irrKlang Tutorial: Override File Access (C#)

This example will show how to override file access with irrKlang. This is useful if you want to read sounds from other sources than just files, for example from custom internet streams or an own encypted archive format.

Let's start

At the beginning, we simply create a class and add the namespace IrrKlang in which all sound engine classes are located.

using System;
using System.IO;
using IrrKlang;

namespace CSharp._04._OverrideFileAccess
{
  class Class1
  {

To start, we need to implement the class IFileFactory, which irrKlang uses to open files. The interface consists only of one single method named openFile(String filename). In this method, we return our own file access class and return it:

class MyIrrKlangFileFactory : IrrKlang.IFileFactory
{
  public System.IO.Stream openFile(String filename)
  {
    // we simply could return an opened FileStream here, but to demonstrate
    // overriding, we return our own filestream implementation
    return new MyFileStream(filename);
  }
}

// an own implementation of FileStream to overwrite read access to files 
public class MyFileStream : System.IO.FileStream
{
  public MyFileStream(String filename) : base(filename, FileMode.Open)
  {
  }		

  public override int Read(byte[] array, int offset, int count)
  {
    System.Console.Out.WriteLine("MyFileStream read bytes: " + count);
    return base.Read(array, offset, count);
  }

  public override long Seek(long offset, SeekOrigin origin)
  {
    System.Console.Out.WriteLine("MyFileStream seeked to: " + offset);
    return base.Seek(offset, origin);
  }
};

The main work is done, the only thing missing is to start up the sound engine and tell it to use the created FileFactory for file access:

// irrKlang 3D sound engine example 04, 
  // demonstrating how to override file access of irrKlang
  [STAThread]
  static void Main(string[] args)
  {
    // start the sound engine with default parameters
    ISoundEngine engine = new ISoundEngine();

Create an instance of the file factory and let irrKlang know about it.

  MyIrrKlangFileFactory myfactory = new MyIrrKlangFileFactory();
			  engine.AddFileFactory(myfactory);

That's it, play some sounds with our overriden file access methods:

    // now play some sounds until user presses 'q'

    Console.Out.WriteLine("\nDemonstrating file access overriding.");
    Console.Out.WriteLine("Press any key to play some sound, press ESCAPE to quit.");

    _getch();

    engine.Play2D("../../media/getout.ogg", true);			

    do
    {
      // play some wave sound
      engine.Play2D("../../media/bell.wav");
    }
    while(_getch() != 27); // user pressed eskape key to cancel
  }

  // some simple function for reading keys from the console
  [System.Runtime.InteropServices.DllImport("msvcrt")]
  static extern int _getch();
  }
}

That's it.
Download tutorial source and binary (included in the SDK)