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Re: reading from the iPhone mic with a small buffer size
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Re: reading from the iPhone mic with a small buffer size


  • Subject: Re: reading from the iPhone mic with a small buffer size
  • From: William Stewart <email@hidden>
  • Date: Mon, 24 Nov 2008 15:17:23 -0800

Have a look at the aurioTouch code.

It also shows how you can syphon off the render (I/O) buffer from the input so that you can use it elsewhere (to draw for it for instance).

Bill

On Nov 24, 2008, at 8:49 AM, tahome izwah wrote:

Just curious: why would you need a specific buffer size? You can't
always expect the device to have an adjustable buffer size so relying
on a fixed buffer is generally not a good idea, design wise. You
really should do your own buffer bookkeeping and accept what you are
given... if that is possible in your app (most of the time it is).

HTH
--th

2008/11/24 Nate <email@hidden>:
As you may know from my small flurry of posts (sorry), I'm using Audio Unit
RemoteIO to read from the iPhone microphone. I am unable to set the buffer
size, so I have to just use whatever the default is. The problem is that
when I concatenate two buffers, they don't match up perfectly. It appears
that I lose some data in between the buffers. I managed to draw the buffers
so the phenomenon could be seen:


http://n4te.com/temp/brokenwave.gif

Near the center of the image is where one buffer ends and the next begins.
You'll see there that the wave is not smooth.


All I want to do is read from the mic on the iPhone! My requirements are
1024 samples at a 22050 sample rate (or 2048 samples at 44100 since it is
easy to ignore every other sample). I tried Audio Queue Services but it
internally buffers 8k before invoking my callback multiple times. RemoteIO
is complicated with little documentation and doesn't let me set a buffer
size and it doesn't respect the sample rate I set. Am I really asking too
much from the iPhone? It seems like a reasonably simple task, but I don't
seem to be able to solve it by myself.


Does anyone have sample code for reading from the iPhone mic? Any clues at
all how to solve this? I'm losing it!


Thanks!
-Nate

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References: 
 >reading from the iPhone mic with a small buffer size (From: Nate <email@hidden>)
 >Re: reading from the iPhone mic with a small buffer size (From: "tahome izwah" <email@hidden>)

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