trying to convert avi w/ dolby ac3 audio and it wont sync right

[cduval04]

Hi.....I'm kinda new to this conversion stuff and have limited knowledge, although always eager to learn more. I am trying to convert for ipod an avi file that has the xvid video codec and a dolby ac3 audio codec. All of the other avi files I have converted have an mp3 codec, so i have never converted a file like this and can't seem to get it to synch with the video.
The input file is 48000Hz, 192Kb/sec and video framerate is 29.970 with a dolby ac3 codec. the file I converted is 48000Hz 96Kb/sec has a framerate of 29.970 and has the mp4 AAC LC audio codec. it has the h.264 video codec with an mp4 extension.
What did I do wrong? the wrong framerate, audio bitrate or something else?? I have tried super. I have also tried xvid4psp and going to the video menu------->then interlace/framerate----->then under "detect source type" clicked "analyse" and it analyzes and automatically changes the output framerate from 29.970 to 23.976. When I go to audio-----> editing options, it says the input audio track has a delay of 31ms. Is that part of my problem?? there are just to many factors here and I just dont have the knowledge to know what to change and what to leave alone. Usually I have no problem with audio synch issues when converting, but I am assuming the different audio codec and the specs of this particular file are playing a part in my troubles. Any suggestions would be appreciated. Thanks!

[manono]

31ms isn't too much - probably not enough to even notice. However, determine the amount it's off after the conversion, and then set that amount in the delay section of XviD4PSP when you do it over again.

[tomlee59]

You might have done nothing wrong. First of all, how much of a sync error is there? And is it a constant throughout the video, or does the sync error vary (e.g., grow linearly with time)? You can use mplayer or VLC to measure the actual sync error (indirectly, by varying the offset manually until the sync seems good to you).

As a rule, lip-sync errors are not noticeable until you get to around 100ms, and not super annoying until you get to around 150-200ms. Errors of 50ms are noticeable during discrete impulsive events, like explosions or door slams. A 30ms error corresponds to about one frame, and will not be noticeable to anyone not looking for it frame by frame, essentially.

If the sync error is a constant offset, that's generally easy to fix. If it drifts at a constant rate, that's readily fixable, too, but requires more effort. Any other behavior involves much more labor to correct.