> >This tells me to use aac_adtstoasc to fix it but as usual cannot quite >get the command. What is the -bsf:a aac_adtstoasc command... > That's OK (bsf=bit stream filter). Add "-bsf:a aac_adtstoasc" to your command and try again like this... ffmpeg -i foo.mp3 -c copy -bsf:a aac_adtstoasc foo.m4a