Another audio sync problem

[BwanaP]

I have an avi download that is out of synch. Checking previous posts I tried using VirtualDub following the suggestion to make the frame rates the same duration, this made the audio even more out of synch. There was another post suggested using SyncView which when I open the avi in, it plays in sync automatically without showing any adjustments necessary (although I'm not entirely sure if I am understanding this program correctly) .

Since this is a download and not something I have encoded myself, is there something else I should be doing first?

[Suntan]

demux the audio from the file (in vdubmod Stream->Stream List->Demux) and open it in Auacity. If it is out of sync by a set amount throughout the movie then change the offset so that the two are in sync. If audio goes out of sync gradually, then play with tempo and pitch and whatnot so that they sync up.

Check for sync by advancing to a frame (like a gunshot) in vdubmod and advancing to that sound in Audacity. The timestamp for both should be the same with respect to the beginning of the two files. For gradual loss of sync check a scene at the beginning and at the end.

Mux new audio stream back with the video stream.

-Suntan

[BwanaP]

Trying to figure out how to use these programs. Have demuxed the avi and it looks like the audio is off by about 1 sec. I adjusted the offset by adding 1 sec of silence in audacity, is this the correct way? Now how do I mux them back together, with vdubmod or something else? Don't see the option. Also vdubmod created a separate audio, but audio still exists on the video, will this be overwritten on muxing?

[Suntan]

Your on the right track. I assume you either exported a new .WAV file from Audacity and converted to your desired format (MP3, Ogg,etc.) with a different program (like Headac3he)or you converted within Audacity to your prefered format. Anyway, for example say you now have an MP3 file that has the audio corrected. Open vdubmod (doing this from memory as I am at work) open the movie (with the original track that is out of sync) go to Streams->Stream List and it should show the info for the stream that is part of the video. Delete it (not sure if you can right click on it and select delete or just highlight it and hit delete). now select "Add" and browse to and select your new MP3 with the corrected audio. It should show up as the only stream in the stream list now.

Close out of the stream list box and hit F4 (Save As). In the dropdown box at the bottom select "direct stream" (You should see something like that, the other options are fast recompress, full processing mode, etc. These all re-encode the video. Direct Stream does not.)

Now give it a new name and hit save. You should get a video with the new audio stream and hopefully it will be in sync if you added the right amount of offset. If it isn't then try again with a different offset.

-Suntan