Try using the tools of Womble Mpeg Video Wizard to demux the video. Then take the demuxed streams and remux them again with Womble Mpeg Video Wizard. When you remux there's an option to change the A/V sync. Note: When you demux Womble will save the audio as an .mpa file unless you change the name to .ac3, even if you allow the default of .mpa womble will know it's ac3 when you remux and won't re-encode the audio, it will still be AC3. I hope that helps. Mike.