Audio/Video sync problem, when converting from divx to VCD.

[EmptyMy]

Hi, I'm a newbie, so I guess I'm posting this in the correct forum...
I guess this is a pretty common question around here. In fact I saw an older post which handled the same problem, but there was never a sollution. And the search function didn't seem to work, so I decided to start a new topic.
I followed the guides on this site to convert a divx AVI to an mpeg VCD. It seemed like a success until after about 20 minutes into the movie, when the audio problem appeared. The sound comes about 5 seconds too early.
When I opened the original AVI with VirtualDub, to extract the audio, I got the following warning:
VBR audio stream detected
VirtualDub has detected an improper VBR audio encoding in the source AVI file and will rewrite the audio header with standard CBR values during processing for better compability. This may introduce up to 75964 ms of skew from the video stream. If this is unacceptable, decompress the "entire" audio stream to an uncompressed WAV file and recompress with constant bitrate encoder (bitrate: 141.3 +- 28.9 kbps)

But the guide on VCDHelp says to ignore possible warnings, so I did. Even when I read the above warning, I don't know what it says, and what to do. Don't forget, I'm a newbie. So, I continued to follow the guide (full processing mode, no compression and a sampling rate of 44100Hz).
This was the second movie I made a VCD of. My first attempt went without trouble (except for a minor lipsync issue). In that case, the source file was a mpeg. There was no warning from vdub, and I didn't bother with full processing mode (because I hadn't read that far into the guide )
Yeah, I know. I could try to use the same settings as I did with my first movie. But that would mean I'd have to go through the long and dull process of converting the AVI to mpeg VCD again. I thought that I could try to fix the audio directly on the output file, so I don't have to go through that again. Will that be possible?

Also, the video suffers from very small, but still anooying, twitches. Unlike the audio problem, I can live with it, but if there is a way of getting rid of them, I would love to hear about it.

I really hope you can help me out here.
Thanks in advance
/Tommy

[banjazzer]

The guide I see says

If you get audio errors, out of sync problems or bad audio or no audio at all Try to convert the audio to wav before converting. http://www.vcdhelp.com/virtualdubaudio.htm

[EmptyMy]

Yeah I know... I did. I suck at explaining stuff....
Anyway, I'm sorry. I don't see how I missed the sticky called "FAQ, read this before posting!"
I'll just read this http://forum.vcdhelp.com/userguides/100617.php and see id it can help me.
And the twitchy video is prolly a result of converting from NTSC to PAL...

[banjazzer]

It's almost certainly because of converting. Why bother? If you have a PAL player it will most likely play NTSC.

[EmptyMy]

Yeah. I could try it. Although, I'm afraid that some trouble from my PAL DVD and TV is to be expected. Black & white, or something.
I feel like I'll be trashing lots of CD-Rs.
All of this business would be so much smoother if the damn convertion didn't take all day!

[EmptyMy]

Well, I tried it... didn't work (the guide, I mean)

[banjazzer]

In what way did it not work? Did it come out B&W? Did nothing at all happen? Was it just very jerky?

Is your DivX NTSC or NTSC(film)? If the latter (most NTSC DivX I've come across are), all is not lost, because it is relatively simple to convert a 23.976fps DivX to 25fps.

[EmptyMy]

Oh, sorry... I meant I tried the guide to avoid the drifting audio... haven't tried to watch NTSC yet...

[banjazzer]

If your DivX is in sync to start with, and you follow the guide to extracting VBR audio as an uncomressed wav, and the key phrase in the guide is Select under Audio->Full processing mode, then the standard methods used with TMPG described on this site will always produce an in-sync mpeg.

[EmptyMy]

So, you're saying that I shoulp keep trying, because I did something wrong? Ok, sounds good... thanks.
At least I believe the audiofile is completely uncompressed. It's about 1000MB! Is there anything special I have to do, or is it just to choose "no compression"?
Oh, and I was going to try and convert the file without using an extracted audiofile for audio source. But TMPGEnc gave me a cryptic error message. Just a bunch of numbers.

[EmptyMy]

So, what do you make of this? The extracted audiofile is 100 min and 18 sec, while the original AVI is 100 min and 33 sec... the audiofile is shorter! But I'm positive that the original divx a/v sync is perfect.
Also, when I convert the file, I also divide it into two pieces. You think that can cause trouble? Perhaps I should try and encode the entire movie, and then split the mpeg...?

[banjazzer]

You've got an uncompressed wav, certainly, at that size. You don't choose compression, (and if you do you make sure it says no compression!). You should also choose conversion and select 44100Hz.

Your wav file and avi should be the same length - at least to the nearest second, so there is something strange about your DivX. What you should do is encode several short samples at the beginning, middle and end, and see if the the sync is out a constant amount. If it is, it is a simple matter to correct this when you encode. If it creeps out, getting worse or better, then it can still be corrected, but it is more complicated, and you have to ask yourself whether it is worth the effort. Stretching the wav to fit the avi may or may not work!

A correctly encoded DivX is a piece of cake to convert to VCD or SVCD, but unfortunately, many DivX out there are not done correctly. 8)

[macleod]

here is the cause (my belief anyway). Open the divx in media player and check the properties (summary) and post back with the fps number (frames per second).

When you post that number back to this forum, you should receive a billion replys immediately telling you the fps is way to low and it will never happen. I have had fps of 12.5fps (and lower) and I have yet to get a sync'ed video. If someone can prove me wrong, please tell me. I have followed all of the guides for this and read everything in the search section under "divx fps", "divx", "low fps", etc. and the only thing I could gleen from the posts is that it wont work. I'd like to make vcd's of those movies vs. dragging my damn computer downstairs to hook up to the tv.