Out of synch audio

[Maxwellbest]

Hello

Tools
Avisynth
CCE Basic
Virt dub
DVD Author Gui
IMG Burn
Goal:avi to dvd
Source. Xvid. AC3 soundtrack. I demux soundtrack, save as wav wth virtdub. Back to AC3 wth bsliced. Frameserve from avisynth to CCE. The resulting mpv is very good quality. Looked great on the tele. I then author with DVD Author gui, burn with IMG. It all looks great until playing on my DVD player I find the audio is well out of synch. I open one of the Vobs in Virt dub mpeg and it comes up with something like B frame lag on the screen, plus some error message "anachronistic sound" or some such. I immediately trashed the files in a fit of anger. I'll never get that time back. So any pointers as to why these messages came up, why was the sound so out of synch, how to overcome out of synch sound.
Here is my avisynth script

AviSource("c:\Movie\Movie.avi")

LanczosResize(720,556)

AddBorders(0,10,0,10 )

AssumeFPS(25, True)

[AlanHK]

Source. Xvid. AC3 soundtrack. I demux soundtrack, save as wav wth virtdub.

AS it's AC3, why convert to WAVE and back to AC3?
Just demux, run through BeSplit to fix the headers, and use it.

[Maxwellbest]

Besliced is just a front end for Besplit. Virtdub saves as wav regardless of format of sountrack, apparently, correct me if I am wrong

[Nelson37]

Yes it does, but then that is not demuxing. Use something else. The less you mess with it, the better off you are. Unless you want to lower the bitrate or something?

Was the audio off by a constant value? AC3 often has a startup delay, basically a fraction of a second of silence should be added to the beginning, but what the softwares do is simply add a delay factor. This means that once the files are seperated, you need to know that delay factor to put them back together and maintain synch.

[AlanHK]

Besliced is just a front end for Besplit.

Yes it is. I thought it might be easier to use the GUI. You just drag-and-drop an AC3 into it and select "fix".

If you prefer the CLI, I use a batch file like:

for %%I in (*.avi) do (
avi2raw -a %%I %%~nI.raw
P:\BeSplit\BeSplit.exe -core^( -input %%~nI.raw -fix -type ac3 -output %%~nI.ac3 ^)
del "%%~nI.raw"
)

To demux the AC3 (with avi2raw) and fix it with BeSplit

Virtdub saves as wav regardless of format of sountrack, apparently, correct me if I am wrong

The file may be named a WAV, and have a wave header, but it is not a PCM file, as a WAVE usually is.

Just look at the file size: A normal wave file is about 10 MB/min. An MP3 or AC3 is 1-2 MB/min, usually.

I generally use VirtualDubMod. It has a few more features in this regard than VirtualDub.
See Streams/Stream List/demux

After demuxing your "wave", rename it and fix the header to get a "normal" AC3 file.

Was the audio off by a constant value? AC3 often has a startup delay, basically a fraction of a second of silence should be added to the beginning, but what the softwares do is simply add a delay factor. This means that once the files are seperated, you need to know that delay factor to put them back together and maintain synch.

And use DelayCut to add a delay to an AC3.
Or most DVD authoring apps let you specify this when you load the audio file.