spessasynth_lib/midi_parser/midi_sequence.js

/**
 * This is the base type for MIDI files. It contains all the "metadata" and information.
 * It extends to:
 * - BasicMIDI, which contains the actual track data of the MIDI file. Essentially the MIDI file itself.
 * - MIDIData, which contains all properties that MIDI does, except for tracks and the embedded soundfont.
 * MIDIData is the "shell" of the file which is available on the main thread at all times, containing the metadata.
 */
class MIDISequenceData
{
    /**
     * The time division of the sequence, representing the number of ticks per beat.
     * @type {number}
     */
    timeDivision = 0;
    
    /**
     * The duration of the sequence, in seconds.
     * @type {number}
     */
    duration = 0;
    
    /**
     * The tempo changes in the sequence, ordered from the last change to the first.
     * Each change is represented by an object with a tick position and a tempo value in beats per minute.
     * @type {{ticks: number, tempo: number}[]}
     */
    tempoChanges = [{ ticks: 0, tempo: 120 }];
    
    /**
     * A string containing the copyright information for the MIDI sequence if detected.
     * @type {string}
     */
    copyright = "";
    
    /**
     * The number of tracks in the MIDI sequence.
     * @type {number}
     */
    tracksAmount = 0;
    
    /**
     * The track names in the MIDI file, an empty string if not set.
     * @type {string[]}
     */
    trackNames = [];
    
    /**
     * An array containing the lyrics of the sequence, stored as binary chunks (Uint8Array).
     * @type {Uint8Array[]}
     */
    lyrics = [];
    
    /**
     * An array of tick positions where lyrics events occur in the sequence.
     * @type {number[]}
     */
    lyricsTicks = [];
    
    /**
     * The tick position of the first note-on event in the MIDI sequence.
     * @type {number}
     */
    firstNoteOn = 0;
    
    /**
     * The MIDI key range used in the sequence, represented by a minimum and maximum note value.
     * @type {{min: number, max: number}}
     */
    keyRange = { min: 0, max: 127 };
    
    /**
     * The tick position of the last voice event (such as note-on, note-off, or control change) in the sequence.
     * @type {number}
     */
    lastVoiceEventTick = 0;
    
    /**
     * An array of MIDI port numbers used by each track in the sequence.
     * @type {number[]}
     */
    midiPorts = [0];
    
    /**
     * An array of channel offsets for each MIDI port, using the SpessaSynth method.
     * @type {number[]}
     */
    midiPortChannelOffsets = [0];
    
    /**
     * A list of sets, where each set contains the MIDI channels used by each track in the sequence.
     * @type {Set<number>[]}
     */
    usedChannelsOnTrack = [];
    
    /**
     * The loop points (in ticks) of the sequence, including both start and end points.
     * @type {{start: number, end: number}}
     */
    loop = { start: 0, end: 0 };
    
    /**
     * The name of the MIDI sequence.
     * @type {string}
     */
    midiName = "";
    
    /**
     * A boolean indicating if the sequence's name is the same as the file name.
     * @type {boolean}
     */
    midiNameUsesFileName = false;
    
    /**
     * The file name of the MIDI sequence, if provided during parsing.
     * @type {string}
     */
    fileName = "";
    
    /**
     * The raw, encoded MIDI name, represented as a Uint8Array.
     * Useful when the MIDI file uses a different code page.
     * @type {Uint8Array}
     */
    rawMidiName;
    
    /**
     * The format of the MIDI file, which can be 0, 1, or 2, indicating the type of the MIDI file.
     * @type {number}
     */
    format = 0;
    
    /**
     * The RMID (Resource-Interchangeable MIDI) info data, if the file is RMID formatted.
     * Otherwise, this field is undefined.
     * Chunk type (e.g. "INAM"): Chunk data as a binary array.
     * @type {Object<string, IndexedByteArray>}
     */
    RMIDInfo = {};
    
    /**
     * The bank offset used for RMID files.
     * @type {number}
     */
    bankOffset = 0;
    
    /**
     * If the MIDI file is a Soft Karaoke file (.kar), this flag is set to true.
     * https://www.mixagesoftware.com/en/midikit/help/HTML/karaoke_formats.html
     * @type {boolean}
     */
    isKaraokeFile = false;
    
    /**
     * Indicates if this file is a Multi-Port MIDI file.
     * @type {boolean}
     */
    isMultiPort = false;
    
    /**
     * Converts ticks to time in seconds
     * @param ticks {number} time in MIDI ticks
     * @returns {number} time in seconds
     */
    MIDIticksToSeconds(ticks)
    {
        let totalSeconds = 0;
        
        while (ticks > 0)
        {
            // tempo changes are reversed, so the first element is the last tempo change
            // and the last element is the first tempo change
            // (always at tick 0 and tempo 120)
            // find the last tempo change that has occurred
            let tempo = this.tempoChanges.find(v => v.ticks < ticks);
            
            // calculate the difference and tempo time
            let timeSinceLastTempo = ticks - tempo.ticks;
            totalSeconds += (timeSinceLastTempo * 60) / (tempo.tempo * this.timeDivision);
            ticks -= timeSinceLastTempo;
        }
        
        return totalSeconds;
    }
    
    /**
     * INTERNAL USE ONLY!
     * DO NOT USE IN SPESSASYNTH_LIB
     * @param sequence {MIDISequenceData}
     * @protected
     */
    _copyFromSequence(sequence)
    {
        // properties can be assigned
        this.midiName = sequence.midiName;
        this.midiNameUsesFileName = sequence.midiNameUsesFileName;
        this.fileName = sequence.fileName;
        this.timeDivision = sequence.timeDivision;
        this.duration = sequence.duration;
        this.copyright = sequence.copyright;
        this.tracksAmount = sequence.tracksAmount;
        this.firstNoteOn = sequence.firstNoteOn;
        this.lastVoiceEventTick = sequence.lastVoiceEventTick;
        this.format = sequence.format;
        this.bankOffset = sequence.bankOffset;
        this.isKaraokeFile = sequence.isKaraokeFile;
        this.isMultiPort = sequence.isMultiPort;
        
        // copying arrays
        this.tempoChanges = [...sequence.tempoChanges];
        this.lyrics = sequence.lyrics.map(arr => new Uint8Array(arr));
        this.lyricsTicks = [...sequence.lyricsTicks];
        this.midiPorts = [...sequence.midiPorts];
        this.trackNames = [...sequence.trackNames];
        this.midiPortChannelOffsets = [...sequence.midiPortChannelOffsets];
        this.usedChannelsOnTrack = sequence.usedChannelsOnTrack.map(set => new Set(set));
        this.rawMidiName = sequence.rawMidiName ? new Uint8Array(sequence.rawMidiName) : undefined;
        
        // copying objects
        this.loop = { ...sequence.loop };
        this.keyRange = { ...sequence.keyRange };
        this.RMIDInfo = { ...sequence.RMIDInfo };
    }
}

export { MIDISequenceData };