Document the Denon MC3000 controller mapping

Replace the stub page (no content, just a note asking for a
contribution) with full documentation for the rewritten mapping:
compatibility notes, audio interface setup, and per-section control
tables (mixer, deck, hot cue, loop, FX, sampler, library), plus a
Known Issues section covering the DECK CHG/LOAD A-B interaction, the
decks C/D EQ-kill limitation, and the unconfirmed DUCKING LED.

Written directly as MyST Markdown (2.6's format for this page, migrated
from RST) rather than ported from an RST draft.

Author: dtavan

source/hardware/controllers/denon_mc3000.md

@@ -1,12 +1,180 @@
 # Denon MC3000
 
 
--  [Manufacturer’s product page](https://web.archive.org/web/20140713040211if_/https://www.denondj.com/products/view/mc3000) (archived)
+The Denon MC3000 is a 4-channel, 4-deck DJ controller and mixer with a
+built-in USB audio interface. It has two physical deck sections (jog wheel,
+transport, hot cues, loop controls) and a 4-channel mixer, but only two FX
+units and eight sampler pads shared across all four decks. The manual
+describes this as a "deck layer function that can control four decks
+separately": the left deck section can be switched between controlling deck
+A or deck C with the {hwlabel}`DECK CHG.` buttons, and the right deck
+section between deck B or deck D.
 
