[FFmpeg-user] ProRes Quicktimes with audio not playing back reliably

[Thomas Worth]

On Fri, Oct 26, 2012 at 9:57 AM, Bob Maple <bobm-ffmpeg at burner.com> wrote:
> It marks it as part of a bunch of other metadata in an XML chunk, and also
> browsing through with a hex editor I do see some reference to 'FIEL' that
> looks like it's probably in a 'udta' atom (user data.)

"fiel" (always lowercase) should not be in udta. It should be in stsd
(sample description) in the video "trak" atom. Other atoms that may be
right next to it are "gama," "colr" and "pasp." These atoms are
typically appended to the mandatory stsd fields. Final Cut Pro 7
writes these atoms when you modify a clip's timecode.

Also keep in mind that sometimes giant blocks of atoms are actually
enclosed within a "free" atom, meaning they are ignored entirely by
the reader. A fresh encode from FFmpeg shouldn't do this, but when FCP
7 adds timecode information, it marks the old video track atom as
"free," invalidating it.