midiproxy

Proxies a MIDI connection for sniffing both sides of the communication

This program connects to the input and output of a target device, creates virtual input and output ports then relays messages between them. It also prints out the messages to stdout which is useful for reverse-engineering vendor-specific messages.

Prerequisites

• Mido
• python-rtmidi

Example usage

Get a list of potential target devices:

$ ./midiproxy -h
usage: midiproxy [-h]
                 {KMidimon 129:0,Midi Through 14:0,RtMidiIn Client
                 130:0,RtMidiIn Client 132:0,nanoKONTROL2 36:0}

Proxy MIDI connection

positional arguments:
  {KMidimon 129:0,Midi Through 14:0,RtMidiIn Client 130:0,RtMidiIn Client 132:0,nanoKONTROL2 36:0}
                        Target device name

optional arguments:
  -h, --help            show this help message and exit

Run the proxy:

$ ./midiproxy "nanoKONTROL2 36:0"

Check the ports are up:

$ aconnect -l
[...]
client 131: 'RtMidiIn Client' [type=user]
    0 'Proxy Input     '
client 132: 'RtMidiOut Client' [type=user]
    0 'Proxy Output    '
client 133: 'RtMidiIn Client' [type=user]
    0 'RtMidi Input    '
    Connected From: 36:0
client 134: 'RtMidiOut Client' [type=user]
    0 'RtMidi Output   '
    Connecting To: 36:0[real:0]

Connect an application to the proxy:

Log some messages:

$ ./midiproxy "nanoKONTROL2 36:0"
=> F0 7E 7F 06 01 F7
<= F0 7E 00 06 02 42 13 01 00 00 03 00 01 00 F7
=> F0 42 40 00 01 13 00 1F 12 00 F7
<= F0 42 40 00 01 13 00 5F 42 00 F7

=> signifies a message sent from the application to the target device

<= signifies a message sent from the target device to the application