[FFmpeg-user] What is my problem with concat?

Nicolas George nicolas.george at normalesup.org
Wed May 8 10:36:14 CEST 2013

L'octidi 18 floréal, an CCXXI, Tom Horsley a écrit :
> I can run -show_packets, but I can't interpret the output :-).
> What would indicate a reset?

You have to look at the pts_time and dts_time, in each separate streams
(stream_index=X). The dts_time should be in more or less regular
progressively ascending order, and the dts_time should be the same values,
possibly with a small offset or slightly out of order if there are B-frames.
Something like that:


(obtained with ffprobe -show_packets -of compact -show_entries
packet=dts_time,pts_time -select_streams 0 file)

You notice that dts_time progresses by 0.04 each time, meaning exactly 25
frames per second (audio would have a different interval, possibly
irregular, but still ascending), while pts_time are the same values, out of
order in groups of 4.

A timestamp reset would just be both values going back to 0 in the middle of
the stream, or possibly a value different from 0 but completely unrelated to
what comes before.

> (I also can't pinpoint the time of the audio sync glitch because
> there is a lot of non-dialogue action leading up to the dialogue
> where it becomes obvious the audio doesn't match the actors lips).

A rough estimate is enough.


  Nicolas George
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 198 bytes
Desc: Digital signature
URL: <http://ffmpeg.org/pipermail/ffmpeg-user/attachments/20130508/27ef3286/attachment.asc>

More information about the ffmpeg-user mailing list