Help with sample rate mixup please

seasiderecording · Post by **seasiderecording** » Sun Feb 18, 2007 11:50 am

Here's my problem, I am clocking Digital Performer to my Mackie Digital Board. The Mackie is the Master clock and is usually set to 44.1 as is DP. I use a MOTU 2408 in between.
I did a voiceover session to a quicktime movie that had some audio in it already. The audio in the movie was at 48k and somehow switched my DP file to 48k before I started recording and I didn't notice because everything sounded and played back fine even though the master clock was at 44.1 and DP was at 48k. Confused yet?
When my client put the voice recording files that they took with them on a small USB flashdrive into the movie at their place someone eventually noticed that the Voiceover sounded a bit like Alvin the chipmunk. I can get it to play correctly if I duplicate the mismatched sample rate clocking and probably do an analog pass and make new files that are correct.
Is there a quick way to process the files to make them play correctly? I'm hoping some of you smart people can come to my rescue. Thanks in advance for any help.

Timeline · Post by **Timeline** » Sun Feb 18, 2007 1:52 pm

If you had an RME FF800 there is a feature in the setup menu that will allow you to pitch down the session to original but you would have to mix there to analog. Also in Peak LE there is a way to chang SR and correct each track independantly.

Good luck.

seasiderecording · Post by **seasiderecording** » Sun Feb 18, 2007 2:04 pm

Timeline wrote:If you had an RME FF800 there is a feature in the setup menu that will allow you to pitch down the session to original but you would have to mix there to analog. Also in Peak LE there is a way to chang SR and correct each track independantly.

Good luck.

Doing a sample rate conversion only causes the file to play too fast at the new sample rate. The files were recorded at 48 while slaved to a 44.1 clock somehow.

Timeline · Post by **Timeline** » Sun Feb 18, 2007 3:28 pm

I know this.

I have had it happen to me.

My post and it's recommendations do work. Peak has a way to do this. Call them tuesday and they will explain.

Jim · Post by **Jim** » Sun Feb 18, 2007 4:13 pm

Let's see. Divide 48000 by 44100 and you get 1.08843537415. So, if you enter that value into a time-stretcher (a ratio of 1:1.08843537415).

Or, taking the other way, you could slow down the file at 0.91875%, and that should get you to the same place.

Yes? Somebody please correct me if my math doesn't add up. It's not my strong suit.

dweiss · Post by **dweiss** » Sun Feb 18, 2007 4:30 pm

The free utility called Soundhack enables you to rewrite audio file headers. In other words, your file is one sample rate but it's header tells the host software otherwise. Depending on how many files you have to change, Soundhack can save you a lot of hassle.

Tim · Post by **Tim** » Sun Feb 18, 2007 4:31 pm

Get Soundhack and change the VO file header from 48000 to 44100.

Timeline · Post by **Timeline** » Sun Feb 18, 2007 4:37 pm

Hey tim.

Yea if soundhack is free go for it. The header is the deal though. I had forgotten.

Tim · Post by **Tim** » Sun Feb 18, 2007 5:38 pm

It be free!
No batch processing though.........but for this case, a single v/o track.....

seasiderecording · Post by **seasiderecording** » Sun Feb 18, 2007 8:06 pm

Thanks for the input everyone. Your math is correct on the 48k 44.1k ratio. I ended up doing a pitch change in Peak by about -104 cents, allowing the duration to change, then convert to 44.1 and it sounds fine. I'm curious about the soundhack for future screw ups so I'll have a look.
But guess what? they want to redo the session with a different talent and script changes so i dodged the bullet.

seasiderecording · Post by **seasiderecording** » Fri Feb 23, 2007 10:37 pm

I did try soundhack to change the header. This worked great!!!! No need to degrade with pitch or duration conversions. Thanks for the tips everyone.