What is Web Audio API? and what are its applications?

What is Web Audio API?

The Web Audio API is a JavaScript interface for processing and synthesizing audio in web applications. It provides a way to manipulate audio data in real time, allowing developers to create audio effects, audio visualizations, music sequencers, and other audio-related applications that can run directly in the browser without requiring any plugins.

What are Web Audio API applications?

Some of the applications of the Web Audio API include:

Music and Audio Streaming: The Web Audio API can be used to create web-based music players, audio streaming applications, and other audio-related services.
Audio Effects: The API provides a wide range of audio processing modules, such as filters, distortion, delay, and reverb. These modules can be used to create audio effects, such as guitar distortion, vocal reverb, and audio spatialization.
Games: The Web Audio API can be used to add audio to web-based games, including background music, sound effects, and voiceovers.
Interactive Audio Visualizations: The API can be used to create interactive audio visualizations that respond to changes in audio data, such as music beat detection, waveform visualization, and spectrogram analysis.
Educational Tools: The API can be used to create interactive educational tools for learning about sound, music, and audio processing.
Overall, the Web Audio API is a powerful tool for creating web-based audio applications that can run in real-time directly in the browser, without requiring any external plugins.

Hello World Web Audio API example

Here we want to illustrate simple web audio circuit that is build with one source and one destination circuit node. The source node which is the oscillator creates tones which is sent to the destination node which is the default speaker of your computer or mobile device. A function called connect acts as wires connecting the oscillator node to the speaker node. The source, destination as well as the connect live inside the constructor called AudioContext.

Below is the simplest hello world web audio API program code.

     
<div>
        <button onclick='hello()'>Hello!</button>
        <button onclick='bye()'>Bye!</button>
        <script>
        function hello(){
            context= new AudioContext()
            Tone= context.createOscillator()
            Tone.start()
            Tone.connect(context.destination)
        }
        function bye(){
            Tone.stop()
        }
    </script>
 </div>
 

The given html interface and javascript program inside the script tag is a simple example of how to use the Web Audio API to create an audio tone using an oscillator.

Here's what each line does:

The first two lines of code create two buttons with the labels "Hello!" and "Bye!" respectively, each calling the "hello()" and "bye()" functions when clicked.
The "hello()" function is called when the "Hello!" button is clicked. This function creates a new AudioContext object, which is the main entry point for the Web Audio API.
Next, the code creates an oscillator using the "createOscillator()" method on the AudioContext object. An oscillator generates a periodic waveform, such as a sine wave, square wave, or sawtooth wave. In this example, no specific waveform is specified, so the default is a sine wave.
The "start()" method is called on the oscillator, which causes it to begin generating the waveform.
The oscillator is then connected to the destination of the AudioContext using the "connect()" method. The destination is the default output of the AudioContext, which in this case is the speakers or headphones connected to the device.
The "bye()" function is called when the "Bye!" button is clicked. This function stops the oscillator by calling the "stop()" method on it.

To demonstrates how the above web audio api application program works just click on the hello and bye button below.

Overall, this code creates a simple "Hello World" example of how to use the Web Audio API to generate an audio tone using an oscillator. Clicking the "Hello!" button will start the tone, while clicking the "Bye!" button will stop it.

References

[1] Web Audio API Volume Control with Gain Slider

[2] Create Oscillator with Web Audio API

[3] Filters with Audio Web API

[4] Web Audio API : Visualizing Frequency Response