[FFmpeg-devel] [PATCH 2/2] lavc/vaapi_hevc: Don't require exact profiles

[Xiang, Haihao]

On So, 2024-04-28 at 15:14 +0100, Mark Thompson wrote:
> On 24/04/2024 14:45, Xiang, Haihao wrote:
> > On Ma, 2024-04-22 at 22:23 +0100, Mark Thompson wrote:
> > > Rather than turning the constraint flags into a single profile and then
> > > searching for that profile (and failing if it doesn't match any profile
> > > exactly), instead search all supported profiles and use the first one
> > > which supports the given set of constraint flags.
> > > ---
> > > This fixes decode of rext 8-bit 4:2:0; it will correctly pick Main 12 or
> > > Main
> > > 4:2:2 10 or Main 4:4:4 (first one available) to use as the decoding
> > > profile
> > > after this patch.
> > 
> > sw decoding and vaapi decoding might have different bits (There is the same
> > issue if applying Fei's patchset).  
> > 
> > For example:
> > $ ffmpeg -hwaccel vaapi -f lavfi -i testsrc -vf 'format=nv12,hwupload' -c:v
> > hevc_vaapi -profile:v rext -vframes 30 -y out.mp4
> > 
> > 8bit ouput if using sw decoding:
> > $ ffmpeg -i out.mp4 -f null - 
> > [...]
> > Stream #0:0(und): Video: wrapped_avframe, yuv420p(tv, progressive), 320x240
> > [SAR
> > 1:1 DAR 4:3], q=2-31, 200 kb/s, 25 fps, 25 tbn (default)
> > 
> > 12bit output if using vaapi decoding:
> > $ ffmpeg -hwaccel vaapi -i out.mp4 -f null -
> > [...]
> >  Stream #0:0(und): Video: wrapped_avframe, p012le(tv, progressive), 320x240
> > [SAR
> > 1:1 DAR 4:3], q=2-31, 200 kb/s, 25 fps, 25 tbn (default)
> 
> That comes from what the driver reports support for, though?
> 
> E.g. with the Intel iHD driver, I have
> 
>         {
>             "profile": 23,
>             "name": "HEVCMain12",
> ...
>                     "surface_formats": [
>                         {
>                             "rt_format": "YUV420",
>                             "max_width": 16384,
>                             "max_height": 16384,
>                             "memory_types": [
>                                 "VA",
>                                 "DRM_PRIME_2",
>                             ],
>                             "pixel_formats": [
>                                 "P012",
>                                 "P016",
>                             ],
>                         },
> 
> So to decode a 4:2:0 8-bit input it is asking for a P012 or P016 surface.
> 
> If the driver reported that a Main 12 profile 4:2:0 8-bit input could be
> decoded to an NV12 surface then it would be picked by the logic in
> vaapi_decode_find_best_format(), since it would be a better match than the
> higher-depth formats.

You are right, the iHD driver doesn't report the support for HEVCMain12 8bit. 

Thanks
Haihao