Avidemux Forum

Avidemux => Main version 2.6 => Topic started by: kevmeister on March 28, 2012, 02:11:02 AM

Title: Audio sync slips when transcoding to AAC
Post by: kevmeister on March 28, 2012, 02:11:02 AM
I'm running 2.6 7787. I am working on TS files from an AVERMedia HD DVR unit at 1080p. I am only clipping the unwanted portions at the beginning and end of the video and transcoding the audio to AAC (FAAC), saving as an MP4 -V2). When I do this, the audio sync of the audio starts in sync with hte video, but gradually slips out of sync. After a couple of minutes, it is very noticeably off.

I am working around this by using a commercial package from AVS, but it has a really crappy editor (no stepping) and won't copy the video. It insists on transcoding it, even if it's H.264 to H.264, so I have and extra lossy operation.

Any ideas or is this a known problem?
Title: Re: Audio sync slips when transcoding to AAC
Post by: mean on March 28, 2012, 04:56:09 AM
Please provide a sample
Does it happen if you use something else than aac, e.g. ac3 for example ?
Title: Re: Audio sync slips when transcoding to AAC
Post by: karl-otto on April 06, 2012, 05:59:47 PM
I made the same experience having input stream .ts (MPEG-TS):

  Video Decoder: Lavcodec
  Video Output: Mpeg4 AVC (x264)
  Audio Output: AAC (lav)
  Output Format: MP4v2 Muxer

and it was not reproduceable with

  Audio Output: AC3 (lav)
Title: Re: Audio sync slips when transcoding to AAC
Post by: karl-otto on April 06, 2012, 06:04:53 PM
Used Avidemux version:
avidemux_r7848_win64.7z 06-Apr-2012 07:05   12M
Title: Re: Audio sync slips when transcoding to AAC
Post by: Jan Gruuthuse on April 07, 2012, 07:34:43 AM
You need to provide sample! No sample no cure. How to provide sample, read this: Cut TS sample (http://www.avidemux.org/admWiki/doku.php?id=tutorial:cut_ts_sample). Upload that sample and provide the link to it.