Question

I am trying to make a musical instrument type of application. The problem I am having is that a new sound will only play if the old one is finished. I would like to be able to play them simultaneously.

This is how my code looks like:

First, the MyWave class which simply holds an audio buffer and some other info:

class MyWave
{
    public AudioBuffer Buffer { get; set; }
    public uint[] DecodedPacketsInfo { get; set; }
    public WaveFormat WaveFormat { get; set; }
}

In the SoundPlayer class:

    private XAudio2 xaudio;
    private MasteringVoice mvoice;
    Dictionary<string, MyWave> sounds;

    // Constructor
    public SoundPlayer()
    {
        xaudio = new XAudio2();
        xaudio.StartEngine();
        mvoice = new MasteringVoice(xaudio);
        sounds = new Dictionary<string, MyWave>();
    }

    // Reads a sound and puts it in the dictionary
    public void AddWave(string key, string filepath)
    {
        MyWave wave = new MyWave();

        var nativeFileStream = new NativeFileStream(filepath, NativeFileMode.Open, NativeFileAccess.Read, NativeFileShare.Read);
        var soundStream = new SoundStream(nativeFileStream);
        var buffer = new AudioBuffer() { Stream = soundStream, AudioBytes = (int)soundStream.Length, Flags = BufferFlags.EndOfStream };

        wave.Buffer = buffer;
        wave.DecodedPacketsInfo = soundStream.DecodedPacketsInfo;
        wave.WaveFormat = soundStream.Format;

        this.sounds.Add(key, wave);
    }

    // Plays the sound
    public void Play(string key)
    {
        if (!this.sounds.ContainsKey(key)) return;
        MyWave w = this.sounds[key];

        var sourceVoice = new SourceVoice(this.xaudio, w.WaveFormat);
        sourceVoice.SubmitSourceBuffer(w.Buffer, w.DecodedPacketsInfo);
        sourceVoice.Start();
    }
}

Google wasn’t very helpful, I couldn’t find anything useful. So how can I play multiple sounds simultaneously?

Answer 1

You’ll have to create (and preferably pool) multiple SourceVoice instances and play them back simultaneously.

In fact, your current code should work, no? You may want to add a StreamEnd event listener to the SourceVoice to dispose of itself after playback is complete, and remember to enable callbacks when calling the constructor of the SourceVoice.