ios之audio unit的录音和播放一起，解决audioqueue播放PCM延迟问题

    因为用audioqueue的录音播放，或者用audioqueue录音，openal播放都有延迟。

    然后用底层些的audio unit，果然延迟问题就好很多了，至少一边录一边播的问题可以很好的解决。。有不少audio unit的三方库，暂时没去细研究，查了点，自己修改了下。需要在进行录音的时候和播放单开线程。。之前有问题没明白，卡了一天突然明白了。。。直接上代码来得方便。。。多余的代码和变量也不在进行删除修改了，也为自己以后看吧

.h文件   

#import <Foundation/Foundation.h>#import <AudioToolbox/AudioToolbox.h>#define kOutputBus 0#define kInputBus 1#define  kSampleRate 8000#define kFramesPerPacket 1#define kChannelsPerFrame 1#define kBitsPerChannel 16#define BUFFER_SIZE 1024@interface AudioController : NSObject@PRoperty (readonly) AudioComponentInstance audioUnit;@property (readonly) AudioBuffer audioBuffer;@property (strong, readwrite) NSMutableData *mIn;@property (strong, readwrite) NSMutableData *mOut;@property (strong, readwrite) NSMutableData *mAllAudioData;- (void)hasError:(int)statusCode file:(char*)file line:(int)line;- (void)processBuffer: (AudioBufferList* )audioBufferList;+ (AudioController *) sharedAudioManager;-(void)clearDataArray;-(void)startAudio;@end
.m文件的内容
#import "AudioController.h"static NSMutableData *mIn;static NSMutableData *mOut;static NSMutableData *mAllAudioData;static bool mIsStarted; // audio unit startstatic bool mSendServerStart; // send server continue loopstatic bool mRecServerStart; // rec server continue loopstatic bool mIsTele; // telephone callstatic OSStatus recordingCallback(void *inRefCon,                                                                    AudioUnitRenderActionFlags *ioActionFlags,                                  const AudioTimeStamp *inTimeStamp,                                  UInt32 inBusNumber,                                  UInt32 inNumberFrames,                                  AudioBufferList *ioData) {        // the data gets rendered here    AudioBuffer buffer;    // a variable where we check the status    OSStatus status;    //This is the reference to the object who owns the callback.    AudioController *audioProcessor = (__bridge AudioController* )inRefCon;    /**     on this point we define the number of channels, which is mono     for the iphone. the number of frames is usally 512 or 1024.     */    buffer.mDataByteSize = inNumberFrames * 2; // sample size    buffer.mNumberChannels = 1; // one channel    buffer.mData = malloc( inNumberFrames * 2 ); // buffer size    // we put our buffer into a bufferlist array for rendering    AudioBufferList bufferList;    bufferList.mNumberBuffers = 1;    bufferList.mBuffers[0] = buffer;    // render input and check for error    status = AudioUnitRender([audioProcessor audioUnit], ioActionFlags, inTimeStamp, inBusNumber, inNumberFrames, &bufferList);//    [audioProcessor hasError:status file:__FILE__ line:__LINE__];    // process the bufferlist in the audio processor    [audioProcessor processBuffer: &bufferList];    // clean up the buffer    free(bufferList.mBuffers[0].mData);        dispatch_async(dispatch_get_global_queue(0, 0), ^{        [audioProcessor clearDataArray];    });        return noErr;    }#pragma mark Playback callbackstatic OSStatus playbackCallback(void *inRefCon,                                                                  AudioUnitRenderActionFlags *ioActionFlags,                                 const AudioTimeStamp *inTimeStamp,                                 UInt32 inBusNumber,                                 UInt32 inNumberFrames,                                 AudioBufferList *ioData) {        long len = [mIn length];    len = len > 1024 ? 1024 : len;    if (len <= 0)    {        return noErr;    }        for (int i = 0; i < ioData -> mNumberBuffers; i++)    {//        NSLog( @"len:%ld", len);        AudioBuffer buffer = ioData -> mBuffers[i];        NSData *pcmBlock = [mIn subdataWithRange: NSMakeRange(0, len)];        UInt32 size = (UInt32)MIN(buffer.mDataByteSize, [pcmBlock length]);        memcpy(buffer.mData, [pcmBlock bytes], size);        [mIn replaceBytesInRange: NSMakeRange(0, size) withBytes: NULL length: 0];        buffer.mDataByteSize = size;    }    return noErr;}@implementation AudioController@synthesize audioUnit;@synthesize audioBuffer;/*  * It's Singleton pattern  * the flow is init(if