Avidemux Forum

Avidemux => Main version 2.6 => Topic started by: MiStr on May 20, 2012, 02:31:49 PM

Title: r7969 - avidemux causes audio shift
Post by: MiStr on May 20, 2012, 02:31:49 PM
I was very pleased to find out that version 2.6 of avidemux was able to process the AVCHD files recorded by my camcorder.

However, I noticed that the time line always started at 0.444 s. Looking at the terminal output I found:

  [addReferenceVideo]  The first frame has a PTS >0, adjusting to 444 ms

During playback and after playing back the avidemux encoded file, a shift between audio and video became apparent.
When clicking on "Audio output - shift" I get an error message. It seems that this function is not implemented - yet.

The audio shift is not present in the source material (VLC).

It seems that avidemux demuxes the audio portion without problems, skips the beginning of the video stream, but failed to adjust the beginning of the audio accordingly.

Is there any work-around?

Thanks

Ubuntu amd64, 11.10, r7969-git
Title: Re: r7969 - avidemux causes audio shift
Post by: mean on May 20, 2012, 03:05:35 PM
Could you provide a sample source file + your tinypy project ?
Title: Re: r7969 - avidemux causes audio shift
Post by: MiStr on May 21, 2012, 08:23:38 AM
While preparing the test case I noticed that the audio shift only occurs if the audio is "copied" through.
The same file with the audio re-encoded to MP3 seems to stay in sync.

Attached are the two project files (1. copy, 2. MP3).

I would also attached the source file, but 6 secs of HD footage are approx. 11 MB in size - too large to attach them. Where can I put it?
Title: Re: r7969 - avidemux causes audio shift
Post by: mean on May 21, 2012, 08:35:11 AM
rapidshare or similar would do
Title: Re: r7969 - avidemux causes audio shift
Post by: MiStr on May 21, 2012, 12:07:49 PM
The source file can be found here: https://rapidshare.com/files/1148063109/00092.MTS?bin=1
Title: Re: r7969 - avidemux causes audio shift
Post by: mean on May 21, 2012, 01:00:09 PM
I think the problem is the avi plugin that does not handle correctly the "does not start at 0" audio
When re-encoding avidemux adds silence at the beginning so it works

Real fix : Improve avi writter plugin
workaround : use another format, mp4 or mkv