减少扬声器输出的音频流延迟

Question

我正在尝试编写一个可以稍微延迟播放音频麦克风的应用。我的问题是它太长了。我不是手机上的音频流最好的，我在这里使用了很多回收代码，但延迟感觉就像1秒，理想情况下我希望它在100毫秒到200毫秒之间。任何建议表示赞赏

public class MicrophoneSource : MediaStreamSource
{
    // Standard constants
    const int ChannelCount = 1;
    const int BitsPerSample = 16;
    const int BufferSamples = 2038;     // can be changed
    const int BufferSize = ChannelCount * BufferSamples * BitsPerSample / 8;

    Dictionary<MediaSampleAttributeKeys, string> mediaSampleAttributes;
    MediaStreamDescription mediaStreamDescription;
    MemoryStream memoryStream;

    // The rate at which we sample the microphone in ms
    private int SAMPLE_RATE = 100;

    // Object representing the physical microphone on the device
    private Microphone microphone = Microphone.Default;

    // the buffer that we'll be using to copy samples over with
    private byte[] buffer;
    public void setBufferRate(int newRate)
    {
        SAMPLE_RATE = newRate;
    }
    public MicrophoneSource()
    {
        // Create empty mediaSampleAttributes dictionary for OpenReadAsync
        mediaSampleAttributes = new Dictionary<MediaSampleAttributeKeys, string>();

        // Create re-usable MemoryStream for accumulating audio samples
        memoryStream = new MemoryStream();
    }

    private void Microphone_initialization()
    {
        // Event handler for getting audio data when the buffer is full
        microphone.BufferReady += new EventHandler<EventArgs>(microphone_BufferReady);

        // set the sample rate
        microphone.BufferDuration = TimeSpan.FromMilliseconds(SAMPLE_RATE);

        // Allocate memory to hold the audio data
        buffer = new byte[microphone.GetSampleSizeInBytes(microphone.BufferDuration)];
    }

    protected override void OpenMediaAsync()
    {
        int byteRate = microphone.SampleRate * ChannelCount * BitsPerSample / 8;
        short blockAlign = (short)(ChannelCount * (BitsPerSample / 8));

        // Build string-based wave-format structure
        string waveFormat = "";
        waveFormat += ToLittleEndianString(string.Format("{0:X4}", 1));      // indicates PCM
        waveFormat += ToLittleEndianString(string.Format("{0:X4}", ChannelCount));
        waveFormat += ToLittleEndianString(string.Format("{0:X8}", microphone.SampleRate));
        waveFormat += ToLittleEndianString(string.Format("{0:X8}", byteRate));
        waveFormat += ToLittleEndianString(string.Format("{0:X4}", blockAlign));
        waveFormat += ToLittleEndianString(string.Format("{0:X4}", BitsPerSample));
        waveFormat += ToLittleEndianString(string.Format("{0:X4}", 0));

        // Put wave format string in media streams dictionary
        var mediaStreamAttributes = new Dictionary<MediaStreamAttributeKeys, string>();
        mediaStreamAttributes[MediaStreamAttributeKeys.CodecPrivateData] = waveFormat;

        // Make description to add to available streams list
        var availableMediaStreams = new List<MediaStreamDescription>();
        mediaStreamDescription = new MediaStreamDescription(MediaStreamType.Audio, mediaStreamAttributes);
        availableMediaStreams.Add(mediaStreamDescription);

        // Set some appropriate keys in the media source dictionary
        var mediaSourceAttributes = new Dictionary<MediaSourceAttributesKeys, string>();
        mediaSourceAttributes[MediaSourceAttributesKeys.Duration] = "0";
        mediaSourceAttributes[MediaSourceAttributesKeys.CanSeek] = "false";

        // Initialize the microphone completely
        Microphone_initialization();

        // Signal that the open operation is completed
        ReportOpenMediaCompleted(mediaSourceAttributes, availableMediaStreams);
    }

    // For building string-based wave-format structure
    string ToLittleEndianString(string bigEndianString)
    {
        StringBuilder strBuilder = new StringBuilder();

        for (int i = 0; i < bigEndianString.Length; i += 2)
            strBuilder.Insert(0, bigEndianString.Substring(i, 2));

        return strBuilder.ToString();
    }

    // Provides audio samples from AudioSampleProvider property.
    //  (MediaStreamType parameter will always equal Audio.)
    protected override void GetSampleAsync(MediaStreamType mediaStreamType)
    {
        // start the microphone capture if it's not started yet
        if (microphone.State == MicrophoneState.Stopped)
        {
            microphone.Start();
        }
    }

    // gets called back when the microphone's buffer is ready
    private void microphone_BufferReady(object sender, EventArgs e)
    {
        // Retrieve audio data
        microphone.GetData(buffer);

        // Reset MemoryStream object
        memoryStream.Seek(0, SeekOrigin.Begin);

        // Write the newly acquired data into the memory stream
        memoryStream.Write(buffer, 0, buffer.Length);

        // Send out the sample
        ReportGetSampleCompleted(new MediaStreamSample(mediaStreamDescription,
                                                        memoryStream,
                                                        0,
                                                        buffer.Length,
                                                        0, // NOTE: Can this be set to 0?
                                                        mediaSampleAttributes));
    }

    protected override void SeekAsync(long seekToTime)
    {
        // is this valid? no seek calls are made so it should be okay
        ReportSeekCompleted(seekToTime);
    }

    protected override void CloseMedia()
    {
        if (microphone.State == MicrophoneState.Started)
        {
            microphone.Stop();
        }
        microphone.BufferReady -= new EventHandler<EventArgs>(microphone_BufferReady);

    }

    // Shouldn't get a call here because only one MediaStreamDescription is supported
    protected override void SwitchMediaStreamAsync(MediaStreamDescription mediaStreamDescription)
    {
        throw new NotImplementedException();
    }

    protected override void GetDiagnosticAsync(MediaStreamSourceDiagnosticKind diagnosticKind)
    {
        throw new NotImplementedException();
    }
}