AppleMIDI (aka rtpMIDI) for Arduino
Enables an Arduino with IP/UDP capabilities (Ethernet shield, ESP8266, ESP32, …) to participate in an AppleMIDI session.
Features
- Build on top of the popular FortySevenEffects MIDI library
- Tested with AppleMIDI on Mac OS (Tahoe) and using rtpMIDI from Tobias Erichsen on Windows 10 & 11.
- Send and receive all MIDI messages
- Uses callbacks to receive MIDI commands (no need for polling)
- Automatic instantiation of AppleMIDI object (see at the end of ‘AppleMIDI.h’)
- Compiles on Arduino, MacOS (XCode) and Windows (MSVS)
New in 3.5.0
- Safer session and RTP parsing (known-SSRC MIDI only, UDP datagram isolation, wrap-safe sequence numbers)
- RTP is sent only after the data-port handshake; invitation reject matches by initiator token
- Size gates:
APPLEMIDI_SMALL, ONE_PARTICIPANT, NO_SESSION_NAME (see Memory footprint)
- Large SysEx is split per RFC 6295 (
F0/F7); see SysEx and extra F0/F7 bytes
Installation
Clone locally or download from the Arduino IDE Library Manager, search for AppleMIDI
This will also install FortySevenEffects MIDI library
Basic Usage
#include <Ethernet.h>
#include <AppleMIDI.h>
byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };
APPLEMIDI_CREATE_DEFAULTSESSION_INSTANCE();
void setup()
{
Ethernet.begin(mac);
MIDI.begin(); // listens on channel 1
}
void loop()
{
// Listen to incoming notes
MIDI.read();
....
if (something) {
// Send MIDI note 40 on, velocity 55 on channel 1
MIDI.sendNoteOn(40, 55, 1);
}
}
More usages in the examples folder and in the wiki
Hardware
- Arduino/Genuino (Mega, Uno, Arduino Ethernet, MKRZERO, …)
- ESP8266 (Adafruit HUZZAH ESP8266, Sparkfun ESP8266 Thing Dev)
- ESP32 (Adafruit HUZZAH32 – ESP32 Feather Board) Wi-Fi
- ESP32 with W5500 Setup
- ESP32 ETH W5500 (Native ESP32 W5500 support)
- Seeed Studio XIAO ESP32 C3
- Teensy 3.2 & 4.1
- Adafruit Feather M0 WiFi - ATSAMD21 + ATWINC1500
Network Shields
- Arduino Ethernet shield (Wiznet W5100 and W5500)
- Arduino Wifi R3 shield
- MKR ETH shield (W5500 and W6100 based)
- Teensy WIZ820io W5200
- Teensy 4.1 with Ethernet Kit
- ESP32 with W5500
Notes
SysEx and extra F0/F7 bytes
Outgoing SysEx that does not fit in MaxMidiOutSize (default 64) is split across RTP packets per RFC 6295: the current packet ends with F0 and the next starts with F7. USB, serial, and BLE do not add those markers, so a capture can look malformed (#169). AppleMIDI/rtpMIDI receivers reassemble them. Raise MaxMidiOutSize (and usually MaxBufferSize) in a custom Settings struct if you need a larger SysEx in one command section.
Session names
Session names can get really long on Macs (eg ‘Macbook Pro of Johann Gambolputty … von Hautkopft of Ulm’) and will be truncated to MaxSessionNameLen.
Define these in the sketch before #include <AppleMIDI.h>:
ONE_PARTICIPANT — one remote peer (saves a participant slot)NO_SESSION_NAME — do not store session names (~100 bytes)APPLEMIDI_SMALL — skip unused journal parsing and outbound RS
(APPLEMIDI_PARSE_JOURNALS / APPLEMIDI_KEEP_RECEIVER_FEEDBACK keep those while still using APPLEMIDI_SMALL)
APPLEMIDI_SMALL is used in examples/AVR_MinMemUsage. More on the wiki.
Ethernet buffer size
It’s highly recommended to modify the Ethernet library - learn more
Latency
Use wired Ethernet to reduce latency, Wi-Fi increases latency and latency varies. More of the wiki
Contributing
I would love to include your enhancements or bug fixes! In lieu of a formal styleguide, please take care to maintain the existing coding style. Please test your code before sending a pull request. It would be very helpful if you include a detailed explanation of your changes in the pull request.
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