[FFmpeg-user] Assumefps() equivalent in FFMPEG

[Reuben Martin]

On Wednesday, July 30, 2014 07:02:49 AM Eugene Gekhter wrote:
> In my avisynth workflow, I stretch the audio to 36% of its original rate to
> get it to play at the right speed and with perfect sync with the video,
> something like video.*assumefps(*18*)*.*TimeStretch(*rate=36*).*

In ffmpeg you would normally use a filter called "atempo".  However, this much 
stretching is beyond the range on what it can handle. (it's range is 0.5 - 
2.0)

If you want to use an ffmpeg workflow, your best bet is to split the audio off 
into a separate file and process it with rubberband, and then splice it back in 
with the stretched video.

-Reuben