mota-js/libs/thirdparty/mid.min.js

var sampleRate=44100;function AudioPlayer(context,generator,loop){sampleRate=context.sampleRate;var channelCount=2;var bufferSize=4096*4;var node=context.createScriptProcessor(bufferSize,0,channelCount);node.onaudioprocess=function(e){process(e)};function process(e){if(generator.finished){if(loop){generator.reset();generator.finished=false}else{node.disconnect();return}}var dataLeft=e.outputBuffer.getChannelData(0);var dataRight=e.outputBuffer.getChannelData(1);var generate=generator.generate(bufferSize);for(var i=0;i<bufferSize;++i){dataLeft[i]=generate[i*2];dataRight[i]=generate[i*2+1]}}return{"play":function(){node.connect(context.destination)},"pause":function(){node.disconnect()}}}function MidiFile(data){function readChunk(stream){var id=stream.read(4);var length=stream.readInt32();return{"id":id,"length":length,"data":stream.read(length)}}var lastEventTypeByte;function readEvent(stream){var event={};event.deltaTime=stream.readVarInt();var eventTypeByte=stream.readInt8();if((eventTypeByte&240)==240){if(eventTypeByte==255){event.type="meta";var subtypeByte=stream.readInt8();var length=stream.readVarInt();switch(subtypeByte){case 0:event.subtype="sequenceNumber";if(length!=2){throw"Expected length for sequenceNumber event is 2, got "+length}event.number=stream.readInt16();return event;case 1:event.subtype="text";event.text=stream.read(length);return event;case 2:event.subtype="copyrightNotice";event.text=stream.read(length);return event;case 3:event.subtype="trackName";event.text=stream.read(length);return event;case 4:event.subtype="instrumentName";event.text=stream.read(length);return event;case 5:event.subtype="lyrics";event.text=stream.read(length);return event;case 6:event.subtype="marker";event.text=stream.read(length);return event;case 7:event.subtype="cuePoint";event.text=stream.read(length);return event;case 32:event.subtype="midiChannelPrefix";if(length!=1){throw"Expected length for midiChannelPrefix event is 1, got "+length}event.channel=stream.readInt8();return event;case 47:event.subtype="endOfTrack";if(length!=0){throw"Expected length for endOfTrack event is 0, got "+length}return event;case 81:event.subtype="setTempo";if(length!=3){throw"Expected length for setTempo event is 3, got "+length}event.microsecondsPerBeat=((stream.readInt8()<<16)+(stream.readInt8()<<8)+stream.readInt8());return event;case 84:event.subtype="smpteOffset";if(length!=5){throw"Expected length for smpteOffset event is 5, got "+length}var hourByte=stream.readInt8();event.frameRate={0:24,32:25,64:29,96:30}[hourByte&96];event.hour=hourByte&31;event.min=stream.readInt8();event.sec=stream.readInt8();event.frame=stream.readInt8();event.subframe=stream.readInt8();return event;case 88:event.subtype="timeSignature";if(length!=4){throw"Expected length for timeSignature event is 4, got "+length}event.numerator=stream.readInt8();event.denominator=Math.pow(2,stream.readInt8());event.metronome=stream.readInt8();event.thirtyseconds=stream.readInt8();return event;case 89:event.subtype="keySignature";if(length!=2){throw"Expected length for keySignature event is 2, got "+length}event.key=stream.readInt8(true);event.scale=stream.readInt8();return event;case 127:event.subtype="sequencerSpecific";event.data=stream.read(length);return event;default:event.subtype="unknown";event.data=stream.read(length);return event}event.data=stream.read(length);return event}else{if(eventTypeByte==240){event.type="sysEx";var length=stream.readVarInt();event.data=stream.read(length);return event}else{if(eventTypeByte==247){event.type="dividedSysEx";var length=stream.readVarInt();event.data=stream.read(length);return event}else{throw"Unrecognised MIDI event type byte: "+eventTypeByte}}}}else{var param1;if((eventTypeByte&128)==0){param1=eventTypeByte;eventTypeByte=lastEventTypeByte}else{param1=stream.readInt8();lastEventTypeByte=eventTypeByte}var eventType=eventTypeByte>>4;event.channel=eventTypeByte&15;event.type="channel";switch(eventType){case 8:event.subtype="noteOff";event.noteNumber=param1;event.velocity=stream.readInt8();return event;case 9:event.noteNumber=param1;event.velocity=stream.readInt8();if(event.velocity==0){event.subtype="noteOff"}else{event.subtype="noteOn"}return event;case 10:event.subtype="noteAftertouch";event.noteNumber=param1;event.amount=stream.readInt8();return event;case 11:event.subtype="controller";event.controllerType=param1;event.value=stream.readInt8();return event;case 12:event.subtype="programChange";event.programNumber=param1;return event;case 13:event.subtype="channelAftertouch";event.amount=param1;return event;case 14:event.subtype="pitchBend";event.value=param1+(stream.readInt8()<<7);return event;default:throw"Unrecognised MIDI event type: "+eventType}}}stream=Stream(data);var headerChunk=readChunk(stream);if(headerChunk.id!