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  #1  
Old 01-15-2021, 05:44 PM
Sonopolis Sonopolis is offline
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Default 32bit SRC bug

When I import a 32bit file and use sampling rate conversion the resulting file is wrong.

When I import it with 4.1667% pull up (50kHz) it results in a file playing much too fast and Mickey Mousey high. The resulting file is precisely 1/4 the length of the original. When importing it with 0.1% pull up the result is actually longer than the original. I have not tested all options so it’s possible there are problems with other SRC settings, too.

Can somebody confirm this, please? Reimporting a simple 32bit sine tone with these SRC settings should give the same result.

This is on Mojave with 2020.12 Ultimate
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  #2  
Old 01-15-2021, 11:59 PM
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cwsand cwsand is offline
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Default Re: 32bit SRC bug

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Originally Posted by Sonopolis View Post
When I import a 32bit file and use sampling rate conversion the resulting file is wrong.
Bit Depth/Sample Rate - 2 different things.

Quote:
Originally Posted by Sonopolis View Post
When I import it with 4.1667% pull up (50kHz) it results in a file playing much too fast and Mickey Mousey high. The resulting file is precisely 1/4 the length of the original. When importing it with 0.1% pull up the result is actually longer than the original. I have not tested all options so it’s possible there are problems with other SRC settings, too.

Can somebody confirm this, please? Reimporting a simple 32bit sine tone with these SRC settings should give the same result.

This is on Mojave with 2020.12 Ultimate
Exactly as it should be. If you check Apply SRC in the Import Audio window and using that drop down box to select a custom sample rate, keep in mind you're telling Pro Tools that the Source sample rate is different than what the source file actually is. Pro Tools treats the file as being at the sample rate you selected and converts it to the sample rate of the session. As a result, the file length and pitch will change if you selected a source sample rate other than what the original file was. Again, this is converting the sample rate, not changing the bit depth.
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  #3  
Old 01-16-2021, 12:10 AM
Sardi Sardi is offline
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Default Re: 32bit SRC bug

Bit depth not bit rate.


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Old 01-16-2021, 01:24 AM
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Default Re: 32bit SRC bug

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Originally Posted by Sardi View Post
Bit depth not bit rate.
Right!
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  #5  
Old 01-16-2021, 10:23 AM
Pete Gates Pete Gates is online now
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Default Re: 32bit SRC bug

No it's not exactly as it should be. Sonopolis is right, if you go to "48KHz (pull up/down)" and select either 50,050 or 50,000 then look at what Pro Tools puts as the source sample rate... It's a bug.

Cheers,
Pete
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Old 01-16-2021, 10:34 AM
Sonopolis Sonopolis is offline
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Default Re: 32bit SRC bug

Ok, so you're all assuming the error is in the user, great.
To clear things up, I am very well aware of the difference in sampling rate and bit depth. What I'm saying is that the this sampling rate conversion error only happens with files that have a bit depth of 32.

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Originally Posted by cwsand View Post
Bit Depth/Sample Rate - 2 different things.



Exactly as it should be. If you check Apply SRC in the Import Audio window and using that drop down box to select a custom sample rate, keep in mind you're telling Pro Tools that the Source sample rate is different than what the source file actually is. Pro Tools treats the file as being at the sample rate you selected and converts it to the sample rate of the session. As a result, the file length and pitch will change if you selected a source sample rate other than what the original file was. Again, this is converting the sample rate, not changing the bit depth.
No, not exactly how it should be. I am also aware of how sampling rate conversion in Pro Tools works. However the resulting file should not have exactly 1/4 the length of the original but instead be be 4.1667% shorter and playing higher. Wouldn't you agree?
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Old 01-16-2021, 10:40 AM
Sonopolis Sonopolis is offline
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Default Re: 32bit SRC bug

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Originally Posted by Pete Gates View Post
No it's not exactly as it should be. Sonopolis is right, if you go to "48KHz (pull up/down)" and select either 50,050 or 50,000 then look at what Pro Tools puts as the source sample rate... It's a bug.

Cheers,
Pete
Exactly. just realized this, too. So I stand corrected, 0.1 pull up works and not only 32 bit files are affected.
Bildschirmfoto 2021-01-16 um 18.31.05.jpg
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Old 01-16-2021, 11:15 PM
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Default Re: 32bit SRC bug

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Originally Posted by Sonopolis View Post
No, not exactly how it should be. I am also aware of how sampling rate conversion in Pro Tools works. However the resulting file should not have exactly 1/4 the length of the original but instead be be 4.1667% shorter and playing higher. Wouldn't you agree?
I don't know - last night when I tested the 2 settings you listed, the resulting files were exactly as they should have been, but I didn't test it any further. But when selecting any of the Pull Up/Pull Down presets now, some show the correct sample rate and some don't. It's bizarre because I still have the session and the file imported at 0.1% Up is only slightly faster than the original. It may be an intermittent problem.

I installed PT 2020.3.0 and all the Pull Up/Down settings show the correct source sample rate when selected so some of the settings in 2020.12.0 are showing up as the wrong sample rate. I'll report the bug and hopefully it gets fixed in the next release.

At least you can enter the correct sample rate manually as a workaround.
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  #9  
Old 01-17-2021, 04:08 AM
Sonopolis Sonopolis is offline
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Default Re: 32bit SRC bug

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Originally Posted by cwsand View Post
It's bizarre because I still have the session and the file imported at 0.1% Up is only slightly faster than the original. It may be an intermittent problem.
Like I said, 0.1% works, it's 50050 and 50000 that cause the problems.

Thanks for reporting, I did too.
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Old 01-18-2021, 01:33 AM
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Default Re: 32bit SRC bug

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Like I said, 0.1% works, it's 50050 and 50000 that cause the problems.

Thanks for reporting, I did too.
Yes, the 50,050 that is 0.1% Up NTSC to PAL is messed up, but the 48,048 0.1% Up NTSC to Film is ok.
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