I am trying to fix an audio sync issue for a video file that is off by a second from the 25th-26th minutes of a 30 minute file. I have looked at a few different tools such as avidemux etc. I see similar questions on here also, but they all appear to fix sync issues for the entire file which is not my case. Any help for this problem would be much appreciated.
My answer is relevant to VLC media player, which is avaliable for most systems.
A nice tutorial by lifehacker
You can reset the offset of the audio on the parts it OK (just set it to zero).
If you want to save the corrected file for future use, instead of single shot streaming/watching then you could try OpenShot video editor in combination with Audacity (both available for Linux). Or if you're fan of commandline have a look at this:http://ubuntuforums.org/showthread.php?t=2074181.
The basic steps are: - separate audio from video - use Audacity to cleanup you video file - merge back video and audio.
Separating and merging can be done using OpenShot (http://www.openshotvideo.com/2009/07/audio-editing-with-openshot.html) or FFMPEG (see link earlier in this post).