="MThd"||headerChunk.length!=6){throw"Bad .mid file - header not found"}var headerStream=Stream(headerChunk.data);var formatType=headerStream.readInt16();var trackCount=headerStream.readInt16();var timeDivision=headerStream.readInt16();
    if(timeDivision&32768){throw"Expressing time division in SMTPE frames is not supported yet"}else{ticksPerBeat=timeDivision}var header={"formatType":formatType,"trackCount":trackCount,"ticksPerBeat":ticksPerBeat};var tracks=[];for(var i=0;i<header.trackCount;i++){tracks[i]=[];var trackChunk=readChunk(stream);if(trackChunk.id!="MTrk"){throw"Unexpected chunk - expected MTrk, got "+trackChunk.id}var trackStream=Stream(trackChunk.data);while(!trackStream.eof()){var event=readEvent(trackStream);tracks[i].push(event)}}return{"header":header,"tracks":tracks}}function Replayer(midiFile,synth){var trackStates=[];var beatsPerMinute=120;var ticksPerBeat=midiFile.header.ticksPerBeat;var channelCount=16;var channels=[];var nextEventInfo;var samplesToNextEvent;function Channel(){var generatorsByNote={};var currentProgram=PianoProgram;function noteOn(note,velocity){if(generatorsByNote[note]&&!generatorsByNote[note].released){generatorsByNote[note].noteOff()}generator=currentProgram.createNote(note,velocity);synth.addGenerator(generator);generatorsByNote[note]=generator}function noteOff(note,velocity){if(generatorsByNote[note]&&!generatorsByNote[note].released){generatorsByNote[note].noteOff(velocity)}}function setProgram(programNumber){currentProgram=PROGRAMS[programNumber]||PianoProgram}return{"noteOn":noteOn,"noteOff":noteOff,"setProgram":setProgram}}function getNextEvent(){var ticksToNextEvent=null;var nextEventTrack=null;var nextEventIndex=null;for(var i=0;i<trackStates.length;i++){if(trackStates[i].ticksToNextEvent!=null&&(ticksToNextEvent==null||trackStates[i].ticksToNextEvent<ticksToNextEvent)){ticksToNextEvent=trackStates[i].ticksToNextEvent;nextEventTrack=i;nextEventIndex=trackStates[i].nextEventIndex}}if(nextEventTrack!=null){var nextEvent=midiFile.tracks[nextEventTrack][nextEventIndex];if(midiFile.tracks[nextEventTrack][nextEventIndex+1]){trackStates[nextEventTrack].ticksToNextEvent+=midiFile.tracks[nextEventTrack][nextEventIndex+1].deltaTime}else{trackStates[nextEventTrack].ticksToNextEvent=null}trackStates[nextEventTrack].nextEventIndex+=1;for(var i=0;i<trackStates.length;i++){if(trackStates[i].ticksToNextEvent!=null){trackStates[i].ticksToNextEvent-=ticksToNextEvent}}nextEventInfo={"ticksToEvent":ticksToNextEvent,"event":nextEvent,"track":nextEventTrack};var beatsToNextEvent=ticksToNextEvent/ticksPerBeat;var secondsToNextEvent=beatsToNextEvent/(beatsPerMinute/60);samplesToNextEvent+=secondsToNextEvent*synth.sampleRate}else{nextEventInfo=null;samplesToNextEvent=null;self.finished=true}}function generate(samples){var data=new Array(samples*2);var samplesRemaining=samples;var dataOffset=0;while(true){if(samplesToNextEvent!=null&&samplesToNextEvent<=samplesRemaining){var samplesToGenerate=Math.ceil(samplesToNextEvent);if(samplesToGenerate>0){synth.generateIntoBuffer(samplesToGenerate,data,dataOffset);dataOffset+=samplesToGenerate*2;samplesRemaining-=samplesToGenerate;samplesToNextEvent-=samplesToGenerate}handleEvent();getNextEvent()}else{if(samplesRemaining>0){synth.generateIntoBuffer(samplesRemaining,data,dataOffset);samplesToNextEvent-=samplesRemaining}break}}return data}function handleEvent(){var event=nextEventInfo.event;switch(event.type){case"meta":switch(event.subtype){case"setTempo":beatsPerMinute=60000000/event.microsecondsPerBeat}break;case"channel":switch(event.subtype){case"noteOn":channels[event.channel].noteOn(event.noteNumber,event.velocity);break;case"noteOff":channels[event.channel].noteOff(event.noteNumber,event.velocity);break;case"programChange":channels[event.channel].setProgram(event.programNumber);break}break}}function reset(){for(var i=0;i<midiFile.tracks.length;i++){trackStates[i]={"nextEventIndex":0,"ticksToNextEvent":(midiFile.tracks[i].length?midiFile.tracks[i][0].deltaTime:null)}}for(var