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This feature is well established and works across many devices and browser versions. The Web Audio API provides a powerful and versatile system for controlling audio on the Web, allowing developers to choose audio sources, add effects to audio, create audio visualizations, apply spatial effects (such as panning) and much more. The Web Audio API involves handling audio operations inside an audio context, and has been designed to allow modular routing. Basic audio operations are performed with audio nodes, which are linked together to form an audio routing graph. Several sources - with different types of channel layout - are supported even within a single context. This modular design provides the flexibility to create complex audio functions with dynamic effects. Audio nodes are linked into chains and simple webs by their inputs and outputs. They typically start with one or more sources. Sources provide arrays of sound intensities (samples) at very small timeslices, often tens of thousands of them per second.
These could be either computed mathematically (such as OscillatorNode), or they can be recordings from sound/video files (like AudioBufferSourceNode and MediaElementAudioSourceNode) and audio streams (MediaStreamAudioSourceNode). In fact, sound files are just recordings of sound intensities themselves, which come in from microphones or electric instruments, and get mixed down into a single, complicated wave. Outputs of these nodes could be linked to inputs of others, which mix or modify these streams of sound samples into different streams. A common modification is multiplying the samples by a value to make them louder or quieter (as is the case with GainNode). Once the sound has been sufficiently processed for the intended effect, it can be linked to the input of a destination (BaseAudioContext.destination), which sends the sound to the speakers or headphones. This last connection is only necessary if the user is supposed to hear the audio. 5. Connect the sources up to the effects, and the effects to the destination. Timing is controlled with high precision and low latency, allowing developers to write code that responds accurately to events and is able to target specific samples, even at a high sample rate.
So applications such as drum machines and sequencers are well within reach. The Web Audio API also allows us to control how audio is spatialized. Using a system based on a source-listener model, it allows control of the panning model and deals with distance-induced attenuation induced by a moving source (or moving listener). Note: You can read about the theory of the Web Audio API in a lot more detail in our article Basic concepts behind Web Audio API. The Web Audio API can seem intimidating to those that aren't familiar with audio or music terms, and as it incorporates a great deal of functionality it can prove difficult to get started if you are a developer. However, it can also be used to create advanced interactive instruments. With that in mind, it is suitable for both developers and musicians alike. We have a simple introductory tutorial for those that are familiar with programming but need a good introduction to some of the terms and structure of the API.
There's also a Basic Concepts Behind Web Audio API article, to help you understand the way digital audio works, specifically in the realm of the API. This also includes a good introduction to some of the concepts the API is built upon. Learning coding is like playing cards - you learn the rules, then you play, then you go back and learn the rules again, then you play again. So if some of the theory doesn't quite fit after the first tutorial and article, there's an advanced tutorial which extends the first one to help you practice what you've learnt, and apply some more advanced techniques to build up a step sequencer. We also have other tutorials and comprehensive reference material available that covers all features of the API. See the sidebar on this page for more. If you aren't familiar with the programming basics, you might want to consult some beginner's JavaScript tutorials first and then come back here - see our Beginner's JavaScript learning module for a great place to begin.
The Web Audio API has a number of interfaces and associated events, which we have split up into nine categories of functionality. General containers and definitions that shape audio graphs in Web Audio API usage. The AudioContext interface represents an audio-processing graph built from audio modules linked together, each represented by an AudioNode. An audio context controls the creation of the nodes it contains and the execution of the audio processing, or decoding. You need to create an AudioContext before you do anything else, as everything happens inside a context. The AudioNode interface represents an audio-processing module like an audio source (e.g. an HTML or element), audio destination, intermediate processing module (e.g. a filter like BiquadFilterNode, or volume control like GainNode). The AudioParam interface represents an audio-related parameter, like one of an AudioNode. It can be set to a specific value or a change in value, and can be scheduled to happen at a specific time and following a specific pattern.
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