使用 AudioQueue 和 Monotouch 静态声音录制

Question

我在 MonoTouch 中编写了一个小程序，使用 InputAudioQueue 从我的 iPhone 4s 的麦克风录制声音。

我将录制的数据保存在一个数组中，并将这个缓冲区提供给我的音频播放器进行播放（使用 OutputAudioQueue）。

播放时只是一些断断续续的垃圾/静态声音。我曾尝试在播放前用正弦波填充缓冲区，然后听起来不错，所以我猜问题出在录音中，而不是播放。谁能帮我看看有什么问题？ （代码如下）

public class AQRecorder
{
    private const int CountAudioBuffers = 3;
    private const int AudioBufferLength = 22050;
    private const int SampleRate = 44100;
    private const int BitsPerChannel = 16;
    private const int Channels = 1;
    private const int MaxRecordingTime = 5;
    private AudioStreamBasicDescription audioStreamDescription;
    private InputAudioQueue inputQueue;
    private short[] rawData;
    private int indexNextRawData;

    public AQRecorder ()
    {
        this.audioStreamDescription.Format = AudioFormatType.LinearPCM;
        this.audioStreamDescription.FormatFlags = AudioFormatFlags.LinearPCMIsSignedInteger | 
                                                  AudioFormatFlags.LinearPCMIsPacked;
        this.audioStreamDescription.SampleRate = AQRecorder.SampleRate;
        this.audioStreamDescription.BitsPerChannel = AQRecorder.BitsPerChannel;
        this.audioStreamDescription.ChannelsPerFrame = AQRecorder.Channels;
        this.audioStreamDescription.BytesPerFrame = (AQRecorder.BitsPerChannel / 8) * AQRecorder.Channels;
        this.audioStreamDescription.FramesPerPacket = 1;
        this.audioStreamDescription.BytesPerPacket = audioStreamDescription.BytesPerFrame * audioStreamDescription.FramesPerPacket;
        this.audioStreamDescription.Reserved = 0;
    }

    public void Start ()
    {
        int totalBytesToRecord = this.audioStreamDescription.BytesPerFrame * AQRecorder.SampleRate * AQRecorder.MaxRecordingTime;
        this.rawData = new short[totalBytesToRecord / sizeof(short)];
        this.indexNextRawData = 0;
        this.inputQueue = SetupInputQueue (this.audioStreamDescription);
        this.inputQueue.Start ();
    }

    public void Stop ()
    {
        if (this.inputQueue.IsRunning)
        {
            this.inputQueue.Stop (true);
        }
    }

    public short[] GetData ()
    {
        return this.rawData;;
    }

    private InputAudioQueue SetupInputQueue (AudioStreamBasicDescription audioStreamDescription)
    {
        InputAudioQueue inputQueue = new InputAudioQueue (audioStreamDescription);

        for (int count = 0; count < AQRecorder.CountAudioBuffers; count++)
        {
            IntPtr bufferPointer;
            inputQueue.AllocateBuffer(AQRecorder.AudioBufferLength, out bufferPointer);
            inputQueue.EnqueueBuffer(bufferPointer, AQRecorder.AudioBufferLength, null);
        }
        inputQueue.InputCompleted += HandleInputCompleted;
        return inputQueue;
    }

    private void HandleInputCompleted (object sender, InputCompletedEventArgs e)
    {
        unsafe
        {
            short* shortPtr = (short*)e.IntPtrBuffer;

            for (int count = 0; count < AQRecorder.AudioBufferLength; count += sizeof(short))
            {
                if (indexNextRawData >= this.rawData.Length)
                {
                    this.inputQueue.Stop (true);
                    return;
                }
                this.rawData [indexNextRawData] = *shortPtr;
                indexNextRawData++;
                shortPtr++;
            }
        }
        this.inputQueue.EnqueueBuffer(e.IntPtrBuffer, AQRecorder.AudioBufferLength, null);
    }
}

Answer 1

好的，这可能为时已晚，但我也遇到了同样的问题，只听到垃圾声音并找到了解决方案。

您不能直接从 e.IntPtrBuffer 读取音频数据。此指针是指向 AudioQueueBuffer 对象的指针，而不是指向音频数据本身的指针。因此，要读取音频数据，您可以使用 e.UnsafeBuffer 来访问该对象并使用其 AudioData 指针。这是一个 IntPtr，您可以将其（在不安全的上下文中）转换为 byte* 或 short* 并且您拥有音频数据。

最好的问候

亚历克斯