Cocoa Mac音频模块关键步骤总结
1. .driver 插件
#include 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 Captured
if(inOperationID == kAudioServerPlugInIOOperationReadInput)
{
return sendDataToOtherApp(inIOBufferFrameSize, inIOCycleInfo, ioMainBuffer);
}
// other app -> virutal device
if(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id
AudioObjectGetPropertyData(deviceID, &address, 0, NULL, &size, &prop);
//创建和析构监听
AudioObjectAddPropertyListener(...kAudioDevicePropertyDeviceIsAlive)
AudioObjectRemovePropertyListener(...kAudioDevicePropertyNominalSampleRate)
#import
#import
//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
//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callback
AudioQueueNewOutput(&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 CFString
AudioQueueSetProperty(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callback
for _ 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callback
private 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)
}
//stop
AudioQueueStop(self.audioQueue!, true)
AudioQueueDispose(self.audioQueue!, true)
5. AudioQueue 采集
//创建 queue
JBAssertNoError(AudioQueueNewInput(&_mDataFormat,
captureAudioDataCallback,
(__bridge void *)(self),
NULL,
kCFRunLoopCommonModes,
0,
&_mQueue),
//获取asbd
AudioQueueGetProperty(_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");