> ## Documentation Index > Fetch the complete documentation index at: https://docs.sampler.meiji.industries/llms.txt > Use this file to discover all available pages before exploring further. # MIDI Implementation > Complete reference for MIDI mappable actions, control identification, mapping behavior, monitor coverage, and transport response. # MIDI implementation Meiji Sampler's MIDI surface covers control mapping, a live monitor, and optional transport response. ## Control identification Each MIDI control is uniquely identified by three properties: | Property | Range | Description | | ------------ | ---------- | ------------------------ | | Channel | 1-16 | MIDI channel | | Message type | CC or Note | ControlChange or NoteOn | | Number | 0-127 | CC number or note number | A CC on channel 1 number 60 and a Note on channel 1 number 60 are treated as two separate controls. ## Mapping behavior Mappings are one-to-one in both directions: * One control maps to at most one action. * One action maps to at most one control. When you move a control that already has a mapping, MIDI Learn returns to the Listening list, selects that mapping row, and briefly shows `already mapped`. Press `Enter` on the selected row to edit that control's assignment. When you pick an action that is already mapped to a different control, MIDI Learn also selects the existing mapping row instead of replacing it. Mappings are persisted in the settings file and survive app restarts. After assigning a trigger action, MIDI Learn preselects the next matching trigger target for the next unmapped control: | Last assigned action | Next preselected action | | -------------------- | ----------------------- | | Pad N trigger | Pad N+1 trigger | | Loop N trigger | Loop N+1 trigger | | Scene N trigger | Scene N+1 trigger | | Pad X Chop N trigger | Pad X Chop N+1 trigger | Pad, loop, scene, and chop indices stop at the final display slot, `0`. Non-trigger actions keep the exact last assigned action as the next preselected action. ## Mappable actions ### Transport | Action | Description | | -------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | Play/Stop | Follow the focused row's `Space` behavior. Pads stops pad or preview audio first, Loops starts cued or armed transport unless loops are already playing, and Scenes uses the selected scene's play/cue/stop flow. | | Record/Overdub | Toggle recording or punch into overdub on the currently selected loop slot. | ### Pads | Action | Description | | -------------- | ------------------------------------------------------------------------------------------------------------------------------------- | | Pad 1-0 | Trigger the pad sample and select the channel. If no sample is assigned, the channel is selected but no source-selection modal opens. | | Pad N Chop 1-0 | Trigger a specific chop slice on the pad. Enters chop mode and plays from the chop marker. | Pad slots use display numbering 1-9 then 0 (matching the keyboard number row). ### Loops | Action | Description | | ---------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | Loop 1-0 Trigger | Same behavior as pressing the slot's number key on the loops row. Empty slots arm, idle stopped slots cue, idle cued slots stop, playing slots queue `STOP+`, and `STOP+` slots stop immediately. | | Loop 1-0 Mute | Toggle mute on the loop slot. If any layers are muted, unmutes all first. | | Loop 1-0 Solo | Toggle solo on the loop slot. If already soloed, un-solos all. | | Loop 1-0 Undo | Undo the most recent loop edit. Note: undo is global, not scoped to the targeted slot. The slot number controls which slot gets UI focus. | | Loop 1-0 Clear | Clear all recorded content from the loop slot. | ### Scenes | Action | Description | | ----------------- | --------------------------------------------------------------------------------------- | | Scene 1-0 Trigger | Activate the scene (same behavior as pressing the slot's number key on the scenes row). | | Scene 1-0 Cue | Cue the scene using the `Space`-style scene behavior. | | Scene Stop | Stop the currently active scene. If a stop is already queued, executes immediately. | ### Mixer | Action | Description | | ---------------- | ------------------------------- | | Channel 1-0 Mute | Toggle mute on a mixer channel. | ### Keypress | Action | Description | | -------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | Keypress | Replay one captured keyboard key through the normal app key handler. Supported keys include printable characters, `Enter`, `Space`, `Tab`, `Backspace`, `Delete`, `Insert`, arrows, `Home`, `End`, `PageUp`, `PageDown`, and function keys `F1` through `F24`. `Esc` is reserved for cancel during capture. Modifier combinations are not supported in this version. | ### PerformFX These actions are available when the PerformFX feature is enabled. | Action | Description | | ---------------------------------- | ------------------------------------------------------- | | FX Slot `[1]` through `[9]`, `[0]` | Trigger the fixed PerformFX slot at the given position. | | Bank Toggle | Switch between PerformFX banks. | | Kill All FX | Kill all active PerformFX effects. | ## MIDI learn flow phases The learn flow uses these phases and capture states: | Phase | What happens | | ---------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | Listening | Waiting for a MIDI control movement. Shows existing mappings. | | Assigning | Hierarchical menu for choosing an action. Navigate with `Up`/`Down`/`Enter`/`Esc`. Re-trigger the same MIDI control to select the highlighted row without touching the keyboard. | | Keypress Capture | Inside Assigning, the Keypress category captures the next supported physical key. `Esc` cancels capture and returns to the category menu. | | Editing Behavior | After a CC leaf action is picked for a Gate-eligible target (Loop slot, Channel Mute, Transport, Scene slot), choose Trigger or Gate, threshold, and invert. `Enter` saves, `Esc` returns to Assigning. One-shot CC targets (Pad, Cue, Kill All, etc.), Note triggers, and Keypress mappings skip this step and commit directly with the default behavior. Press `B` on any existing