GeCo-Join — User Guide

GeCo-Join is a MIDI file joiner that lets you concatenate multiple .mid files into a single sequence using a Forth-style stack. The result is rendered as standard music notation and can be played back in the browser or exported as a new MIDI file.

📥 Importing MIDI Files

• Import MIDI — Opens a file picker that accepts one or more .mid / .midi files. Each selected file is pushed onto the stack and the full stack is immediately joined and rendered.
• Append MIDI — Adds a single file to the top of the existing stack (after the current sequence), then re-joins automatically.

📚 Stack (Forth-style)

Files are managed on a last-in / first-out stack. The top of the stack is always the last item in the list. Every stack operation immediately re-joins the remaining files and re-renders the notation.

• Pop — Removes the top (last) file from the stack.
• Rotate — Moves the top file to the bottom ([A, B, C] → [C, A, B]), cycling the play order.
• Swap — Exchanges the last two files on the stack ([A, B, C] → [A, C, B]).
• Reset — Clears the stack, removes the score, and reloads the page to restore all defaults.

💾 MIDI Export

• Download MIDI — Saves the currently joined sequence as geco_join.mid, ready for import into any DAW or notation software.

🎹 Playback

• Play — Starts in-browser playback of the joined sequence using an acoustic grand piano soundfont at the current BPM.
• Pause / Continue — Freezes playback; press again to resume from the same position.
• Stop — Stops playback immediately and resets the transport.
• Loop — When checked, playback restarts automatically at the end of the sequence.
• BPM slider (top right) — Sets the playback tempo (60–240 BPM). This does not alter the exported MIDI file.

🥁 Metronome

• Metronome checkbox — Activates a click track during playback. Beat 1 of each bar is accented.
• Volume slider 🔊 — Controls the metronome level independently from the music (0–100 %).
• Click sound — Three options:
  • DAW (noise) — Short white-noise burst, filtered for a crisp studio feel.
  • Beep (sine) — Pure sine-tone click.
  • Wood block — Synthesised wood-block transient.

🎼 Score Display

After each import or stack operation the joined sequence is sent to the backend, converted to MusicXML, and rendered as standard notation using OpenSheetMusicDisplay. Part names and abbreviations are hidden for a cleaner view.

ℹ️ Contextual Help

Hover over (or tab-focus) any control to see a short description in the help strip below the main panel.