i=0;i<channelCount;i++){channels[i]=Channel()}samplesToNextEvent=0;getNextEvent()}reset();var self={"reset":reset,"generate":generate,"finished":false};return self}function Stream(str){var position=0;function read(length){var result=str.substr(position,length);position+=length;return result}function readInt32(){var result=((str.charCodeAt(position)<<24)+(str.charCodeAt(position+1)<<16)+(str.charCodeAt(position+2)<<8)+str.charCodeAt(position+3));position+=4;return result}function readInt16(){var result=((str.charCodeAt(position)<<8)+str.charCodeAt(position+1));position+=2;return result}function readInt8(signed){var result=str.charCodeAt(position);if(signed&&result>127){result-=256}position+=1;return result}function eof(){return position>=str.length}function readVarInt(){var result=0;while(true){var b=readInt8();if(b&128){result+=(b&127);result<<=7}else{return result+b}}}return{"eof":eof,"read":read,"readInt32":readInt32,"readInt16":readInt16,"readInt8":readInt8,"readVarInt":readVarInt}}function SineGenerator(freq){var self={"alive":true};var period=sampleRate/freq;var t=0;self.generate=function(buf,offset,count){for(;count;count--){var phase=t/period;var result=Math.sin(phase*2*Math.PI);buf[offset++]+=result;
    buf[offset++]+=result;t++}};return self}function SquareGenerator(freq,phase){var self={"alive":true};var period=sampleRate/freq;var t=0;self.generate=function(buf,offset,count){for(;count;count--){var result=((t/period)%1>phase?1:-1);buf[offset++]+=result;buf[offset++]+=result;t++}};return self}function ADSRGenerator(child,attackAmplitude,sustainAmplitude,attackTimeS,decayTimeS,releaseTimeS){var self={"alive":true};var attackTime=sampleRate*attackTimeS;var decayTime=sampleRate*(attackTimeS+decayTimeS);var decayRate=(attackAmplitude-sustainAmplitude)/(decayTime-attackTime);var releaseTime=null;var endTime=null;var releaseRate=sustainAmplitude/(sampleRate*releaseTimeS);var t=0;self.noteOff=function(){if(self.released){return}releaseTime=t;self.released=true;endTime=releaseTime+sampleRate*releaseTimeS};self.generate=function(buf,offset,count){if(!self.alive){return}var input=new Array(count*2);for(var i=0;i<count*2;i++){input[i]=0}child.generate(input,0,count);childOffset=0;while(count){if(releaseTime!=null){if(t<endTime){while(count&&t<endTime){var ampl=sustainAmplitude-releaseRate*(t-releaseTime);buf[offset++]+=input[childOffset++]*ampl;buf[offset++]+=input[childOffset++]*ampl;t++;count--}}else{self.alive=false;return}}else{if(t<attackTime){while(count&&t<attackTime){var ampl=attackAmplitude*t/attackTime;buf[offset++]+=input[childOffset++]*ampl;buf[offset++]+=input[childOffset++]*ampl;t++;count--}}else{if(t<decayTime){while(count&&t<decayTime){var ampl=attackAmplitude-decayRate*(t-attackTime);buf[offset++]+=input[childOffset++]*ampl;buf[offset++]+=input[childOffset++]*ampl;t++;count--}}else{while(count){buf[offset++]+=input[childOffset++]*sustainAmplitude;buf[offset++]+=input[childOffset++]*sustainAmplitude;t++;count--}}}}}};return self}function midiToFrequency(note){return 440*Math.pow(2,(note-69)/12)}PianoProgram={"attackAmplitude":0.2,"sustainAmplitude":0.1,"attackTime":0.02,"decayTime":0.3,"releaseTime":0.02,"createNote":function(note,velocity){var frequency=midiToFrequency(note);return ADSRGenerator(SineGenerator(frequency),this.attackAmplitude*(velocity/128),this.sustainAmplitude*(velocity/128),this.attackTime,this.decayTime,this.releaseTime)}};StringProgram={"createNote":function(note,velocity){var frequency=midiToFrequency(note);return ADSRGenerator(SineGenerator(frequency),0.5*(velocity/128),0.2*(velocity/128),0.4,0.8,0.4)}};PROGRAMS={41:StringProgram,42:StringProgram,43:StringProgram,44:StringProgram,45:StringProgram,46:StringProgram,47:StringProgram,49:StringProgram,50:StringProgram};function Synth(sampleRate){var generators=[];function addGenerator(generator){generators.push(generator)}function generate(samples){var data=new Array(samples*2);generateIntoBuffer(samples,data,0);return data}function generateIntoBuffer(samplesToGenerate,buffer,offset){for(var i=offset;i<offset+samplesToGenerate*2;i++){buffer[i]=0}for(var i=generators.length-1;i>=0;i--){generators[i].generate(buffer,offset,samplesToGenerate);if(!generators[i].alive){generators.splice(i,1)}}}return{"sampleRate":sampleRate,"addGenerator":addGenerator,"generate":generate,"generateIntoBuffer":generateIntoBuffer}};