Author Topic: Systematic audio desynchronization  (Read 1180 times)

nasruddin

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Systematic audio desynchronization
« on: May 28, 2016, 11:45:17 PM »
Windows 7, up to date
Avidemux 2.6.12-release

Trying to repair audio from video files recorded on a pc
at low level, and not synchronized very well in the first place.

I've found that avidemux systematically desynchronizes audio
if aac or mp3 audio output is used.  Or if audio is re-imported
in mp3 (like from Audacity).  In a 2 hour segment, the audio has
gained more than 3 seconds by the end.

Resync an out of sync segment, and save the results (copy audio
only, with appropriate shift to resync).  The saved results are
in good synchronization from beginning to end.   Now save this
result using aac or mp3  - the audio will lose sync with the
video as the track is played , getting farther and farther ahead.

Importing an edited audio track (noise reduction, gain) from
the audio editor is also unsatisfactory.  The speed up might
be worse.

Any ideas on how to resolve this?

AAC import doesn't seem to work for any path or method I tried -
I always get loud pops and sizzles, no identifiable audio, in the
avidemux result.

There are other options that don't seem to work but that's enough
for now.

AQUAR

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Re: Systematic audio desynchronization
« Reply #1 on: May 29, 2016, 09:27:05 AM »
Avidemux has never been able to import AAC audio until recently.
You can now import AAC if its in an ADTS container.

Don't know about your sync issues but might be a time stamp issue as ADM is a time based editor.

Jan Gruuthuse

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Re: Systematic audio desynchronization
« Reply #2 on: May 29, 2016, 10:06:50 AM »
Quote
(copy audio only,)
Audio duration is not going to change (10:30:05) stays (10:30:05) unless video duration is shorter like (10:29:00) you end up with audio time like the video duration (10:29:00)

You don't provide a point of reference, there is nothing to compare to, we are only left with your claim:
Quote
I've found that avidemux systematically desynchronizes audio

For starters update to http://www.avidemux.org/nightly/

Give your exact workflow, your understanding could be different then ours.
If we can't reproduce what your are doing, getting the same end result: end of discussion, nothing we can do.
« Last Edit: May 29, 2016, 10:10:28 AM by Jan Gruuthuse »