I downloaded avidemux and opened the avi and it came up with the follwing 2 prompts:
Build VBR time map?
Avidemux detected VBR MP3 audio in this file. For keeping the audio/video in sync, time map is needed, build it now? Yes / No
Packed Bitstream Detected
Do you want me to unpack it? yes / No
I clicked ok to both, I then pressed play in avidemux and it was absolutely perfect, I saved it and it starts ok but then gradually goes out of sync.
Can someone give me some instructions on how to sort it