[FFmpeg-devel] [PATCH] lavc/libvpxenc: prevent fifo from filling up

[Anton Khirnov]

Quoting James Zern (2023-07-05 21:16:37)
> On Wed, Jul 5, 2023 at 12:15 PM James Zern <jzern at google.com> wrote:
> >
> > Hi,
> >
> 
> +ffmpeg-dev. I took the wrong email off the reply.
> 
> > On Mon, Jul 3, 2023 at 10:08 PM David Lemler <david at lemler.family> wrote:
> > >
> > > Prevent the fifo used in encoding VPx videos from filling up and stopping
> > > encode when it reaches 21845 items, which happens when the video has more
> > > than
> > > that number of frames.
> > >
> >
> > What failure do you see, a memory allocation error? 21845 sounds
> > somewhat arbitrary, maybe specific to your machine, so I'd leave it
> > off the comment and commit message.
> >
> > > This problem occurs when performing the first pass of a 2-pass encode, as
> > > otherwise, the fifo is properly drained, preventing it from overflowing.
> > >
> > > Problem is fixed by manually draining the fifo when performing the first
> > > pass
> > > of a 2-pass encode.
> > >
> > > Fixes the regression originally introduced in
> > > 5bda4ec6c3cb6f286bb40dee4457c3c26e0f78cb
> > >
> >
> > Anton, any comments here?

Is it guaranteed by the libvpx API that no encoded packets are returned
for the first pass of 2pass encoding? If so, then it probably makes most
sense not to send anything to the fifo in the first place.

-- 
Anton Khirnov