source: main/trunk/model-sites-dev/respooled/collect/popup-video-respooled/js/midi/plugin.audiotag.js@ 29863

/*
    ----------------------------------------------------------------------
    AudioTag <audio> - OGG or MPEG Soundbank
    ----------------------------------------------------------------------
    http://dev.w3.org/html5/spec/Overview.html#the-audio-element
    ----------------------------------------------------------------------
*/

(function(root) { 'use strict';

    window.Audio && (function() {
        var midi = root.AudioTag = { api: 'audiotag' };
        var noteToKey = {};
        var volume = 127; // floating point 
        var buffer_nid = -1; // current channel
        var audioBuffers = []; // the audio channels
        var notesOn = []; // instrumentId + noteId that is currently playing in each 'channel', for routing noteOff/chordOff calls
        var notes = {}; // the piano keys
        for (var nid = 0; nid < 12; nid ++) {
            audioBuffers[nid] = new Audio();
        }

        var playChannel = function(channel, note) {
            if (!root.channels[channel]) return;
            var instrument = root.channels[channel].instrument;
            var instrumentId = root.GM.byId[instrument].id;
            var note = notes[note];
            if (note) {
                var instrumentNoteId = instrumentId + '' + note.id;
                var nid = (buffer_nid + 1) % audioBuffers.length;
                var audio = audioBuffers[nid];
                notesOn[ nid ] = instrumentNoteId;
                if (!root.Soundfont[instrumentId]) {
                    if (root.DEBUG) {
                        console.log('404', instrumentId);
                    }
                    return;
                }
                audio.src = root.Soundfont[instrumentId][note.id];
                audio.volume = volume / 127;
                audio.play();
                buffer_nid = nid;
            }
        };

        var stopChannel = function(channel, note) {
            if (!root.channels[channel]) return;
            var instrument = root.channels[channel].instrument;
            var instrumentId = root.GM.byId[instrument].id;
            var note = notes[note];
            if (note) {
                var instrumentNoteId = instrumentId + '' + note.id;
                for (var i = 0, len = audioBuffers.length; i < len; i++) {
                    var nid = (i + buffer_nid + 1) % len;
                    var cId = notesOn[nid];
                    if (cId && cId == instrumentNoteId) {
                        audioBuffers[nid].pause();
                        notesOn[nid] = null;
                        return;
                    }
                }
            }
        };
    
        midi.audioBuffers = audioBuffers;
        midi.send = function(data, delay) { };
        midi.setController = function(channel, type, value, delay) { };
        midi.setVolume = function(channel, n) {
            volume = n; //- should be channel specific volume
        };

        midi.programChange = function(channel, program) {
            root.channels[channel].instrument = program;
        };

        midi.pitchBend = function(channel, program, delay) { };

        midi.noteOn = function(channel, note, velocity, delay) {
            var id = noteToKey[note];
            if (!notes[id]) return;
            if (delay) {
                return setTimeout(function() {
                    playChannel(channel, id);
                }, delay * 1000);
            } else {
                playChannel(channel, id);
            }
        };
    
        midi.noteOff = function(channel, note, delay) {
//          var id = noteToKey[note];
//          if (!notes[id]) return;
//          if (delay) {
//              return setTimeout(function() {
//                  stopChannel(channel, id);
//              }, delay * 1000)
//          } else {
//              stopChannel(channel, id);
//          }
        };
    
        midi.chordOn = function(channel, chord, velocity, delay) {
            for (var idx = 0; idx < chord.length; idx ++) {
                var n = chord[idx];
                var id = noteToKey[n];
                if (!notes[id]) continue;
                if (delay) {
                    return setTimeout(function() {
                        playChannel(channel, id);
                    }, delay * 1000);
                } else {
                    playChannel(channel, id);
                }
            }
        };
    
        midi.chordOff = function(channel, chord, delay) {
            for (var idx = 0; idx < chord.length; idx ++) {
                var n = chord[idx];
                var id = noteToKey[n];
                if (!notes[id]) continue;
                if (delay) {
                    return setTimeout(function() {
                        stopChannel(channel, id);
                    }, delay * 1000);
                } else {
                    stopChannel(channel, id);
                }
            }
        };
    
        midi.stopAllNotes = function() {
            for (var nid = 0, length = audioBuffers.length; nid < length; nid++) {
                audioBuffers[nid].pause();
            }
        };
    
        midi.connect = function(opts) {
            root.setDefaultPlugin(midi);
            ///
            for (var key in root.keyToNote) {
                noteToKey[root.keyToNote[key]] = key;
                notes[key] = {id: key};
            }
            ///
            opts.onsuccess && opts.onsuccess();
        };
    })();

})(MIDI);