Quick question on DGIndex

[dimtim]

Hey I generally use DVD Decrypter. DGIndex, and Gordian Knot to convert from dvd to avi, and I noticed that when I ripped a dvd, in the information from DVD Decrypter it said the audio delay was -75 ms. Then when I used DGIndex to seperate the video and audio streams, it said the delay should be -9 ms. Why is there a discrepancy? The video and audio actually came out in sync (at least as far as I can tell) but I'm curious as to why those two numbers were different.

Thanks
Tim

[manono]

Hi-

Why is there a discrepancy?

Because DVD Decrypter is wrong.

DGIndex includes one or 2 more frames at the beginning than does DVD Decrypter when computing the delay. It's the same reason as for the earlier DVD2AVI and older versions of DGIndex:

Q13: Why isn't the DELAY value the same when I demux an AC3 file with v1.76/1.77.3 and 1.3.0dg/DGMPGDec?
A: Because there is one or (usually) two more video frames at the start of the video in neuron2's version (See Q34 below). This will account for up to 83ms difference. But it may also mean that a different starting position is chosen for the audio, which in itself may introduce a few ms of delay and the total effect may be as much as 100ms or more.

http://forum.doom9.org/showthread.php?t=87809

[dimtim]

Awesome thanks for that info. Is that the same reason why DGIndex seems to add frames in comparison with the original VOB file. I opened the originial VOB file with Vdub and it said it had 39837 frames but DGIndex says it has "coded" 39840 frames, and the final video has 39840. Does DGIndex account for this with the audio syncing?

Thanks again
Tim

[manono]

I don't encode from VOB files opened in VDub(Mod). And that's one reason (of several). If you want to do it right, make a D2V using DGIndex and frameserve into VDub(Mod) using an AviSynth script file. If you're doing this just to test, although I'm no expert on the subject, I think it's not taking into account some opening P and/or B frames. I think it's the same as the DVD Decrypter problem you noticed, and the DVD2AVI/early DGIndex explanation in the DGIndex FAQ to which I linked. DGIndex isn't adding frames; these other programs are losing frames.

Use the delay given out by DGIndex, use a method that preserves the framecount determined by DGIndex, and you should be OK. Unless you decrypted inproperly (using DVD Decrypter on a DVD with "modern" copy protections, for example). Then anything might happen with the delays.