iPhone 3G Line In recording


#1

So I built a cable for connecting some line source to the iPhone’s Line In Pins on the connector. Would I be able to record this Line In signal using JUCE? Or is JUCE always recording from the iPhone’s Mic input?


#2

Just a wild guess but don’t you need to open the audio device and request at least one input channel, then do something with those buffers in the audioDeviceIOCallback ?


#3

Ofcourse, but first of all I’d need to either get a developer license from Apple or Jailbreak my iPhone before I can even run some selfmade app on it. So I wanna make sure in advance that the Line Input is actually exposed by the OS.


#4

That makes sense. Try asking in #iphonedev on effnet IRC


#5

Yes:

https://developer.apple.com/library/ios/#DOCUMENTATION/AudioToolbox/Reference/AudioSessionServicesReference/Reference/reference.html

https://developer.apple.com/library/ios/#DOCUMENTATION/AVFoundation/Reference/AVAudioSession_ClassReference/Reference/Reference.html#//apple_ref/doc/uid/TP40008240

The system can be fickle about routing to accessory jack devices, but it basically works.


#6

Well that’s the whole point, I do NOT want to record from the (mono) jack input, but from the stereo LINE input, which is located on pins 5 & 6 of the dock connector. See here for reference: http://www.allpinouts.org/index.php/Apple_iPod,_iPad_and_iPhone_dock
In The AudioSession services, I can’t see any information on how to do that.


#7

That’s because the dock connector isn’t iO from an applicaiton’s perspective. You can only route to accessories, which generally have to be certified.

On some hardware, the stereo analog in is deprecated, replaced with a digital input. Other hardware, like the camera kit, are seemingly constrained to iPad only for marketting reasons, not physical limitations.

Take a look at existing accessories, like GuitarJack, for iOS for a better idea.