title: Typescript web audio API missing definitions
body: <p>I'm interested in beginning to use Typescript for some of my projects. Right now I would like to use the Web Audio API for some real time audio processing using a microphone as the input stream source. I'm working inside Visual Studio 2015 as I'll be working with ASP.NET 5.</p>
  
  <p>I'm defining my audio context like this:
  <code>var audioCtx: AudioContext;</code></p>
  
  <p>It works as the AudioContext definition is present in the lib.d.ts file located at <code>A:\Program\Microsoft Visual Studio 14.0\Common7\IDE\CommonExtensions\Microsoft\TypeScript</code></p>
  
  <p>Though when I'm later trying to use <code>audioCtx.createMediaStreamSource(stream)</code>I get an error when trying to transpile the TS-code that tells me <code>Property "createMediaStreamSource" does not exist on type 'AudioContext'</code>. </p>
  
  <p>This error seems to be correct, as this is the content from the lib.d.ts file that's used:</p>
  
  <pre><code>interface AudioContext extends EventTarget {
      currentTime: number;
      destination: AudioDestinationNode;
      listener: AudioListener;
      sampleRate: number;
      createAnalyser(): AnalyserNode;
      createBiquadFilter(): BiquadFilterNode;
      createBuffer(numberOfChannels: number, length: number, sampleRate: number): AudioBuffer;
      createBufferSource(): AudioBufferSourceNode;
      createChannelMerger(numberOfInputs?: number): ChannelMergerNode;
      createChannelSplitter(numberOfOutputs?: number): ChannelSplitterNode;
      createConvolver(): ConvolverNode;
      createDelay(maxDelayTime?: number): DelayNode;
      createDynamicsCompressor(): DynamicsCompressorNode;
      createGain(): GainNode;
      createMediaElementSource(mediaElement: HTMLMediaElement): MediaElementAudioSourceNode;
      createOscillator(): OscillatorNode;
      createPanner(): PannerNode;
      createPeriodicWave(real: any, imag: any): PeriodicWave;
      createScriptProcessor(bufferSize?: number, numberOfInputChannels?: number, numberOfOutputChannels?: number): ScriptProcessorNode;
      createStereoPanner(): StereoPannerNode;
      createWaveShaper(): WaveShaperNode;
      decodeAudioData(audioData: ArrayBuffer, successCallback: DecodeSuccessCallback, errorCallback?: DecodeErrorCallback): void;
  }
  </code></pre>
  
  <p>So what I'm wondering is basically if there's away to get more "complete" definitions for the audio API? So that I can at least use the majority of the available functions and objects.</p>
  
  <p>I don't feel like adding the definitions myself, then I rather use standard ES5. But I think it would be rather strange if there are not more complete TS definitions for the Web Audio API as it has existed for a couple of years now (although it's still changing a little bit now and then). </p>