Yamaha E-Seq Converter

Yamaha E-Seq Converter is a ES6 JavaScript tool that helps to convert a midi file into the Yamaha's standard E-Seq format.

Focus

Because most midi files only use one channel, the primary goal of this library is to correctly assign notes to the left and right hands. As a result, the features of software like Smart Pianist can work properly.

Before	After

Getting started

Provided midi files should not be in format 0 and should ideally have 2 tracks. If not, you will have to assign the tracks manually using the Midi class.

If a piano midi file has more than two tracks, the last two are usually the right and left hands.

Installation

npm install @ablaise/yamaha-eseq-converter

Events

Events are available and described on the table below.

Name	Description
`EVENT_READY`	Triggered when the midi file is loaded.
`EVENT_ID`	Triggered when a message event is being read.

Convert a piano midi file

Here is how you can use the library to convert your midi files. Change the code according to your needs.

import Midi from "@ablaise/yamaha-eseq-converter/lib/Midi";
import Utils from "@ablaise/yamaha-eseq-converter/lib/Utils";

const midi = new Midi({
    autorun: true,
    path: './path/to/file.mid',
    //buffer: new ArrayBuffer(...) // or "buffer" option if you prefer to work with ArrayBuffer
});

/**
 * Here is how you can handle a two-tracks midi file for piano.
 */
window.addEventListener(Midi.EVENT_ID, (event) => {
    const data = event.data;
    if (Utils.isChannelAssignable(data.id)) {
        let track = 0
        switch (data.index) {
            case 0:
                track = Midi.TRACKS.PIANO_LEFT_HAND;
                break;
            case 1:
                track = Midi.TRACKS.PIANO_RIGHT_HAND;
                break;
            default:
                console.warn('Unhandled channel.')
                break;
        }

        // update the byte ID with the expected channel
        data.dv.setUint8(data.offset, Utils.setChannel(data.id, track));
    }
});

/**
 * Downloads the output midi file.
 */
window.addEventListener(Midi.EVENT_READY, (event) => {
    const data = event.data;
    const header = data.context.getHeader();
    if (0 === header.getType()) {
        throw 'Invalid midi type.';
    }

    midi.download();
});

You can also use a callback instead of the EVENT_READY event.

import Midi from "@ablaise/yamaha-eseq-converter/lib/Midi";
import Utils from "@ablaise/yamaha-eseq-converter/lib/Utils";

const midi = new Midi({
    autorun: true,
    path: './path/to/file.mid',
    //buffer: new ArrayBuffer(...) // or "buffer" option if you prefer to work with ArrayBuffer
}, (data) => {
    const context = data.context;
    const header = context.getHeader();
    if (0 === header.getType()) {
        throw 'Invalid midi type.';
    }

    // ...
});

Running tests

Yamaha E-Seq Converter uses the Jest Javascript testing framework. You can run them using the following command.

npm run test

Final note

🚧 This tool is still experimental and was created to solve a specific problem. The midi file parser is not a hundred percent complete and may be incorrect in some cases, use it with caution.

What's next?

A demo website for batch conversion
Improving the midi parser and fixes
More events are coming soon
More tests are coming soon

Useful resources

Here are resources that helped me to understand the midi format.

drkzrg / yamaha-eseq-converter Goto Github PK