[FFmpeg-devel] [PATCH 1/3] avcodec/vp56: Require 1 undamaged frame for 5 damaged frames for concealment to be used

wm4 nfxjfg at googlemail.com
Wed Mar 15 21:08:16 EET 2017

On Wed, 15 Mar 2017 15:02:08 -0400
"Ronald S. Bultje" <rsbultje at gmail.com> wrote:

> Hi,
> On Wed, Mar 15, 2017 at 2:51 PM, Michael Niedermayer <michael at niedermayer.cc
> > wrote:  
> > On Wed, Mar 15, 2017 at 08:58:39AM -0400, Ronald S. Bultje wrote:  
> > > I'm actually starting to believe that the error concealment code in this
> > > decoder (vp56) is fuzz-specific code also. Is there a real-world input
> > > where the user experience is improved by this code?  
> >
> > I have no real world damaged vp56 files iam aware of, in fact i dont
> > think i remember seeing vp56 in the wild, what i have are just our
> > samples or at least thats what iam concioulsy aware of
> >
> > Damaged data is inevitable though from packet loss, damaged sectors
> > and other, so damaged data is real it occurs with anything eventually
> > that is stored or transmitted. The only way it can never occur is if
> > a codec is never used more or less
> >
> > and error concealment can provide better quality than lack of EC.
> >
> > when fixing fuzz issues iam trying to do something usefull when theres
> > a related feature like implementing the very basic EC code in vp56.
> > Working error concealment code would be nice for every codec IMO
> >  
> I agree in general, but we need a way of verifying that it actually works,
> which in this case means "leads to an improvement in decoded stream
> quality". I don't think that has been verified here.
> No benefit (..) for a very quickly escalation in code complexity related to
> this feature makes me wonder whether that's the right approach.
> but if people dont want EC code in vp56 then we can drop this code of
> > course, makes no difference to me.  
> I would personally probably vote to remove EC from vp56. I'd like to hear
> other people's opinions also, don't remove it just because I said so ;-).

I think the right question is: are vp56 streams usually broken?

For example, for mpeg2 or h264, the answer can be "yes" because those
are used in DVB (i.e. very unreliable transport).

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