[Cin] Audio Offset Finder

[Andrea paz]

> So it builds a linear timeline?

No, just duplicate sources but with the external audio embedded and
synchronized. A little like the transcode function that asks you to
hide the original media leaving only the newly transcoded.

1- collect the files into one folder (video files with internal audio
+ external audio). Duplicate they. Calculate the length of each file
by timecode.  If the external audio is not unique, concatenate and
insert blanks to maintain timecode linearity. [?]
2- Synchronize the files with the external audio track (your choice of
timecode {or waveform}). [?; you consider the external audio track to
be the "master," you synchronize the other media with reference to its
timecode. Or you take advantage of CinGG's code for "Align
Timecodes".]
3- Duplicate and trim the external audio track so that there are
coincidental chunks with every files. [?; you assign each media a
timecode based on that of the master and trim on copies of the master
for each media; ffmpeg -ss, -t, map]
4- Associate the external audio chunks with the relative files. [ffmpeg map]
5- Delete the internal audio tracks leaving only the external one. [ffmpeg map]