Hi! Is there a way to change a length of the audio file (this applies to ads that will be broadcast on the radio and must have the same time accurate to milliseconds). Let’s say I have 20 audio ads, which were originally meant to be 30 seconds, but they have small differences of up to less than a second. I would like to do a one-off activity that will change their length to equal 30.000 seconds. Can i stretch several audio files for the same length at a same time ?
Effect - Change Tempo will allow you to specify a new length. I’ve never used [u]Batch Processing[/u] so I can’t help you with the automation.
Let’s say I have 20 audio ads
With only 20 tracks, I’d do it manually and I’d be done by now. 
You’ll probably want to check the files one at a time to make sure they are right anyway. And, you may need to remove any silence at the beginning & end before you start.
Change Speed will change speed & pitch together, which is simpler and less prone to artifacts, but it won’t allow you to specify a length and you’d have to calculate the percentage change manually.
P.S.
Since these files are for broadcast, I ASSUME they are NOT MP3 or any lossy format? (MP3 compression will add a few milliseconds of silence to the file.)
I would suggest as an alternative Stretch audio to a specified length then you won’t have to keep changing the length control in the effect. It’s a Nyquist plug-in - see Download Nyquist Plug-ins - install for how to install it. It does change the pitch as well as length, though, which you may not want.
You can also use that Stretch plug-in in a Chain (see Doug’s link).
Gale
Steve’s plugin, based on Nyquist effect was exactly what I needed.
I am very grateful, thank you!