[FFmpeg-user] Trying to create matching multi-audio-track mp4s from ProRes sources

[Ted Park]

> On Feb 13, 2019, at 3:01 PM, Harvey Pikelberger <communque at gmail.com> wrote:
> 
> BUT for some reason the time code changed.  So a clip that had started at TC start/end of 12:31:20:13 / 12:31:42:16 converted to 12:30:35:12 / 12:30:57:15.

The 0.1% change makes me think the timecode was converted to/from drop frame. Take another look at the separator before sub-second time to see if they really are both “:”

> I'm not familiar with the -f option and didn't immediately find it in the FFmpeg documentation
> How does that work?

It sets the output file format, overriding what is guessed from the filename extension. There are some subtle (and some not so subtle) differences between quicktime, iso base media and mp4 formats. Files with timecode and edit list from an NLE, sometimes with references to external files = qt in my mind.