Virtualdub audio sync - but only sometimes

[andybray]

I'm using Virtualdub to convert MPEG2 video with an AC3 2 channel soundtrack to AVI. The source has come from a standalone DVD Recorder (mostly TV source material).

In the conversion I pick Audio full processing and pick MPEG Layer 3 and tick the 48k 24kHz option. It's about the top one on the list I get.

Problem is on some conversions it all works perfectly. One some (seemingly a minority) I get audio sync problems where the audio is about 1 second delayed throughout the recording.

But the process I'm doing is the same and the source material has come from the same recorder with the same settings. The MPEG source file is perfectly in sync.

Any ideas why I might get this problem but only occasionally?
Andy

[Bjs]

What the ? , strange process your using there .

From what I can recall from my usage of virtualdub , full processing is correct .

Click File , File Information , check audio source , if it is 48khz , dont use the conversion process listed under audio .

If audio is 44.1khz , it shouldnt be a problem either .

If other , use conversion process ... change to either 48 or 44.1

Just click File , Save Wav , pick place to store it , name it (may need to add the wav extension) .

When done , goto Audio , select Wav , locate the wav file that was just produced .

--------------------------------------------------------------------------------

Now you setup video compressor , audio compression .

I personally use resize filter (720x576 too 544x288)

Dont ask me about these numbers , so long as it is near the same aspect ratio and dividable by 4 .

Compress video using xvid via 2 pass method .

Compress audio using mpeg-layer3 , choose to show all , sellect 2nd from top (I find 6kbs and 4kbs types dont cause vdub to complian)

Process file now .

Its how I jammed van helsing onto a single cd for my xms player to play , and the audio is smashing .

The video could have done with a touch more tweaking , but everybody who's seen it ask's me how the heck I done it ...

[andybray]

Doesn't really address the sync problem I'm afraid. The audio processing I'm doing appears much the same the procedure you describe. I pick one of the MP3 options which is about 6kB/sec.

Actually on doing some more tests I think the problem is due to some sort of minor file corruption in getting the MPG source onto my PC. I had no end of problem with one MPG file and then in the end I just started again, read the MPG file off the DVD-RAM and then it all worked. I've also found that cranking the file through TMPGEnc tools to simply re write the MPG file also fixes the problem. Problem is I can't tell which files will fail and have a sync problem and so I either have to TMPGenc all files as a precaution or wait and see whether the AVI coming out of Virtualdub works. But on my PC with a couple of video filters I only get about 15fps in Virtualdub and so it can be a long wait.

Note that I don't get an error in Virtualdub when importing the file. Sometimes I have seen an error message about "Anachronistic...... blah blah ..... improper join......" but there is no link between getting this error and the sync problem