Worsening synch issue

JohnK

Someone I know on a different forum made a video last week on a mini-dv camera. He’s extracted the video to his PC as an MPG but when it plays the audio although fine at the start begins to get more and more out of synch. He’s supposed to be sending me the MPGs but might be a while before I actually see them due to the size of them but I’m hoping to use the time between now and then to try and figure out what sort of software could help fix this. The clips shouldn’t be too long, about 5 minutes each or so but are approx 1GB in size. Any ideas? I know if it was just a static bit out of synch I could fix that but since its progressively getting worse I’m a bit stumped. To be honest I’m just hoping he has a low spec machine that’s struggling with 1gb video files.

Thanks.

subway

i know of two things that can cause this (im not a pro)

one is variable rate mp3 audio, if the audio is mp3 try converting to cbr and muxing it back in.

the other is ntsc and pal.
because they have different frame rates the sound can get progressively more out of synch.
the fix for this is to properly identify the type of video you have.
if you tell a machine to play back a pal file as ntsc it wont match the audio properly and vice versa.

JohnK

Thanks subway. I dont think the audio would be MP3 but I'll certainly check when I get my hands on the video. The PAL/NTSC thing could be a posibility though. I wonder also, if the camera was recording in NTSC or PAL and the import application tried to capture it in the other (ie. camera records ntsc and importer tries to grab pal) could that cause something like this?

subway

from my experience, if a conversion from pal to ntsc is done wrong you will lose synch.
it could have been done wrong at import