View Full Version : Audio asynch when converting captured avi's

31st December 2001, 10:38
I have an ATI TV Wonder card and I am capturing with Virtual Dub in 320x240 resolution. I am using the Intel Indeo 5.10 quick compression. I then cut parts of the avi for each episode of a show that I captured. When I view the avi files they are completely synch with no problems. But when I encode them with TMPG using the correct settings (95% sure) they become asynch. I even tried fixing the fps in virtual dub becuase it was capturing at some weird 14.990 fps instead of 14.985. They always seem to go asynch though. I then tried converting to divx and they are still synch, but then converting to mpg they become asynch!

i have also noted that these synch problems happen spurratically throughout the mpg (the first few minutes will be fine and then all of a sudden it gets off synch, and gets worse like this further into the file)

here are some possiblities i have concluded:
1. i have done something wrong trying to convert to mpg since its only mpg and not avi that i get the asynch
2. some frames might have been dropped during the capture due to the cpu not being able to keep up with the Indeo Video compression and thus causing spurratic asynch problems. i watched the cpu meter in virtual dub for a few minutes and it never went over 70% so it seemed like the cpu shouldnt have had problems keeping up with the compression.

so what i am asking is where does the problem lie?
in the capturing process? should i use a some different compression or no compression at all?
or is it the encoding process? why do the avi's appear synch but the encoded mpg's are asynch?
is my only solution that horrible thought of manually synching each of my mpg's using cooledit? if this is the case i dont think my capture card is worth the $50 i paid for it. this is a terrible hassle just to get synch'ed audio/video to put on a VideoCD for a standalone player.

Thanks in advance to whoever can help me out.

31st December 2001, 21:22
My guess is that it's a problem with TMPGEnc. Have you tried using VirtualDub to extract the WAV data from the AVI file and then encoding it separate from the video in TMPGEnc?


P.S. If you've got enough hard drive space, Huffyuv (and possibly MJPEG) are higher quality capture codecs.

1st January 2002, 10:22
what program are u using to cut out parts of the avi (im assuming you mean the commercials) cuz vdub wont do it, i tried that many times it does some sort of offset by a few seconds or smth when u delete a section, but the audio isnt offset or something so its majorly messed up

i use adobe premiere to edit the commercials/etc.. then save to mpg then encode in vdub

1st January 2002, 21:04
I don't have Huffyuv or MJPEG in my list of video compression codecs, do I have to download these from somewhere? If so, where? I have about 10-15 gigs of space to play around with, this should be enough right? Especially if I am only capturing about an hour or more of video?

Socko, Im using Virtual Dub to cut out the commercials by selecting part of the video and saving to another avi, and then joining the little avi's that I extracted. That offset you are talking about, do you mean because it can only cut from keyframes? I told the compression to put a keyframe every second so I would be able to cut the video pretty accurately.

2nd January 2002, 01:14
I am not sure what you meant about seperate encoding with virtual dub so i tried 2 different methods, both failed.

1. I just extracted the WAV data in virtual dub and then used this file in TMPG and got the exact same output as using the avi audio in TMPG.
2. I extracted the WAV data in virtual dub and then used the BeSweet GUI 0.5 to convert the mp3 to mp2. I then used TMPG to do a Video-Only encoding of my captured avi to an .mv1 file. Then under the TMPG tools I multiplexed the mv1 and the mp2 file into a video cd and I got an error, "1 s packets cause buffer underflow, the MPEG file might cause error when it played". And in fact the mpg is not playable.

2nd January 2002, 08:37

One MJPEG codec:

Exactly what capture settings and compresion codecs are you using? Why are you capturing in half the frame rate? How big is the AVI you're trying to encode? Are you using the latest version of TMPGEnc?

I'd try capturing with one of the codecs I mentioned using 16-bit uncompressed PCM audio. You might want to try frameserving the video to TMPGEnc to see if it resolves the problem.


2nd January 2002, 20:49
I am sorta new to capturing, actually this is the first time I have ever tried it. I read almost your entire web site, it looks very complete, good job. I think I am going to just follow everthing in your guide and try again with full fps and huffyuv or mjpeg and see how that works out. Thanks a lot for your help if I have any more problems I'll make a new thread later.

Best regards, happy new years,