[FFmpeg-devel] [PATCH][RFC] avcodec: disallow hwaccel with frame threads

[wm4]

On Tue, 19 Jan 2016 21:31:19 +0100
Hendrik Leppkes <h.leppkes at gmail.com> wrote:

> On Tue, Jan 19, 2016 at 9:27 PM, Andreas Cadhalpun
> <andreas.cadhalpun at googlemail.com> wrote:
> > On 19.01.2016 21:22, Hendrik Leppkes wrote:  
> >> On Tue, Jan 19, 2016 at 9:13 PM, Andreas Cadhalpun
> >> <andreas.cadhalpun at googlemail.com> wrote:  
> >>> On 22.10.2015 11:44, Hendrik Leppkes wrote:  
> >>>> On Thu, Oct 22, 2015 at 11:27 AM, Wang Bin <wbsecg1 at gmail.com> wrote:  
> >>>>> VLC is using frame threading with hwaccel  
> >>>>
> >>>> Then they should fix their usage, its broken by design, as explained
> >>>> in detail my post earlier in this thread.  
> >>>
> >>> Care to provide a patch for them?  
> >>
> >>
> >> This requires deep understanding of the code in question, so nothing
> >> anyone not familiar with the code can easily fix, so no patches for
> >> downstreams will be provided.  
> >
> > That suggests that fixing it properly requires a lot of time.
> >  
> >>> They now made VLC's configure error out when compiling with FFmpeg [1],
> >>> because they currently lack time [2] to fix this the way you suggest
> >>> and Libav doesn't return this error.
> >>>  
> >>
> >> They don't lack time, they lack understanding of the flaws in the system.  
> >
> > How can you know that?  
> 
> Because I read the ticket, which says he doesn't want to do it, not
> that he doesn't have time to do it, and because I know that particular
> person and his attitude.

It was discussed to death on #libav-devel too.

> Its fundamentally broken, and making it a warning would re-introduce
> known crashes. So no.

+1

There was this idea that this could be fixed by having some sort of
wrapper decoder, which could take care of the fallback transparently
and without getting into these nasty threading issues. But no idea how
much work that would be.