如何反转音频文件？

我想在 iOS 上反转现有的音频文件（例如 WAV、CAF...）。关于如何实现这一目标有什么建议吗？开源库？

我开发了一个示例应用程序，它记录用户所说的话并向后播放。我使用 CoreAudio 来实现这一点。链接到应用程序代码。

由于每个样本的大小为 16 位（2 字节）（单通道）。您可以一次加载每个样本，方法是从记录末尾开始向后读取，将其复制到不同的缓冲区中。当您到达数据的开头时，您已经反转了数据，并且播放也将反转。

    // set up output file
AudioFileID outputAudioFile;

AudioStreamBasicDescription myPCMFormat;
myPCMFormat.mSampleRate = 16000.00;
myPCMFormat.mFormatID = kAudioFormatLinearPCM ;
myPCMFormat.mFormatFlags =  kAudioFormatFlagsCanonical;
myPCMFormat.mChannelsPerFrame = 1;
myPCMFormat.mFramesPerPacket = 1;
myPCMFormat.mBitsPerChannel = 16;
myPCMFormat.mBytesPerPacket = 2;
myPCMFormat.mBytesPerFrame = 2;


AudioFileCreateWithURL((__bridge CFURLRef)self.flippedAudioUrl,
                       kAudioFileCAFType,
                       &myPCMFormat,
                       kAudioFileFlags_EraseFile,
                       &outputAudioFile);
// set up input file
AudioFileID inputAudioFile;
OSStatus theErr = noErr;
UInt64 fileDataSize = 0;

AudioStreamBasicDescription theFileFormat;
UInt32 thePropertySize = sizeof(theFileFormat);

theErr = AudioFileOpenURL((__bridge CFURLRef)self.recordedAudioUrl, kAudioFileReadPermission, 0, &inputAudioFile);

thePropertySize = sizeof(fileDataSize);
theErr = AudioFileGetProperty(inputAudioFile, kAudioFilePropertyAudioDataByteCount, &thePropertySize, &fileDataSize);

UInt32 dataSize = fileDataSize;
void* theData = malloc(dataSize);

//Read data into buffer
UInt32 readPoint  = dataSize;
UInt32 writePoint = 0;
while( readPoint > 0 )
{
    UInt32 bytesToRead = 2;

    AudioFileReadBytes( inputAudioFile, false, readPoint, &bytesToRead, theData );
    AudioFileWriteBytes( outputAudioFile, false, writePoint, &bytesToRead, theData );

    writePoint += 2;
    readPoint -= 2;
}

free(theData);
AudioFileClose(inputAudioFile);
AudioFileClose(outputAudioFile);