audio sync problem; DVD to SVCD

[jrbling]

I believe my procdeure to be correct, however, my final mpg2 file has a slight audio sync problem for some reason. Here are my procedures.
1. Rip VOB using smartripper
2. DVD2AVI; when previewed video type is about 98% film, so i turn on forced film (23.976), and i demux the audio (ac3). The ac3 audio has no delay (0ms) as reported by dvd2avi.
3. open ac3 in besweet, downconvert to 44.1khz, and create a 224kbs mp2 file.
4. Open d2v project in tmpgenc, load svcdfilm template, the only setting i change is my desired bitrate, and then ecnode to m2v file.
5. Load m2v and mp2 in bbmpg, and mux to create final mpg2 file

After this process my mpeg looks great, but audio is not in sync, this has happened before with another dvd following the same process, any help would be great thnx.

[poopyhead]

1) outta sync gradually

or

2) outta sync same amount throughout movie


latter much easier to fix.

[yf2001usa]

do i read it right that you forced your video to 23,976? did you change the fps of the audio to?

[jrbling]

Poopyhead, my audio seems out of sync from the beginning of the video, and doesnt seem any more out of sync throughtout the movie, so it does not seem gradual.

I also noticed that my video is not the length of the source dvdfilm (7 seconds shorter), however, my audio is exactly the same lenght as the dvd video, dont know if this could be an issue or not. What do i have to do to sync? thnx.

[yf2001usa]

Then you're having to problem i'm talking about.

Your source file isn't 23,976 fps but our encoded video is so thats why it is shoter then the source file. But because you still have the audio form the source file (which isn't 23,976) your audio is the same length as the source file but shorter then the encoded file. So thats why it is out of sync.

But what can you do. use gspot to check what the fps of the source file is. If it is 25 fps then use besweet to encoded the audio from 25 -> 23.976. If it has another fps then 25. Use a program like goldwav or sound force to time stretch your audio to the right length (the time of the encoded video).

I hope this helps.

Yf

[jrbling]

@yf2001usa: I also suspected the framerate to be the problem, however, im unfamiliar with g-spot. Am i to load the audio stream from the source (ac3 to wav)? Because i did decode ac3 to wav, and loaded this file, which gave no information concerning framerate, only basic information such as type, bitrate, and sample rate.

Logically, wouldnt the audio fr be the same as the video? The source is NTSC (DVD2AVI), so would i also need to telelcine inverse (i think thats what its called, correct me if im wrong) the audio stream in besweet to film, 23.976?

This is kind of irritating, when i use this method i cannot seem to get a synced audio and video, so i am obviously not doing something right, if you can help any more or not thnx.

[poopyhead]

@jrbling, did you enable the "3:2 pulldown on playback"?

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assuming you did, frame rate shouldn't be an issue. the audio is meant for 29.97 fps...yes, but w/ 3:2 pulldown..the 23.976 fps NTSC FILM will be played back as 29.97 fps on the TV, so the video should match the audio.

even if there was a framerate problem, the audio should gruadually get outta sync, not stay constant.

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there may be an easy fix, but you may need to use tmpgenc's audio encoder, instead of an external one, like besweet...lemme know.

[jrbling]

@poopyhead: In tmpgenc 3:2 pulldown when playback is chosen, however, i wasnt aware that could be an issue, and in bbmpg i did notice that once i had loaded and began muxing, the console displayed a message saying 2:3 pulldown was detected, so could this be the problem?
thnx.

[poopyhead]

haven't personally used bbmpeg, so i wouldn't exactly know.

however, it would seem that could be a problom.

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if you're willing to try something difference.....

tmpgenc has it's own cutting tool, so you can use that to cut/join, as well as demux and remux. that might eliminate the need for bbmpeg.

also, have you thought of using tmpgenc to encode the audio, rather that using an external audio encoder?

tmpgenc has an audio skew feature that lets you tell tmpgenc to start the audio earlier or later...however, this only works if the audio is outta sync by the same length throughout the entire movie. also, only works if you let tmpgenc encode the audio...no external audio encoder.

but, it could just be the combination of external audio encoder + bbmpeg that's causing the audio desync...

[jrbling]

Thnx, what i did on this particular rip was re-encode the video with the same settings using the d2v project and decoded ac3 to wav. This seemed to fix any synch problem, at least on playback on my computer.

Now another problem has emerged! , this is unrelated to svcd ripping, and ive already posted this in the correct forum, but regardless, the problem im having is now during playback in my player. This is the only vcd ive ever had problems with during playback, so im lost as to what the problem could be, since ive always used the same authoring process (vcd easy and blindwrite). The mpg plays fine on my computer, and so does the authored vcd (using power dvd).

[poopyhead]

what's the problem?

[jrbling]

oh i didnt realize i didnt even write the problem, anywayz audio is out of sync during playback.
My player is an ns315 sony, however, i dont think that is an issue since this is the only vcd this has happened with.

[poopyhead]

have you tried limiting your burn speed to 4X?

3:2 pulldown on playback enabled?

did you downsample your audio from 48 KHz to 44.1 KHz?

[jrbling]

no i did not downsample the audio, still 48khz, i suspect that would be the problem. Thnx poopy, but maybe you could explain why this is a problem on a player and not the pc?

[poopyhead]

PC's are much less picky than dvd players...that's why the PC is not a good compatibility test for dvd players. many times, if a problem shows up on your dvd player, but not on the PC...there's usually a media/burning/authoring problem.

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even then, compatibility for various formats (and bitrates) differ from dvd player to dvd player

some can handle 48 KHz, some can't.

some needs the 3:2 pulldown flag in the .mpg, while others will do so, even without the flag.

some can support -X- non-standard, compliant formats, while others can't. even the max bitrate of these -X- formats varies from one dvd player to another. one may handle up to 4 mbit/s, while another one may "poop" out at 3 mbit/s.

even SVCD support is variable...though some may still play it with the VCD Header trick....for example, your particular sony model can play SVCDs using the VCD header trick.

the type, brand of media is also quite a big issue. some players have stronger lasers and can stand crappier media, while weaker lasers may not be able to pick those up.

DVD-R/+R, DVD-RW/RW compatibility has been subject to many wars lately. even then, most new players supports both.

[jrbling]

I see, well thnx for the help and info.