Cocoa Mac音频模块关键步骤总结

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1. .driver 插件

#include <CoreAudio/AudioServerPlugIn.h> 头文件
static AudioServerPlugInDriverInterface gAudioServerPlugInDriverInterface = 静态函数struct，返回一系列回调的函数指针
//开始io，代表有对象链接进来了，如果是第一个启动引擎，创建circle buffer
static OSStatus xxx_StartIO(AudioServerPlugInDriverRef inDriver, AudioObjectID inDeviceObjectID, UInt32 inClientID)
//如果是最后一个的话，关闭引擎，销毁circle buffer
static OSStatus xxx_StopIO(AudioServerPlugInDriverRef inDriver, AudioObjectID inDeviceObjectID, UInt32 inClientID)

//真正的方法
static OSStatus CamStudioAudio_DoIOOperation(....)

里面真正执行任务，接收和发送都在这里完成。// virutal device -> Other Capturedif(inOperationID == kAudioServerPlugInIOOperationReadInput){return sendDataToOtherApp(inIOBufferFrameSize, inIOCycleInfo, ioMainBuffer);}// other app -> virutal deviceif(inOperationID == kAudioServerPlugInIOOperationWriteMix){return getDataFromOtherApp(inIOBufferFrameSize, inIOCycleInfo, ioMainBuffer);}

//这个函数可以不管
static OSStatus xxx_EndIOOperation(...)

2. CoreAudio 驱动

//准备获取ID

    AudioObjectPropertyAddress address = makeOutputPropertyAddress(kAudioHardwarePropertyDevices);UInt32 devicesDataSize;//获取具体列表的内存大小OSStatus status = AudioObjectGetPropertyDataSize(kAudioObjectSystemObject,&address,0,NULL,&devicesDataSize);RETBOOL(status, "findMyAudioDevice-AudioObjectGetPropertyDataSize")//判断长度，并请求填充内存int count = devicesDataSize / sizeof(AudioDeviceID);AudioDeviceID deviceIDs[count];status = AudioObjectGetPropertyData(kAudioObjectSystemObject,&address,0,NULL,&devicesDataSize,deviceIDs);//轮询列表获取合适的idAudioObjectGetPropertyData(deviceID, &address, 0, NULL,  &size, &prop);//创建和析构监听AudioObjectAddPropertyListener(...kAudioDevicePropertyDeviceIsAlive)AudioObjectRemovePropertyListener(...kAudioDevicePropertyNominalSampleRate)

#import <CoreAudio/CoreAudio.h>
#import <CoreAudio/AudioHardware.h>
//绑定
OSStatus status = AudioDeviceCreateIOProcID(设备ID, deviceIOProcFunc/*回调函数*/, this, &mDeviceIOProcID/*创建的io句柄*/);
//开始
OSStatus status = AudioDeviceStart(mDevice.getNeedID(), mDeviceIOProcID);
//回调
。。。
//销毁
AudioDeviceDestroyIOProcID(mDevice.getNeedID(), mDeviceIOProcID);

3. AudioConvertRef 转码

头文件 #include <AudioToolbox/AudioToolbox.h>

 //创建转换对象AudioConverterRef audioConverter;AudioConverterNew(&_inASBD, &_outASBD, &audioConverter);

//重新从 Audio Convert 获取被校正过的 ASBD数据
AudioConverterGetProperty(audioConverter, kAudioConverterCurrentInputStreamDescription, &size, &_inASBD);

//将获取的MagicCookie 设置到 converter 中
AudioConverterSetProperty(converter,kAudioConverterDecompressionMagicCookie,cookieDataSize,cookieData),

//计算输入缓冲区的大小，及缓冲区能容纳的packet 数量
_inBuffer = malloc(4096*8)
//vbr 需要从文件中读取。kAudioFilePropertyPacketSizeUpperBound是预估不是打开计算
AudioFileGetProperty(_inFile, kAudioFilePropertyPacketSizeUpperBound, &size, &inSizePerPacket)

//计算和开辟输出缓冲区
//vbr得到最大输入的每包最大输出大小
AudioConverterGetProperty(audioConverter, kAudioConverterPropertyMaximumOutputPacketSize, &size, outData);

