Midi

True when the runtime exposes navigator.requestMIDIAccess. During prerender/SSR the check returns false rather than throwing, so defer it to OnAfterRenderAsync.

@inject Bit.Butil.Midi midi

var supported = await midi.IsSupported();

RequestAccess prompts the user and returns the ports the grant covers. The resolved access is cached for the page, so calling it again is cheap and does not re-prompt; GetPorts re-reads the same list.

var access = await midi.RequestAccess(sysex: false);
foreach (var input in access!.Inputs)  { /* input.Id, input.Name */ }
foreach (var output in access.Outputs) { /* output.Id, output.Name */ }

var current = await midi.GetPorts();

Subscribes to one input, or - with no id - to every input at once, which is usually what an app wants since the user's controller is whichever one they touch.

await using var messages = await midi.SubscribeMessages(message =>
{
    // message.Data[0] is the status byte: 0x90|channel is note-on
    // message.TimeStamp is on the performance.now() clock
});

SendNoteOn and SendNoteOff are the two messages every synth understands; Send takes raw bytes for everything else. Clear drops whatever is still queued - the way out of a note left hanging.

await midi.SendNoteOn(outputId, note: 60, velocity: 100);
await midi.SendNoteOff(outputId, note: 60);

// raw: program change to patch 5 on channel 1
await midi.Send(outputId, [0xC0, 0x05]);

await midi.Clear(outputId);

Fires when a port is connected or disconnected. A port that has been unplugged stays in the list as disconnected, so a subscription survives the cable being re-seated.

await using var watch = await midi.SubscribeStateChange(port =>
{
    // port?.Name, port?.State, port?.Connection
});