Sequencer - abudaan/qambi GitHub Wiki

#####Properties

Returns an object that contains all currently loaded songs. The id of the songs are the keys of the object.

Returns the AudioContext that is used by the sequencer. Note that you should have only one AudioContext instance per document.

• 0 → logs errors only
• 1 → logs errors and warnings
• 2 → logs errors, warnings and info messages
• 3 → logs everything

The default value is 0

There are 4 note name modes that you can choose from:

• sharp → C, C#, D, D#, E, F, F#, G, G#, A, A#, B
  
• flat → C, Db, D, Eb, E, F, Gb, G, Ab, A, Bb, B
  
• enharmonic-sharp → B#, C#, C##, D#, D##, E#, F#, F##, G#, G##, A#, A##
  
• enharmonic-flat → Dbb, Db, Ebb, Eb, Fb, Gbb, Gb, Abb, Ab, Bbb, Bb, Cb
  

The default note name mode is sharp.

You can also use the following statics:

sequencer.SHARP
sequencer.FLAT
sequencer.ENHARMONIC_SHARP
sequencer.ENHARMONIC_FLAT

In the near feature scales will be added to place the use of accidentals within a more or less harmonic context:

D-major → D, E, F#, G, A, B, C# and for the chromatic notes the accidental # will be used: D#, E#, G#, A#, B#.

D-major-molldur→ the chromatic note A# will be Bb because IV moll-dur in D is G, Bb, D and not G, A#, D.

Sets or gets the master volume of the sequencer. Besides setting the master volume you can set the volume of a song and of a track.

Array with all available MIDI inports in alphabetical order. The MIDI inports are instances of MIDIPort.

Array with all available MIDI outports in alphabetical order. The MIDI inports are instances of MIDIPort.

Returns the time seconds of the AudioContext that is used by the sequencer.

sequencer.createMidiEvent(0, sequencer.NOTE_ON, 60, 100) // creates a note on event for C4 with velocity 100 at ticks position 0
sequencer.createMidiEvent(480, sequencer.NOTE_OFF, 60) // creates a note off for the same note 480 ticks later

// if you set the velocity of a note on event to 0, it will be interpreted as a note off event
sequencer.createMidiEvent(480, sequencer.NOTE_ON, 60, 0) // same as above


sequencer.createMidiEvent(1920, sequencer.TIME_SIGNATURE, 6, 8) // changes the time signature to 6/8 at ticks 1920

Read more

Creates a new Part, you can provide a name, if left empty the name of the part will be the same as its globally unique id.

Creates a new Track, you can provide a name, if left empty the name of the track will be the same as its globally unique id.

Creates a new Song based on the data provided in the configurarion object, see Song.

You can configure the master compressor by passing a configuration object. You can use one or more of the following keys:

  threshold; // in Decibels
  knee; // in Decibels
  ratio; // unit-less
  reduction; // in Decibels
  attack; // in Seconds
  release; // in Seconds

See this MDN page for more explanation of the effect of the various keys

Initializes the sequencer. You must call it before you can use the sequencer. It returns a promise:

sequencer.init().then(

    function onFulFilled(){
      // your stuff
    },

    function onRejected(e){
      // something went wrong
      alert(e);
    }
  );

In general the promise only gets rejected if the browser doesn't support the WebAudio API so it is pretty save to omit an onRejected callback.

Returns a note object which with the following read-only properties:

name → the name of the note, a letter from A to G
octave → the octave, a number from -1 to 9
fullName → the name and the octave, e.g. C4 for central C
number → the midi note number
frequency → the frequency of the note
blackKey → whether the note is a black key or not

######arguments

createNote(noteNumber)
createNote(noteNumber, noteNameMode)
createNote(noteName) // actually this is wrong because no value for octave is given; octave will default to 0
createNote(noteName, noteNameMode)
createNote(fullNoteName)
createNote(fullNoteName, noteNameMode)
createNote(noteName, octave)
createNote(noteName, octave, noteNameMode)

All methods return a note object where all the above mentioned properties have the correct value. For instance if you want to know the note number of C#3 you could do this:

console.log(sequencer.createNote('C#3').number);

But there are also special shortcut methods for getting a property of a note based on another property:

• getNoteName() → createNote(...args).name
  
• getNoteOctave() → createNote(...args).octave
  
• getFullNoteName() → createNote(...args).fullName
  
• getNoteNumber() → createNote(...args).number
  
• getFrequency() → createNote(...args).frequency
  
• isBlackKey() → createNote(...args).blackKey
  

These methods can be called with the same parameters as createNote(). For instance:

getNoteOctave(0) → returns -1 because 0 is interpreted as the note number which is the note C-1.

######examples:

getFullNoteName('C#3', 'flat') // returns Db3
getFullNoteName('C#', 3, 'flat') // same as above
getFullNoteName('C#', '3', 'flat') // same as above

getNoteName('Bb', 'sharp') // returns A#
getNoteName('C', 'enharmonic-sharp') // returns B#
getNoteName('C', 'enharmonic-flat') // returns Dbb

getNoteOctave(60) // returns 4

getFrequency('A4') // returns 440
getFrequency('C4') // returns 261.626

sequencer.pitch = 432 // Verdi tuning
getFrequency('A4') // returns 432
getFrequency('C4') // returns 256.869

createNote(102) // returns {name: "F#", octave: 7, fullName: "F#7", number: 102, frequency: 2959.955}
createNote(102, 'flat') // returns {name: "Gb", octave: 7, fullName: "Gb7", number: 102, frequency: 2959.955}

createNote('E7') // returns {name: "E", octave: 7, fullName: "E7", number: 100, frequency: 2637.020}
createNote('e7') // same as above
createNote('E', 7) // same as above
createNote('E', '7') // same as above
createNote('E', '7', 'sharp') // same as above

######standards The naming of the note is according to the scientific pitch notation, and the numbering and the frequency of the notes follows the Midi Tuning Standard. The frequency is based on the pitch set for A4; the standard pitch is 440 Hz but you can change it by setting the value sequencer.pitch. The central C is C4 and has with A4 = 440 Hz a frequency of 261.626 Hz.

The function sequencer.unlockWebAudio() is called when you call song.play(), which means that if you are calling song.play() in the eventlistener of a user interaction, the WebAudio context will be unmuted automatically and you don't need to worry about anything.

However if you want to start your song by code, you should call sequencer.unlockWebAudio() on beforehand. This also applies if you call sequencer.processEvent() by code.