jasmid - A Javascript MIDI file reader and synthesiser

Originally presented at BarCamp London 8, 13-14 November 2010

Instructions:
Open index.html in browser. Turn up volume. Click on link.

Sound output is via one of the following mechanisms, according to what your
browser supports:
* Mozilla Audio Data API <https://wiki.mozilla.org/Audio_Data_API>
* Web Audio API
    <https://dvcs.w3.org/hg/audio/raw-file/tip/webaudio/specification.html>
* a Flash fallback originally taken from dynamicaudio.js by Ben Firshman
    <https://github.com/bfirsh/dynamicaudio.js> and hacked around by me.


The code:
stream.js - helper library for reading a string as a stream of typed data
midifile.js - parses the MIDI file format into a header and a list of tracks,
    each consisting of a list of event objects
replayer.js - steps over the data structure generated by midifile.js and calls
    the appropriate operations on the synthesiser
synth.js - audio synthesiser; generates waveforms according to tweakable
    parameters
audio.js - passes the generated waveform to either the Audio Data API or the
    Flash fallback widget (da.swf)


Limitations:
* The only event types supported by replayer.js are note on, note off, tempo
    change and program change
* There are currently only two instrument presets defined in synth.js - one for
    strings and a 'piano' one for everything else - and neither of them are
    particularly good (just a single volume-modulated sine wave).


Matt Westcott <[email protected]> - @gasmanic - http://matt.west.co.tt/