 :::{versionadded} 2.0
 :::
+:::{versionchanged} 2.6
+Added full 4-deck (A/B/C/D) support, current EffectRack/beatloop/
+QuickEffect controls, and LED feedback for all four decks.
+:::
+## Useful links
+
+
+- [Manufacturer's product page](https://web.archive.org/web/20140713040211if_/https://www.denondj.com/products/view/mc3000) (archived, product discontinued)
+- [Forum thread](https://mixxx.discourse.group/t/denon-mc3000-midi-script/12283)
+- [Owner's manual (PDF)](https://cdn.inmusicbrands.com/denondj/legacy/mc3000/MC3000EM_ENG_IM_v00.pdf)
+- [Quick setup guide (PDF)](https://cdn.inmusicbrands.com/denondj/legacy/mc3000/MC3000EM_Quick_Setup_Guide.pdf)
+- [Windows driver v1.0.0, 2015](<https://cdn.inmusicbrands.com/denondj/legacy/mc3000/Denon_DJ_MC3000_Driver_v1.0.0(2015).zip>)
+
+## Compatibility
+
+
+- **macOS**: no driver installation is required. The official quick setup
+  guide's only macOS step is configuring the device in Audio MIDI Setup,
+  with no driver install step at all, consistent with class-compliant USB
+  audio.
+- **Windows**: requires the official ASIO driver, linked above (also
+  originally shipped on the controller's Resource CD-ROM). After
+  installing, check that MC3000 has a checkmark in the ASIO driver control
+  panel and is enabled. The driver is old (2015) and not verified against
+  recent Windows versions - if it fails to install, Windows' generic USB
+  audio class driver may still work for basic use.
+- **Linux**: not explicitly documented by the manufacturer; expected to
+  work with the kernel's built-in ALSA USB audio driver as a
+  class-compliant device, but not verified.
+
+## Audio Interface Setup
+
+
+The MC3000's built-in USB audio interface is documented (official quick
+setup guide) as:
+
+- Channels 1-2 = Master output.
+- Channels 3-4 = Headphone output.
+
+Configure these in Mixxx's Sound Hardware preferences accordingly. The
+single 1/4" microphone input and the LINE 1/2 inputs are analog mixer
+inputs only - not available to Mixxx as audio devices.
+
+:::{note}
+{hwlabel}`MASTER LEVEL`, {hwlabel}`MIC LEVEL`, {hwlabel}`MONITOR PAN`,
+{hwlabel}`MONITOR PHONES`, and {hwlabel}`LINE TO MASTER` are fully analog
+on this hardware and are not sent over MIDI at all, so adjusting them
+changes nothing on screen in Mixxx.
+:::
+## Mixer Section
+
+
+| Control | Function |
+| --- | --- |
+| Channel fader, Cross fader | Standard volume and crossfader control. |
+| {hwlabel}`LEVEL` | Channel pregain/trim. |
+| {hwlabel}`FILTER` | QuickEffect filter. |
+| {hwlabel}`HI` / {hwlabel}`MID` / {hwlabel}`LOW` | 3-band channel EQ. |
+| {hwlabel}`CUE DECK A` / {hwlabel}`CUE DECK B` / {hwlabel}`CUE DECK C` / {hwlabel}`CUE DECK D` | Headphone cue (PFL) toggle, one button per deck letter. |
+| {hwlabel}`KEY LOCK` | Toggles keylock for the deck. |
+| {hwlabel}`SYNC` | Beat-syncs the deck. |
+| {hwlabel}`SAMPLE` (deck A) / {hwlabel}`EFX` (deck B) | Kills the mid EQ band. Not available on decks C/D - there are no spare buttons to extend this further. |
+| {hwlabel}`BROWSE` (deck A) / {hwlabel}`RECORD` (deck B) | Kills the low EQ band. Not available on decks C/D. |
+| {hwlabel}`SHIFT` + {hwlabel}`BROWSE` (deck A) / {hwlabel}`SHIFT` + {hwlabel}`RECORD` (deck B) | Kills the high EQ band instead of the low band. |
+| {hwlabel}`DUCKING` | Cycles microphone ducking mode (off / auto / manual). |
+
 :::{note}
-Unfortunately a detailed description of this controller mapping is still missing.
-If you own this controller, please consider
-[contributing one](https://github.com/mixxxdj/mixxx/wiki/Contributing-Mappings#user-content-documenting-the-mapping).
+{hwlabel}`SAMPLE`, {hwlabel}`EFX`, {hwlabel}`BROWSE`, and
+{hwlabel}`RECORD` are originally window-switch buttons for
+Traktor/VirtualDJ's on-screen browser panes, which Mixxx doesn't have.
+This mapping repurposes them as EQ kill switches instead.
 :::
+## Deck Section
+
+
+| Control | Function |
+| --- | --- |
+| {hwlabel}`PLAY` | Standard play/pause. |
+| {hwlabel}`CUE` | Standard cue-point behavior. |
+| Jog wheel (touch + turn) | Scratches when touched with {hwlabel}`VINYL MODE` on; otherwise bends pitch while turning. |
+| {hwlabel}`VINYL MODE` | Toggles scratch (vinyl) mode for the deck. |
+| Pitch fader | Adjusts the deck's playback rate. |
+| {hwlabel}`PITCH BEND -` / {hwlabel}`PITCH BEND +` | Temporary pitch bend while playing. |
