[FFmpeg-devel] [PATCH 1/2] avcodec: add av1 hardware acceleration decoder

[Wang, Fei W]

> -----Original Message-----
> From: ffmpeg-devel <ffmpeg-devel-bounces at ffmpeg.org> On Behalf Of James
> Almer
> Sent: Saturday, August 22, 2020 1:22 AM
> To: ffmpeg-devel at ffmpeg.org
> Subject: Re: [FFmpeg-devel] [PATCH 1/2] avcodec: add av1 hardware
> acceleration decoder
> 
> On 8/21/2020 2:05 PM, Derek Buitenhuis wrote:
> > On 21/08/2020 16:00, James Almer wrote:
> >> If you actually look at the patch, you'll notice that this is
> >> basically the template of what eventually will become the native
> >> decoder, that for now only includes the high level bitstream parsing
> >> and the hwaccel hooks (And thus will only output frames if one is
> >> plugged in). So the names are fine.
> >
> > Isn't there overlap with the parser here (global motion params)?
> 
> cbs_av1 parses global motion params, yes. I'm not sure why this decoder
> attempts to do it too, but it acknowledges the fact it's also done by CBS. Maybe
> Fei Wang can explain why the duplication.
It should not be duplication. According to spec, gm_params process is:
decode_signed_subexp_with_ref() {
    decode_unsigned_subexp_with_ref() {
        decode_subexp
        inverse_recenter
    }
}
And csb_av1 just implement decode_subexp part. And all other part
need the reference frame's gm_params to calculate current frame's
gm_params. So here is the calculation implementation by using result
from cbs_av1 with decode_subexp.

> 
> The cbs_av1 gm params parsing code should be fixed, in any case.
> 
> >
> > - Derek
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