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Re: Implementing FFT for an EQ filter on iPhone
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Re: Implementing FFT for an EQ filter on iPhone


  • Subject: Re: Implementing FFT for an EQ filter on iPhone
  • From: Aran Mulholland <email@hidden>
  • Date: Tue, 8 Sep 2009 09:47:48 +1000

you dont want to use fft, too much processing, what you want is a simple high pass filter (high pass allows all freq above a certain hz value to pass thru) set at 1000hz, there are some good code resources at:

  www.musicdsp.org/archive.php?classid="">

On Tue, Sep 8, 2009 at 6:53 AM, Darren Baptiste <email@hidden> wrote:
Hello all,
I am trying to figure out how to process audio data inside the callback of the an mixer AU.
I'd like to be able to remove all bass frequencies, say below 1000Hz, by setting the gain levels for those packets to 0, before passing the audio through to the next AU in the graph.

From my readings, I think that FFTs are useful for this sort of analysis. However, I am unable to understand exactly how to implement one in this scenario. I am attempting to reuse the fft classes from the aurioTouch sample in the iPhone SDK.

I seem to be getting stuck in figuring out how to properly call the SpectrumAnalysisProcess() method, and then what next? Once the data is analyzed, how can I operate on just the parts I want?

Maybe I going about this all wrong? The addition of the graphics processing makes the aurioTouch sample quite complicated for me to follow. Any suggestions are most welcome.

Cheers,
Darren




Darren Baptiste
pélau imagineering
http://HotWaxPlayer.com
 
Email: email@hidden
Phone: 647.407.0118

"Be the change you wish to see in the world" - Mahatma Ghandi






Darren Baptiste
http://HotWaxPlayer.com

"Be the change you wish to see in the world" - Mahatma Ghandi


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  • Follow-Ups:
    • Re: Implementing FFT for an EQ filter on iPhone
      • From: William Stewart <email@hidden>
References: 
 >Implementing FFT for an EQ filter on iPhone (From: Darren Baptiste <email@hidden>)

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