WebMIDI In/Out extension by lselden · Pull Request #2022 · TurboWarp/extensions

lselden · 2025-03-10T14:17:35Z

This is an extension that adds MIDI support using the WebMIDI API. It tries to cover most use cases - it supports notes, CC, Pitch Bend, Program Change messages, etc.

Features

Device detection/enumeration
MIDI Input (When Note On/Off, When any midi event)
MIDI Output (similar syntax to the "Music" extension) - uses music "tempo" if set
Event reporter for thread context's current event
human-readable (and forgiving) string formatting of events for parsing/formatting

Todo

Translations
Add blocks documentation
Add string format documentation
Add "Getting Started" / browser compatibility documentation
Test on target devices (in particular mac / android)
Feedback on blocks - are any missing? should some be pruned? Better naming convention?
Image
(OPTIONAL) Separate icons for input vs output?

Added midi extension for input/output of midi using the WebMidi API. Still pending documentation and peer-review

use "t=<time>" instead of "@<time>". Allow using "type=note pitch=60" instead of "note 60" if need to be verbose. Some bugfixes

Brackets-Coder · 2025-03-11T01:11:01Z

At a glance, this looks much better than mine. You'll definitely need to add it to the list in extensions.json and probably make a gallery thumbnail too for it to be accepted though. You probably spent a lot more than four hours on it like I did. I might give it a full review (just for my opinion) when I have more time but I'm a bit busy right now. If you'd like, I can submit a PR or so to your fork that adds translations so you have one less thing to worry about (but again, I'm a bit busy right now, I'll have to get around to it when I can).

Brackets-Coder · 2025-03-11T15:51:43Z

+   */
+  function noteNameToMidiPitch(note, defaultOctave = 4) {
+    const parts =
+      /(?<pitch>[A-G])(?<flat>[b♭]+)?(?<sharp>[#♯]+)?_?(?<octave>-?\d+)?/i.exec(


This should be more human-readable if possible

It's a regex with named groups to describe what's matched. added method comments to help describe what's valid. If anyone's interested in other implementations I used these for reference: strudel and tonaljs

Brackets-Coder · 2025-03-11T15:52:59Z

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+  function stringToMidi(text, opts = {}) {
+    if (typeof text !== "string") text = Cast.toString(text);
+    const fullRe =
+      /^\s*(?<type>[a-zA-Z]{2,})?\s*((?<pitch>[A-G][#b♯♭_]*-?\d?)|(?<data1>\b-?[0-9a-f]{1,5}\b))?\s*(?<data2>\b[0-9a-f]{1,3}\b)?\s*(?<keyvals>.+)\s*$/;


This isn't fun to try to understand... Also you should use Scratch.Cast instead of Cast

Cast here is a local const of Scratch.Cast. Switched to the verbose Scratch.Cast to avoid confusion in the future

Brackets-Coder · 2025-03-11T16:02:48Z

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+      // sanity check - don't let a note be more than 1 minute
+      // if anyone ever needs a longer note then they should manually write event string


Why?
I know it's a rare occurrence but as a musician (pianist), developer, and Scratch user you shouldn't generally limit the user's capabilities unless necessary. Notes technically can be a minute long and a user shouldn't have that length unexpectedly cut off...
Keep in mind this is just a quick look-over and I haven't fully analyzed it in depth yet

I hear ya. I checked and the Scratch Music extension clamps to 100 beats max (100 seconds at 60bpm) - updated code accordingly

Brackets-Coder · 2025-03-11T16:06:57Z

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+  }
+
+  //#endregion
+  Scratch.extensions.register(new MidiExtension());


This class name is a bit overgeneralized?
Also your code style is not exactly like mine but I guess it's just a matter of preference. seems a bit cluttered to me but I guess it's just a personal problem.

Other than that it looks fine

Brackets-Coder · 2025-03-11T16:10:17Z

Just a quick review, nothing in depth. Going over best practices for TW extensions in particular, not necessarily anything related to the functionality of the code.

