Coppersynth (General MIDI synthesizer)

Copperline includes Coppersynth, a built-in 16-part General MIDI / GS SoundFont synthesizer with a front panel in the style of a Roland SC-55 and an automatic MT-32 translation layer.

Coppersynth’s output is mixed with the Amiga’s four Paula channels. It needs no ROM files and no host MIDI software.

Configuration¶

In the launcher:

Navigate to I/O Ports -> Serial Port.
Set Device / Mode to MIDI.
Set MIDI output to Coppersynth.
Optionally set the SoundFont, Front panel, and MT-32 mode rows.

In copperline.toml:

[serial]
mode = "midi"
midi_out = "coppersynth"
# coppersynth_soundfont = "/path/to/bank.sf2"  # Optional custom SoundFont
# coppersynth_mt32_mode = "auto"               # "auto", "on", or "off"
# coppersynth_panel = true                     # Show front panel on boot

Command-line usage:

copperline --model A1200 --midi-out coppersynth KICK31.ROM

`[serial]` configuration keys¶

Key	Values	Description
`midi_out`	`"coppersynth"`	Route MIDI output to built-in synthesizer
`coppersynth_soundfont`	File path	Path to `.sf2` SoundFont or `.zip` archive
`coppersynth_mt32_mode`	`"auto"`, `"on"`, `"off"`	MT-32 SysEx/patch translation mode (default: `"auto"`)
`coppersynth_panel`	`true` / `false`	Display virtual front panel (default: `false`)

SoundFonts¶

Coppersynth has the GeneralUser GS SoundFont by S. Christian Collins built in, with the full General MIDI instrument set, sound effects, and drum kits.

To use another SoundFont (an .sf2 file, or a .zip holding one):

Set coppersynth_soundfont = "/path/to/bank.sf2" in your configuration, or pick it on the launcher’s SoundFont row.
Click LOAD on the front panel, or use Serial Port -> Coppersynth -> SoundFont -> Load... in the pop-up menu, during a session. Reset in the same submenu returns to the built-in bank.

With no coppersynth_soundfont set, Coppersynth looks for a replacement bank in the file or directory named by COPPERLINE_SOUNDFONT, then for GeneralUser-GS.zip or GeneralUser-GS.sf2 next to the executable or in a share/copperline directory beside or above it, and otherwise uses the built-in bank.

MT-32 translation mode¶

Many Amiga games with MIDI support target the Roland MT-32. With coppersynth_mt32_mode = "auto" (the default):

Coppersynth plays incoming MIDI as General MIDI until it sees MT-32 SysEx (Roland model ID $16). From then on it translates MT-32 patches, custom timbre uploads, and rhythm to General MIDI / GS instruments and drum mappings, and shows text the game writes to the MT-32 display.
A GM System On or GS reset message switches translation back off.
"on" translates from the first byte; "off" never translates.

Virtual front panel¶

When enabled (coppersynth_panel = true), the virtual front panel appears beneath the video display.

Left click: Press a button.
Right click: Latch a button down for multi-button combinations (up to four buttons).

Primary controls¶

Button	Function
PART < >	Select part (1-16)
INSTRUMENT < >	Select the current part’s instrument
LEVEL < >	Adjust part volume
PAN < >	Adjust stereo panning
REVERB < >	Adjust reverb send level
CHORUS < >	Adjust chorus send level
KEY SHIFT < >	Transpose part pitch
ALL	While lit, LEVEL, PAN, REVERB, CHORUS and KEY SHIFT change all 16 parts at once, and MIDI CH sets the device ID (1-32)
MUTE	Mute the selected part (or all parts if `ALL` is lit)
MIDI CH < >	Set MIDI channel for current part (1-16 or Off)
LOAD	Choose another SoundFont
VOLUME	Main output level
POWER	Switch the synthesizer off or on

Multi-button combinations (Power on)¶

Combination	Function
`ALL` + `MUTE`	Solo the selected part; with `ALL` lit, sound every part, muted ones included
`PART <` + `PART >`	Part parameter menu (bend range, vibrato, filter cutoff, portamento, and more)
`PART <` + `PART >` (with `ALL`)	System menu (master tune, reverb and chorus types, bar display and peak hold, receive switches)
`INSTRUMENT <` + `INSTRUMENT >`	Instrument variation bank selection
Both halves of `LEVEL`, `PAN`, `REVERB`, `CHORUS`, `KEY SHIFT` or `MIDI CH`	Show that setting for all 16 parts on the bar display

Multi-button combinations (Power off)¶

With power turned off, latch the buttons (right-click) and click POWER:

Combination	Function
`INSTRUMENT <` + `POWER`	“Init MT-32?”: `ALL` turns MT-32 translation on, `MUTE` turns it off
`INSTRUMENT >` + `POWER`	“Init GS?”: `ALL` returns to the GS basic setting, `MUTE` carries on
`INSTRUMENT <` + `INSTRUMENT >` + `POWER`	“Init All?”: `ALL` restores the factory settings and the built-in SoundFont
`PART <` + `PART >` + `POWER`	Demo mode: `ALL` plays, `MUTE` stops, `PART` picks the song
Both halves of `INSTRUMENT` and of `MIDI CH` + `POWER`	Version and credits screen

Coppersynth keeps its settings in battery-backed memory, stored as coppersynth.nvram in the NVRAM folder ([paths] nvram) when the synthesizer is switched off or the session ends. --factory neither reads nor writes it.

Runtime controls¶

While Coppersynth is the MIDI output, the pop-up menu’s Serial Port -> Coppersynth submenu toggles the Front Panel, loads or resets the SoundFont, and sets the MT-32 Mode (Auto, On, or Off). Serial Port -> MIDI Out switches between Coppersynth, the MT-32, and host MIDI ports.

COPPERLINE_COPPERSYNTH_CAPTURE=FILE writes every byte the guest sends to Coppersynth into FILE, for replaying a session’s MIDI stream offline.

Building without Coppersynth¶

To exclude Coppersynth when compiling from source, leave out the coppersynth feature (see Cargo features):

cargo build --release --no-default-features \
  --features "midi,frontend,wasm-boards,control,ctl-bin,import-uae-bin,net-nat,net-bridge,fluxbridge,mt32,cpu-jit,profile-stats,game-library,mhi,cd-mp3,cd32-fmv,gdb,dap,netplay-internet,host-serial"