Using audio from 25fps source on 29.97fps video

[headless chicken]

I have audio I extracted from a 25fps PAL DVD that I would like to supplant onto a video at 29.97fps. The audio is from an alternate language of the film. I can tell the speeds are out of sync because simply trying to overlay the 25fps sound onto the video in iMovie does not work (yes, I'm on a Mac). Can anyone guide me through the simplest and easiest way to "stretch" the sound out correctly? Currently the audio in the language I want is playing a bit too fast when overlayed onto the video.

[manono]

You're on a Mac? Then post in the Mac section. No one else cares.

By the way, you mentioned 'film' and your NTSC version being 29.97fps. But film isn't 29.97fps. Already that points to the encoder being a clueless incompetent. Most likely it's supposed to be 23.976fps and you should stretch your PAL audio (lengthen it) by a ratio of 25/23.976, rather than shortening it by a ratio of 25/29.97. Your statement that Currently the audio in the language I want is playing a bit too fast when overlayed onto the video confirms what I wrote.

[jman98]

This is NOT an audio problem. This is a Mac problem. You need Mac specific help. The tools to do this exist under Windows. On a Mac, you're VERY limited.

You can either use ffmpeg or Audacity on a Mac, but as if I had to do this I would use a program that only exists on Windows, I can't tell you exactly what you have to do. You know what programs to use now so you can do some research to find out how to use them. You do need to remember one thing though - if the audio sounds unnaturally low pitched after conversion, you'll have to find a way to change the pitch along with the time.

Since you failed to post this in the Mac forum like you should have, you're welcome to use the "Report" button under your own post and ask a moderator to move it to the Mac forum if you don't get any more responses than mine. ALWAYS post under the Mac forum if you are using a Mac and you need Mac specific help. If you're using a Mac, the vast majority of the time you need Mac specific help. Mac forum posts have a special symbol and we have members who look for that symbol to provide help to other Mac users.

[headless chicken]

You can either use ffmpeg or Audacity on a Mac, but as if I had to do this I would use a program that only exists on Windows, I can't tell you exactly what you have to do.

I could always use a friend's PC if need be. What programs would you recommend if I were to use Windows?

[manono]

I could always use a friend's PC if need be. What programs would you recommend if I were to use Windows?

If on a Windows machine first demux the 2 movies into video, audio, cells (chapters) and subs (if any). PGCDemux.

Then stretch your audio. I use BeSweet which has a preset for the job. I make a WAV file and then reencode to AC3. There are lots of programs for that and I use SoftEncode. I believe eac3to can do the whole thing at one go (slow to 23.976fps and reencode the AC3).

Then remux the new audio/video/cells/subs. Muxman.

Then replace the 'new' DVD back into the original. VobBlanker.

Baldrick has a guide for replacing subs in a DVD, that uses the same method as replacing audio. Check his method 2:

(his guide is down. Baldrick, where's your replacing subs in a DVD guide?)

I'm assuming your NTSC source is also a DVD, but you didn't say it was, and it probably isn't, so you can use the stretched audio by remuxing it into your 29.97fps video, or when making a DVD from it.

[headless chicken]

Thanks for the step-by-step, manono.