AudioContext

AudioContext is a primary interface of the Web Audio API that represents an audio-processing graph and provides the control surface for managing audio in web applications. It coordinates sources, processors, and the final output, which is delivered to the device speakers via an AudioDestinationNode.

An AudioContext is created by new AudioContext() in most browsers; in older Safari and some WebKit-based browsers, window.webkitAudioContext() is used. Contexts may start in a suspended state and require a user gesture to resume, due to autoplay policies. The state property reports suspended, running, or closed. Key timing information includes sampleRate, the number of samples per second, and currentTime, the elapsed time since creation or resume.

The audio graph is built by creating nodes with methods such as createOscillator(), createGain(), createBiquadFilter(), createDelay(), createAnalyser(), and createBufferSource(). Nodes are connected with connect() to route audio between them, ending at context.destination. AudioBufferSourceNode can play AudioBuffer objects; decoding of external data uses decodeAudioData to obtain an AudioBuffer (with promise-based or callback-based variants in different implementations).

Common use cases include synthesizing sounds, applying real-time effects and routing, analyzing audio with an AnalyserNode, streaming media elements, and capturing microphone input via createMediaStreamSource(). The AudioContext API is widely supported in modern browsers, with legacy webkit-prefixed versions in older Safari releases.