sound trouble mystery from captured DV

[unstuck2]

Hi All,
what do you think about this problem:
I transfered a DV from camcorder to PC using firewire. The resulting avi looks and sounds fine.
I converted the avi to mpeg1. The resulting file looks/sounds fine.
I converted teh avi to mpeg2 using TMPGenc+ (demultiplxing to m2v and mpa files). When I tried to author in TMPG DVD author here's what happens:
First ~20 minutes of video look and sound fine.
Middle 40 minutes look OK, but the sound is screwed up: ssslllowww ssounding and very low in pitch. Hard to explain this, as if the tape was running slow.
Last couple of minutes sound fine again!

The tape plays fine on the camcorder and as I said the avi and mpeg conversion are fine.
Curious that the sound trouble started and stopped right at scene changes (ie taping start/stop) but there was plenty of starts and stops (including camera power downs) before and in between.
Here's what I tried:
converting the avi to mpeg2 using different software (WinCoder) and had exactly the same result.
Using every imaginable audio setting in TMPGenc+. No help.
Tried recapturing a smaller piece ~1min before and after the "bad sound" transition. Same result: good avi file, sound bad right at the scene change boundry, but only when convereted to mpeg2.
Finally out of desperation I recaptured the video starting the tape AFTER the scene where the sound trouble starts. The avi was fine as before, but this time the encoding with TMPGenc+ went fine with good sound and I could go ahead with authoring to dvd!

I hope I have explained this well enough.
What do you think may have happened?
I'd be glad to answer any questions if I can. FYI this was a 60 minute tape with ~5 months worht of home movies on it, and treated probably the same as you would treat yours, ie a lot of starts and stops, maybe some rewinding and viewing, but no "settings" changes.
Any ideas? I'm baffled. Would like to keep this from happening again!
thanks.

[Tommyknocker]

I think what may have happened is the one thing we home moviemakers always neglect to do. Timecode an entire tape before using it. So when we start taping and retaping over and over again, we constantly add new time codes to the same tape.

You may want to take your next fresh tape and put the lens cover ON your camera and record blank video from beginning to the end. This will put one time code on the entire tape, and may stop this from happening again

[unstuck2]

ok, but how does that ensure a single timecode for the entire tape.
After taping the entire blank tape, then rewind to the begining and as you say tape normally with a lot of starts and stops, wouldn't each piece again get a new time code stamp?
Has anyone seen this problem with DV before?
thanks

[Tommyknocker]

Preparing Your Tapes
...Record black on the entire tape. This lays down a continuous time code track on the tape guaranteeing unbroken time code when recording your shots.

--

Collier, Maxie D. 2001. The IFilm Digital Video Filmmaker's Handbook. Hollywood, CA: Lone Eagle Publishing Company.

-- Okay?

[unstuck2]

well not really okay :P
not that I don't believe you (no need for credentials) just trying to understand it. Does it make sense to you?
you know not everything in print is right.