how can i stretch an AC3 file

[sandman112]

im trying to create a DVD from 2 xvid files with ac3 sound, problem is that the lip sync starts off ok, but by the end of the movie its about a second out, both files show the same length in DVD-lab, im thinkin that i need to strech the ac3 audio by about second or so but i cannot find any tools that will do this for me, any ideas out there

and this is only my second atempt at this dvd stuff so go easy please LOL

edit/
maybe i should say that i created the one big ac3 file by appending the 2 files together in vitualdubmod and demux-ing the whole thing, i created the m2v file from the 2xvids using tmpgenc-plus

cheers guys

[Cobra]

You need a thick rope, a car with a towbar and a sturdy post. Remember too ease on the gas gently, so you don't corrupt the stream.

I think GoldWave can do this, but I'm not sure. I would expect it to, since it's a semi-pro audio editor that supports AC3 files. Find the total length of your video file, and use GoldWave to make the audio file an identical size. That should sort it out.

Apart from that, I can't really suggest any other solutions.

Good luck!

Cobra

[CaseyComb]

Look...check the framerate of the Xvid's to the framerate you encoded at. I bet they are off. Re-Encode the .ac3 to the proper framerate using ffmpegx or besweet. Im just venturing a guess here but I think your Xvid's are PAL(25fps) and not what you encoded at NTSC(29.97fps)...or vice versa.

If that don't work you're probably S.O.L. There's no way to "stretch" an .ac3 file.

...and if all that don't work just encode the video in two chunks. I've done it before when you author it to DVD there will be a small hiccup during playback but nothing too terribly distracting.

[Cobra]

There's no way to "stretch" an .ac3 file.

I just told you my first post that GoldWave can probably do it. It can.

- Install GoldWave
- File --> Open and drop down the Filt Type menu and select "All Files"
- Open the AC3. Wait for it to decode.
- Go to Effect --> Time Warp and enter your video length.

Your AC3 is now stretched/shrunk to meet your requirements.

CaseyComb could be right about the framerate, but a conversion usually results in jerky video. Use GSpot to check what framerate the files are, and compare it to what you have encoded. If the files are 23.976 then you need to perform a 3:2 pulldown to get them up to DVD standard 29.97.

If you have encoded the files correctly, which is seems you may have, then you can just stretch/shrink the AC3 file. I assume you are after AC3 audio in your final DVD.

Cobra

[sandman112]

ummmmm ok

i stripped the AC3 from the original xvids before any encoding, framerate of the xvids is 23.9

AVI video was encoded in TMPGenc with the inverse 3:2 pulldown setting used, TMPGenc said its framerae would be 29.9 but when i play the converted M2V file in media player classic it tells me that its 23.9 FPS

i tried goldwave, it opens the 2 seperae AC3 files but not the large one, im thinkin i might have some sort of trouble at the point where the 2 xvids joined together

would that make sence /?

[sLiMpAuLy]

You need a thick rope, a car with a towbar and a sturdy post. Remember too ease on the gas gently, so you don't corrupt the stream.

HAHAHAHA just what I was thinking :P

[Cobra]

You said the sync gradually goes over the entire file. This suggests a framerate problem. If the sync suddenly goes, you need to work out a pause to put/remove at the exact time that video number 1 stops and number 2 starts.

Also, do you get sync problems with the original AVI when you play it back on your machine?

Cobra

PS - sLiMpAuLy, I was wondering when someone would spot that...

[CaseyComb]

Yes, okay I stand corrected it is possible to stretch any audio file. I just assumed he didn't want it to sound different. It sounds like a framerate problem. I don't understand the point of "stretching" the file as it would only distort the sound. Also I've never needed to do a 3:2 pulldown for a 23.97 to 29.97 conversion.