Coppersynth (General MIDI synthesizer)

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

Coppersynth mixes its output alongside the Amiga’s four Paula audio channels without requiring external ROM files or MIDI daemon software.

Configuration¶

In the launcher:

Navigate to I/O Ports -> Serial Port.
Set Device / Mode to MIDI.
Set MIDI output to Coppersynth.
Configure SoundFont, MT-32 translation mode, and front panel options as desired.

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 includes the GeneralUser GS SoundFont by S. Christian Collins by default, providing complete General MIDI instruments, SFX, and drum sets.

To use an alternate SoundFont:

Set coppersynth_soundfont = "/path/to/bank.sf2" in your configuration.
Click LOAD on the virtual front panel during an active session.
Select a SoundFont file from the launcher settings tab.

MT-32 translation mode¶

Many Amiga games with MIDI support target the Roland MT-32 specifically. When coppersynth_mt32_mode = "auto" is active:

MT-32 SysEx messages and patch numbers are automatically translated to corresponding General MIDI / GS instruments and drum mappings.
If standard General MIDI or GS reset messages are received, translation mode disengages automatically.
Translation can be explicitly forced ("on") or disabled ("off").

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/hold a button down for multi-button shortcuts.

Primary controls¶

Button	Function
PART < >	Select part (1-16)
INSTRUMENT < >	Select timbre/instrument for current part
LEVEL < >	Adjust part volume
PAN < >	Adjust stereo panning
REVERB < >	Adjust reverb send level
CHORUS < >	Adjust chorus send level
KEY SHIFT < >	Transpose part pitch
ALL	When active, edits apply to all 16 parts simultaneously
MUTE	Mute the selected part (or all parts if `ALL` is lit)
MIDI CH < >	Set MIDI channel for current part (1-16 or Off)
VOLUME	Main output level
POWER	Power cycle the synthesizer engine

Multi-button combinations (Power on)¶

Combination	Function
`ALL` + `MUTE`	Solo the selected part
`PART <` + `PART >`	Part parameter edit menu (Bend range, vibrato, filter cutoff, portamento)
`PART <` + `PART >` (with `ALL`)	System setup menu (Master tune, reverb/chorus DSP types, meter modes)
`INSTRUMENT <` + `INSTRUMENT >`	Instrument variation bank selection

Multi-button combinations (Power off)¶

With power turned off, hold combinations (right-click) and click POWER:

Combination	Function
`INSTRUMENT <` + `POWER`	Toggle MT-32 translation mode
`INSTRUMENT >` + `POWER`	Reset parameters to GS factory standard
`INSTRUMENT <` + `INSTRUMENT >` + `POWER`	Master factory reset (restores default SoundFont)
`PART <` + `PART >` + `POWER`	Play built-in demo sequences
`INSTRUMENT` + `MIDI CH` + `POWER`	Display version and credits info

Building without Coppersynth¶

To exclude Coppersynth when compiling from source:

cargo build --release --no-default-features \
  --features "midi,frontend,wasm-boards,control,ctl-bin,net-nat,net-bridge,fluxbridge,mt32,cpu-jit,profile-stats,game-library,mhi,cd-mp3"