audiosynth
Dynamic waveform audio synthesizer, written in Javascript.
Generate musical notes dynamically them in your browser using the HTML5 Audio Element.
No static files required. (Besides the source, of course!)
Demo
To see a demo of audiosynth in action, visit http://keithwhor.com/music/
Installation
Assuming audiosynth.js is in your current directory, import package using:
<script src="audiosynth.js"></script>
Usage
audiosynth implements a singleton class, AudioSynth
. By default, the global (window) variable Synth
is the instance of the class.
Any attempt to instantiate new AudioSynth
object will only create references to
the original object.
Synth instanceof AudioSynth; // true
var testInstance = new AudioSynth;
testInstance instanceof AudioSynth; // true
testInstance === Synth; // true
To use AudioSynth
to generate .WAV files...
Synth.generate(sound, note, octave, duration);
/*
Will generate a base64-encoded dataURI wavefile (.WAV) containing your data.
sound
a numeric index or string referring to a sound profile (by id or name, respectively)
note
the note you wish to play (A,B,C,D,E,F,G). Supports sharps (i.e. C#) but not flats.
(Use the respective sharp!)
octave
the octave # of the note you wish to play
duration
the duration (in seconds) of the note
*/
You can play notes instantly using...
/*
Same arguments as Synth.generate,
only this creates an HTML Audio element, plays it, and unloads it upon completion.
*/
Synth.play(sound, note, octave, duration);
You may also create individual instruments (objects that reference .generate and .play, bound to specific sounds).
var piano = Synth.createInstrument('piano');
piano.play('C', 4, 2); // plays C4 for 2s using the 'piano' sound profile
Sound Profiles
AudioSynth
comes with four default sound profiles.
piano (id 0)
organ (id 1)
acoustic (id 2)
edm (id 3)
var acoustic = Synth.createInstrument('acoustic'); // play with your acoustic guitar!
Changing Settings
Poor performance? The default sampling rate for AudioSynth is 44100Hz (CD quality). This can be taxing on your browser.
To change the sampling rate, use Synth.setSampleRate(n)
Please note that lower sampling rates will equate to poorer sound quality, especially for higher notes.
// Can only set values between 4000Hz and 44100Hz.
Synth.setSampleRate(20000); // sets sample rate to 20000Hz
Synth.getSampleRate(); // returns 20000
Volume a bit much? Adust the volume of the sample similarly.
Synth.setVolume(1.00); // set volume to 100%
Synth.setVolume(0.40); // no, wait, 40%.
Synth.setVolume(0.1337); // even better.
Synth.getVolume(); // returns 0.1337
Advanced Usage
Additional sound profiles can be loaded using Synth.loadSoundProfile()
// Load a sound profile from an object...
Synth.loadSoundProfile({
// name it
name: 'my_sound',
// WIP: return the length of time, in seconds, the attack lasts
attack: function(sampleRate, frequency, volume) { ... },
// WIP: return a number representing the rate of signal decay.
// larger = faster decay
dampen: function(sampleRate, frequency, volume) { ... },
// wave function: calculate the amplitude of your sine wave based on i (index)
wave: function(i, sampleRate, frequency, volume) {
/*
Here we have access to...
this.modulate : an array of loaded frequency
this.vars : any temporary variables you wish to keep track of
*/
}
});
A rough guide to waveform generation can be found at http://keithwhor.com/music/
Debugging
If you're hanging on note generation (for default or custom sound profiles), use Synth.debug()
to enable debugging.
This will log note generation times in your console.
Credits and Acknowledgements
Special thanks to Albert Pham (http://www.sk89q.com/) for Dynamic .WAV file generation, the work off of which this is based (http://www.sk89q.com/playground/jswav/) and Hasen el Judy (http://dev.hasenj.org/post/4517734448) for information regarding Karplus-Strong String Synthesis.
Further Reading
.WAV Audio Files
http://en.wikipedia.org/wiki/.WAV_file
Sound Synthesis
http://www.acoustics.salford.ac.uk/acoustics_info/sound_synthesis/
"acoustic" sound profile generated using Karplus-Strong String Synthesis:
http://en.wikipedia.org/wiki/Karplus%E2%80%93Strong_string_synthesis http://music.columbia.edu/cmc/musicandcomputers/chapter4/04_09.php
Contact
Feel free to e-mail me at keithwhor at gmail dot com
or follow me on Twitter, @keithwhor
If you like, feel free to share! :) Always appreciated.