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Re: Some help about how to process a signal.
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Re: Some help about how to process a signal.


  • Subject: Re: Some help about how to process a signal.
  • From: Gregory Wieber <email@hidden>
  • Date: Sun, 15 May 2011 09:31:42 -0700

If you've read about playing a wav file, the difference is that instead of reading frames of an audio file, you want to read frames from your signal array. 

- The Audio Stream Basic Description (ASBD) of your project will determine what range the numbers in your signal array should be. (eg. -1 to 1, -32768 to 32768 for signed 16bit, etc).
- I'd suggest creating a struct that holds a phase_index variable, which you increase each time through your render loop (look up remote-IO and render input proc) and use it to access the numbers in your signal array. (In my project, phase_index is a float for accuracy, and I round it to use as an array index value.) 
- The same struct should have a phase_increment value. The phase_increment is based on the sample rate and your desired tone-frequency.
- Fully read and understand the documentation regarding buffers, frames, etc. 

I haven't had any coffee yet, so that info is a little off-the-cuff.

best,

Greg Wieber
gregorywieber.com

2011/5/15 Jose María Gómez <email@hidden>
I am new to CoreAudio and I am trying to figure out how to make a quite simple thing. What I would like to do is to output a simple sinosoidal signal to my audio card. I have read about how to play a .wav, but that is not what I need to do. What I really would like to do is to put some values of a discrete signal in an array and depending on a frecuency creating a signal and make it to sound in my computer.

Could you please give me some sample code ... thanks in advance.
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References: 
 >Some help about how to process a signal. (From: Jose María Gómez <email@hidden>)

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