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.