[FFmpeg-user] Comparing audio to sync video

[Joshua Grauman]

Yes, exactly. Thanks for the mathematical name for what I'm trying to do. 
I don't necessarily need to do it in ffmpeg, so I found this, which should 
be easy to adapt for my needs (includes sample C code).

http://paulbourke.net/miscellaneous/correlate

Josh

>
>>  I have two video cameras recording an event 30 minutes long. I hit start
>>  on the two cameras at different times. I would like to figure out a
>>  command-line script that can basically diff the audio to figure out the
>>  difference between the start times and align the videos. The audio won't
>>  be exactly identical as they are two different cameras, different mics,
>>  different locations, but they are both recording an interview, so the
>>  audio should be able to be synced. Any ideas?
>
> I think to automatically find the best-fit audio delay between the two tracks 
> you would need to calculate a cross correlation of the two audio tracks. As 
> far as I know this doesn't exist in ffmpeg. But it would be nice to have.
>
> Michael
>
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