Audio Sync problems in NTSC DVD re-authoring

[superfresko]

Hi everybody.

I have an NTSC DVD with ac3 5.1 audio track, and i want to add another audio 2.0 track.

So, I extracted both m2v video and 5.1 audio track, prepared my 2.0 track, and reauthored everything (with TDA Pro).

Problem is, both audio tracks (the original 5.1 and my 2.0) are out of sync. No matter what I do, even the original 5.1 track is out of sync.

In order to extract video and audio tracks, I tried the following:
- DVDDecrypter,
- SmartRipper,
- even TDA (to extract the mpg file) + TMPGEnc (to demux m2v and ac3 from the extracted mpg file).

Once separated, the m2v and the 5.1 ac3 track are out of sync.

In fact, when I put back together both the original m2v video file and ac3 5.1 audio file, audio is out of sync (it gradually goes slower).

I've chosen an NTSC project in the re-authoring process.

When I extraxt the mpg file with TDA (m2v+ac3) the audio is still in sync. After the demultiplexing process, it's mysteriously out of sync. And if I put them back together (multiplexing them in an mpg file), the audio is (obviously) out of sync.

How is that possible? If it was my 2.0 track, it could me my mistake. But the problem is with the original track, without processing neither the video nor the audio!

Is there somthing I should do in the demultiplexing process that would preserve the audio sync?

Anybody can help?

Thankyou very much.

Byebye,
Massi.

[towerblocks]

look at the log .txt file within the VIDEO_TS folder that dvddecrypter created and see if there is an audio delay to be applied.

[superfresko]

look at the log .txt file within the VIDEO_TS folder that dvddecrypter created and see if there is an audio delay to be applied.

I've checked: Both DVDDecrypter and SmartRipper indicate no delay.

Furthermore, it is not a fixed delay: it gradually increases.

Byebye,
Massi.

[hech54]

You mention NTSC quite often in your original post.
Why?
Are you sure the source is NTSC?

[superfresko]

Correction.

Once multiplexed back together both video and 5.1 audio track, the resulting mpg file is in sync.

Even if I multiplex video track with my 2.0 audio track.

At this point, may be it's TDA that doesn't put correctly together the tracks...

I keep on trying.

Thanks for any help.

Byebye,
Massi.

[superfresko]

You mention NTSC quite often in your original post.
Why?
Are you sure the source is NTSC?

The source is definitely NTSC.

I mentioned it because I've read that NTSC sources may give problems and sometimes need special processing (pulldown, telecine, etc.).

May be the problem lies in a missing processing that I didnt' perform.

Byebye,
Massi.

[superfresko]

Mmmm...

I tried another authoring program, and the audio sync is just fine, with both tracks (5.1 and 2.0).

Thus, I'm afraid it'a TDA problem...

Byebye,
Massi.