c# - Detect current volume level while a file is playing using Naudio

Question

So I have

    IWavePlayer waveOutDevice;
    WaveStream mainOutputStream;
    WaveChannel32 volumeStream;

    private WaveStream CreateInputStream(string fileName)
    {
        WaveChannel32 inputStream;
        if (fileName.EndsWith(".mp3"))
        {
            WaveStream mp3Reader = new Mp3FileReader(fileName);
            inputStream = new WaveChannel32(mp3Reader);
        }
        else
        {
            throw new InvalidOperationException("Unsupported extension");
        }
        volumeStream = inputStream;
        return volumeStream;
    }

    private void Stop()
    {
        if (waveOutDevice != null)
        {
            waveOutDevice.Stop();
        }
        if (mainOutputStream != null)
        {
            // this one really closes the file and ACM conversion
            volumeStream.Close();
            volumeStream = null;
            // this one does the metering stream
            mainOutputStream.Close();
            mainOutputStream = null;
        }
        if (waveOutDevice != null)
        {
            waveOutDevice.Dispose();
            waveOutDevice = null;
        }
    }

    private void Play(string was)
    {
        waveOutDevice = new WaveOut();
        mainOutputStream = CreateInputStream(was);
        waveOutDevice.Init(mainOutputStream);
        waveOutDevice.Play();

    }

    private void Form1_Load(object sender, EventArgs e)
    {
        Play(@"E:\Eigene Audiodateien\Musik\Alben\Pur\Abenteuerland\ -  - .mp3");
    }

    private void button1_Click(object sender, EventArgs e)
    {
        Stop();
    }

There is a Stop-Button ( button1 ), which stops playback. When the form is loaded, the file is played. While the file is playing I want to get the current volume of the file by running a function. So what does a function like this has to look like at "...."?

private int currentVolumeLevel(...some suitable parameters...)
{
  int currentVolumeLevelValue = 0;
  //....
  return currentVolumeLevelValue;
}

I am not talking about the volume level you can adjust with windows' sound controls. I am talking about the currently played sound file's volume at this very position it is playing right now, based on something like a byte[] array.

Answer 1

NAudioDemo 展示了如何做到这一点。查看AudioPlaybackPanel.cs如何将 aMeteringSampleProvider添加到播放管道中。MeteringSampleProvider将定期引发StreamVolume事件，告诉您在过去 100 毫秒内收到的最大样本值（这是可配置的）。您需要决定是否要放置MeteringSampleProvider在任何软件音量调整之前或之后（对于波形绘制，通常在之前，对于音量测量，通常在之后）

这是一个有效的 WindowsForms 演示，将流卷写入控制台：

var player = new WaveOut();
var file = new AudioFileReader(@"test.mp3");
var meter = new MeteringSampleProvider(file);
meter.StreamVolume += (s,e) => Console.WriteLine("{0} - {1}", e.MaxSampleValues[0],e.MaxSampleValues[1]);
player.Init(new SampleToWaveProvider(meter));

var form = new Form();
form.Load += (s,e) => player.Play();
form.FormClosed += (s,e) => player.Dispose();
form.ShowDialog();