…onds

Existing code uses "dur" for "duration", and "pitch" for "noteName"

midi precision doesn't go under 2-5 milliseconds, so forcing numbers to be readable 1ms precision

Added midi extension for input/output of midi using the WebMidi API. Still pending documentation and peer-review

Brackets-Coder · 2026-01-23T15:03:47Z

@SharkPool-SP mind doing a quick review?
@lselden is there anything you know you want done prior to merging?

SharkPool-SP · 2026-01-23T16:52:10Z

I don't have a midi to test with

Brackets-Coder · 2026-01-23T17:22:08Z

I don't have a midi to test with

That's right, I forgot you told me
I don't suppose any of the others do either...
Could you just do a quick code skim and see if I missed anything? You don't have to approve if you feel like you can't test

SharkPool-SP · 2026-01-23T19:00:27Z

I don't have a midi to test with

That's right, I forgot you told me I don't suppose any of the others do either... Could you just do a quick code skim and see if I missed anything? You don't have to approve if you feel like you can't test

okay

SharkPool-SP · 2026-01-23T19:01:14Z

ill do it when they fix the other requested changes

added extra block for outputting devices as json, allow outputting active notes as json

… ext_midi

lselden · 2026-03-07T20:11:04Z

@SharkPool-SP I addressed comments and added some JSON output blocks. I also plan on adding some documentation.

SharkPool-SP · 2026-03-07T20:39:44Z

Then I'll wait until documentation is made before merging

Brackets-Coder · 2026-05-12T19:31:44Z

Hi @lselden,

I'd like to get this extension merged as soon as possible. Is there anything I can do to help you with that?

samuellouf · 2026-05-12T21:07:05Z

Hello! I've taken a look at your WebMIDI I/O extension and it looks very good!
I do have a few suggestions though :

I think it would be nice if you could choose the input device in the "when note" / "when event" hat blocks.
Maybe the "Input Event" reporter could have a dropdown in which you can choose the part of the event you want.

But other than that, it's really good.

samuellouf · 2026-05-12T21:12:08Z

Btw I think I'm going to do a MIDI Player extension, if anybody here wants to contribute just dm me on discord @ samuelloufcoder.

AliceC-W · 2026-05-12T21:16:43Z

Btw I think I'm going to do a MIDI Player extension, if anybody here wants to contribute just dm me on discord @ samuelloufcoder.

Will that extension record/write files too?

… to "is note active", not just the pitch

return promise to suspend execution for duration of event

lselden · 2026-05-22T07:21:22Z

Hello! I've taken a look at your WebMIDI I/O extension and it looks very good! I do have a few suggestions though :

I think it would be nice if you could choose the input device in the "when note" / "when event" hat blocks.

Maybe the "Input Event" reporter could have a dropdown in which you can choose the part of the event you want.

But other than that, it's really good.

@samuellouf I added the input device selection to the when hats - good idea! I didn't get a chance to add the type filter to the input event hat. Sounds like a good idea though, and I'd welcome the contribution

lselden · 2026-05-22T07:23:08Z

Hi @lselden,

I'd like to get this extension merged as soon as possible. Is there anything I can do to help you with that?

Hi @Brackets-Coder - thanks for the nudge. I've added some help docs and a sample project, and made a couple of bugfixes.

@SharkPool-SP I've added the documentation - hopefully it makes sense and is useful

Brackets-Coder · 2026-05-22T11:28:51Z

Okay, I'll probably take a look sometime tomorrow or after

Brackets-Coder · 2026-06-03T22:42:22Z

@lselden sorry for the delay, I'll review this weekend if I remember

Brackets-Coder

This isn't a code review, I'm just looking over the documentation with two quick suggestions. Let me know if you have any questions or need anything.

I haven't tested the sample project or code yet after my previous review, but everything else looks okay

Brackets-Coder · 2026-06-07T19:44:01Z

p.s. sorry for my tardiness

lselden · 2026-06-23T21:40:57Z

@Brackets-Coder sorry for my tardiness in seeing your comments. I updated as per your comments.

