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Old 11-09-2017, 02:00 AM   #1
mibes
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Join Date: Apr 2017
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Default Upsample incoming audio

Hi,

Trying to implement a frequency shifter / ring mod. It appears I need to upsample the incoming audio in order to avoid aliasing. Using the wdl resampler in the processDoubleReplacing loop is nowhere near fast enough.

Any ideas?
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Old 11-09-2017, 11:52 AM   #2
earlevel
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Quote:
Originally Posted by mibes View Post
Hi,

Trying to implement a frequency shifter / ring mod. It appears I need to upsample the incoming audio in order to avoid aliasing. Using the wdl resampler in the processDoubleReplacing loop is nowhere near fast enough.

Any ideas?
I haven't used the wdl resampling facilities. But SRC always involves tradeoffs, and you really need to understand them well—whether the wdl resampling is flexible enough to allow you to dictate those tradeoffs, or whether you have to roll your own. I assure you it can be done. I wrote Amp Farm 20 years ago, for a 40 MHz 56002 (Pro Tools of the day)—that's 800 cycles for the entire amp-cabinet sim with two-stage oversampling. Even old decrepit hosts of today blow that processing power away.

This will be purely amplitude modulation, right? So just 2x? Hard to believe the wdl resampler won't do that easily...
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