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采集方式

音频采集可以参考上次的视频采集方式，在里面添加相应的音频采集即可，只不过可定制型不强。(视频采集)
使用audioUnit，可定制型强，本文主要介绍这种方式。

实现方式

详细介绍参考（iOS 音频AudioComponentDescription类型设置）

 AudioComponentDescription acd; acd.componentType = kAudioUnitType_Output;//类型输出 //acd.componentSubType = kAudioUnitSubType_VoiceProcessingIO;// acd.componentSubType = kAudioUnitSubType_RemoteIO;// acd.componentManufacturer = kAudioUnitManufacturer_Apple;//ios固定这么写，mac不同 acd.componentFlags = 0; acd.componentFlagsMask = 0; //用来描述音频组件 AudioComponent component = AudioComponentFindNext(NULL, &acd); //用来表示特定音频组件的实例 AudioComponentInstance componetInstance; OSStatus status = noErr; //创建实例 status = AudioComponentInstanceNew(component, &componetInstance); UInt32 flagOne = 1; //打开IO，1 是麦克风，0 是扬声器 AudioUnitSetProperty(componetInstance, kAudioOutputUnitProperty_EnableIO, kAudioUnitScope_Input, 1, &flagOne, sizeof(flagOne));

设置输出音频属性

 AudioStreamBasicDescription desc = {0}; desc.mSampleRate = 44100;//采样率 desc.mFormatID = kAudioFormatLinearPCM;//类型交错存储PCM desc.mFormatFlags = kAudioFormatFlagIsSignedInteger | kAudioFormatFlagsNativeEndian | kAudioFormatFlagIsPacked; desc.mChannelsPerFrame = 2;//声道数 desc.mFramesPerPacket = 1;// 非压缩数据，固定填1 desc.mBitsPerChannel = 16;//每声道占的位数 desc.mBytesPerFrame = desc.mBitsPerChannel / 8 * desc.mChannelsPerFrame; desc.mBytesPerPacket = desc.mBytesPerFrame * desc.mFramesPerPacket;

设置采集回调

 AURenderCallbackStruct cb;//采集回调 cb.inputProcRefCon = (__bridge void *)(self); cb.inputProc = handleInputBuffer; status = AudioUnitSetProperty(componetInstance, kAudioUnitProperty_StreamFormat, kAudioUnitScope_Output, 1, &desc, sizeof(desc));//设置流格式 status = AudioUnitSetProperty(componetInstance, kAudioOutputUnitProperty_SetInputCallback, kAudioUnitScope_Global, 1, &cb, sizeof(cb));//设置回调

初始化

 AVAudioSession *session = [AVAudioSession sharedInstance]; NSError *error; //设置采样率 [session setPreferredSampleRate:44100 error:&error]; //设置类型 [session setCategory:AVAudioSessionCategoryPlayAndRecord withOptions:AVAudioSessionCategoryOptionDefaultToSpeaker | AVAudioSessionCategoryOptionInterruptSpokenAudioAndMixWithOthers error:&error]; // [session setActive:YES withOptions:kAudioSessionSetActiveFlag_NotifyOthersOnDeactivation error:&error]; [session setActive:YES error:&error]; //创建一个线程 taskQueue = dispatch_queue_create("com.mt.audioCapture", NULL);

开始采集

- (void)startRecord{ dispatch_async(taskQueue, ^{ NSLog(@"开始录音"); //每次设置一下状态，防止别的地方被修改或者出现其他情况 [[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryPlayAndRecord withOptions:AVAudioSessionCategoryOptionDefaultToSpeaker | AVAudioSessionCategoryOptionInterruptSpokenAudioAndMixWithOthers error:nil]; AudioOutputUnitStart(self->componetInstance); }); }

结束采集

- (void)endRecord{ dispatch_async(taskQueue, ^{ NSLog(@"停止录音"); AudioOutputUnitStop(self->componetInstance); }); }

采集的回调，数据获取

static OSStatus handleInputBuffer(void *inRefCon, AudioUnitRenderActionFlags *ioActionFlags, const AudioTimeStamp *inTimeStamp, UInt32 inBusNumber, UInt32 inNumberFrames, AudioBufferList *ioData) { @autoreleasepool { Test *source = (__bridge Test *)inRefCon; if (!source) { return -1; } AudioBuffer buffer; buffer.mData = NULL; buffer.mDataByteSize = 0; buffer.mNumberChannels = 1; AudioBufferList bufferList; bufferList.mNumberBuffers = 1; bufferList.mBuffers[0] = buffer; static int64_t get_audio_base_timesss = 0; Float64 currentTime = CMTimeGetSeconds(CMClockMakeHostTimeFromSystemUnits(inTimeStamp->mHostTime)); if (get_audio_base_timesss == 0) { get_audio_base_timesss = currentTime; } int64_t pts = (int64_t)((currentTime - get_audio_base_timesss) * 1000); ///获取数据 OSStatus status = AudioUnitRender(source->componetInstance, ioActionFlags, inTimeStamp, inBusNumber, inNumberFrames, &bufferList); if ((NO)/*静音*/) { for (int i = 0; i < bufferList.mNumberBuffers; i++) { AudioBuffer ab = bufferList.mBuffers[i]; memset(ab.mData, 0, ab.mDataByteSize); } } if (status == noErr) { // //音频数据 // bufferList.mBuffers[0].mData // //音频长度 // bufferList.mBuffers[0].mDataByteSize // //pts // pts // //转为NSData // [NSData dataWithBytes:bufferList.mBuffers[0].mData length:bufferList.mBuffers[0].mDataByteSize] } /*如果有分离左右声道需求的话 // NSData *data = [NSData dataWithBytes:buffers.mBuffers[0].mData length:buffers.mBuffers[0].mDataByteSize]; // // NSMutableData *leftData = [NSMutableData dataWithCapacity:0]; // NSMutableData *rightData = [NSMutableData dataWithCapacity:0]; // // 分离左右声道 // for (int i = 0; i < data.length; i+=4) { // [leftData appendData:[data subdataWithRange:NSMakeRange(i, 2)]]; // [rightData appendData:[data subdataWithRange:NSMakeRange(i+2, 2)]]; // } */ return noErr; } }

Demo地址整理后奉上。
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