Crate lv2_midi

MIDI message extension for lv2_atom.

This crate adds a new atom type for the lv2_atom crate: The MidiEvent, a message conformant to the MIDI specification. Due to the one-crate-per-spec policy of the rust-lv2 project, this relatively small crate isn't integrated into the main atom crate.

If compiled with the optional wmidi dependency, the crate also has an additional module containing the WMidiEvent. This atom uses the MidiMessage type defined in by wmidi instead of byte slices.

Example

This example showcases a MIDI event processor that modulates every played note up a forth, using the wmidi optional dependency.

use lv2_core::prelude::*;
use lv2_atom::prelude::*;
use lv2_midi::prelude::*;
use lv2_units::prelude::*;
use wmidi::*;
use urid::*;

#[derive(URIDCollection)]
struct MyURIDs {
    atom: AtomURIDCollection,
    midi: MidiURIDCollection,
    units: UnitURIDCollection,
}

#[derive(PortCollection)]
struct MyPorts {
    input: InputPort<AtomPort>,
    output: OutputPort<AtomPort>,
}

/// Something like a plugin's run method.
fn run(ports: &mut MyPorts, urids: MyURIDs) {
    // Retrieving the input and output sequence.
    let input_sequence = ports.input.read(urids.atom.sequence, urids.units.beat).unwrap();
    let mut output_sequence = ports.output.init(
        urids.atom.sequence,
        TimeStampURID::Frames(urids.units.frame)
    ).unwrap();

    for (timestamp, atom) in input_sequence {
        // If the atom encodes a message...
        if let Some(message) = atom.read(urids.midi.wmidi, ()) {
            // Calculate the message to send.
            let message_to_send = match message {
                MidiMessage::NoteOn(channel, note, velocity) => {
                    let note = note.step(5).unwrap(); // modulate up five half-steps.
                    MidiMessage::NoteOn(channel, note, velocity)
                },
                MidiMessage::NoteOff(channel, note, velocity) => {
                    let note = note.step(5).unwrap(); // modulate up five half-steps.
                    MidiMessage::NoteOff(channel, note, velocity)
                }
                _ => message,
            };
            // Write the modulated message or forward it.
            output_sequence.init(timestamp, urids.midi.wmidi, message_to_send);
        } else {
            // Forward the other, uninterpreted message.
            output_sequence.forward(timestamp, atom);
        }
    }
}

Modules

prelude	Prelude for wildcard use, containing many important types.
raw	Atom types to give raw access to MIDI messages.

Structs

MidiURIDCollection

Collection with the URIDs of all UriBounds in this crate.