Gents, I've been at this for 2-3 months already... I've got following dilemma - WIN XP box, ffmpeg 0.4.9-pre1; input files: AVI - XVID 702x480 29.97 1500kbps with 1ch 44.1 16bit pcm/ and various WMV v.7/v.8/v.9 --- all need to be converted to 3gp for 1 phone model. First mencoder converts these to libavc mp4 and scales it to 176x144, preprocessing it fo ffmpeg so to say. Then ffmpeg encodess it to 3gp like so: ffmpeg -async 100 -i 176_libav_pcm.avi -bitexact -vcodec mpeg4 -s qcif -b 50 -r 8 -acodec amr_nb -ac 1 -ar 8000 -ab 12 -nr -hq -preme -qmin=3 -pass 1 async100_12_8fps.3gp As you can see I tried multiple async values, fps and a/v brate. I noticed that different -ab / -r shift audio track differently, almost none of them hit the spot. It's only .2 - .3 second behind, but it does get annoying. It seems that delay is constant across 5 min files. I tried -itsoffset -0:00:00.xx and of course it works but it seems to vary from file to file.. So, is there a way to convert xvid/wmv to 3gp without loosing audio sync? there's really no explanation of -async function anywhere.. has anyone links to some more detailed docs regaqrding it? Any help is appreciated guys. Thanks. Dennis.