Woodshed E-Drum Practice Room

Overview

Woodshed is a browser practice room for electronic drum kits. It runs in Chrome or Edge with nothing to install: plug a Roland TD-07 in, pick a song, and play it on a Guitar Hero style highway that scores every hit, then slow the hard bars down, loop them, and take the full run. The name is jazz slang for practising alone until it sits.

It is a fork of DRUMKILLER by sam1am, released under the MIT license. The highway, scoring, song folders, pad setup wizard, performance video, and the Studio with its chart editor are DRUMKILLER's. Woodshed is what it took to practise real songs on a real kit with that as the base.

Following the heard audio

The highway, miss detection, and playhead were drawn against the audio context's clock, while hits were already mapped through the output timestamp. On wired headphones that is a 5 to 30 ms mismatch. With the Mac's audio going to the TD-07 over Bluetooth it was 280 ms, and notes crossed the strike line a quarter second before the drum was heard. The audio engine now reports the time you hear, interpolated between output timestamps so the highway moves smoothly, and the transport draws against it while scheduling stays on the raw clock. On a wired rig into the module's MIX IN, calibration measures hits within 3 ms.

Holding 120 Hz

Expert charts stuttered, but JavaScript draw time was 0.5 ms a frame. The cost was raster work: every hit spawned a blurred ripple larger than a 3008 by 1606 canvas, ghosts and notes each carried their own blur layer, and busy passages stacked up to ten full-canvas blurs a frame. The road, lanes, strike line, and glow are now painted once into offscreen canvases and copied in. Each blurred shape is rendered once into a small sprite and drawn under its crisp glyph. The HUD animates without forcing layout. On an M4 that took the mean frame from 17.6 ms to 8.33 ms, with none of 3,000 frames over 12 ms.

Practising in bars

DRUMKILLER's practice mode looped between A and B points. Woodshed's works in bars: a bar counter, loops of 1, 2, 4, or 8 bars from where you are, stepping bar by bar with a one-beat run-up, and guide drums that switch on and off mid-take. The results screen colours every bar by accuracy, picks the weakest four-bar stretch, and one key drops you into practice looping it. The title screen checks the kit, the pad map, and calibration, each with a button to fix it.

The menus can be driven from the kit: toms to move, the floor tom twice to select, the crash twice to go back. Because the pads are also the instrument, a hit only counts as a gesture after 600 ms of silence, any other pad switches navigation off, and a double hit closer than 60 ms is read as one stroke bouncing.

Charts and collab takes

Only the demo songs are bundled, so a song starts as your own audio file. Demucs separates the drums, a transcription model turns the stem into MIDI, and a script pins the tempo map, snaps the notes to the grid so the easier difficulties survive, and builds a song folder ready to import. The chart is then fixed by ear in the editor.

For a band's collab clip, a Swift tool plays the reference track and stamps each hit with its CoreMIDI timestamp, relative to when the reference is heard. It folds Roland's edge zones onto General MIDI notes, since GarageBand ignores them, and renders the take with macOS's built-in drum sounds. A session script records takes back to back and reads a spoken report into the headphones after each one, so the drummer never leaves the kit. A last script finds the camera by cross-correlating its microphone against the drums, and stacks the band's panels and the drum camera into one portrait video with a fresh mix.