Sample Rate Mismatch Conversion

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mjbennett
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Sample Rate Mismatch Conversion

Postby mjbennett » Fri Feb 27, 2015 14:07

I've been given some files from an engineer which have a sample rate mis-match, and I'm hoping that someone might have an idea of how to remedy the issue.

The files are WAV, and the meta says that they are 88.2. However it seems that his Adobe Audition was actually recording 44.1 files. The project sample rate was set at 88.2 but somewhere a device was only at 44.1k.
When I play them back in Pyramix they play half speed. I've tried to resample them, and I've tried to render them - all with no success.

Any ideas welcome!
Best,
Matthew

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fl
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Re: Sample Rate Mismatch Conversion

Postby fl » Fri Feb 27, 2015 17:36

I'm a little confused - is your session SR set at 88.2? If that is the case, and they're playing back at half speed, wouldn't their actual sample rate be 176.4? (This stuff always hurts my head.) Do you have another player, such as Foobar, which can play the file(s) and display the file's information? Do they play properly or improperly there?

Is Pyramix's Realtime Sample Rate conversion enabled (Settings > Application > Playback/Record)? How do your files play back with this disabled? Enabled?

My confusions aside, if it turns out you need to edit the file's header information to change its currently reported sample rate to the actual one, you need a utility like Sound Devices' "Wave Agent": http://www.sounddevices.com/products/waveagent/
Of course, you'll want to work on a copy...
Frank Lockwood, Toronto, ON, Canada
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mjbennett
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Joined: Sat Sep 25, 2010 15:05

Re: Sample Rate Mismatch Conversion

Postby mjbennett » Fri Feb 27, 2015 17:47

Hi Frank,
Sorry it is confusing - I'm very confused.
With the session sample rate set at 88.2 they play half speed, as they are actually at 44.1. Setting it to 176.4 does make them play back normally. But I need to edit them into material from latter sessions after the engineer realised his mistake and started recording regular 44.1k files.

The files are recorded in Adobe Audition.

Will try the waveagent suggestion! Thanks
Last edited by mjbennett on Fri Feb 27, 2015 18:51, edited 1 time in total.

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fl
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Re: Sample Rate Mismatch Conversion

Postby fl » Fri Feb 27, 2015 18:15

mjbennett wrote:With the session sample rate set at 88.2 they play half speed, as their actually at 44.1.


I believe that if they're playing at half speed, their actual SR is 176.4. As is proved by:
mjbennett wrote:Setting it to 176.4 does make them play back normally.


On the other hand, if you have Pyramix's Realtime Sample Rate Conversion turned on, you could be getting any manner of wackiness, depending on the SR mismatch in the files' header(s), so make sure that feature is turned OFF in the Pyramix Settings.

mjbennett wrote:But I need to edit them into material from latter sessions after the engineer realised his mistake and started recording regular 44.1k files.
Will try the waveagent suggestion! Thanks


Since you need to wind up with 44.1 files, you need to do a two step process. Use Wave Agent to change the header information so that the reported SR corresponds to their actual SR - 176.2 kHz. That process just changes the header, it doesn't change the file in any other way, so you still need to do the actual sample rate conversion to 44.1, which you can do in Pyramix, either as a Quick Convert in the Media Manager, or as a Render from the Timeline. With Realtime SR Conversion turned off, you'll be able to hear when you've got it right, and everything is playing back properly in a 44.1 session.
Frank Lockwood, Toronto, ON, Canada
http://LockwoodARS.com
• Pyramix Native
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• HP 7100 Mini-tower - Win10 Pro 64 1809
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mjbennett
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Joined: Sat Sep 25, 2010 15:05

Re: Sample Rate Mismatch Conversion

Postby mjbennett » Sat Feb 28, 2015 17:07

Hi Frank,
Thanks again.
The wave agent didn't like the files as they were 32-bit. I followed your steps, but in Pyrmamix. So, in the end I made a 176.4k project and dumped the files in that. Rendered them to 176.4/24bit, and they played back fine. I then sample rate converted them and they worked fine. Built a new project and normality is restored!
Thanks,
Matthew

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fl
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Re: Sample Rate Mismatch Conversion

Postby fl » Sun Mar 01, 2015 00:54

Good to hear, and good to learn about that limitation to Wave Agent.
Frank Lockwood, Toronto, ON, Canada
http://LockwoodARS.com
• Pyramix Native
• Mac Mini 6.2 (Quadcore i7) - Bootcamp 5.1.5621 - Win7 Pro SP1 64
• HP 7100 Mini-tower - Win10 Pro 64 1809
• RME Fireface 800 ASIO driver 3.125 or ASIO4All 2.13