Software that can precisely adjust audio length without changing pitch?

[bizzybody]

I have a video and the audio that goes with it, but they're from different sources and the audio runs too fast. The audio must be stretched *precisely* to 7060 seconds or 1:57:40 and not a tick more or less or the dialog sync will be off.

I tried Audacity for Windows and when it does a tempo stretch and export, my 7060 second desire comes out as 7066 seconds. So the dialog in the video gets progressively off. The video is 7063 seconds but the audio cuts off 3 seconds before the end. I've trimmed the silence off end of the too fast audio, will add 3 seconds of silence back when I can get it stretched to the proper length.

I have Adobe Audition 3 but for it and the rest of the CS2 era Adobe software, Windows 10 Pro X64 refuses to allow their installers to work. The programs themselves *will* run in Windows 10, if they were installed prior to upgrading to 10 or prior to whatever recent update is blocking the installers.

[hello_hello]

The Change Tempo plugin for Audacity seems pretty accurate to me (I don't use Audacity much but I just tried it). Is that what you're using?

Other than that, maybe it'd be better to change the frame rate rather than mess with the audio as you can probably do that without re-encoding. You'd need the appropriate muxing program, such as MKVToolNixGUI for MKVs (it'll open lots of file types).

If you're an Avisynth user this seems like an appropriate time to mention my script. AudioSpeed

Or it can be done with ffmpeg if you don't mind using a command line program. I have a few ffmpeg encoder configurations set up with foobar2000, but the command line goes something like this for an NTSC->PAL speedup with no pitch change:

"C:\Program Files\foobar2000\encoders\ffmpeg.exe" -i SomeFile.wav -ignore_length true -af "rubberband=tempo='1001.0/960.0'" -c:a pcm_s24le "Some File Name.wav"

or

"C:\Program Files\foobar2000\encoders\ffmpeg.exe" -i SomeFile.wav -ignore_length true -af "atempo='1001.0/960.0'" -c:a pcm_s24le "Some File Name.wav"

You could try them both to see which one gives you the better quality. You can change "1001.0/960.0" to any value such as the start/end time in seconds (or is it the end/start time in seconds... I'm easily confused), or as a percentage.

If you happen to be applying a standard NTSC/PAL speedup/slowdown, there's a few GUI's that'll do it for you (such as MeGUI).

[bizzybody]

The video stream is from a source that had two audio tracks, both overdubbed with Eastern European languages. The un-fooled-around-with English audio stream, I got from a version that's uncut but 'time compressed' by almost 20 minutes, and lower resolution. At least whomever compressed it did it in a way to keep the pitch right.

On the Audacity forum it's been said I should try change speed instead of change tempo. Change tempo, with or without using the high quality option, overshot the desired time. So I'll try change speed and see if it can nail the runtime precisely.

[hello_hello]

20 minutes is a fair difference. The difference in duration between film and the speedup for PAL is only 5-6 minutes for a two hour movie. Maybe that's why Audacity's Change Tempo plugin wasn't being accurate. I only tried duration changes of 1-2%.

[raffriff42]

my 7060 second desire comes out as 7066 seconds.

Agree w/ hello_hello that Audacity's time estimate might be off with such a large speed change. Try asking for 7054 seconds and see what you get. Keep adjusting your requested run time until the result is good enough.

Also, 6 seconds over 7060 seconds is very close to the difference in run time between 30.00 fps and 29.97 fps. Probably a coincidence...

[bizzybody]

I tried an export to MP3 and it came out the exact length I entered. Seems to be a problem with Audacity's AC3 export.