[FFmpeg-user] Please release me from despair: multiple overlay images with fade in + out

[Stefano Sabatini]

On date Wednesday 2015-01-21 23:04:49 +0100, Dog Film wrote:
> Dear Master Sabatini,
> 
> thank you so much, it finally works now. In fact I had a very similar
> solution yesterday and was so sure, that this must be right, I was
> reading the overlay and fade manual entries over and over again, but I
> missed the fact that -t  is needed here and it did not work.
> 
> Without the -t $DURATION parameter what happens is, that ffmpeg
> renders to the last frame, then the fps goes down to something between
> 1.7 - 3.4 or similar and the drop value is constantly rising - and the
> encoding never stops. Looks like this:
> 
> > frame=  751 fps=3.3 q=28.0 size=    1526kB time=00:00:27.72 bitrate= 451.0kbits/s dup=0 drop=13218
> 
> The video is generated and the result is ok, but the process never
> stops (at least it does not stop in an expected timeframe)
> 
> Why does this happen? Why does this need the -t value, when I feed a
> video with fixed length?
> 
> Is it possible to avoid having to use -t ? (Saving me one roundtrip of
> getting the length of the input video.)

My guess is that the behavior is due to a defect, I checked on trac
and I found this:
http://trac.ffmpeg.org/ticket/3789

I'm willing to have a look at the bug, but don't hold your breath. For
the moment you can get the video input duration through scripting as a
workaround.

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