+| {hwlabel}`SHIFT` + {hwlabel}`PITCH BEND -` / {hwlabel}`SHIFT` + {hwlabel}`PITCH BEND +` | While paused, jumps to the track start/end instead of bending pitch. |
+| {hwlabel}`SHIFT` | Modifier used by several controls throughout this mapping. |
+| {hwlabel}`DECK CHG.` (A/B/C/D) | Switches the left (A/C) or right (B/D) deck layer. See "Known Issues" below for a limitation of this control. |
+
+## Hot Cue Section
+
+
+| Control | Function |
+| --- | --- |
+| {hwlabel}`CUE1` - {hwlabel}`CUE4`, {hwlabel}`CUE5` - {hwlabel}`CUE8` (with {hwlabel}`CUE5-8 MODE`) | Sets/jumps to a hot cue point. |
+| {hwlabel}`SHIFT` + hot cue button | Clears the hot cue instead. |
+| {hwlabel}`AUTO LOOP` + hot cue button | Sets a beat-synced loop starting at that hot cue point, 8 beats long. |
+
+## Loop Section
+
+
+| Control | Function |
+| --- | --- |
+| {hwlabel}`AUTO LOOP` | Engages/releases a beat-synced loop at the current position. |
+| {hwlabel}`SHIFT` + {hwlabel}`AUTO LOOP` | Deletes the current loop points instead of engaging a loop. |
+| {hwlabel}`LOOP IN` / {hwlabel}`LOOP OUT` | Manually sets the loop start/end point. |
+| {hwlabel}`LOOP CUT -` / {hwlabel}`LOOP CUT +` | Halves or doubles the active (or next) loop's length. |
+| {hwlabel}`AUTO LOOP` + track select knob | Moves the active loop earlier/later. |
+
+## FX Section
+
+
+| Control | Function |
+| --- | --- |
+| {hwlabel}`EFX.1` - {hwlabel}`EFX.4` buttons | Toggles the corresponding effect slot on/off in the side's assigned effect unit (left = Unit 1, right = Unit 2). |
+| {hwlabel}`EFX.1` - {hwlabel}`EFX.4` knobs | Adjusts the effect's meta knob parameter. |
+| {hwlabel}`FX ON 1` / {hwlabel}`FX ON 2` | Assigns effect Unit 1 or Unit 2 to whichever deck is currently active on that side. |
+
+## Sampler Section
+
+
+:::{note}
+Per the official manual, the four {hwlabel}`EFX.1` - {hwlabel}`EFX.4`
+knob/button pairs above are dual-purpose, switched entirely in hardware
+by the {hwlabel}`SAMP.` button: "OFF: Switches to the effect mode. EFX.
+1-4 are used to operate the effects. ON: Switches to the sample deck
+mode. EFX. 1-4 are used to operate the sample deck." There is no
+separate physical SAMP 1-4 control - it is the same EFX.1-4
+buttons/knobs, relabeled in hardware.
+:::
+| Control | Function |
+| --- | --- |
+| {hwlabel}`EFX.1` - {hwlabel}`EFX.4` as SAMP 1-4 buttons (while {hwlabel}`SAMP.` is on) | Plays the corresponding sampler from its cue point. |
+| {hwlabel}`SHIFT` + SAMP button | Stops the sampler if playing, or ejects the loaded track if stopped. |
+| {hwlabel}`EFX.1` - {hwlabel}`EFX.4` as SAMP 1-4 knobs (while {hwlabel}`SAMP.` is on) | Adjusts the sampler's gain. |
+
+## Library Section
+
+
+| Control | Function |
+| --- | --- |
+| Track select knob ({hwlabel}`SEL.`) | Browses the track library. |
+| {hwlabel}`SHIFT` + track select knob | Nudges the cue point instead of browsing. |
+| Track select knob push ({hwlabel}`SW`) | Loads the highlighted track into the first stopped deck. |
+| {hwlabel}`FWD` / {hwlabel}`BCK` | Selects the next/previous playlist or crate. |
+| {hwlabel}`LOAD A` / {hwlabel}`LOAD B` | Loads the selected track. See "Known Issues" below for how these route to the correct deck. |
+
+## Known Issues
+
+
+- {hwlabel}`LOAD A` / {hwlabel}`LOAD B` do not read the
+  {hwlabel}`DECK CHG.` buttons directly - their MIDI signal has not yet
+  been confirmed working for this purpose. Instead, LOAD tracks whichever
+  deck was most recently interacted with on that side (left = A/C, right
+  = B/D). After switching layers with {hwlabel}`DECK CHG.`, touch any
+  other control on the newly active deck (jog wheel, a hot cue, a loop
+  button, and so on) before pressing LOAD, otherwise LOAD still targets
+  whichever deck was last used on that side.
+- EQ Kill ({hwlabel}`SAMPLE` / {hwlabel}`EFX` / {hwlabel}`BROWSE` /
+  {hwlabel}`RECORD`) is only available on decks A/B - there are no spare
+  buttons to extend it to C/D.
+- {hwlabel}`CF MODE` is not mapped: its stock function, toggling the
+  crossfader between audio and video assignment, has no Mixxx equivalent.
+- {hwlabel}`MASTER LEVEL`, {hwlabel}`MIC LEVEL`, {hwlabel}`MONITOR PAN`,
+  {hwlabel}`MONITOR PHONES`, and {hwlabel}`LINE TO MASTER` are fully analog
+  hardware controls, invisible to MIDI.
+- {hwlabel}`DUCKING`'s LED feedback is a best-effort implementation derived
+  from the manual's MIDI command list, not yet confirmed on real hardware.