Assuming the captured file is an .mpeg, have your tried running it through an .mpeg editor like VideoRedo or Womble? Mpeg editors can recalculate the time stamps. It's not a guarantee, but they can correct some audio sync problems. VideoRedo Plus has a free 30 trial: http://www.videoredo.com/
You don't have to actually edit it. It's just that with some audio sync problems running the .mpeg file through an .mpeg editor can fix the sync problem. It doesn't always work but it's an easy thing to try first. I'm more familiar with VideoRedo than Womble. I think in Womble Mpeg Video Wizard you could select Tools, Mpeg systems stream converter, then select your your .mpeg file. Give a new name for the output file, select mpeg2 program stream, then convert. There may be other ways to open and then save an .mpeg file in Womble. The basic idea is to let the .mpeg editor remux the file. In VideoRedo Plus you would open your .mpeg file, select Tools, Quick Stream Fix, give the output file a name, then start quick fix. Then save the file. I have fixed an audio sync problem on an .mpeg file using VideoRedo this way. http://www.videoredo.com/ An .mpeg editor can recalculate the time stamps of an .mpeg file. It depends upon what caused the audio sync problem in the first place as to how successful this approach will be.