| Message ID | 20190610085250.3255-2-boris.brezillon@collabora.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | media: uapi: h264: First batch of adjusments | expand |
Hi, On Mon, 2019-06-10 at 10:52 +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@collabora.com> Looks good to me: Reviewed-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com> Cheers, Paul > --- > Changes in v2: > * None > > Note: we might want to add a nal_header_size field to allow drivers to > quickly find where the actual payload start. That'd be particularly > useful here since ANNEX B start codes can be of arbitrary size > (2+(0x00 bytes) + 1(0x01 byte)). The other option would be to enforce > the number of leading 0x00 bytes (a minimum of 2 is required). > --- > 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 d6ea2ffd65c5..82547d5de250 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. > > .. note:: >
diff --git a/Documentation/media/uapi/v4l/ext-ctrls-codec.rst b/Documentation/media/uapi/v4l/ext-ctrls-codec.rst index d6ea2ffd65c5..82547d5de250 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. .. note::
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@collabora.com> --- Changes in v2: * None Note: we might want to add a nal_header_size field to allow drivers to quickly find where the actual payload start. That'd be particularly useful here since ANNEX B start codes can be of arbitrary size (2+(0x00 bytes) + 1(0x01 byte)). The other option would be to enforce the number of leading 0x00 bytes (a minimum of 2 is required). --- Documentation/media/uapi/v4l/ext-ctrls-codec.rst | 1 + 1 file changed, 1 insertion(+)