AMY MIDI Mode

AMY assigns synths between 1 and 16 to MIDI channels and listens to MIDI messages on those synths. For example, to set up a MIDI channel with a Juno-6 patch, you simply do

amy.send(synth=1, patch_number=3, num_voices=5)

Where num_voices indicates the polyphony supported for that channel. AMY will handle note stealing and voice allocation.

Note ons, offs, pitch bend, sustain

AMY responds to MIDI note ons and note offs.

AMY responds to MIDI pitch bend messages. This does apply to every note played on the entire AMY instance.

AMY responds to MIDI sustain pedal messages.

Control changes

AMY will turn off all notes when receiving an All Notes Off control change.

If you enable a MIDI input hook you can add more controller mappings. In the AMY source we provide midi_mappings.c with examples. The juno_filter_midi_handler assigns MIDI CC 70 to filter_freq and 71 to resonance. You probably want to make your own MIDI input hook to expand on this for your use cases.

AMY responds to a so far small set of MIDI CC changes to apply to CtrlCoefs on that channel.

TODO: fill this in

Program changes

AMY responds to MIDI program changes. Since program changes are limited to 0-127, right now, we only support switching within an AMY "bank" -- if a synth is setup for Juno-6 (0-127), you can only change between other Juno-6 patches. If a synth is setup for DX-7 (128-255), you can set any DX-7 patch. For example, to change a DX7 patch from 5 to 3, send a program change to that synth with 128+3 = 131.

TODO: BANKS

SYSEX

AMY can receive its wire messages over SYSEX. Since wire messages are always in lower ASCII, you do not need to encode your wire message before sending it to AMY.

Preface your wire message with AMY's SYSEX manufacturer code: 0x00 0x03 0x45.

For example, to send the wire message v0f440l1 (sine wave, 440Hz, note on) to AMY over SYSEX, you'd send 0xF0 0x00 0x03 0x45 v 0 f 4 4 0 l 1 0xF7.

Others

AMY supports MIDI realtime transport for the internal sequencer:

• 0xF8 (Timing Clock): advances the sequencer from external clock input.
• 0xFA (Start): starts sequencer playback from tick 0 in external clock mode.
• 0xFC (Stop): stops sequencer playback.

External realtime sync is off by default — AMY ignores incoming clock/start/stop and keeps its own tempo. Enable it with the C API amy_external_midi_sync(1), or over the wire with amy.send(external_midi_sync=1) (wire command zC1). Set it back to 0 to return to the internal clock.

MIDI Timing Clock is 24 PPQ. AMY's sequencer runs at 48 PPQ, so AMY advances two sequencer ticks per one MIDI clock pulse.

You can also start and stop the sequencer transport directly, independent of MIDI clock sync, with amy.send(sequencer_run=1) / amy.send(sequencer_run=0) (wire command zY1 / zY0).

Sending MIDI out

As well as responding to incoming MIDI, AMY can send MIDI out. Set any oscillator's wave to amy.AMY_MIDI and it stops producing audio — instead, every note you play on that osc is emitted as a MIDI message out whatever MIDI interface you've configured (amy_config.midi, e.g. UART or USB gadget).

amy.send(osc=0, wave=amy.AMY_MIDI)   # osc 0 is now a MIDI sender, not an audio oscillator
amy.send(osc=0, note=60, vel=1)      # -> MIDI note on:  channel 1, note 60, velocity 127
amy.send(osc=0, note=60, vel=0)      # -> MIDI note off (sent as a note on with velocity 0)

• Messages always go out on MIDI channel 1 (status byte 0x90).
• The event's note (midi_note) and vel become the MIDI note number and velocity. Velocity is scaled from AMY's 0.0–1.0 range to 0–127. A note-off is sent as a note-on with velocity 0.
• Notes that AMY received over MIDI in are not echoed back out, so you won't create a feedback loop. Only notes you generate inside AMY — directly, or from the sequencer — are forwarded.

Sequencing MIDI out

Because an AMY_MIDI osc emits MIDI in response to ordinary note events, you can drive it from AMY's sequencer to get tightly-timed MIDI output — a step sequencer or drum pattern clocked by AMY that plays an external synth. Schedule note-ons and note-offs on the osc just like you would schedule audio notes:

amy.send(osc=0, wave=amy.AMY_MIDI)                    # set up the MIDI sender once

# Send a MIDI note on channel 1 every quarter note (48 ticks), held for an eighth note.
amy.send(osc=0, note=60, vel=1, sequence="0,48,1")    # note on  at tick 0  of each 48-tick period
amy.send(osc=0, note=60, vel=0, sequence="24,48,2")   # note off at tick 24 of each 48-tick period

AMY keeps sending those MIDI messages out the port at the configured tempo until you remove them (by their tag) or reset the sequencer. See the sequencer docs for tick / period / tag details.