Audio / video synch problems with MPEG 1

[Muscles]

Hi all,

I've been trying to convert some MPEG 1 files that were created with a video capture card in NTSC format, to MPEG 2 format so that they can be burned to DVD.

The files play fine, but when converted to MPEG 2 the audio gradually becomes out of synch.

I have tried using PVAStrumento after hunting around this site, but alas it is only able to identify the frames which are out of synch, but it won't fix the problems.

I have also tried using TMPEG Encoder Plus to de-multiplex the files and then mulitplex them to create a MPEG 2, but again the same out of synch problems occur.

I did notice that the video stream is two seconds longer than the audio, so I remove the first two seconds of the video and tried multiplexing them. This time the audio was way out at the start, but back in synch at the end!

Here's the details about the files as reported by PVAStrumento:

Found 1 video stream.
Found 1 MPEG audio stream.

VIDEO #1
	Resolution 352 x 240 
	Aspect ratio is reserved (= 0xc)
	Frame rate 29.97 fps
	Nominal bitrate 1150000 bps
	First PTS: 13:15:21.858

MPEG AUDIO #1
	MPEG1, Layer 2
	stereo, sampled at 44.1 kHz.
	Bitrate 224 kbps
	Each frame contains 26.1 ms audio (731 bytes)
	First PTS: 00:03:53.221

Any advice on what I can do fix the problem is greatly appreciated.

- Muscles -

[bunyip]

There are ways to shrink or stretch the audio - but before you go to all that trouble, are you aware the MPEG1 video is already DVD compliant.
The DVD standard accepts MPEG1 at 352x240 - all you need to do is change the audio from 44100 hz to 48000 hz.

[Muscles]

Hi bunyip,

I wasn't aware of that fact.

When using TMPEG DVD author, the conversion process to VOBs introduces the audio/video out of synch problem. It is also created when converting the files to MPEG 2 format.

Any other suggestions?

[bunyip]

Well first thing I would try is to process the audio manually.
I would use VirtualDubMod to extract the audio as a WAV file, then use BeSweet to convert the WAV to a 48Mhz MP2 file.
I would then load the original MPEG1 file into TMPGencDVDAuthor but point the audio to the MP2 file just created.
This often overcomes problems in the audio.

Give that a go.

[Muscles]

Hi bunyip,

Thanks for the advice.

I'll give it a go over the weekend.

- Muscles -

[Muscles]

Hi again,

Unfortunately, it only made the audio/video synch worse!

- Muscles -