[FFmpeg-devel] [PATCH] set ulMaxDisplayDelay cuvidec parser option to zero if low_delay flag is on

clime clime7 at gmail.com
Sat Feb 20 01:38:48 EET 2021


On Sat, 20 Feb 2021 at 00:29, Timo Rothenpieler <timo at rothenpieler.org> wrote:
>
> On 19.02.2021 23:33, clime wrote:
> >       ctx->cuparseinfo.ulMaxNumDecodeSurfaces = ctx->nb_surfaces;
> > -    ctx->cuparseinfo.ulMaxDisplayDelay = 4;
> > +    ctx->cuparseinfo.ulMaxDisplayDelay = avctx->flags & AV_CODEC_FLAG_LOW_DELAY ? 0 : 4;
>
> I'd prefer this with proper braces, to make sure no compiler gets the
> crazy idea to evaluate this as avctx->flags & 4.
>
> Otherwise this is probably fine, but will severely gimp the performance,
> to the point that it might not even be able to sustain 60 FPS anymore.
> Printing a warning might be in order.

I have tested this with h264 2880x1620 120fps and some other use-cases
and performance was fine (on Quadro RTX 4000, that is).

Can I just send the fixed patch again to ffmpeg-devel at ffmpeg.org?

ctx->cuparseinfo.ulMaxDisplayDelay = (avctx->flags &
AV_CODEC_FLAG_LOW_DELAY) ? 0 : 4;

Like this?

Btw. there is a related ticket: https://trac.ffmpeg.org/ticket/6495

Best regards
Michal Novotny

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