What Mac app for time stretching 5.1 audio track?

[pwes]

Need help to build MKV w. custom audio
I've got an MKV Bluray rip and a DVD-rip. The DVD is at 25 fps and the MKV rip is at 23,976 fps. I need to bring the audio track from the DVD into the MKV container using MKVtoolnix after having synced the audio track correctly as right now it's 4,270833% to short and to high pitched.

What is the easy way to go about this? If FCP is the best solution, I'm ready to get access to that but if something simpler can do it, that's even better. Audacity can handle MKV but not 5.1 AC3 and Amadeus can't just open MKVs...

[Baldrick]

Moving you to our mac section.

Nope, I don't know any mac software that can stretch 5.1 ac3 audio.

[Meritocracy]

Audacity can handle MKV but not 5.1 AC3...

Audacity with the ffmpeg plugin can handle and export 5.1 AC3 audio. Just make sure to specify 'use custom mix' in preferences.

[phase52001]

I've done something like this with MovieConvertor-Studio.
http://www.movieconverter-studio.com
Not sure if it was with 5.1 AC3.

I wanted to add the english audio track from the english version of a CGI film to the french print of the film, which also had french audio.
Two copies of the same film, one at 24 fps and one at 25 fps. I used MovieConvertor-Studio to convert one film to the frame rate of the other, then extracted the audio. Then added the audio to the other film. MovieConvertor-Studio does an excellent job at frame rate conversion and adjusts the audio to fit without any obvious changes. (Nothing I can hear).

If you convert the 25 fps DVD to 23.9776 (24FPS) then extract the audio with eg MPEG STREAMCLIP you should be able to mux the audio into the MKV file with MKVToolnix without any trouble, provided both prints are indentical. No additional material.

Only problem is that MovieConvertor-Studio isn't a freebie.

[pwes]

Audacity with ffmpeg plugin basically does it. The hard thing is getting the percentage right as my "theoretic" calculations wasn't the factual difference, and audio needs cropping in one end and may need it in the other as well..

[pwes]

Seems Audacity doesn't do what it says it does, when it comes to speeding it down. It consequently makes the file too long or too short... And three decimal places may be too little precision anyway.

@ phase502001: Handbrake can convert 25 fps to 23,976, but keeps the length of the movie instead of keeping all the frames...

Maybe another simple tool would do that right...

[pwes]

BTW MovieConvertor-Studio is nothing, really...

[phase52001]

@ phase502001: Handbrake can convert 25 fps to 23,976, but keeps the length of the movie instead of keeping all the frames... Maybe another simple tool would do that right...

I didn't mention Handbrake, so why bring it up? Unless you're replying to a post in another thread .... ?

BTW MovieConvertor-Studio is nothing, really...

"is nothing, really ...." means what exactly? You've used it extensively and it does nothing?
Why even say something like that if you're not going to explain why?

You ask for help, but it appears you don't really what it. Fine. Where's that igore button ....

[pwes]

@phase52001: Sorry for thinking aloud... I just wish Handbrake could do it. Downloaded MovieConverter - and while it's probably fine for its purpose, it's not very allround and does not seem to offer a solution to my problem.

So I need help. And sorry if I offended you, phase52001!

[Herve]

hello

MovieConverter - and while it's probably fine for its purpose, it's not very allround and does not seem to offer a solution to my problem.

not sure I well understood the topic but here is some details…

No, my app (I'm the author of MovieConverter) does not convert a PAL 5.1 audio to a NTSC FILM 5.1 audio (it only converts it to a NTSC FILM or VIDEO stereo audio). Why? 'cause while trying to keep 5.1 audio during stretch process, I have some random behaviors = the app is not reliable anymore, some "audio samples" could be lost = out of synch or final "metallic sound" (so, I continue to force conversion to stereo while converting from one standard to another)

PS: you can try to
- manually convert your 5.1 audio to a pcm file (wave)
- stretch it. E.g.: with audacity (if it handles multi channels audio, I didn't check it) or with Amadeus (shareware app)
- compress it to ac3 (FFmpeg or Compressor)
- …mix your video (.mkv) with your new stretched audio (.ac3)

PPS: (just my 2 cents) personnaly I don't mind about the pitch. My television standard is PAL, so TV or DVD are accelerated from original movie picture, but pitch is not often adapted and … I don't think it's a concern (it's just my personal opinion )

P…PS: I don't understand the meaning of "it's not very allround" (I'm not a native english speaker), could you explain it to me (by private mail if you want )

bye

[Selur]

Hybrid does offer options to stretch/shrink audio,...

[pwes]

@Selur: Thanks! Was checking back on this. Will see what Hybrid can do!

[Selur]

Do that, if you run into problem let me know, since I'm always happy to get some feedback.