mob_midi

MIDI in + out for Mob apps, over USB-MIDI and BLE-MIDI. Unlike classic Bluetooth, MIDI is first-class on both platforms, so this is a real cross-platform surface: CoreMIDI on iOS, android.media.midi on Android.

# Discover
MobMidi.list_devices(socket)
# => {:midi, :devices, [%{id: 7, name: "Oxygen 49", direction: :input}, ...]}

# Receive
MobMidi.open_input(socket, device_id)
# => {:midi, :raw, %{device: 7, bytes: <<0x90, 60, 100>>}}
#    parse it: MobMidi.parse(bytes) -> [%{type: :note_on, channel: 0, note: 60, velocity: 100}]

# Send
MobMidi.open_output(socket, device_id)
MobMidi.send_note_on(socket, device_id, 0, 60, 100)
MobMidi.send_cc(socket, device_id, 0, 7, 90)

The NIF layer is deliberately thin (device enumeration + raw byte I/O); message encode/parse lives in Elixir (MobMidi) where it's pure and unit-tested.

Demo screens (tier 3)

Two screens the host auto-lists via Mob.Plugins.screens():

• MobMidi.KeyboardScreen (/midi/keyboard) — a two-octave keyboard; tap a key to send a note to the selected output. Meant to be landscape; currently portrait-stubbed (white keys, two rows) until Mob.Device.lock_orientation/1 lands in mob core (mob#49).
• MobMidi.InputScreen (/midi/input) — pick a source, watch incoming notes light up plus a decoded event log. Visual-first; an audible sine per note is a fast follow once Mob.Audio grows a tone primitive.

Status

Early. The Elixir surface (API, parser, screens) is built and unit-tested. The native layers (iOS priv/native/ios/mob_midi_nif.m over CoreMIDI; Android priv/native/android/MobMidiBridge.kt + priv/native/jni/mob_midi_nif.zig over MidiManager) are a first pass, not yet device-compiled or verified — device verification (USB controller on a Moto G; CoreMIDI on an iPhone) is the next step. Android currently assumes a single port per device (multi-port is a follow-up).