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Re: CoreAudio and equalization
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Re: CoreAudio and equalization


  • Subject: Re: CoreAudio and equalization
  • From: Paul Russell <email@hidden>
  • Date: Fri, 28 Jun 2002 16:08:27 -0700

Thanks for everyone's helpful help!

Things are better. However, some fuzz still remains if I try to boost the desired frequencies more than a modest amount (certainly much less than a clean sounding boost in a professional audio application). Making the adjustment anything more than 2.0 or 3.0 starts a noticeable fuzz. It isn't the result of the signal clipping, although it certainly is worse then.

I thought perhaps it might be the code I use to determine what buffer to alter for the particular frequency, as I am getting strange results on the upper bands - 10000-16000hz. Is there an easy way to determine which buffer corresponds to which frequency?


i) are you initialising the imaginary part of your time domain input buffer correctly, i.e settign all teh imaginary parts to zero (assuming this is a complex FFT routine) ?

ii) are you maintaining symmetry in the frequency domain ? For each frequency there are two corresponding bins (the positive and negative frequency) whose values should be a complex conjugate pair. You need to scale both of these bins by the same factor otherwise you will end up with a complex time domain signal when you do your IFFT, and the Mac hardware does not support playback of imaginary components (;-)).

Paul

--
| Paul Russell email@hidden |
| ARC Software Ltd http://www.arc-software.com |
| Santa Cruz, CA |
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References: 
 >Re: CoreAudio and equalization (From: john <email@hidden>)

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