import * as midiFile from 'midi-file';
import * as fs from 'fs';
import { MidiFile, MidiEvent, MidiTrack } from '../types/midi.js';
export class MidiParser {
static parseMidiFile(filePath: string): MidiFile {
try {
const buffer = fs.readFileSync(filePath);
const parsed = midiFile.parseMidi(buffer);
return {
formatType: (parsed.header as any).formatType || 1,
ticksPerBeat: (parsed.header as any).ticksPerBeat || 480,
tracks: parsed.tracks.map(track => this.parseTrack(track))
};
} catch (error) {
throw new Error(`Failed to parse MIDI file: ${error instanceof Error ? error.message : 'Unknown error'}`);
}
}
private static parseTrack(track: any): MidiTrack {
return {
events: track.map((event: any) => this.parseEvent(event))
};
}
private static parseEvent(event: any): MidiEvent {
const midiEvent: MidiEvent = {
deltaTime: event.deltaTime,
type: event.type
};
if (event.channel !== undefined) {
midiEvent.channel = event.channel;
}
if (event.noteNumber !== undefined) {
midiEvent.noteNumber = event.noteNumber;
midiEvent.velocity = event.velocity || 0;
midiEvent.data = [event.noteNumber, event.velocity || 0];
} else if (event.data) {
midiEvent.data = event.data;
}
if (event.meta === true) {
midiEvent.meta = true;
// Copy all meta-specific properties
Object.keys(event).forEach(key => {
if (key !== 'deltaTime' && key !== 'type' && key !== 'meta') {
(midiEvent as any)[key] = event[key];
}
});
}
if (event.running) {
midiEvent.running = event.running;
}
return midiEvent;
}
static normalizeEventType(type: string): string {
// midi-file library already provides string event types
// Just normalize some common variations
const typeMap: { [key: string]: string } = {
'noteOn': 'noteOn',
'noteOff': 'noteOff',
'noteAftertouch': 'noteAftertouch',
'controller': 'controller',
'programChange': 'programChange',
'channelAftertouch': 'channelAftertouch',
'pitchBend': 'pitchBend',
'sysEx': 'sysEx',
'endOfTrack': 'endOfTrack',
'setTempo': 'setTempo',
'timeSignature': 'timeSignature',
'keySignature': 'keySignature',
'text': 'text',
'copyrightNotice': 'copyright',
'trackName': 'trackName',
'instrumentName': 'instrumentName',
'lyrics': 'lyrics',
'marker': 'marker',
'cuePoint': 'cuePoint'
};
return typeMap[type] || type;
}
}
