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authorcbdev <cb@cbcdn.com>2021-06-21 21:02:20 +0200
committercbdev <cb@cbcdn.com>2021-06-21 21:02:20 +0200
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parent91764dfc3ad86994ce27e5c80a92c034e12b849c (diff)
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@@ -11,10 +11,11 @@ The MIDI backend provides read-write access to the MIDI protocol via virtual por
#### Instance configuration
-| Option | Example value | Default value | Description |
-|---------------|-----------------------|-----------------------|-----------------------|
-| `read` | `20:0` | none | MIDI device to connect for input |
-| `write` | `DeviceName` | none | MIDI device to connect for output |
+| Option | Example value | Default value | Description |
+|-----------------------|-----------------------|-----------------------|-----------------------|
+| `read` / `source` | `20:0` | none | MIDI device to connect for input |
+| `write` / `target` | `DeviceName` | none | MIDI device to connect for output |
+| `epn-tx` | `short` | `full` | Configures whether to clear the active parameter number after transmitting an `nrpn` or `rpn` parameter |
MIDI device names may either be `client:port` portnames or prefixes of MIDI device names.
Run `aconnect -i` to list input ports and `aconnect -o` to list output ports.
@@ -30,25 +31,39 @@ The MIDI backend supports mapping different MIDI events to MIDIMonster channels.
* `pressure` - Note pressure/aftertouch messages
* `aftertouch` - Channel-wide aftertouch messages
* `pitch` - Channel pitchbend messages
+* `program` - Channel program change messages
+* `rpn` - Registered parameter numbers (14-bit extension)
+* `nrpn` - Non-registered parameter numbers (14-bit extension)
A MIDIMonster channel is specified using the syntax `channel<channel>.<type><index>`. The shorthand `ch` may be
used instead of the word `channel` (Note that `channel` here refers to the MIDI channel number).
-The `pitch` and `aftertouch` events are channel-wide, thus they can be specified as `channel<channel>.<type>`.
+The `pitch`, `aftertouch` and `program` messages/events are channel-wide, thus they can be specified as `channel<channel>.<type>`.
MIDI channels range from `0` to `15`. Each MIDI channel consists of 128 notes (numbered `0` through `127`), which
additionally each have a pressure control, 128 CC's (numbered likewise), a channel pressure control (also called
'channel aftertouch') and a pitch control which may all be mapped to individual MIDIMonster channels.
+Every MIDI channel also provides `rpn` and `nrpn` controls, which are implemented on top of the MIDI protocol, using
+the CC controls 101/100/99/98/38/6. Both control types have 14-bit IDs and 14-bit values.
+
Example mappings:
```
midi1.ch0.note9 > midi2.channel1.cc4
midi1.channel15.pressure1 > midi1.channel0.note0
midi1.ch1.aftertouch > midi2.ch2.cc0
midi1.ch0.pitch > midi2.ch1.pitch
+midi1.ch0.nrpn900 > midi2.ch0.rpn1
+midi2.ch15.note1 > midi1.ch2.program
```
#### Known bugs / problems
+Extended parameter numbers (EPNs, the `rpn` and `nrpn` control types) will also generate events on the controls (CC 101 through
+98, 38 and 6) that are used as the lower layer transport. When using EPNs, mapping those controls is probably not useful.
+
+EPN control types support only the full 14-bit transfer encoding, not the shorter variant transmitting only the 7
+high-order bits. This may be changed if there is sufficient interest in the functionality.
+
To access MIDI data, the user running MIDIMonster needs read & write access to the ALSA sequencer.
This can usually be done by adding this user to the `audio` system group.