Audio gone after merging .avi files

[junee]

I merged three .avi files into one using D-Vision but now the audio is gone in the merged file. I am viewing these in QuickTime Player. (I don't have QuickTime Pro.) FWIW, I do have Perian. Do I need a codec? In the end I want to post this on YouTube. Thanks for your help.

Update: Here's what I have tried so far. Nothing worked. 1) Used D-Vision with avimerge option. 2) Used D-Vision with mencoder option. 3) used ffmpegX. 4) Have tried playback with QT Player, VLC and WMP.

 

[junee]

Figured it out

I was able to solve this problem. Here's what I did in case it's useful to anyone.

1) Used Flv Crunch to convert each .avi into an .mp4.
2) Used MPEG Streamclip to join all three .mp4 files into a single .mp4 file.

It took a few hours, but the audio is intact. But after all this, the file was rejected by YouTube for being too long. Somehow fitting.