Use-Cases

Basic Examples

What can web developers do with the Web Audio API?

• Looping sounds without gaps: Code Example
• Creating seamless playlists
• FadeIns / FadeOuts / Crossfades
• Add filters to the audio such as: Bass/Treble EQ Control
• Changing parameters such as volume, pan, speed/pitch over time
• Cross-fading between two sounds.
• Synchronizing sounds to begin playing at the same time, or at specific times.
• Playing sounds with rhythm: EG: Drum beats
• Sound level meter to monitor the volume of audio
• Create audio visualizations
• Low-Latency Sound Playback eg:
  • In response to user-input from keyboard/mouse etc
  • Collisions of objects in games
• JavaScript access to audio data
  • Create custom audio processing effects
  • Music synthesis

Use Cases

Use Cases from Audio Incubator Group http://www.w3.org/2005/Incubator/audio/wiki/Audio_API_Use_Cases

Scenarios from MediaStream Processing API http://hg.mozilla.org/users/rocallahan_mozilla.com/specs/raw-file/tip/StreamProcessing/StreamProcessing.html#scenarios

Requirements

OpenAL/EAX Style Effects for Games

• Doppler Shift
• Distance attenuation
• Obstruction
• Room simulation
• 3D Positioning

Features Realting to Accessibility

• Changing pitch of voices without effect the speed
• Change speed of voices without effecting the pitch
• Smooth changes over time of audio parameters like volume, pan etc

Resource Management

• Playing Short Sound now with minimal latency
• Loading and managing short-medium length audio assets
• Load audio assets faster than real-time

DAW Applications

• Creating an multi-track mixer
  • Insert effects
  • sends
  • sub-mixes
  • mute
  • solo

Modular routing,

Dynamics Compressor

Faster than real time mix-down (such as exporting a track to a file)

Scheduling of many overlapping audio clips on multiple tracks Automation curves for volume, panning, other effect params Analysis and metering (Temporal frequency domain)

Synthesizer Playback

• Basic sample-based synthesizer playback - ADSR envelopes, waveforms etc

Basic Example Code

Loop Sounds Without Gaps

  var context = new webkitAudioContext()
    , source  = context.createBufferSource()
    ;

  // Request & decode audio
  ... source.buffer = decoded_data; ...

  source.connect( context.destination );
  source.loop = true;
  source.noteOn( 0 );