[FFmpeg-devel] [PATCH] lavc/vvc: AVERROR_PATCHWELCOME for subpictures

[Wang, Fei W]

On Mon, 2024-03-11 at 21:57 -0300, James Almer wrote:
> On 3/11/2024 9:49 PM, Michael Niedermayer wrote:
> > On Mon, Mar 11, 2024 at 06:53:31PM +0000, Frank Plowman wrote:
> > > VVC's subpictures feature is not yet implemented in the native
> > > decoder.
> > > Throw an AVERROR_PATCHWELCOME when trying to decode a bitstream
> > > using
> > > the feature.  Fixes crashes when trying to decode bitstreams
> > > which
> > > use the feature.
> > > 
> > > Signed-off-by: Frank Plowman <post at frankplowman.com>
> > > ---
> > >   libavcodec/vvc/vvc_ps.c | 15 +++++++++++++++
> > >   1 file changed, 15 insertions(+)
> > 
> > This breaks fate-vvc-conformance-SUBPIC_A_3
> > 
> > make fate-vvc-conformance-SUBPIC_A_3
> > TEST    vvc-conformance-SUBPIC_A_3
> > --- ./tests/ref/fate/vvc-conformance-SUBPIC_A_3	2024-03-05
> > 02:37:36.235300141 +0100
> > +++ tests/data/fate/vvc-conformance-SUBPIC_A_3	2024-03-12
> > 01:47:27.301593567 +0100
> > @@ -1,9 +0,0 @@
> > -#tb 0: 1/25
> > -#media_type 0: video
> > -#codec_id 0: rawvideo
> > -#dimensions 0: 1920x1080
> > -#sar 0: 0/1
> > -0,          0,          0,        1,  6220800, 0xa419cfb6
> > -0,          1,          1,        1,  6220800, 0xa419cfb6
> > -0,          2,          2,        1,  6220800, 0xa419cfb6
> > -0,          3,          3,        1,  6220800, 0xa419cfb6
> > Test vvc-conformance-SUBPIC_A_3 failed. Look at
> > tests/data/fate/vvc-conformance-SUBPIC_A_3.err for details.
> > tests/Makefile:318: recipe for target 'fate-vvc-conformance-
> > SUBPIC_A_3' failed
> > make: *** [fate-vvc-conformance-SUBPIC_A_3] Error 69
> > 
> > thx
> 
> The sample appears to decode fine and doesn't crash, although all
> four 
> frames are exactly the same (I don't know is that's intended).

The result is correct. Assume native decode can handle subpic, at least
a part of the feature.

> Maybe the crashes can be fixed in some other form? And abort only if 
> FF_COMPLIANCE_STRICT is requested.

Previous I made a patch to fix the crash in setup ps, but still get
error in decoding slice, it's better to return AVERROR_PATCHWELCOME
only in case of pps_single_slice_per_subpic_flag.

https://github.com/intel-media-ci/ffmpeg/pull/723

Thanks
Fei
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