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我是 iOS 编程新手，目前正在开发一个解调 FSK 信号的项目。我调整了 Michael Tyson 循环缓冲区的实现，但是当我尝试注销样本以查看它是否类似于方波时，我只看到一个常量值“67638612”。我已经有一个通过音频插孔的麦克风发送 FSK 调制信号的电路。这是我用来注销样本的代码：

// Init circular buffer
BOOL TPCircularBufferInit(TPCircularBuffer *buffer, int32_t length);

// Listing 10.28 Initial Setup of Render Callback from RemoteIO
static OSStatus InputFSKDemodulationRenderCallback (

                                                void                        *inRefCon,            // A pointer to a struct containing the complete audio data
                                                //    to play, as well as state    information such as the
                                                //    first sample to play on this invocation of the callback.
                                                AudioUnitRenderActionFlags  *ioActionFlags, // Unused here. When generating audio, use ioActionFlags to indicate silence
                                                //    between sounds; for silence, also memset the ioData buffers to 0.
                                                const AudioTimeStamp        *inTimeStamp,   // Unused here.
                                                UInt32                      inBusNumber,    // The mixer unit input bus that is requesting some new
                                                //        frames of audio data to play.
                                                UInt32                      inNumberFrames, // The number of frames of audio to provide to the buffer(s)
                                                //        pointed to by the ioData parameter.
                                                AudioBufferList             *ioData         // On output, the audio data to play. The callback's primary
                                                //        responsibility is to fill the buffer(s) in the 
                                                //        AudioBufferList.
                                                ) {
AudioStruct* effectState = (AudioStruct*) inRefCon;
// Listing 10.29 Copying Captured Samples to Play-Out Buffer in RemoteIO Render Callback
// Just copy samples
UInt32 bus1 = 1;
CheckError(AudioUnitRender(effectState->rioUnit,
                           ioActionFlags,
                           inTimeStamp,
                           bus1,
                           inNumberFrames,
                           ioData),
           "Couldn't render from RemoteIO unit");

// Listing 10.30 Performing FSK demodulation Effect on a Buffer of Samples
// Walk the samples
AudioUnitSampleType* outSample = (AudioUnitSampleType* )ioData->mBuffers[0].mData;
AudioUnitSampleType sample = (AudioUnitSampleType) &outSample;
memset(outSample, 0, inNumberFrames * kUnitSize * 2);

// if (effectState->bufferIsReady && !effectState->playbackWasInterrupted){

    for (int bufCount = 0; bufCount<ioData->mNumberBuffers; bufCount++){
        int currentFrame = 0;
 while (currentFrame <= inNumberFrames) {
    // Pull audio from circular buffer
int32_t availableBytes;
AudioUnitSampleType *bufferTail     = TPCircularBufferTail( &effectState->circularBuffer,     &availableBytes);

memcpy(outSample, bufferTail, MIN(availableBytes, inNumberFrames * kUnitSize * 2) );
TPCircularBufferConsume(&effectState->circularBuffer, MIN(availableBytes, inNumberFrames *   kUnitSize * 2) );
effectState->currentSampleNum += MIN(availableBytes / (kUnitSize * 2), inNumberFrames);

     NSLog(@" currentsamplenumber  is: %ld", sample);

在控制台上，这就是我所看到的：

2013-08-26 15:55:27.886 ElisaDongle[880:907] hardwareSampleRate = 44100.000000
RIO started!
2013-08-26 15:55:28.013 ElisaDongle[880:6403]  currentsamplenumber  is: 67638612
2013-08-26 15:55:28.016 ElisaDongle[880:6403]  currentsamplenumber  is: 67638612
2013-08-26 15:55:28.018 ElisaDongle[880:6403]  currentsamplenumber  is: 67638612
2013-08-26 15:55:28.020 ElisaDongle[880:6403]  currentsamplenumber  is: 67638612
2013-08-26 15:55:28.022 ElisaDongle[880:6403]  currentsamplenumber  is: 67638612
2013-08-26 15:55:28.024 ElisaDongle[880:6403]  currentsamplenumber  is: 67638612
2013-08-26 15:55:28.026 ElisaDongle[880:6403]  currentsamplenumber  is: 67638612
2013-08-26 15:55:28.031 ElisaDongle[880:6403]  currentsamplenumber  is: 67638612
2013-08-26 15:55:28.036 ElisaDongle[880:6403]  currentsamplenumber  is: 67638612
2013-08-26 15:55:28.038 ElisaDongle[880:6403]  currentsamplenumber  is: 67638612
2013-08-26 15:55:28.041 ElisaDongle[880:6403]  currentsamplenumber  is: 67638612

拜托，我需要帮助。有什么我做错或遗漏的事情吗？随时问我任何问题。

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