[FFmpeg-user] AVCHD to QT and Avid

[Carl Eugen Hoyos]

Thomas Worth <dev <at> rarevision.com> writes:

> > I've tested with FFmpeg, but the result was a file that 
> > starts with a couple of frames white,

I can reproduce this,

> > and has repeated frames every now and then in QT player.

I wonder how this can be reproduced...

> > Besides Avid refuses to AMA to it.

Perhaps an AVID-specific atom is missing?
I cannot test this, but if you have a file with 
similar characteristics that plays with AVID, you 
could search for atoms and try to damage them until 
AVID does not play the file anymore (but FFmpeg 
does).

> > Input file here if you like it: http://wtrns.fr/grXVo5ikaUWgk
> 
> The file you linked is compressed H.264 with B frames. I've 
> never had luck with ffmpeg / FFmbc when rewrapping H.264 with 
> B frames to MOV. Did you try MP4 with FFmbc? That's the only 
> way I've gotten it to work without the playback problems you 
> mention. ffmpeg still won't work even with MP4. You'll still 
> get the white frames because of what seems to be a bug in the 
> MOV muxer.

Could you confirm with a high certainty that this 
was ever reported? (I ask because I think I only found 
out now about this problem.)

> Carl, as a technical note the reason he is getting the white 
> frames at the head with ffmpeg output is because of a bug in 
> movenc.c. The the elst atom is being written with incorrect 
> values because it is confused by the negative DTS delay with 
> B frame media. Baptiste fixed this in FFmbc. The fix involves 
> modifying the start_time value based on I believe first_dts 
> and then adding packet.duration to it. I don't have the source 
> in front of me, but if you compare the source of ffmbc.c and 
> ffmpeg.c you'll see what I'm talking about.

The last sentence sounds extremely unlikely to me, 
but see above...

Carl Eugen