Play a synthesizer from whatever is to hand: the mouse, a touchscreen, the letter keys, or a MIDI keyboard on a cable. Press Record, play, and stop, and the take is ready as a WAV file or a MIDI file.
Computer keyboard layout
The letter keys follow the layout most DAWs use for the same job. The home row plays the white keys and the row above it the black keys, so the board reads like a short piano keyboard.
| Keys | Notes |
|---|---|
| A S D F G H J K L ; ’ | white keys, C up to F an octave higher |
| W E T Y U O P | black keys between them |
| Z / X | octave down / up |
| C / V | velocity down / up by 20 |
| Space | sustain pedal, held |
The keys are read by position, not by the letter printed on them, so an AZERTY or QWERTZ board plays the same notes from the same physical keys.
On screen, where you strike a key sets how hard it is played: near the top is soft (velocity 50) and the bottom edge is full force (127). Drag across the keys for a glissando.
Voices
Fifteen voices, all built from oscillators and an envelope. The piano, bell, and organ add a fixed set of harmonics to a sine. The strings, brass, and lead use a band-limited sawtooth, and the reed uses a square wave. The pad is a slow-attack triangle. The plain sine, triangle, square, and sawtooth voices are there for test tones and chiptune lines.
Each voice has an attack, decay, sustain, and release. A piano or bell note dies away even with the key held, because the sustain level is zero. An organ or pad note holds steady for as long as the key is down.
Recording a take
Record starts the clock and Stop ends it. The take begins at the first note you played, not when you pressed Record, so there is no silence to trim from the front. The file then runs on past the last note for as long as the voice takes to release, up to three seconds.
The take is kept as a list of notes, which has two consequences:
- Changing the voice or volume after recording changes the download. Play a line on the piano voice, then switch to strings to hear it bowed.
- The MIDI file holds exactly what was played: note, start time, length, and velocity. Open it in a DAW to play it on a sampled piano, or to quantize it there.
MIDI keyboards in the browser
Connect MIDI keyboard asks the browser for Web MIDI access. Every connected input is used at once, and one plugged in later is picked up without reconnecting. Notes arrive with their velocity, and controller 64 drives the sustain pedal.
When the page is embedded in another site, the host’s frame has to allow MIDI as well. The embed code for this tool includes that permission.
Latency
The sound starts the moment the browser hears the key. What adds delay is the path to your ears. Bluetooth headphones are the worst case at 150 ms or more, enough to make fast playing feel loose. Wired headphones or built-in speakers usually sit under 20 ms, and the page asks the browser for its lowest-latency output to keep it there.