[FFmpeg-devel] [PATCH]lavf/decimate: Fix total difference for the first frame

[Clément Bœsch]

On Mon, Jan 04, 2016 at 08:53:24PM +0000, Carl Eugen Hoyos wrote:
> Clément Bœsch <u <at> pkh.me> writes:
> 
> > +    if (cyclestart == 0) {
> > +        vdm->vmi[0].maxbdiff = vdm->vmi[1].maxbdiff;
> > +        vdm->vmi[0].totdiff = vdm->scthresh + 1;
> > +    }
> > +
> 
> > I suggest to "cherry-pick" this if it works.
> 
> Nicolas has already found a very similar solution 
> that only differs in rare cases (although the change 
> should be ported) and not for the file in question.
> Sorry to say this but I wonder how the filter ever 
> passed any test without this (or a similar) change.
> 

I must confess that my initial testing was very light (it did match the
behaviour I was trying to copy with the sample I was using though), but I
remember saying that I was waiting for more testing from users since it
was supposedly a very much requested feature. Unfortunately, the issues
were raised very late, at a time when I didn't actually have much time to
look into this (like right now).

BTW, the main reason I pasted the commit was because of the explanation
for the "+1" you seemed to be wondering about.

> The OP of ticket #4990 claims that for his sample 
> the first frames are correctly handled with avisynth.
> (I have no idea how to test this.)
> 

You can maybe test with Vapoursynth (works on Linux). It was IMO a real
pain to use years ago, and documentation was severely lacking
(understandable because of the ambition of the project), but it might be
simpler nowadays.

[...]

-- 
Clément B.
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