訪問使用AudioFileReadPackets

Question

我試圖訪問發送到音頻隊列回調原始音頻數據音頻隊列原始音頻數據，但I，的字節（的numBytes）的數目是0。

void AQRecorder::MyInputBufferHandler(void *inUserData, AudioQueueRef inAQ, AudioQueueBufferRef inBuffer, const AudioTimeStamp * inStartTime, UInt32 inNumPackets, const AudioStreamPacketDescription* inPacketDesc) { 

AQRecorder *aqr = (AQRecorder *)inUserData; 

try { 
    if (inNumPackets > 0) { 

     //read packets 
     UInt32 numBytes; 

     OSStatus result = AudioFileReadPackets(aqr->mRecordFile,  // The audio file from which packets of audio data are to be read. 
               FALSE,     // Set to true to cache the data. Otherwise, set to false. 
               &numBytes,    // On output, a pointer to the number of bytes actually returned. 
               (__bridge AudioStreamPacketDescription*)inPacketDesc, // A pointer to an array of packet descriptions that have been allocated. 
               aqr->mRecordPacket, // The packet index of the first packet you want to be returned. 
               &inNumPackets,    // On input, a pointer to the number of packets to read. On output, the number of packets actually read.           
               inBuffer->mAudioData); // A pointer to user-allocated memory. 

     inBuffer->mAudioDataByteSize = numBytes;  
     SInt16 *testBuffer = (SInt16*)inBuffer->mAudioData; 

     for (int i=0; i < numBytes; i++) 
     { 
      UInt16 currentData = testBuffer[i]; 
      printf("Current data in testbuffer is %d", currentData); 
     } 

    // if we're not stopping, re-enqueue the buffe so that it gets filled again 
    if (aqr->IsRunning()) 
     XThrowIfError(AudioQueueEnqueueBuffer(inAQ, inBuffer, 0, NULL), "AudioQueueEnqueueBuffer failed"); 
} catch (CAXException e) { 
    char buf[256]; 
    fprintf(stderr, "Error: %s (%s)\n", e.mOperation, e.FormatError(buf)); 
} 
} 

當我打印出testBuffer的第一個索引時，我能夠獲得0到4294967296之間的值，所以它看起來不是空的。 AudioFileReadPackets執行後numBytes爲0的任何想法？

Answer 1

我還不確定爲什麼numBytes是0，但我從this問題中找到了一個可行的解決方案。

要獲得testBuffer的大小我用下面的代碼：

int sampleCount = inBuffer->mAudioDataBytesCapacity/sizeof(SInt16);