How to stretch AC3 audio by .00001%

[5js]

I've been searching and cannot find the answer Im looking for.

I have a movie that I'd like to add another foreign language AC3 audio file to.

The foreign language AC3 is shorter by 1 second and I need to stretch it.

The Foreign Language AC3 audio file is: 01:04:38.368

It needs to be 01:04:39.712


I have tested the number above using MKVmerge it works perfectly. BUT MKVmerge does not re-encode and I want to make a BLURAY so I need to stretch the actual AC3 file. HOW?

Is there a guide or walk-through please.

Thank You.

[Bjs]

AC3 what ?

2 or more channels

Install audacity, then file > preferences > libraries

Hit download mainly for the ffmpeg library and install.

Then edit menu > preferences > import/export, select "use custom mix"

You will be presented with a "channel mapping" option during Export that allows you to select which Audacity track goes to which audio channel in your exported file

Once done you should be able to open the ac3 in audacity ... may take time to load the file

Audio align:

Next in lower right of main screen change "audio position" by clicking the arrow on its right hand side and select hh:mm: ss + milliseconds.

From here in your case and if audio sync is fine, simply copy silence portion equal to 1. 344 seconds and paste into each channel on the end.

Then file > export, name file, hit save and a panel with channel output opens allowing you to set and reorder channels, hit ok and wait.

Enjoy new file.

[5js]

From here in your case and if audio sync is fine, simply copy silence portion equal to 1. 344 seconds and paste into each channel on the end.

Thats not stretching the file.

I need to Stretch the audio file by 1.344 seconds not add 1.344 seconds.

I am not trying to be mean, because you are trying to help, but if you read my original post you will see that if I use stretch by in mkvmerge it works. But MKVmerge does not reencode the audio and i need to stretch and reencode the audio.

[hello_hello]

Maybe my math is bad but I work it out as original x 1.00035, or .035% (to within about 10ms).

Audacity has a couple of "Change Speed" effects which seem to allow you to specify a stretch in .001% increments.
There's a DSP for foorbar2000 which can be used while converting called SoundTouch, but it'll only do .01% increments.

[5js]

Maybe my math is bad but I work it out as original x 1.00035, or .035% (to within about 10ms).

Audacity has a couple of "Change Speed" effects which seem to allow you to specify a stretch in .001% increments.
There's a DSP for foorbar2000 which can be used while converting called SoundTouch, but it'll only do .01% increments.

Thank You.

Can you please tell me how you got to .035%

I mean the actual steps please so I can redo it.

[jagabo]

Yes, use Effect -> Change Speed in Audacity. Positive values decrease the length, negative values increase the length. Ie, you want to enter -0.035 (I didn't check the math) to make the audio longer.

[5js]

Yes, use Effect -> Change Speed in Audacity. It's not limited to 3 digits to the right of the decimal point if you type in a value.

Ok cool.

Now how do I get that value.

The Foreign language ac3 is 01:04:38.368
I need to stretch it to 01:04:39.712

Can you please tell me how to get the % value for that.
Also pardon my ignorance, but if you can supply me with a % please show me the steps to get that %.

I realize now its a calculator issue. Got the 2nd part out the way with your help.

[hello_hello]

01:04:38.368 = 64 minutes, 38.368 seconds or 3878.368 seconds.

01:04:39.712 = 64 minutes, 39.712 seconds or 3879.712 seconds.

3879.712 / 3878.368 = 1.000346573513

To confirm:

3878.368 x 1.00035 = 3879.725 or

3878.368 x .035 / 100 = 1.357
3878.368 + 1.357 = 3879.725 (13ms out due to rounding).

[jagabo]

hello_hello beat me.

[5js]

THANK YOU to both jagabo and hello_hello

It worked!