ios - 如何从 NSdata 创建 AudioBuffer/Audio

Question

我是流媒体应用程序的初学者，我从 AudioBuffer 创建了 NSdata 并将 nsdata 发送到客户端(接收器)。但我不知道如何将 NSdata 转换为音频缓冲区。

我正在使用以下代码将 AudioBuffer 转换为 NSdata(效果很好)

- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection 
{               
 AudioStreamBasicDescription audioFormat;
 memset(&audioFormat, 0, sizeof(audioFormat));
 audioFormat.mSampleRate = 8000.0;
 audioFormat.mFormatID = kAudioFormatiLBC;
 audioFormat.mFormatFlags = kAudioFormatFlagIsBigEndian | kLinearPCMFormatFlagIsSignedInteger | kLinearPCMFormatFlagIsPacked | kAudioFormatFlagIsAlignedHigh;
 audioFormat.mFramesPerPacket = 1;
 audioFormat.mChannelsPerFrame = 1;
 audioFormat.mBitsPerChannel = 16;
 audioFormat.mBytesPerPacket = 2;
 audioFormat.mReserved = 0;
 audioFormat.mBytesPerFrame = audioFormat.mBytesPerPacket = audioFormat.mChannelsPerFrame* sizeof(SInt16);

 AudioBufferList audioBufferList;
 NSMutableData *data=[[NSMutableData alloc] init];
 CMBlockBufferRef blockBuffer;
 CMSampleBufferGetAudioBufferListWithRetainedBlockBuffer(sampleBuffer, NULL, &audioBufferList, sizeof(audioBufferList), NULL, NULL, 0, &blockBuffer);
  for( int y=0; y<audioBufferList.mNumberBuffers; y++ )
  {
      AudioBuffer audioBuffer = audioBufferList.mBuffers[y];
      Float32 *frame = (Float32*)audioBuffer.mData;
      [data appendBytes:frame length:audioBuffer.mDataByteSize];
  }
}

如果这不是正确的方法，请帮助我....谢谢。

Answer 1

您可以使用以下代码从 CMSampleBufferRef 创建 NSData，然后使用 AVAudioPlayer 播放它。

- (void)captureOutput:(AVCaptureOutput *)captureOutput  didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection {

    AudioBufferList audioBufferList;
    NSMutableData *data= [NSMutableData data];
    CMBlockBufferRef blockBuffer;
    CMSampleBufferGetAudioBufferListWithRetainedBlockBuffer(sampleBuffer, NULL, &audioBufferList, sizeof(audioBufferList), NULL, NULL, 0, &blockBuffer);

    for( int y=0; y< audioBufferList.mNumberBuffers; y++ ){

        AudioBuffer audioBuffer = audioBufferList.mBuffers[y];
        Float32 *frame = (Float32*)audioBuffer.mData;

        [data appendBytes:frame length:audioBuffer.mDataByteSize];

    }

    CFRelease(blockBuffer);
    CFRelease(ref);

    AVAudioPlayer *player = [[AVAudioPlayer alloc] initWithData:data error:nil];
    [player play];
}