there isn't existed self) -> initializeAudioConfig(set audio format, io pipe and callback functions)  *                                              -> recordingCallback -> processBuffer  *                                              -> playbackCallback  */// 封装一个单例+ (AudioController *) sharedAudioManager{        static AudioController *sharedAudioManager;    @synchronized(self)    {        if (!sharedAudioManager) {            sharedAudioManager = [[AudioController alloc] init];        }        return sharedAudioManager;    }}- (AudioController* )init {        self = [super init];        if (self) {                [self initializeAudioConfig];                mIn = [[NSMutableData alloc] init];        mOut = [[NSMutableData alloc] init];        mAllAudioData = [[NSMutableData alloc] init];                mIsStarted = false;        mSendServerStart = false;        mRecServerStart = false;        mIsTele = false;    }    return self;}- (void)initializeAudioConfig {        OSStatus status;    AudioComponentDescription desc;    desc.componentType = kAudioUnitType_Output; // we want to ouput    desc.componentSubType = kAudioUnitSubType_RemoteIO; // we want in and ouput    desc.componentFlags = 0; // must be zero    desc.componentFlagsMask = 0; // must be zero    desc.componentManufacturer = kAudioUnitManufacturer_Apple; // select provider    AudioComponent inputComponent = AudioComponentFindNext(NULL, &desc);    status = AudioComponentInstanceNew(inputComponent, &audioUnit);    [self hasError:status file:__FILE__ line:__LINE__];    // define that we want record io on the input bus    UInt32 flag = 1;    status = AudioUnitSetProperty(audioUnit,kAudioOutputUnitProperty_EnableIO, // use io                                  kAudioUnitScope_Input, // scope to input                                  kInputBus, // select input bus (1)                                  &flag, // set flag                                  sizeof(flag));    [self hasError:status file:__FILE__ line:__LINE__];    // define that we want play on io on the output bus    status = AudioUnitSetProperty(audioUnit,                                kAudioOutputUnitProperty_EnableIO, // use io                                  kAudioUnitScope_Output, // scope to output                                  kOutputBus, // select output bus (0)                                  &flag, // set flag                                  sizeof(flag));    [self hasError:status file:__FILE__ line:__LINE__];    // specifie our format on which we want to work.    AudioStreamBasicDescription audioFormat;    audioFormat.mSampleRate	= kSampleRate;    audioFormat.mFormatID	= kAudioFormatLinearPCM;    audioFormat.mFormatFlags	= kAudioFormatFlagIsPacked | kAudioFormatFlagIsSignedInteger;    audioFormat.mFramesPerPacket	= kFramesPerPacket;    audioFormat.mChannelsPerFrame	= kChannelsPerFrame;    audioFormat.mBitsPerChannel	= kBitsPerChannel;    audioFormat.mBytesPerPacket	= kBitsPerChannel * kChannelsPerFrame * kFramesPerPacket / 8;    audioFormat.mBytesPerFrame	= kBitsPerChannel * kChannelsPerFrame / 8;    // set the format on the output stream    status = AudioUnitSetProperty(audioUnit,                                  kAudioUnitProperty_StreamFormat,                                  kAudioUnitScope_Output,                                  kInputBus,                                  &audioFormat,                                  sizeof(audioFormat));    [self hasError:status file:__FILE__ line:__LINE__];    // set the format on the input stream    status = AudioUnitSetProperty(audioUnit,                                  kAudioUnitProperty_StreamFormat,                                  kAudioUnitScope_Input,                                  kOutputBus,                                  &audioFormat,                                  sizeof(audioFormat));    [self hasError:status file:__FILE__ line:__LINE__];    /**     We need to define a callback structure which holds     a pointer to the recordingCallback and a reference to     the audio processor object     */    AURenderCallbackStruct callbackStruct;    // set recording callback struct    