IOS音频架构之Audio Unit ：http://blog.csdn.net/u014011807/article/details/46980699
音频单元组件服务参考（Audio Unit Component Services Reference） http://www.lxway.com/802012256.htm
1、描述音频单元
AudioComponentDescription desc;
desc.componentType = kAudioUnitType_Output;
desc.componentSubType = kAudioUnitSubType_RemoteIO;
desc.componentFlags = 0;
desc.componentFlagsMask = 0;
desc.componentManufacturer = kAudioUnitManufacturer_Apple;
2、查找音频单元
AudioComponent inputComponent = AudioComponentFindNext(NULL, &desc);
3、获取音频单元实例
status = AudioComponentInstanceNew(inputComponent, &audioUnit);
4、启用录制功能、启用播放功能
UInt32 flag = 1;
status = AudioUnitSetProperty(audioUnit,
kAudioOutputUnitProperty_EnableIO,
kAudioUnitScope_Input,
kInputBus,
&flag,
sizeof(flag));
status = AudioUnitSetProperty(audioUnit,
kAudioOutputUnitProperty_EnableIO,
kAudioUnitScope_Output,
kOutputBus,
&flag,
sizeof(flag));
5、音频流描述
AudioStreamBasicDescription audioFormat;
audioFormat.mSampleRate
= 44100.00;
audioFormat.mFormatID
= kAudioFormatLinearPCM;
audioFormat.mFormatFlags
= kAudioFormatFlagIsSignedInteger | kAudioFormatFlagIsPacked;
audioFormat.mFramesPerPacket
= 1;
audioFormat.mChannelsPerFrame
= 1;
audioFormat.mBitsPerChannel
= 16;
audioFormat.mBytesPerPacket
= 2;
audioFormat.mBytesPerFrame
= 2;
6、应用录制和播放的音频流描述
status = AudioUnitSetProperty(audioUnit,
kAudioUnitProperty_StreamFormat,
kAudioUnitScope_Output,
kInputBus,
&audioFormat,
sizeof(audioFormat));
status = AudioUnitSetProperty(audioUnit,
kAudioUnitProperty_StreamFormat,
kAudioUnitScope_Input,
kOutputBus,
&audioFormat,
sizeof(audioFormat));
7、设置回调
AURenderCallbackStruct callbackStruct;
callbackStruct.inputProc = recordingCallback;
callbackStruct.inputProcRefCon = self;
status = AudioUnitSetProperty(audioUnit,
kAudioOutputUnitProperty_SetInputCallback,
kAudioUnitScope_Global,
kInputBus,
&callbackStruct,
sizeof(callbackStruct));
callbackStruct.inputProc = playbackCallback;
callbackStruct.inputProcRefCon = self;
status = AudioUnitSetProperty(audioUnit,
kAudioUnitProperty_SetRenderCallback,
kAudioUnitScope_Global,
kOutputBus,
&callbackStruct,
sizeof(callbackStruct));
8、回调方法
static OSStatus recordingCallback(void *inRefCon,
AudioUnitRenderActionFlags *ioActionFlags,
const AudioTimeStamp *inTimeStamp,
UInt32 inBusNumber,
UInt32 inNumberFrames,
AudioBufferList *ioData) {
AudioBufferList *bufferList;
OSStatus status = AudioUnitRender([(shockmanViewController *)inRefCon audioUnit],
ioActionFlags,
inTimeStamp,
inBusNumber,
inNumberFrames,
bufferList);
return noErr;
}
static OSStatus playbackCallback(void *inRefCon,
AudioUnitRenderActionFlags *ioActionFlags,
const AudioTimeStamp *inTimeStamp,
UInt32 inBusNumber,
UInt32 inNumberFrames,
AudioBufferList *ioData) {
return noErr;
}
