WMV to AVI desync - vfr or different audio / video durations?

[DK-II]

When converting a wmv file to avi the av desyncs. Could this be caused by the wmv having variable framerate and the audio and video not being the same length? In other words, is it possible that I'll have to fix both problems to sync the av rather than just having to fix one? If this is the case what's the best way to do this?
Thanks in advance.

[redwudz]

Usually VBR video doesn't cause sync problems, but VBR audio does when encoding. Drop the AVI into VirtualDub or VD Mod (My favorite) and check the lengths of both audio and video.

Two common types of sync problems, the audio has the same amount of sync error throughout the video. Or the sync drifts off and is worse at the end of the video. The first can be fixed by changing the offset. VD can do that. The second would need to have the running time of the video or the audio adjusted. This is more common with VBR audio. Neither are that easy to get right, so it's something to avoid in the future. A third problem can be dropped or corrupted frames and that can cause a combination of the above problems. Hard to fix.

And what are you using for the conversion? That may have a bearing on the sync problem.

[DK-II]

Usually VBR video doesn't cause sync problems, but VBR audio does when encoding.

I wasn't talking about VBR, I was talking about VFR (variable framerate).

A third problem can be dropped or corrupted frames and that can cause a combination of the above problems.

I don't think it's that because I've checked for bad frames with Virtual Dub and none were found.

And what are you using for the conversion? That may have a bearing on the sync problem.

I have tried many different methods of converting the wmv to avi. I've used different programs (Virtual Dub, TMPGEnc Xpress, Windows Media Encoder 9, Stoik, SUPER, ASF Tools, Graph Edit, AVI Synth) in different arrangements (e.g TX to convert wmv to xvid video & mp3 audio then VD to mux xvid & mp3 into avi) and I've tried different codecs (xvid, divx, uncompressed...) with different settings (variable bitrate, constant bitrate, higher / lower bitrate, sampling rate, B-VOPS on / off, no of passes...). Nothing has worked so far. At first I thought the problem was VFR so I tried to convert to a CFR wmv before converting to avi. Didn't work (after trying lots of different methods) so then I tried converting to desync avi and then syncing the avi by changing audio / video lengths (many different methods again) but it's still not working. The beginning is always in sync and I can get the end close to being in sync but the middle is never in sync. I managed that by stretching the audio but if it's only the middle that's out of sync I'm thinking it can't (just) be the audio and video lengths that are the problem. That's why I want to know if both VFR and audio / video lengths are causing desync.

[chucklee]

use graphedit and build a graph.
the file will come out double the framerate.
run it thru v-dub
and process every other frame
to get rid of all the extras
it works ive done it
its the only way to do it
i found if you cant figure it let me know ill leave more detailed description

[DK-II]

use graphedit and build a graph.
the file will come out double the framerate.

What graph should I build? Doesn't the file have to be interlaced for it to come out double the framerate?

run it thru v-dub
and process every other frame
to get rid of all the extras
it works ive done it
its the only way to do it
i found if you cant figure it let me know ill leave more detailed description

Will running it through Graphedit make it constant framerate without changing the length of the video? If not, the above method won't work will it?

Thanks for your help

[chucklee]

yes it makes it constant framerate.
i have done some videos this way after trying every other way
it took me a few tries to get it right but it worked
i will upload a sample graph and screenshots of the steps for u later

[chucklee]

okay here it is
first load yer wmv in graphedit
it will look like so..

then add from audio compression mp3
from video compression xvid
from directshow source avi mux and file writer
when you add file source make sure you name it thenameyouwant.avi
you have to put the .avi
it will look like so

now connect them so they look like so

now hit play and let finish
when its done load in virtualdub
and if you notice in file information the video is now twice the length of the audio
sort of like this...

this is because there are dropped frames
dont know why there are if anyone knows i'd like to know myself
then pick video and framerate and chose process every other frame
make it direct stream source for processing type
the result will be an in synch x-vid avi file with mp3 audio

let me know if this works for u ok if any problems let me know
ill walk u thru

[DK-II]

Thanks, I'll try it and see if it works. I've spent a helluva lot of time trying to figure this one out. It's kinda fun messing around with different programs, filters, codecs etc. and learning new stuff but it's frustrating when you never end up with the "end product"
I'll let you know if it works

[DK-II]

It hasn't worked I've managed to get the beginning and end of the file in sync but not the middle (same as before). I had to alter the source framerate (I'll call it sf) before re-encoding because VDub was outputting a file with a framerate ~2 times too big and duration ~half the size it should've been. I fixed this by doubling the sf but the av wasn't quite in sync so I kept altering the sf until the av was in sync at the beginning and end of the file. Unfortunately, when I succeeded I found the middle wasn't in sync Have you got any more suggestions? I have a theory about altering audio delay as well as audio or video length to make the whole file in sync but I think that would be a very difficult method to use.

[chucklee]

what is the source of the file ?
do have a sample or something i can look at or work on let me know

[DK-II]

I downloaded the file with Azureus using a torrent. I have another copy of the file but with a lower resolution and bitrate which won't keep sync when converted to avi. I tried downloading the newer file hoping the original was corrupted but I'm having the same problems.

[DK-II]

I don't know if this has any relevance but it just occured to me that you should know the codecs used in the wmv file are wmv1 & wma2.

[chucklee]

i sent u personal message w/my email
send me the torrent and ill see if i can work it out