29,976 fps VOB -->25FPS AVI - Plz. Help with audio sync

[SaSi]

I am trying to convert an episode from an NTSC DVD into 25FPS AVI. I've done this quite a few times with 23.976 fps material however 29.976 source gives the following problem.

After extracting and demuxing the video from the DVD into a VOB with audio and video, I open this with VirtualDUB MPEG or MOD.

The method I used so far was to save the audio as WAV, open in Cooledit, strech by the fps factor and save again, change the frame rate in the video and resize, merge with the stretched audio and convert.

With the 29.976 source, VirtualDUB saves a 34 minute wav file instead of the 43 minute it should. VirtualDUB also reports the VOB file to be 34 minutes long at 29.976 fps. Audio is clearly faster than what it should. So I scraped my VirtualDUB method and used Besweet for audio.

I demuxed the AC3 audio into a separate file, opened it with BeSweet and downmixed to stereo wav both with a frame rate conversion and without.

If I don't change the frame rate, I get what appears to be a 23.976 fps audio file. Stretching it with CoolEdit to 25fps (25/23.976 ratio) gives an audio file that doesn't sync with video properly. Skew is about 2~3 secs in the first 1/3 of the audio and 5~6 secs during the end.

If I convert - with BeSweet - changing frame rate from 23.976 to 25, I get an almost 25 fps length audio file which when muxed with the converted video has about the same sync problem.

BTW - I convert the video separatelly with VirtualDUBMPEG setting FPS to 25 and resizing to PAL.

Is there something obvious I am missing?

[SaSi]

BUMP

Also, some additional info.

I repeated the ripping - demuxing - stretching excercice from scratch, this time using DVDDecrypter instead of SmartRipper, just in case the demuxing messed things up.

DVDDecrypter stated that the title has a duration of 42:56,15 while showing the frame rate at 30fps. It IS an NTSC DVD, however I am not very familiar with NTSC material to know if 30fps is what DVDDecrypter should show.

Opening the VOB file through VirtualDUB MOD shows it contains 62182 frames. Dividing this by 23.976, gives a duration of 2593.47 seconds, which gives 43:13.47 minutes.

To comlicate things further, by processing the VOB file through besweet without any frame rate conversion, the resulting WAV file ends up with a duration of 42:59 minutes.

Clearly, there is a discrepancy of almost 17 seconds between the duration DVDDecrypter reports and the duration assuming a frame rate of 23.976 fps. And the wav file resulting from BeSweet has a different duration

I guess this is where my mess starts.

Anyone able to shed some light?

TIA