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  #1  
Old 09-25-2020, 01:53 PM
SDRooster SDRooster is offline
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Default 1st Sample Rate prob in 20 years

Demo studio with MBP & Focusrite18i20 running PT 2019.5.0

For the last fifteen years we always run our Demo rig at 24-bit 48kHz. This has been a hard rule for simplicity with Demo’s = we don’t even think about this anymore when doing demo’s.

We tracked another great session @ 48k but upon listening to the stereo bounces they played back at the wrong speed on everything but the PT rig.

We found these steps corrected the ten bounced demo’s:
1. Bounce out stereo audio from original 48kHz session
2. Create new session at 44.1kHz
3. Import bounced audio into new sesh & convert to 44.1kHz
4. Force PT drop down for Source Clock to 44.1 -= yes we had to tell PT to convert a 48kHz source file from 44.1 to 44.1
5. Now plays correctly in new PT sesh & all bounces
* without step 4 it was still not the correct speed, different, but still wrong.

Now we have found the original sessions are playing back at different speeds inside Pro Tools after trying to trouble shoot the above sample rate issue.

Anyone have suggestions on addressing the original ten multitrack sessions now? I would prefer not to scrap them if possible. Was thinking of starting a new session for each of the ten demo’s and then just follow similar steps as above to convert all the audio files from the original multitrack session down to 44.1? ✌🏻

** still wondering why/how this happened and if we should worry about it in the future - we have never had this problem going back to ProTools LE w/ a Digi001 even when running audio in thru lightpipe from external source.
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  #2  
Old 09-25-2020, 02:55 PM
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Top Jimmy Top Jimmy is offline
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Default Re: 1st Sample Rate prob in 20 years

Assuming the audio was sped up in everything else other than Pro Tools, the sample rate when recorded was 44.1 but the header of the file is marked as 48. The simple fix is to save session copy changing the sample rate to 44.1 while turning off sample rate conversion. Then if you really want them to be 48, save session copy again changing the sample rate to 48 leaving sample rate conversion on.

Why this happened is difficult to say. If you were clocking from a digital input on the 18i20, the source was probably set to 44.1 while the session was set to 48.

If using internal clock, when using software, stuff happens. Trash prefs for Pro Tools and for the 18i20 and/or Scarlett mix control and see if everything returns to normal.
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Hackintosh - Gigabyte Z77X-UP5TH, Intel Core i7-3770K, 32GB 1600Mhz DDR3, 2x SATA 6Gb/s 240GB SSD, 3x SATA 6Gb/s 1TB HDD, 1x Glyph 2TB USB3 HDD, Mojave 10.14.4.

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  #3  
Old 09-25-2020, 03:40 PM
Darryl Ramm Darryl Ramm is online now
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Default Re: 1st Sample Rate prob in 20 years

Do not trash anything.

What sample rates do the sessions think they are at? (Actually check what they are set to) And what sample rates is the content actually at? Sounds like they thought they agreed and you had an interface driver or clocking issue. And you managed to fix that and now stuff works as expected except for the old content.

If it was not a Pro Tools session rate problem then might find it easier to just use a stand alone utility that can sample rate convert all the files in the audio folder. 2nd Sense ReSample and Voxengo r8brain come to mind. You might have to trick them into adjusting sample rates they think are OK...

How is your hardware clocked? Focusrite drivers might be more prone than others to misset clock rates. Maybe you or a client/other user on the computer had another app open in the background etc. You just have to pull on the string and work though everything that controls clock rates/all relevant settings in Pro Tools are excluded.
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Old 09-26-2020, 03:24 AM
SDRooster SDRooster is offline
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Default Re: 1st Sample Rate prob in 20 years

Thanks so much for both of your replies and suggestions. I was a SysAdmin for more than a decade and this felt like a software glitch to me - this was my initial hunch but I just am not sure WTF happened. Yes, Pro Tools operating at 44.1 but marking the file as 48 sure seems what happened in hind-site.

I looked at all ten sessions in Setup/Session and they all showed to be at 48kHz. The clock is and has always been set to internal with the Focusrite. For this demo rig it was just a set it and forget it kinda deal. We have used 48kHz for so long here with this rig its like muscle memory.

Thanks for the suggestions. Will try the save session copy first. At this point I don’t care if its 44.1 or 48 I’d just like to salvage the drum tracks if nothing else as it was one of those unusually epic sessions.

We’ve never had any issues with this Focusrite> not sure it is the problem now really but It may just be time to upgrade. Any thoughts? The Apollo x8 and 16 both caught my eye... Maybe even go with the HD rig here for the Demo’s...

BTW - how is that Hackintosh? Haven’t built one of those in years.. The last one I did was so long ago it had a brand new core2quad cpu. Jajajaja. Still have the original OSX beta product packet and discs from Apple in storage somewhere.

Thanks 🤙🏻
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  #5  
Old 09-26-2020, 10:28 AM
SDRooster SDRooster is offline
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Default Re: 1st Sample Rate prob in 20 years

Quote:
Originally Posted by Darryl Ramm View Post
Do not trash anything.
If it was not a Pro Tools session rate problem then might find it easier to just use a stand alone utility that can sample rate convert all the files in the audio folder. 2nd Sense ReSample and Voxengo r8brain come to mind. You might have to trick them into adjusting sample rates they think are OK...
Thanks for the info on the above apps. Might not go that route here but I will certainly put that info into the toolbox for the future 🤙🏻
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  #6  
Old 09-26-2020, 10:38 AM
Darryl Ramm Darryl Ramm is online now
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Default Re: 1st Sample Rate prob in 20 years

I was a little asleep, if the issue is just your interface/driver were at the wrong clock rate then I'd use a tool like sox to just correct the sample rates in the wav or aiff headers. sox -r rewrites the sample rate in the header.

Sox is a handy command line utility, with a little UNIX skill you can wrap it in a shell script to process all the files in a session if they are all wrong.

Best way to install it is to install the homebrew package manager first. https://brewinstall.org/Install-sox-on-Mac-with-Brew. If you are stuck on that reply here or PM me and I'll help you get going.

Sox home: http://sox.sourceforge.net

I also have some custom Python programs for stuff like this and some custom repair/inspection (lots of nice python package support for audio... although changing the header sample rate is totally trivial) but sox will do all you need much of the time.

Last edited by Darryl Ramm; 09-26-2020 at 11:45 AM.
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