SharpDX XAudio2: 6 SourceVoice limit

Question

I have been playing around with SharpDX.XAudio2 for a few days now, and while things have been largely positive (the odd software quirk here and there) the following problem has me completely stuck:

I am working in C# .NET using VS2015.
I am trying to play multiple sounds simultaneously.

To do this, I have made:
- Test.cs: Contains main method
- cSoundEngine.cs: Holds XAudio2, MasteringVoice, and sound management methods.
- VoiceChannel.cs: Holds a SourceVoice, and in future any sfx/ related data.

cSoundEngine:

    List<VoiceChannel> sourceVoices;
    XAudio2 engine;
    MasteringVoice master;

public cSoundEngine()
    {
        engine = new XAudio2();
        master = new MasteringVoice(engine);
        sourceVoices = new List<VoiceChannel>();
    }

public VoiceChannel AddAndPlaySFX(string filepath, double vol, float pan)
    {
        /**
         * Set up and start SourceVoice
         */
        NativeFileStream fileStream = new NativeFileStream(filepath, NativeFileMode.Open, NativeFileAccess.Read);
        SoundStream soundStream = new SoundStream(fileStream);
        SourceVoice source = new SourceVoice(engine, soundStream.Format);
        AudioBuffer audioBuffer = new AudioBuffer()
        {
            Stream = soundStream.ToDataStream(),
            AudioBytes = (int)soundStream.Length,
            Flags = SharpDX.XAudio2.BufferFlags.EndOfStream
        };

        //Make voice wrapper
        VoiceChannel voice = new VoiceChannel(source);
        sourceVoices.Add(voice);

        //Volume
        source.SetVolume((float)vol);

        //Play sound
        source.SubmitSourceBuffer(audioBuffer, soundStream.DecodedPacketsInfo);
        source.Start();

        return voice;
    }

Test.cs:

            cSoundEngine engine = new cSoundEngine();
            total = 6;

            for (int i = 0; i < total; i++)
            {
                string filepath = System.IO.Directory.GetParent(System.IO.Directory.GetCurrentDirectory()).Parent.FullName + @"\Assets\Planet.wav";
                VoiceChannel sfx = engine.AddAndPlaySFX(filepath, 0.1, 0);
            }
            Console.Read(); //Input anything to end play.

There is currently nothing worth showing in VoiceChannel.cs - it holds 'SourceVoice source' which is the one parameter sent in the constructor!

Everything is fine and well running with up to 5 sounds (total = 5). All you hear is the blissful drone of Planet.wav. Any higher than 5 however causes the console to freeze for ~5 seconds, then close (likely a c++ error which debugger can't handle). Sadly no error message for us to look at or anything.
From testing:
- Will not crash as long as you do not have more than 5 running sourcevoices.
- Changing sample rate does not seem to help.
- Setting inputChannels for master object to a different number makes no difference.
- MasteringVoice seems to say the max number of inputvoices is 64.
- Making each sfx play from a different wav file makes no difference.
- Setting the volume for sourcevoices and/or master makes no difference.

From the XAudio2 API Documentation I found this quote: 'XAudio2 removes the 6-channel limit on multichannel sounds, and supports multichannel audio on any multichannel-capable audio card. The card does not need to be hardware-accelerated.'. This is the closest I have come to finding something that mentions this problem.

I am not well experienced with programming sfx and a lot of this is very new to me, so feel free to call me an idiot where appropriate but please try and explain things in layman terms.

Please, if you have any ideas or answers they would be greatly appreciated!
-Josh

Answer 1

As Chuck has suggested, I have created a databank which holds the .wav data, and I just reference the single data store with each buffer. This has improved the sound limit up to 20 - however this has not fixed the problem as a whole, likely because I have not implemented this properly. Implementation:

class SoundDataBank
{
    /**
     * Holds a single byte array for each sound
     */

    Dictionary<eSFX, Byte[]> bank;
    string curdir => Directory.GetParent(Directory.GetCurrentDirectory()).Parent.FullName;

    public SoundDataBank()
    {
        bank = new Dictionary<eSFX, byte[]>();
        bank.Add(eSFX.planet, NativeFile.ReadAllBytes(curdir + @"\Assets\Planet.wav"));
        bank.Add(eSFX.base1, NativeFile.ReadAllBytes(curdir + @"\Assets\Base.wav"));
    }

    public Byte[] GetSoundData(eSFX sfx)
    {
        byte[] output = bank[sfx];
        return output;
    }

}

In SoundEngine we create a SoundBank object (initialised in SoundEngine constructor):

    SoundDataBank soundBank;

    public VoiceChannel AddAndPlaySFXFromStore(eSFX sfx, double vol)
    {
        /**
         * sourcevoice will be automatically added to MasteringVoice and engine in the constructor.
         */
        byte[] buffer = soundBank.GetSoundData(sfx);
        MemoryStream memoryStream = new MemoryStream(buffer);
        SoundStream soundStream = new SoundStream(memoryStream);
        SourceVoice source = new SourceVoice(engine, soundStream.Format);
        AudioBuffer audioBuffer = new AudioBuffer()
        {
            Stream = soundStream.ToDataStream(),
            AudioBytes = (int)soundStream.Length,
            Flags = SharpDX.XAudio2.BufferFlags.EndOfStream
        };


        //Make voice wrapper
        VoiceChannel voice = new VoiceChannel(source, engine, MakeOutputMatrix());

        //Volume
        source.SetVolume((float)vol);

        //Play sound
        source.SubmitSourceBuffer(audioBuffer, soundStream.DecodedPacketsInfo);
        source.Start();

        sourceVoices.Add(voice);

        return voice;
    }

Following this implementation now lets me play up to 20 sound effects - but NOT because we are playing from the soundbank. Infact, even running the old method for sound effects now gets up to 20 sfx instances.

This has improved up to 20 because we have done NativeFile.ReadAllBytes(curdir + @"\Assets\Base.wav") in the constructor for the SoundBank.

I suspect NativeFile is holding a store of loaded file data, so you regardless of whether you run the original SoundEngine.AddAndPlaySFX() or SoundEngine.AddAndPlaySFXFromStore(), they are both running from memory?

Either way, this has quadrupled the limit from before, so this has been incredibly useful - but requires further work.