Audio System in place

I've uploaded the audio system for the game. Currently it only supports XAudio2 which is the new API designed to replace DirectSound. The way the audio system is structured is to allow new audio API's to be easily plugged in, it is based around the design presented by Mike McShaffry in Game Coding Complete (3rd edition). The reason I chose this design was because it presents a very clean interface and easy to understand relationships between the various components. The game code requests that the Audio System create it a new sound effect object which it does based on a loaded resource. The game code can then use that sound effect object (AbstractSoundEffect) to play/stop/pause sounds. The use of the interface AbstractSoundEffect by the game code obviously hides any underlying implementations. The AbstractSoundEffect then passes any buffered audio data onto the AudioSystem in order for it to be mixed with other active sounds and the final sound produced through the players speakers.

There are some tweaks that need to be done to my XAudio2 implmentation for performance reasons. I'm finding that having every sound effect maintain it's own "SourceVoice" is killing performance, only a few active sound effects can drop the frame rate quite substantially. In order to solve this I'll probably keep a set of pre-made source voices in the XAudio2AudioSystem class which active SoundEffects can then request and release when they're finished. If a system attempts to play a sound effect but no active source voices are available then the effect will either be queued or not played at all (in the case of extremely timing senstive effects where playing it late would just seem odd).

Although changes do need to be made to the Audio System the interfaces won't change. This means I can use them in other systems without the problem of having to alter that code at a later point.