furnace/doc/4-instrument/game-boy.md

Game Boy instrument editor

the Game Boy instrument editor consists of three tabs: one controlling envelope of sound channels, another for the wave synth and macro tab containing several macros.

Game Boy

• Use software envelope: switch to volume macro instead of envelope.

  • this exploits a bug in the Game Boy sound hardware in order to have software envelopes ("zombie mode").
  • only a couple emulators have accurate reproduction of this bug.

• Initialize envelope on every note: forces a volume reset on each new note.

• Volume: initial channel volume (0 to 15).

• Length: envelope decay/attack duration (0 to 7)

• Sound Length: cuts off channel after specified length, overriding the Length value.

• Direction: up makes the envelope an attack. down makes it decay.

  • note: for attack to have effect, start at a lower volume.

• Hardware Sequence: this allows you to define a sequence of hardware envelope changes for creating complex envelopes. see the next section for more information.

hardware sequence

Furnace provides a sequencer for the hardware envelope. this way you can define timed envelope changes which may be used for simulating ADSR, adding simple release, and other things.

the sequence consists of a list of "commands".

the + button adds a new command, which may be one of the following:

• Envelope: sets envelope values and retriggers note. it is highly recommended to have this as the first command.
• Sweep: sets sweep parameters. only works on the first channel.
• Wait: waits a specific number of ticks.
• Wait for Release: waits until the note is released with === or REL.
• Loop: goes to a previous position in the sequence.
• Loop until Release: same as Loop, but doesn't have effect after releasing the note.

each command in the sequence is represented in three columns:

• Tick: the tick this command will execute, followed by position in the sequence.
• Command: the command and its parameters.
• Move/Remove: allows you to move the command, or remove it.

Wavetable

this allows you to enable and configure the Furnace wavetable synthesizer. see this page for more information.

notes:

• only for Wave channel.
• on Game Boy, using the wave synth may result in clicking and/or phase resets. by default Furnace attempts to mitigate this problem though, but some clicking may still be audible.

Macros

• Volume: volume sequence.
  • note: this only appears if "Use software envelope" is checked.
• Arpeggio: pitch sequence.
• Duty/Noise: pulse wave duty cycle or noise mode sequence.
• Waveform: channel 3 wavetable sequence.
• Panning: output for left and right channels.
• Pitch: fine pitch.
• Phase Reset: trigger restart of waveform.