所以，基本上我想播放一些音频文件(主要是mp3 和caf)。但是回调永远不会被调用。只有当我调用他们准备队列时。

这是我的数据结构:

struct AQPlayerState
{
    CAStreamBasicDescription        mDataFormat;
    AudioQueueRef                   mQueue;
    AudioQueueBufferRef             mBuffers[kBufferNum];
    AudioFileID                     mAudioFile;
    UInt32                          bufferByteSize;
    SInt64                          mCurrentPacket;
    UInt32                          mNumPacketsToRead;
    AudioStreamPacketDescription   *mPacketDescs;
    bool                            mIsRunning;
};

这是我的回调函数:

static void HandleOutputBuffer (void *aqData, AudioQueueRef inAQ, AudioQueueBufferRef inBuffer)
{
    NSLog(@"HandleOutput");
    AQPlayerState *pAqData = (AQPlayerState *) aqData;

    if (pAqData->mIsRunning == false) return;

    UInt32 numBytesReadFromFile;
    UInt32 numPackets = pAqData->mNumPacketsToRead;
    AudioFileReadPackets (pAqData->mAudioFile,
                          false,
                          &numBytesReadFromFile,
                          pAqData->mPacketDescs,
                          pAqData->mCurrentPacket,
                          &numPackets,
                          inBuffer->mAudioData);
    if (numPackets > 0) {    
        inBuffer->mAudioDataByteSize = numBytesReadFromFile;
        AudioQueueEnqueueBuffer (pAqData->mQueue,
                                 inBuffer,
                                 (pAqData->mPacketDescs ? numPackets : 0),
                                 pAqData->mPacketDescs);
        pAqData->mCurrentPacket += numPackets;
    } else {
//        AudioQueueStop(pAqData->mQueue, false);
//        AudioQueueDispose(pAqData->mQueue, true);
//        AudioFileClose (pAqData->mAudioFile);
//        free(pAqData->mPacketDescs);
//        free(pAqData->mFloatBuffer);
        pAqData->mIsRunning = false;
    }
}

这是我的方法:

- (void)playFile
{
    AQPlayerState aqData;

    // get the source file
    NSString *p = [[NSBundle mainBundle] pathForResource:@"1_Female" ofType:@"mp3"];
    NSURL *url2 = [NSURL fileURLWithPath:p];
    CFURLRef srcFile = (__bridge CFURLRef)url2;

    OSStatus result = AudioFileOpenURL(srcFile, 0x1/*fsRdPerm*/, 0/*inFileTypeHint*/, &aqData.mAudioFile);
    CFRelease (srcFile);

    CheckError(result, "Error opinning sound file");

    UInt32 size = sizeof(aqData.mDataFormat);
    CheckError(AudioFileGetProperty(aqData.mAudioFile, kAudioFilePropertyDataFormat, &size, &aqData.mDataFormat),
               "Error getting file's data format");

    CheckError(AudioQueueNewOutput(&aqData.mDataFormat, HandleOutputBuffer, &aqData, CFRunLoopGetCurrent(), kCFRunLoopCommonModes, 0, &aqData.mQueue),
               "Error AudioQueueNewOutPut");

    // we need to calculate how many packets we read at a time and how big a buffer we need
    // we base this on the size of the packets in the file and an approximate duration for each buffer
    {
        bool isFormatVBR = (aqData.mDataFormat.mBytesPerPacket == 0 || aqData.mDataFormat.mFramesPerPacket == 0);

        // first check to see what the max size of a packet is - if it is bigger
        // than our allocation default size, that needs to become larger
        UInt32 maxPacketSize;
        size = sizeof(maxPacketSize);
        CheckError(AudioFileGetProperty(aqData.mAudioFile, kAudioFilePropertyPacketSizeUpperBound, &size, &maxPacketSize),
                   "Error getting max packet size");

        // adjust buffer size to represent about a second of audio based on this format
        CalculateBytesForTime(aqData.mDataFormat, maxPacketSize, 1.0/*seconds*/, &aqData.bufferByteSize, &aqData.mNumPacketsToRead);

        if (isFormatVBR) {
            aqData.mPacketDescs = new AudioStreamPacketDescription [aqData.mNumPacketsToRead];
        } else {
            aqData.mPacketDescs = NULL; // we don't provide packet descriptions for constant bit rate formats (like linear PCM)
        }

        printf ("Buffer Byte Size: %d, Num Packets to Read: %d\n", (int)aqData.bufferByteSize, (int)aqData.mNumPacketsToRead);
    }

    // if the file has a magic cookie, we should get it and set it on the AQ
    size = sizeof(UInt32);
    result = AudioFileGetPropertyInfo(aqData.mAudioFile, kAudioFilePropertyMagicCookieData, &size, NULL);

    if (!result && size) {
        char* cookie = new char [size];
        CheckError(AudioFileGetProperty(aqData.mAudioFile, kAudioFilePropertyMagicCookieData, &size, cookie),
                   "Error getting cookie from file");
        CheckError(AudioQueueSetProperty(aqData.mQueue, kAudioQueueProperty_MagicCookie, cookie, size),
                   "Error setting cookie to file");
        delete[] cookie;
    }

    aqData.mCurrentPacket = 0;
    for (int i = 0; i < kBufferNum; ++i) {
        CheckError(AudioQueueAllocateBuffer (aqData.mQueue,
                                             aqData.bufferByteSize,
                                             &aqData.mBuffers[i]),
                   "Error AudioQueueAllocateBuffer");

        HandleOutputBuffer (&aqData,
                            aqData.mQueue,
                            aqData.mBuffers[i]);
    }

    // set queue's gain

    Float32 gain = 1.0;
    CheckError(AudioQueueSetParameter (aqData.mQueue,
                                       kAudioQueueParam_Volume,
                                       gain),
               "Error AudioQueueSetParameter");

    aqData.mIsRunning = true;
    CheckError(AudioQueueStart(aqData.mQueue,
                               NULL),
               "Error AudioQueueStart");

}

当我按下播放时的输出:

Buffer Byte Size: 40310, Num Packets to Read: 38
HandleOutput start
HandleOutput start
HandleOutput start

我尝试将 CFRunLoopGetCurrent() 替换为 CFRunLoopGetMain() 并将 CFRunLoopCommonModes 替换为 CFRunLoopDefaultMode，但没有任何效果。

难道不应该在我开始队列时就开始播放准备好的缓冲区吗？ 当我启动队列时，不会触发任何回调。 我究竟做错了什么？感谢您的任何想法

最佳答案

您在这里基本上要做的是使用音频队列播放音频的基本示例。在不详细查看您的代码以查看缺少什么(这可能需要一段时间)的情况下，我宁愿向您推荐按照 this basic sample code 中的步骤进行操作这正是您正在做的事情(没有不相关的额外内容..例如，您为什么要尝试添加音频增益？)

您在其他地方尝试使用音频单元播放音频。音频单元比基本的音频队列播放更复杂，在对音频队列非常熟悉之前我不会尝试它们。但是你可以看看这个example project有关音频队列的基本示例。

一般来说，当涉及到 iOS 中的 Core Audio 编程时，最好花时间学习基本示例并逐步构建。很多在线教程的问题在于它们添加了额外的东西并且经常混合使用使用 obj-c 代码.. 当 Core Audio 是纯 C 代码时(即额外的东西不会给学习过程增加任何东西)。我强烈建议你看书Learning Core Audio如果你还没有。所有示例代码都可以在线获得，但您也可以从 this 克隆它。为方便起见 repo 。这就是我学习核心音频的方式。这需要时间:)

关于ios - 未调用音频队列回调，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/20680884/