Another cross-platform, message-based (non-API) approach to sending and receiving MIDI events.

Rationale: Instead of having to worry about linking to special libraries or importing special modules to use your your OS's native MIDI APIs, this tool does that work for you. PortMidi has already made this job fairly easy (and, this tool happens to use PortMidi). But, with this tool, you don't have to link to anything - not even to PortMidi, because this tool creates a pipe-based message interface for your application to use.

Caveat: This tool is based on older (somewhat ad-hoc) ideas, and is not caught up to most recent trends (like JSON!). The message boundaries are also determined by EOL characters (which is great for humans), but with the advent of some standards for framing (namely, WebSocket), more framing options might also be a worthwhile pursuit. Also, running this tool as a separate process, and incurring additional context switches, carries some overhead (hence a desire to support an optional linkable mode, so this operates in the same process/thread). In practice, this tool works fairly nicely and there seems little need to worry about the context switches.

Why not use Open Sound Control? Well, hopefully this tool will soon be compatible with Open Sound Control (OSC). More to be said soon...

• Warning: feature refactoring is going to happen soon (especially, changing how endpoints are named and referenced)!!! (and soon after be fairly stabilized and useful)
• Can list MIDI endpoints (in and out ports).
• Can subscribe to many inputs at once, and can send to many outputs at once.
• Supports encoding as Sexps (Lisp). (To do: JSON and OSC)
• OS support: OS X (at least, whatever was around in 2008), Linux.
• Knows how to turn on realtime scheduling in OS X (THREAD_TIME_CONSTRAINT_POLICY) and Linux (SCHED_FIFO). This probably doesn't do you much good though since these scheduling priorities are only enabled in the tool itself, and not yet in your application.
• Based on PortMidi (included).

Here's how to build:

# If you're on OS X:
make PLATFORM=mac

# If you're on Linux:
sudo apt-get install libasound2-dev
make PLATFORM=linux

Usage to make a recording, and then play it back:

midipipe4 -l # get a list of ports
midipipe4 -i pmi:15 > my-recording.txt # make a recording
midipipe4 -o pmo:14 < my-recording.txt # playback the recording

A simple metronome, in Python, using Sexps:

TODO

Usage over a TCP-socket:

# Using netcat:
# N.B.: there is also an OpenBSD netcat which is missing the "-c" option.
#       (and therefore, will not work!)
nc.traditional -l -p 12345 -c "midipipe4 ..."

• Add a configuration file, to map human-friendly names to MIDI endpoints (using glob-style pattern matching). (especially for Linux!)
• Add an encoding for OSC (Open Sound Control).
• Add an encoding for JSON.
• Add socket modes (netcat-friendly vanilla TCP socket, TCP WebSocket, UDP OSC).
• Add support for Windows.