A/V delay when converting from avi? (DVDAuthorGUI)

[kcay]

I've been converting a series of avi files to dvd for viewing on my TV. The AVIs are AC3, so I've been using ffmpeggui to extract the ac3 streams. So, when authoring in dvdauthorgui, do I need to set the A/V delay to match the audio preload from the avi (gspot says the preload is 69ms), or is the ac3 already adjusted, making this unnecessary?
Even if a 69ms difference isn't noticable, I'd like to get an answer, for future conversions.

[Matthew]

preload =! audio delay

The audio delay is really just some junk bytes at the start of the AC3, and they should be removed before multiplexing.

The only app that I know of that tells you the delay is AviMux GUI. GSpot certainly doesn't.

It can also be calculated manually (e.g. by getting the junk bytes figure when the AC3 is scanned for errors by BeSplit/BeSpliced). This has all been covered in prior threads :)

[kcay]

So I don't need to worry about the preload in the avi? I just strip the ac3, then remux it with my converted mpeg2 video, and I won't get any synching issues?

[Matthew]

The preload is completely irrelevant.

If you scan the AC3 for errors and there are no junk bytes reported then the sync will align with the avi.