5.1 sound passtrhough audio out of sync, why?

[luxirom]

finally managed to convert a .vob file to mpeg4 with ffmpeg and 5.1 sound, but the audio is out of sync...

even if i reencode the sound as .ac3 on a lower mbit level, it doesnt improve.

i don't guess its the speed of my machine on playback... its a dual 2 Ghz G5

whats the problem here?

i play with vlc or mplayer x... both dont work.

regards luxi

[major]

Most probably, it is not the audio track being offsync, but the video track.

[luxirom]

hmm...

thats an option.. indeed...

and what to fix that? i have tried it with different .vobs...

problem doesnt come from them i guess

[major]

You should make sure that you're not changing the framerate while encoding the video track. PAL should be encoded to PAL and NTSC FILM to NTSC FILM.

[luxirom]

hmm.. ok.. tried that one.

tried all presets and manual custom framerates... 20fps, 40fps, and the standard fps for pal, ntsc, ntscfilm

the interesting thing is, if i preview them or play them in mplayer x:

1. the sync-offset is in all settings the same
2. if i “seek forward“ in the movie (fast forward) the sound is starting all over again: different picture, sound from the beginning...

i dont know if it gets better if i let it finish.. but i will try now... hope it helps... i have checked the framerate of the .vob: its 25fps PAL

keep you informed

luxi

[luxirom]

ok.. done... output on console reads:

Encoding started on Sun Dec 26 18:38:17 CET 2004
Input #0, mpeg, from '/Users/admin/Desktop/BABYLON5_RIVER_OF_SOULS/TITLE01-ANGLE1.VOB':
Duration: 00:39:01.4, start: 0.037611, bitrate: 13914 kb/s
Stream #0.0: Video: mpeg2video, 720x576, 25.00 fps
Stream #0.1: Audio: ac3, 48000 Hz, 5:1, 448 kb/s
Output #0, avi, to '/Users/admin/Desktop/BABYLON5_RIVER_OF_SOULS/TITLE01-ANGLE1.VOB.ff.avi':
Stream #0.0: Video: mpeg4, 544x304, 25.00 fps, q=2-15, 928 kb/s
Stream #0.1: Audio: ac3, 48000 Hz, 5:1, 448 kb/s
Stream mapping:
Stream #0.0 -> #0.0
Stream #0.1 -> #0.1
bench: utime=2511.840s
video:593989kB audio:294821kB global headers:0kB muxing overhead 0.808232%
Encoding completed on Sun Dec 26 19:16:37 CET 2004




video still out of sync.