callbackStruct.inputProc = recordingCallback; // recordingCallback pointer    callbackStruct.inputProcRefCon = (__bridge void * _Nullable)(self);    // set input callback to recording callback on the input bus    status = AudioUnitSetProperty(audioUnit,kAudioOutputUnitProperty_SetInputCallback,                                  kAudioUnitScope_Global,                                  kInputBus,                                  &callbackStruct,                                  sizeof(callbackStruct));    [self hasError:status file:__FILE__ line:__LINE__];    // set playback callback struct    callbackStruct.inputProc = playbackCallback;    callbackStruct.inputProcRefCon = (__bridge void * _Nullable)(self);    // set playbackCallback as callback on our renderer for the output bus    status = AudioUnitSetProperty(audioUnit,        kAudioUnitProperty_SetRenderCallback,                                  kAudioUnitScope_Global,                                  kOutputBus,                                  &callbackStruct,                                  sizeof(callbackStruct));    [self hasError:status file:__FILE__ line:__LINE__];    // reset flag to 0    flag = 0;    /*     we need to tell the audio unit to allocate the render buffer,     that we can directly write into it.     */    status = AudioUnitSetProperty(audioUnit,kAudioUnitProperty_ShouldAllocateBuffer,                                  kAudioUnitScope_Output,                                  kInputBus,                                  &flag,                                  sizeof(flag));    /*     we set the number of channels to mono and allocate our block size to     1024 bytes.     kiki: I don't know where the size 1024 bytes comes from...     */    audioBuffer.mNumberChannels = kChannelsPerFrame;    audioBuffer.mDataByteSize = 512 * 2;    audioBuffer.mData = malloc( 512 * 2 );    // Initialize the Audio Unit and cross fingers =)    status = AudioUnitInitialize(audioUnit);    [self hasError:status file:__FILE__ line:__LINE__];}- (void)processBuffer: (AudioBufferList* )audioBufferList {        AudioBuffer sourceBuffer = audioBufferList -> mBuffers[0];    // we check here if the input data byte size has changed    if (audioBuffer.mDataByteSize != sourceBuffer.mDataByteSize)    {        // clear old buffer        free(audioBuffer.mData);        // assing new byte size and allocate them on mData        audioBuffer.mDataByteSize = sourceBuffer.mDataByteSize;        audioBuffer.mData = malloc(sourceBuffer.mDataByteSize);    }    // copy incoming audio data to the audio buffer        memcpy(audioBuffer.mData, audioBufferList -> mBuffers[0].mData, audioBufferList -> mBuffers[0].mDataByteSize);    NSData *pcmBlock = [NSData dataWithBytes:sourceBuffer.mData length:sourceBuffer.mDataByteSize];    [mOut appendData: pcmBlock];}-(void)clearDataArray{    if ([mOut length] <= 0)    {        return;    }//    [mAllAudioData appendBytes:mOut.bytes length:mOut.length];    [mIn appendBytes:mOut.bytes length:mOut.length];    [mOut replaceBytesInRange: NSMakeRange(0, mOut.length) withBytes: NULL length: 0];}- (void)start{    if (mIsStarted)    {//        NSLog( @"-- already start --");        return;    }//    NSLog( @"-- start --");    mIsStarted = true;    [mIn replaceBytesInRange: NSMakeRange(0, [mIn length]) withBytes: NULL length: 0];    [mOut replaceBytesInRange: NSMakeRange(0, [mOut length]) withBytes: NULL length: 0];    OSStatus status = AudioOutputUnitStart(audioUnit);    [self hasError:status file:__FILE__ line:__LINE__];}- (void)stop {    NSLog( @"-- stop --");    OSStatus status = AudioOutputUnitStop(audioUnit);    [self hasError:status file:__FILE__ line:__LINE__];    mIsStarted = false;    [mIn replaceBytesInRange: NSMakeRange(0, [mIn length]) withBytes: NULL length: 0];    [mOut replaceBytesInRange: NSMakeRange(0, [mOut length]) withBytes: NULL length: 0];}#pragma mark Error handling- (void)hasError:(int)statusCode file:(char*)file line:(int)line{    if (statusCode)    {        NSLog(@"Error Code responded %d in file %s on line %d", statusCode, file, line);        exit(-1);    }}-(void)startAudio{    [self stop];    [self start];}@end