Skip to main content

📦 Add Mercury in your Site

It is also possible to include Mercury in your own website. This is done with the mercury-engine. The engine is available as a package on npmjs.com or via unpkg.com.

Examples​

For examples of the Engine used in .html pages please download the repository from github.

  • Navigate to the folder cd mercury-engine
  • Start a localhost server with for example by running npx http-server (install http-server)
  • Go to http://localhost:8080 (or whichever port is assigned by the http-server) and got to examples/.

Install​

Install in node_modules​

$ npm install mercury-engine
const { Mercury } = require('mercury-engine');

const Engine = new Mercury();

Include in html​

Include latest or a specific version of distribution (minified, es5) through url in script index.html

Recommended for most cases:

<script src="https://unpkg.com/mercury-engine/dist/mercury.min.es5.js"></script>

Other options:

<script src="https://unpkg.com/mercury-engine/dist/mercury.js"></script>
<script src="https://unpkg.com/mercury-engine@1.0.0/dist/mercury.min.js"></script>
<script src="https://unpkg.com/mercury-engine@1.0.0/dist/mercury.min.es5.js"></script>

Load the engine in the <script> code like so:

const { Mercury } = MercuryEngine;

const Engine = new Mercury();

Examples​

See the examples folder for a few .html files that demonstrate the usage. Run them locally by cloning this repository with git clone https://github.com/tmhglnd/mercury-engine. Then cd mercury-engine and run a simple http-server, for example with the http-server node package (install globally with npm i -g http-server). Navigate to localhost:8080/examples and try them out.

Usage​

Include and initialize​

Include the package

const { Mercury } = require('mercury-engine');

Initialize the engine and include a callback function through { onload: }, this will be executed when samples are loaded.

const Engine = Mercury({
	onload: () => {
		console.log('This callback is called when samples are loaded!');
		console.log('The loaded samples:', Engine.getBuffers());
	}
});

Resume, evaluate and silence​

Resume the transport and start the webaudio. This has to be done from a user interaction (click or keypress) to allow sound to play from the browser window.

Engine.resume();

Evaluate a mercury code file by providing a string of code. This also resumes the transport if .resume() was not called yet.

Engine.code(`
	set tempo 100
	new sample kick_909 time(1/4)
	new sample hat_909 time(1/4 1/8) gain(0.6)
	new synth saw note(0 0) time(1/16) shape(1 80)
`);

Stop the transport and silence the audio

Engine.silence();

Return the last succesfully evaluated code. If code is evaluated that resulted in an error it is not stored.

Engine.getCode();

Samples​

Add your own samples from for example a url like raw github or freesound. The url can also contain a .json file that references multiple samples and the sample name.

Engine.addBuffers(files, callback);

For example use a json file containing sample names and urls

Engine.addBuffers('https://raw.githubusercontent.com/tmhglnd/mercury-engine/main/examples/samples/freesound-samples.json');

Or load samples directly by creating an array of urls

let s1 = 'https://cdn.freesound.org/previews/671/671221_3797507-lq.mp3';
let s2 = 'https://cdn.freesound.org/previews/145/145778_2101444-lq.mp3';

Engine.addBuffers([s1, s2]);

Add a callback function, this is called when all samples are loaded

Engine.addBuffers('https://someurl.json', () => {
	console.log('This callback is called when samples are loaded!');
	console.log('The loaded samples:', Engine.getBuffers());
});

Get the content of all the loaded Buffers, this is returned as a ToneAudioBuffers class

Engine.getBuffers();

Recording​

Start the recording of the sound

Engine.record(true);

Returns 'started' if the recording is on

Engine.isRecording();

Stop the recording and download the file myRecording.webm

Engine.record(false, 'myRecording');

Meter​

You can add a meter to the main audio output and poll for the amplitude value from the meter to for example create audio-reactive visuals in other programming languages such as Hydra or P5.js.

First add the meter, optionally with a smoothing factor (default=0.7)

Engine.addMeter();

Get the meter value as floating-point between 0-1

Engine.getMeter();

Store the meters amplitude value in a global variable for usage in other places and update regularly with a setInterval at a defined interval in milliseconds.

let amp;

setInterval(() => amp = Engine.getMeter(), 100);

For example control some visual parameter in Hydra

osc(10, 0.2, () => amp * 20).out();

MIDI​

WebMIDI is included and started if the browser is compatible with it. If not, an error will be printed to the console. You can provide a callback function onmidi to execute some code when the WebMIDI enabling was succesful.

const Engine = Mercury({
	onmidi: () => {
		console.log('The WebMIDI status is:', Engine.midi.status);
		console.log('With inputs:', Engine.midi.inputs);
		console.log('And outputs:', Engine.midi.outputs);
	}
});

Settings​

Set the BPM without using set tempo in the Mercury code

Engine.setBPM(140);

Set a randomized BPM

Engine.randomBPM();

Set the volume without using set volume in the Mercury code. Volume in floating amplitude 0 to 1.

Engine.setVolume(0.5);

Set the crossFade between 2 code evaluations without using set crossFade in the Mercury code. Time in milliseconds.

Engine.setCrossFade(500);

Set the HighPass Filter cutoff frequency without using set highPass in the Mercury code.

Engine.setHighPass(400);

Set the LowPass Filter cutoff frequency without using set lowPass in the Mercury code.

Engine.setLowPass(5000);

Get the value for any of the settings

console.log(Engine.bpm);
console.log(Engine.volume);
console.log(Engine.crossFade);
console.log(Engine.highPass);
console.log(Engine.lowPass);

Log function listener​

Logs that are important for the Mercury coder are also emitted as a custom event in the browser. You can create an event listener for mercuryLog. The e.detail contains the printed message. This can be used to for example print things to custom html elements instead of the javascript console.

window.addEventListener('mercuryLog', (e) => {
	let p = JSON.stringify(e.detail).replace(/\,/g, ' ').replace(/\"/g, '');
	document.getElementById('logger').innerHTML += `${p}<br>`;
	console.log('customprint:', e.detail);
});

DOM elements from P5js​

It is possible to control parameters from instruments in the Mercury code by writing a string that contains {} with the js code inside to get the dom value. For example when using DOM elements from the P5js library, such as sliders, they can be used in the code.

let slider;

// p5js setup function
function setup() {
	noCanvas();
	// create a slider with range 50 - 5000, initial 1000
	slider = createSlider(50, 5000, 1000, 0);
}

// use the slider value as a cutoff frequency for the filter
Engine.code(`new synth saw note(0 0) fx(filter low '{slider.value()}' 0.4)`);