Apple

nope

for a VoIP client you should be using the AU Remote IO audio unit - you have one that you use for both input and output and it will give you a much lower latency than you can get from using audio queue for duplex I/O

On Sep 24, 2008, at 1:47 PM, Inca R wrote:

Hi;
Is Audio Queues for iPhone the best interface API to get
Audio Input ( mic ) samples for a real time App ? ( VoIP client )

Thanks
Inca

On Wed, Sep 24, 2008 at 5:00 AM, William Stewart <email@hidden> wrote:

Check the result code returned by AudioQueueNewInput - the ASBD you have for this is not correct - you could specify the ASBD with everything set to zero except for formatID, num channels and sample rate, and the AQ will fill this out for you

Bill

On Sep 23, 2008, at 6:24 AM, Inca R wrote:

Hi;
I'm trying to get ulaw samples at 20 millis from the iPhone mic, but this seems impossible.

The audioFormat definition is:
audioFormat.mSampleRate = 8000.0;
audioFormat.mFormatID = kAudioFormatUlaw;
audioFormat.mFormatFlags = 0;
audioFormat.mFramesPerPacket = 1;
audioFormat.mChannelsPerFrame = 1;
audioFormat.mBitsPerChannel = 8;
audioFormat.mBytesPerPacket = 1;
audioFormat.mBytesPerFrame = 1;

The audio input queue creation:

AudioQueueNewInput (

&audioFormat,
recordingCallback,
mydata, // userData

NULL, // run loop

kCFRunLoopCommonModes,// run loop mode

0, // flags

&queueObject

);

I also create 3 buffers of 160 bytes ( 20 millis ) each and enqueue them into the previously created Audio Input Queue.

Everything works ok, BUT, there is a problem on the frequency I get called to my AudioQueueInputCallback function ( recordingCallback).

It was expected to be every 20 millis. But not. The Callback get called
every 30 to 70 nanoseconds but every 1/2 second the callback is called with a 1/2~1 second delay.

Anybody knows the logic behind this behavior ?
I'm missing any configuration or parameter ????

another issue is that the documentation says that for CBR codecs the last two parameters

of the callback function are set to NULL. But in my example I get called with the last one set to NULL

but the other one with the number of samples returned on the buffer.

This is correct ???

Thanks
Inca

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References:
	>Audio Input Queue on iPhone (From: "Inca R" <email@hidden>)
	>Re: Audio Input Queue on iPhone (From: William Stewart <email@hidden>)