Question

我正在尝试使用NAudio录制8秒的流式音频，将其存储在System.IO.MemoryStream中，然后立即播放。为此，我运行以下代码：

using System.IO;
using NAudio.Wave;

public class AudioCapture{

    static WaveFileWriter wri;
    static bool stopped = false;

    public AudioCapture(){
        //record from loopback
        IWaveIn waveIn = new WasapiLoopbackCapture();
        waveIn.DataAvailable += waveIn_DataAvailable;
        waveIn.RecordingStopped += waveIn_RecordingStopped;

        //write loopback capture to MemoryStream
        Stream sos = new MemoryStream();
        wri = new WaveFileWriter(sos, waveIn.WaveFormat);

        //record 8 seconds of streaming audio
        waveIn.StartRecording();
        System.Threading.Thread.Sleep(8000);
        waveIn.StopRecording();

        //flush and dispose objects
        wri.Flush();
        waveIn.Dispose();
        wri.Dispose();

        //play back recorded audio
        WaveOut waveOut = new WaveOut();
        WaveFileReader waveFileReader = new WaveFileReader(sos);
        waveOut.Init(waveFileReader);
        waveOut.Play();

    }

    static void waveIn_RecordingStopped(object sender, StoppedEventArgs e){
        stopped = true;
    }

    static void waveIn_DataAvailable(object sender, WaveInEventArgs e){
        if (wri != null) wri.Write(e.Buffer, 0, e.BytesRecorded);
    }

}

我收到以下异常，告诉我无法读取流：

Activated   Event   Time    Duration    Thread
    Exception: Exception thrown: 'System.ArgumentException' in NAudio.dll 
("Stream was not readable."). Exception thrown: 'System.ArgumentException' in 
NAudio.dll ("Stream was not readable.") 17.86s      [17404] <No Name>

根据文档，我不太确定问题是什么，因为WaveFileWriter明确接受MemoryStream。我缺少一些转换吗？任何帮助，将不胜感激。谢谢！

澄清：错误似乎在这一行：

WaveFileReader waveFileReader = new WaveFileReader(sos);

Answer 1

WaveFileWriter（不幸的是）设计的方式是始终处理它在处理WaveFileWriter时写入的流。它本可以接受一些标志来控制这种行为，但事实并非如此。因此，如果您以后需要使用该流，则需要过早地处置WaveFileWriter，或者克隆该已关闭的内存流。如果您选择不处理编写器 - 您需要将内存流回退到位置0，以便从头开始读取（在写入位置结束后）：

wri.Flush();
waveIn.Dispose();
// wri.Dispose(); < too early
sos.Seek(0, SeekOrigin.Begin);

如果您想使用克隆 - 不需要快退：

wri.Flush();
waveIn.Dispose();
wri.Dispose();
sos = new MemoryStream(sos.ToArray());

克隆的缺点是它会创建整个字节数组的不必要副本（ToArray调用）。

Answer 2

在此方案中无需使用WaveFileReader或WaveFileWriter。只需将收到的音频写入MemoryStream：

static void waveIn_DataAvailable(object sender, WaveInEventArgs e){
    if (sos != null) sos.Write(e.Buffer, 0, e.BytesRecorded);
}

然后当你完成并准备好播放时，请回放MemoryStream并使用RawSourceWaveStream播放：

//play back recorded audio
var waveOut = new WaveOut();
sos.Position = 0;
var waveFileReader = new RawSourceWaveStream(sos, waveIn.WaveFormat);
waveOut.Init(waveFileReader);
waveOut.Play();

NAudio没有读取包含wav数据的MemoryStream

2 个答案: