about virtualdub sound

[maginniss]

dont mean to be a lameass hemroid but hey lol

with any avi movie...should you do the audio thru virtualdub and save the sound as a wav.file? then load the wav file and the avi file in tmpgenc then start codin?
and yes im tryin to make a vcd

[Craig Tucker]

If the audio has Variable bitrate compression yes. If not then it should not be necessary. Open the file in virtualdub, if it gives a VBR audio warning then you need to save the audio as an uncompressed wav file. Another way to check is to play the file using virtualdub, if the audio is in sync no need to sav wav file. If the audio is out of sync, then you need to save the wave file or it will be out of sync when you encode.

Craig

[edsmith77]

Craig,
If after capture by Vdub the audio and video are not in sync (determined) by playing back in vdub) how will saving the wav file correct the sync problem.??

Ed.

[Craig Tucker]

If you have captured it then it should be in sync. I am referring to AVI files (typically downloaded with P2P applications) which are compressed using a divx codec and the audio is compressed as a VBR mp3. In this case the audio has to be uncompressed, so that it is in sync when encoded to mpeg.

Craig

[edsmith77]

Craig,
I hate to be a dolt but I just do not seem to fathom what you are trying to tell me.
If I use vdub to capture video and audio at a particular resolution and all reamins in sync, then what would change such that at a higher resolution it no longer remains in sync?
Last nite I made a 60 second capture (@480x480) and saved the resulting avi and corresponding wav file. Rendered them together to vcd std with tempgenc. The audio sync did not improve. It is so bad that after a 60 second capture the video and audio are about 3 seconds apart.
I am not sure by what you mean "In this case the audio has to be uncompressed, so that it is in sync when encoded to mpeg." How does one uncompress a wav file??? or get an mp3 audio file from a Vdub capture?

Still confused.
Ed

[Craig Tucker]

We are talking about different situations here. You are obviusly loosing audio sync during capture, I assumed you were loosing audio sync during the encoding process.

When people talk about saving the audio as an uncompressed wav file, this is from a file that has been compressed using a divx codec, and the audio has a vbr mp3. This is obviously not the case in your situation. With this situation if the avi is played the audio is in sync but because encoders such as tmpgenc do not handle vbr audio streams very well the audio goes out of sync during the encoding process. Hence the need to save the audio stream as an uncompressed wav.

Are you using vdub to capture ? what format are you capturing to ? (I would suggest YUY2 with huffyuv compression - good lossless codec). Are you dropping many frames during capture ?.

In virtualdub click on video framerate, do the audio and video framerates match, if not click on change so video and audio durations match, does this help ?

Craig