iPhone AVCaptureDeviceInput如何設置音頻捕捉的質量？

Question

下面的代碼工作正常（一些檢查和代碼消除）在44100深度2這似乎是默認的。由於此界面可用，但沒有很好地記錄，任何人都知道如何更改默認質量？

audioCaptureDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeAudio]; 
captureSession = [[AVCaptureSession alloc] init]; 
audioInput = [AVCaptureDeviceInput deviceInputWithDevice:audioCaptureDevice error:&error]; 
[captureSession addInput:audioInput]; 
audioOutput = [[AVCaptureAudioDataOutput alloc] init]; 
[audioOutput setSampleBufferDelegate:self queue:dispatch_get_main_queue()]; 
[captureSession addOutput:audioOutput]; 

Answer 1

這應該是訣竅。

這裏更多

http://developer.apple.com/library/ios/#documentation/AudioToolbox/Reference/AudioSessionServicesReference/Reference/reference.html

union 
{ 
    OSStatus propertyResult; 
    char a[4]; 
} u; 

Float64 F64sampleRate = 8192.0; 

Float64 F64realSampleRate = 0; 
UInt32 F64datasize = 8; 

u.propertyResult = AudioSessionSetProperty ( kAudioSessionProperty_PreferredHardwareSampleRate ,sizeof(F64sampleRate) , &F64sampleRate); 
NSLog(@"Set Error Set Sample Rate %ld %lx %c%c%c%c",u.propertyResult,u.propertyResult,u.a[3],u.a[2],u.a[1],u.a[0]); 

u.propertyResult = AudioSessionGetProperty (kAudioSessionProperty_CurrentHardwareSampleRate , &F64datasize, &F64realSampleRate); 
NSLog(@"Get Error Current Sample Rate %ld %lx %c%c%c%c",u.propertyResult,u.propertyResult,u.a[3],u.a[2],u.a[1],u.a[0]); 
NSLog(@"Sample Rate is %f",F64realSampleRate);