1.0.1 • Public • Published

Midi Parser

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I needed to decode midi data for FirmataPi. I learned a lot from node-firmata, Essentials of the MIDI protocol and Control Systems for Live Entertainment which is a great book, and this nice little C library Miby: MIDI Byte-stream Parser based off the MIDI 1.0 spec.

The midi-parser library is a node event emitter. You write midi commands in buffers and it emits midi and sysex commands as events. We avoid releasing zalgo by always emitting events immediately.

The SysEx commands are unwrapped of their header and footer bytes and provided on the sysex event with the command, and data. Since any multibyte data (eg strings) or values over 127 need to be "14 bit encoded". The class methods decodeString and encodeString are available to assist.

The Midi command are emitted on the midi event with command, channel (or null if N/A), and an array of data bytes.

Feature Completeness

  • Robust error handling (drop anything that doesn't make sense) which is great because MIDI is self synchronizing
  • All standard midi commands are handled
  • All system realtime commands are handled.
  • All Channel Voice Commands are handled.
  • SysEx commands are handled.
  • Running status is currently not implemented.
  • SysEx realtime commands are not handled specially - I'm not clear if they can occur at anytime. If they occur during normal message flow (eg, not in the middle of something else) they'll work fine.


This is MIT licensed work. Feel free to use it, abuse it, complain about performance, bugs, etc. Patches that add core parser or extensibility features are very welcome. The libraries intention is to decode the messages and make them available to another program, not to decode the meanings of these messages for humans. All Patches are welcome with that in mind.


npm i midi-parser

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  • reconbot