Encode w/ GKnot and your 5.1 AC3 is out of sync? Read This

[I_LIKE_FIRE2005]

Ok, I had been having this problem for a while, and could not figure out how to fix it, untill about 5 minutes ago. The problem is with the extra header information in a 5.1 Dolby AC3 file. VirtualDub was not coded to support the 5.1 AC3 (I guess, its the only reason why it sync's incorrectly with a 5.1 and not with a 2 channel). This problem is actually extremly easy to fix. Open up VirtualDubMod and import the avi. Click Streams -> Stream List and add the 5.1 AC3 created by DVD2AVI. Next, check the length of the movie. Then subtract the length of the AC3 from this value. Right click on the AC3 in the streams list, and set this as the offset (If you calculate the value to be negative, use a negative value in the field). Make sure everything is set to Direct Stream Copy, then save the avi file. Check to make sure, but it should now be perfectly in sync.

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for some reason it doesn't work for me.
my video file is 1:18:54 and the Audio is still 1:18:52.
i opened the ac3 file in the virtualdobmod stream list, right clicked it
- interleaving - delay audio track by: 2000ms-save wav.
is creadted a wave file with the same length!

what did i do wrong?

[I_LIKE_FIRE2005]

First of all, it shouldn't be saving it as a wav at all, it should be encoding the audio directly to the file. You have something set wrong. Secondly, you want to get the difference in miliseconds, thats the number after the '.' in the seconds field. Also, you said that the file you were trying to encode was a 5.1 from a DV device, I doubt this, systems that capture 5.1 surround sounds are huge and cost lots of money, you could probably go with a smaller audio file format.

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which ver of virtualdubmod are you using?

[I_LIKE_FIRE2005]

The one that comes with the new version of Gordian Knot

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i saved the file as avi, but the projected file size is over 60Gb!!!!
what am i doing wrong?

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and one more thing i forgot to mention. when i open the avi file i created
with dvd2avi i get the following massege:
"virtual dub has detected an improper VBR audio encoding in the source avi file (audio stream 1).
the current preference is to rewrite the audio header with standard CBR values during processing for better compatibility. this may introduce up to
38947 ms of skew from the video stream.
If this is unacceptable, decompress the * entire * audio stream to an uncompressed wav file and recompress with a constant bitrate encoder. (bitrate: 124.7+- 15.9kbps)"

what does that mean?

[I_LIKE_FIRE2005]

That error message means that the audio stream was encode with VBR. VirtualDub wants to make the audio stream a CBR without re-encoding the stream. So, the extra bits end up creating more audio data. I think the best thing to do would be to go to the audio menu, and change the stream from DSC to Full Processing Mode. It will take longer to save, but this may fix your problem. Also, the problem with your file size being 60 GB is due to the fact you are saving the video as an uncompressed AVI, change the setting in the Video menu from Full Processing Mode to DSC.

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finally it worked!
thanks!!!
now one last question. the original avi file (the one with no sync) was
800mb this one is about 1.6gb.
1. how come?
2. is there anyway to decrease the size?
3. the file is in vhs quality. i used divX5 codec. if i use xvid codec would i get better quality?

and again thanks!

[I_LIKE_FIRE2005]

Re-encoding with XviD will probably give you a slightly higher bitrate, but not enough to make a noticeable impact on quality or file size. I think the problem with your movie being so large is that when you changed the audio to Full Processing Mode, you did not specify a codec, so VirtualDub used an uncompressed wav. This will pretty much end up having the same effect as an uncompressed video. Go to the audio menu and select compression, change it to MPEG Layer-3 (MP3 audio) and select 192 kBit/s, 44,100 Hz, Stereo (Which is probably what your source audio is, I would find it most unlikely if you had a 48,000 Hz audio. Besides, the difference in quality is almost undetectable.) This should bring your file size back down to about the 700 MB area.
Edit: Do NOT re-encode from your DivX file. Always encode from the original copy. I'm not sure if you know this, but I thought it would be best to tell you. You lose quality every time you "copy a copy".