//写入Magic cookie

status = AudioConverterGetProperty(converter, kAudioConverterDecompressionMagicCookie, &cookieDataSize, cookies);
status = AudioFileSetProperty(_outFile, kAudioFilePropertyMagicCookieData, cookieDataSize, cookies);

//死循环进行数据转换
AudioConverterFillComplexBuffer(....) //会在这里的回调里面填充input数据，内部进行转换，返回值之后，获取到的就是转换后的数据
AudioFileWritePackets 写入文件
outFilePacketOffset += ioOutDataPacketsPerOut;//下次输出文件的时候，需要增加这次输出的数量
AudioConverterDispose(audioConverter)//关闭和释放AudioConverter的资源

4. AudioQueue output 输出

//创建Audioqueue对象，并配置callbackAudioQueueNewOutput(&inASBD,callback,UnsafeMutableRawPointer(Unmanaged.passUnretained(self).toOpaque()),nil,nil,0,&self.audioQueue)

//自定义输出设备，如果不想用默认的话var cuStr = "FC-E8-06-DB-74-1D:output" as CFStringAudioQueueSetProperty(self.audioQueue!, kAudioQueueProperty_CurrentDevice, &cuStr, size)

//获取输出设备的 asbd， 方便后面转码
AudioQueueGetProperty(self.audioQueue!, kAudioQueueProperty_StreamDescription, &outADSB, &size)

//创建三个默认的Audioqueue队列。并塞入静音数据，手动调用一次callbackfor _ in 0..<self.audioQueueNum {var buffer: AudioQueueBufferRef?AudioQueueAllocateBuffer(self.audioQueue!,self.byteSizeInBuffer,&buffer)//往buffer 中填充默认的静音数据let buf = UnsafeMutableRawPointer.allocate(byteCount: Int(self.byteSizeInBuffer), alignment: 1)memset(buf, 0, Int(self.byteSizeInBuffer))TPCircularBufferProduceBytes(&self.tpBuffer, buf, self.byteSizeInBuffer)buf.deallocate()callback(UnsafeMutableRawPointer(Unmanaged.passUnretained(self).toOpaque()), self.audioQueue!, buffer!)}

//正式开始
AudioQueueStart(self.audioQueue!, nil)

//开始后会自动回调callbackprivate let callback: AudioQueueOutputCallback = {inUserData, queue,  bufferRef in.... //判断数据是否足够，从circle bufer拿出数据，进行转码//将合适的格式大小的数据，塞入播放队列AudioQueueEnqueueBuffer(queue,bufferRef,0,nil)}

            //stopAudioQueueStop(self.audioQueue!, true)AudioQueueDispose(self.audioQueue!, true)

5. AudioQueue 采集

  //创建 queueJBAssertNoError(AudioQueueNewInput(&_mDataFormat,captureAudioDataCallback,(__bridge void *)(self),NULL,kCFRunLoopCommonModes,0,&_mQueue),
//获取asbdAudioQueueGetProperty(_mQueue,kAudioQueueProperty_StreamDescription,&_mDataFormat,&size),//内存分配，入队for (int i = 0; i != KNumberBuffers; i++ ){JBAssertNoError(AudioQueueAllocateBuffer(_mQueue, bufferByteSize, &_mBuffers[i]), @"AudioQueueAllocateBuffer");JBAssertNoError(AudioQueueEnqueueBuffer(_mQueue, _mBuffers[i], 0, NULL), @"AudioQueueEnqueueBuffer");}//启动audio queue , 第二个参数设置为NULL表示立即开始采集数据.JBAssertNoError(AudioQueueStart(_mQueue, NULL), @"AudioQueueStart");static void captureAudioDataCallback(void *__nullable  inUserData,...) {
//写入和拷贝数据
...
//释放队列AudioQueueEnqueueBuffer(inAQ, inBuffer, 0, NULL),
}
//关闭JBAssertNoError(AudioQueueStop(_mQueue, true),@"AudioQueueStop");JBAssertNoError(AudioQueueDispose(_mQueue, true), @"AudioQueueDispose");