On Fri, 05 Jul 2019 13:40:03 -0300 Ezequiel Garcia <ezequiel@xxxxxxxxxxxxx> wrote: > Hi Boris, Paul, > > On Wed, 2019-07-03 at 14:28 +0200, Boris Brezillon wrote: > > Looks like some stateless decoders expect slices to be prefixed with > > ANNEX B start codes (they most likely do some kind of bitstream parsing > > and/or need that to delimit slices when doing per frame decoding). > > Since skipping those start codes for dummy stateless decoders (those > > expecting all params to be passed through controls) should be pretty > > easy, let's mandate that all slices be prepended with ANNEX B start > > codes. > > > > If we ever need to support AVC headers, we can add a new menu control > > to select the type of NAL header to use. > > > > Signed-off-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx> > > Reviewed-by: Paul Kocialkowski <paul.kocialkowski@xxxxxxxxxxx> > > --- > > Changes in v3: > > * Add Paul's R-b > > > > Changes in v2: > > * None > > --- > > Documentation/media/uapi/v4l/ext-ctrls-codec.rst | 1 + > > 1 file changed, 1 insertion(+) > > > > diff --git a/Documentation/media/uapi/v4l/ext-ctrls-codec.rst b/Documentation/media/uapi/v4l/ext-ctrls-codec.rst > > index 7a1947f5be96..3ae1367806cf 100644 > > --- a/Documentation/media/uapi/v4l/ext-ctrls-codec.rst > > +++ b/Documentation/media/uapi/v4l/ext-ctrls-codec.rst > > @@ -1726,6 +1726,7 @@ enum v4l2_mpeg_video_h264_hierarchical_coding_type - > > :ref:`h264`, section 7.4.3 "Slice Header Semantics". For further > > documentation, refer to the above specification, unless there is > > an explicit comment stating otherwise. > > + All slices should be prepended with an ANNEX B start code. > > > > Currently, the H264 slice V4L2_PIX_FMT_H264_SLICE_RAW, > is specified to _not_ contain the ANNEX B start code. Yep, we should provably rename the format. > > As you know, this is used in the cedrus driver, which is not > expecting the start code. > > What's the plan regarding that? I had a few patches modifying the cedrus driver accordingly, but I dropped them in v2. I guess we can fix the driver once we've settled on the uAPI changes.
