Sep 17 00:00:00 2001 From: Nicolas Dufresne Date: Tue, 26 Apr 2022 14:57:27 +0200 Subject: 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 Reviewed-by: Sebastian Fricke Signed-off-by: Hans Verkuil Signed-off-by: Mauro Carvalho Chehab --- .../userspace-api/media/v4l/ext-ctrls-codec-stateless.rst | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) (limited to 'Documentation/userspace-api') 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 ` -- cgit v1.2.3