Brackets-Coder · 2026-07-01T20:35:13Z

@lselden Apologies for the delays in getting this merged. I'm currently out of town so things are moving a bit slower but I'll try to help you and review where I can. Thanks for contributing!

lselden added 3 commits March 5, 2025 12:12

Add midi extension

ac6f021

Added midi extension for input/output of midi using the WebMidi API. Still pending documentation and peer-review

updated midi.js - tweak string/parsing/formatting

0be617e

use "t=<time>" instead of "@<time>". Allow using "type=note pitch=60" instead of "note 60" if need to be verbose. Some bugfixes

midi - cleanup comments and types

767e8db

github-actions Bot added the pr: new extension Pull requests that add a new extension label Mar 10, 2025

lselden mentioned this pull request Mar 10, 2025

MIDI Extension #1725

Closed

lselden added 3 commits March 10, 2025 10:28

Update midi.js

2981a0f

midi.js - linting and ensure all inputs use Scratch.Cast

3cbb48a

Update midi.js

4848f42

lselden added 2 commits March 11, 2025 11:30

midi - add "whenDeviceEvent" hat for detecting device connect/disconnect

488e76b

add midi to extensions list

065976d

Brackets-Coder reviewed Mar 11, 2025

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Comment thread extensions/extensions.json

Brackets-Coder reviewed Mar 11, 2025

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Comment thread extensions/midi/midi.js

Brackets-Coder reviewed Mar 11, 2025

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lselden added 7 commits March 11, 2025 14:34

bugfix in string parsing and minor formatting

1b8ec5b

midi - change params for sendOutputEvent

9f8dfea

midi - treat "pos" and "beats" as beats unit, "time" and "dur" as sec…

17a9e6b

…onds

allow string event input into "play note for beats" command

ccda886

reformatting as per comments

eb5b977

ensure device index starts at 1

a12a863

Merge remote-tracking branch 'upstream/master' into ext_midi

13ac2b4

lselden mentioned this pull request Mar 17, 2025

add new extension MIDI Parser #2035

Closed

lselden added 7 commits March 17, 2025 23:40

Merge in MIDI Parser extension by CHCAT1320

3cc720d

minor refactor - rearrange code

3fdf79a

change parseMidiDataUrl to use same keys

74001d8

Existing code uses "dur" for "duration", and "pitch" for "noteName"

round midi file times to 1 millisecond

3209710

midi precision doesn't go under 2-5 milliseconds, so forcing numbers to be readable 1ms precision

fix json to event formatting

8b48acc

fix linting

1c4dfb5

Add midi extension

afb763c

Added midi extension for input/output of midi using the WebMidi API. Still pending documentation and peer-review

lselden added 2 commits March 7, 2026 15:09

midi - add json output for lists, cleanup comments

2711065

added extra block for outputting devices as json, allow outputting active notes as json

Merge branch 'ext_midi' of https://github.com/lselden/extensions into…

d59a9c4

… ext_midi

lselden added 4 commits May 21, 2026 20:14

parse midi string fixes - handle beats, "rest" type

56c0e62

correctly clear input note buffer and allow passing full midi message…

89d7f42

… to "is note active", not just the pitch

Make Send Midi Output event match behavior of Music extension

dc941ea

return promise to suspend execution for duration of event

midi - added documentation and sample file

bfa3d68

lselden requested a review from a team as a code owner May 22, 2026 06:54

add input device selection to when hats

6a332dd

samuellouf mentioned this pull request Jun 3, 2026

MIDI Synth #2525

Closed

Brackets-Coder requested changes Jun 7, 2026

View reviewed changes

Comment thread docs/midi/MIDI.md Outdated

Comment thread samples/Midi.sb3 Outdated

simplify midi docs, remove sample file

ec25293

lselden requested a review from Brackets-Coder June 23, 2026 21:40

		// sanity check - don't let a note be more than 1 minute
		// if anyone ever needs a longer note then they should manually write event string

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lselden commented Mar 10, 2025

Features

Todo

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