If you are having problems with out of sync AC3 audio and trying to correct this with IfoEdit then read on! 8)

This information is taken from another forum http://forum.doom9.org/showthread.php?s=&threadid=37524. I thought it was important to pass along. I am just the Messenger for this one so please don't shoot me just head on over to the other forum for more technical answers!

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AC3 Delay Corrector
http://home.t-online.de/home/520072193568-0001/

There are problems to resynchronize the demultiplexed mpg-streams. Use the program the following way:
Start the program and choose the source file. Set the delay and press "Write". Thats it.
The contents of the information window is automaticaly written in a corresponding txt-file.
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This is "AC3 Delay Corrector". It adds silent or cuts ac3-blocks in front of the ac3 stream. Just input your delay then. Ifoedit is OK with positive delays, you only need this tool for the negative ones. Although the tool adds/cuts full blocks (not single ms), the resulting little positive delay isn't a problem anymore for IfoEdit.

i.e.: You have a delay of -66. Take ac3delay, input -66. It then cuts 64 ms (2 blocks) from the beginning, resulting in a final delay of -2. This you can use in IfoEdit. This little negative shouldn't be the problem now anymore. (With IfoEdit version .95, negative values greater than 40 cause a problem)

i.e.2: You have -117, enter it in ac3delay. It cuts 4 blocks (128 ms) from the beginning, resulting delay to be entered in Ifoedit is +11.
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Did you have DVD2Avi generate ac3 which has the delay in its filename? AC3Delay then automatically takes the delay from the filename, although ac3delay already has edited it a step before.

If the ac3 HAS -181, and ac3delay cuts 192, then you HAVE +11, whatever ac3delay shows when reloading the file. Don't become confused...

Best way is to avoid having delays in filenames.

As your logfile of ac3delay shows, it has cut 192ms from beginning. Period. So it is now +11. (-181+192)

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There are 31.25 frames in one second.

I also got this info. But why? It was a PAL source, so each frame should have 25 fps, right? Or it's because we are dealing with audio?

This means 31.25 AC3-FRAMES. This has nothing to do with the videostream and its video frames. AC3 is also a format which uses frames within itself. (like mp3 )

The videostream has its video frame rate. The AC3-stream has its own ac3 frame rate.