VirtualMidiTranslator

A minimalist midi to midi translator.

Usage

Launching VMT

When prompted select the desired input port and the desired output port.
Example:

$ ./virtualmiditranslator --config "config.json"
[MIDI INPUT] Port no 0 : Midi Through:Midi Through Port-0 14:0
[MIDI INPUT] Port no 1 : DDJ-XP2:DDJ-XP2 MIDI 1 20:0
Input port [0]: 1
[MIDI OUTPUT] Port no 0 : Midi Through:Midi Through Port-0 14:0
[MIDI OUTPUT] Port no 1 : DDJ-XP2:DDJ-XP2 MIDI 1 20:0
Output port [0]: 0

Writing configurations

Configurations are written in JSON. The mapping configuration is put in a map array as a collection of JSON objects in which you can have two types of objects:

• Single notes. It maps a single note to another

{
  "type": "single_note",
  "base": [channel, note],
  "trans": [translated_channel, translated_note]
}

• Through notes. It translates a range of notes to another range. Mapped notes are computed using the following formula : [channel = abs(channel_a - channel_b) + translated_channel + channel_x, note = note_x + translated_note]

{
  "type": "through",
  "range_low_base": [channel_a, note_a],
  "range_high_base": [channel_b, note_b],
  
  "trans_at": [translated_channel, translated_note]
}

• Single note sinks. It blocks a midi note.

{
  "type": "single_note_sink",
  "note": [channel, note]
}

• Through note sinks. It blocks a range of notes. The same formula as through notes is used.

{
  "type": "through_note_sink",
  "range_low": [channel, note],
  "range_high": [channel, note]
}

Example of configuration

{
  "map" : [
    {
      "type": "single_note",
      "base": [9, 50],
      "trans": [1, 1]
    },

    {
      "type": "single_note",
      "base": [9, 51],
      "trans": [1, 2]
    },

    {
      "type": "through",
      "range_low_base": [5, 0],
      "range_high_base": [8, 49],

      "trans_at": [2, 0]
    }
  ]
}

In this example, note [channel = 9, note = 50] will be mapped to [channel = 1, note = 1], note [channel = 9, note = 51] will be mapped to [channel = 1, note = 2] and the range of notes from [channel = 5, note = 0] through [channel = 8, note = 49] will be translated at [channel = 2, note = 0], this means that, for instance, the note [channel = 6, note = 20] will be translated to [channel = 3, note = 20].