mapping in the Listening list to edit its behavior later. | ## Trigger behavior Each mapping carries a Behavior that decides how the control's value drives the action. | Behavior | Fires action | | -------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | | Trigger | Once, on the rising edge above `threshold` (or falling edge if inverted). Default for Pad, PadChop, Scene Cue, Scene Stop, Loop Mute/Solo/Undo/Clear, Record/Overdub, Bank Toggle, Kill All, Keypress. | | Gate | Action's "on" variant on rising edge above `threshold`, "off" variant on falling edge. Default for CC mapped to Loop slot (play/stop), Channel Mute (unmute/mute), Transport (play/stop), Scene slot (start/stop). | Both behaviors carry a `threshold` (1-127, default 64) and an `inverted` flag (default false). * Note triggers always use `Trigger { threshold: 1 }` — note-on with velocity 0 is filtered as Note Off, so any note event is a rising edge. * CC value 0 is forwarded to the app (it is the falling-edge signal for Gate). Gate mappings will not act on a Recording / Armed loop slot to protect takes in progress. * Mappings loaded from configs saved before this version load with `Trigger { threshold: 1 }` so existing projects keep their prior behavior. ## MIDI tab shortcuts ### Mappings sub-view (Listening phase) | Key | Action | | ----------------------- | ---------------------------------------------------------------------- | | `Up` and `Down` | Navigate mapping list | | `Enter` | Edit selected mapping | | `B` | Edit the selected mapping's behavior (Trigger/Gate, threshold, invert) | | `Delete` or `Backspace` | Remove selected mapping | | `Esc` | Leave MIDI tab | ### Mappings sub-view (Assigning phase) | Key | Action | | ----------------------- | --------------------------------------------------------------------- | | `Up` and `Down` | Navigate menu | | `Enter` | Drill into category or confirm action | | Same MIDI control | Drill into the highlighted row or confirm the highlighted leaf action | | `Esc` | Go up one menu level, or return to Listening from the top level | | `Delete` or `Backspace` | Remove this control's mapping and return to Listening | | `Shift+Delete` | Clear all mappings and return to Listening | ### Mappings sub-view (Keypress capture) | Key | Action | | ------------- | -------------------------------------------------- | | Supported key | Assign that keypress to the detected MIDI control | | `Esc` | Cancel key capture and return to the category menu | ### Mappings sub-view (Editing Behavior step) | Key | Action | | ------------------ | -------------------------------------------------------------------------------------------------------------------------------------------------------- | | `Up` and `Down` | Move focus between Mode / Threshold / Invert rows | | `Left` and `Right` | Adjust the focused field (toggle Gate/Trigger on Mode row; ±1 threshold on Threshold row; flip Invert on Invert row). Hold `Shift` for ±10 on Threshold. | | `G` / `T` | Switch directly to Gate / Trigger mode | | `I` | Toggle Invert | | `Enter` | Save the mapping and return to Listening | | `Esc` | Back: return to Assigning (new mapping) or Listening (editing existing) | ### Sub-tab navigation | Key | Action | | ------------------ | --------------------------------------------- | | `Left` and `Right` | Switch between Mappings and Monitor sub-views | ## MIDI transport The settings include a `transport_enabled` toggle. When disabled, transport messages are visible in the monitor but do not trigger transport behavior. ## Monitor coverage The MIDI monitor displays all incoming MIDI events, not just mapping-eligible ones. Visible message types: * Note Off, Note On, Poly Pressure * Control Change, Program Change, Channel Pressure, Pitch Bend * Clock, Start, Stop, Continue * Active Sensing, SysEx, Unknown Clock and Active Sensing generate high message volume and can flood the display. Use monitor filters to suppress them unless diagnosing a sync problem. ## Route allowlist MIDI mappings use two route rules: * **Keypress mappings** replay the captured key through the normal key handler after the MIDI control is resolved. They work anywhere the same keyboard key would work, including the Trim/chop editor and other focused modal or view states. The MIDI Mapping assignment page still blocks mapped-controller actions while it is learning a control. * **Direct app-action mappings** use a conservative allowlist so pad, loop, scene, transport, and mixer actions cannot silently dismiss stateful UI. The direct-action allowlist is: | Route | Direct-action MIDI allowed | Reason | | ---------------- | -------------------------- | --------------------------------------------- | | Pads row | yes | main sampler view | | Loops row | yes | main sampler view | | Scenes row | yes | main sampler view | | Channel Detail | yes | channel overlay — no unsaved state | | Channel Chop | yes | chop overlay — no unsaved state | | Help overlay | yes | read-only; note that pad actions dismiss Help | | All other modals | no | stateful UI could be silently dismissed | | All other views | no | stateful UI could be silently dismissed | New modal or view variants added to the codebase are blocked by default. New `Channel` variants require an explicit allow or block decision at compile time. If a direct app-action mapping does nothing, check whether the current view is on this allowlist. If a keypress mapping does nothing, verify that the same physical key works in the current UI state. See [MIDI And Sync Problems](/troubleshooting/midi-and-sync) for more. ## Current caution The public marketing copy still describes MIDI controller support as emerging. Use this page as the implementation reference, not as a promise of broader DAW-style MIDI coverage. ## Related pages * [MIDI and External Gear](/guides/midi-and-external-gear) — guide to the mapping workflow * [Muting And Soloing](/guides/muting-and-soloing) — explains channel mute versus loop and track mute behavior * [MIDI and Sync Problems](/troubleshooting/midi-and-sync) — troubleshooting * [Keyboard Shortcuts](/reference/keyboard-shortcuts) — full shortcut reference