[FFmpeg-devel] [PATCH] ffmpeg: release the last_frame before the decoders are closed

[Hendrik Leppkes]

On Tue, Oct 16, 2018 at 4:02 PM James Almer <jamrial at gmail.com> wrote:
>
> On 10/16/2018 9:16 AM, Steve Lhomme wrote:
> > If the decoder provides its own buffers it might not be able to release its
> > buffers once it has been closed. (this is the case with dav1d).
> > ---
> >  fftools/ffmpeg.c | 1 +
> >  1 file changed, 1 insertion(+)
> >
> > diff --git a/fftools/ffmpeg.c b/fftools/ffmpeg.c
> > index da4259a9a8..faf62475a2 100644
> > --- a/fftools/ffmpeg.c
> > +++ b/fftools/ffmpeg.c
> > @@ -4738,6 +4738,7 @@ static int transcode(void)
> >          if (ost->encoding_needed) {
> >              av_freep(&ost->enc_ctx->stats_in);
> >          }
> > +        av_frame_unref(ost->last_frame);
> >          total_packets_written += ost->packets_written;
> >      }
>
> I'm not against this change, but this issue should be solved within
> dav1d as well. Either the caller fully owns the picture returned by
> dav1d, or it doesn't. "Partially owns it while some other context is
> still valid" is not really acceptable.

I agree. AVFrames guarantee to remain valid independently of which
component they ever came out of. So if dav1d cannot provide that,
either we need to solve that in the dav1d wrapper (ie. by keeping  an
instance to the dav1d context tied to the frame like we do for some
hardware frames), or dav1d fixes that.

- Hendrik