feat!: implement vsti, along with various refactorings and api changes for it

The RPC and sync library mechanisms were removed for now; they never really worked and contained several obvious bugs. Need to consider if syncs are useful at all during the compose time, or just used during intro.

cmd/sointu-vsti/main.go

@@ -0,0 +1,104 @@
+//go:build plugin
+
+package main
+
+import (
+	"github.com/vsariola/sointu/cmd"
+	"github.com/vsariola/sointu/tracker"
+	"github.com/vsariola/sointu/tracker/gioui"
+	"pipelined.dev/audio/vst2"
+)
+
+type VSTIProcessContext struct {
+	events []vst2.MIDIEvent
+	host   vst2.Host
+}
+
+func (c *VSTIProcessContext) NextEvent() (event tracker.PlayerProcessEvent, ok bool) {
+	var ev vst2.MIDIEvent
+	for len(c.events) > 0 {
+		ev, c.events = c.events[0], c.events[1:]
+		switch {
+		case ev.Data[0] >= 0x80 && ev.Data[0] < 0x90:
+			channel := ev.Data[0] - 0x80
+			note := ev.Data[1]
+			return tracker.PlayerProcessEvent{Frame: int(ev.DeltaFrames), On: false, Channel: int(channel), Note: note}, true
+		case ev.Data[0] >= 0x90 && ev.Data[0] < 0xA0:
+			channel := ev.Data[0] - 0x90
+			note := ev.Data[1]
+			return tracker.PlayerProcessEvent{Frame: int(ev.DeltaFrames), On: true, Channel: int(channel), Note: note}, true
+		default:
+			// ignore all other MIDI messages
+		}
+	}
+	return tracker.PlayerProcessEvent{}, false
+}
+
+func (c *VSTIProcessContext) BPM() (bpm float64, ok bool) {
+	timeInfo := c.host.GetTimeInfo()
+	return timeInfo.Tempo, true
+}
+
+func init() {
+	var (
+		uniqueID = [4]byte{'S', 'n', 't', 'u'}
+		version  = int32(100)
+	)
+	vst2.PluginAllocator = func(h vst2.Host) (vst2.Plugin, vst2.Dispatcher) {
+		modelMessages := make(chan interface{}, 1024)
+		playerMessages := make(chan tracker.PlayerMessage, 1024)
+		model := tracker.NewModel(modelMessages, playerMessages)
+		player := tracker.NewPlayer(cmd.DefaultService, playerMessages, modelMessages)
+		tracker := gioui.NewTracker(model, cmd.DefaultService)
+		tracker.SetInstrEnlarged(true) // start the vsti with the instrument editor enlarged
+		go tracker.Main()
+		context := VSTIProcessContext{make([]vst2.MIDIEvent, 100), h}
+		buf := make([]float32, 2048)
+		return vst2.Plugin{
+				UniqueID:       uniqueID,
+				Version:        version,
+				InputChannels:  0,
+				OutputChannels: 2,
+				Name:           "Sointu",
+				Vendor:         "vsariola/sointu",
+				Category:       vst2.PluginCategorySynth,
+				Flags:          vst2.PluginIsSynth,
+				ProcessFloatFunc: func(in, out vst2.FloatBuffer) {
+					left := out.Channel(0)
+					right := out.Channel(1)
+					if len(buf) < out.Frames*2 {
+						buf = append(buf, make([]float32, out.Frames*2-len(buf))...)
+					}
+					buf = buf[:out.Frames*2]
+					player.Process(buf, &context)
+					for i := 0; i < out.Frames; i++ {
+						left[i], right[i] = buf[i*2], buf[i*2+1]
+					}
+					context.events = context.events[:0]
+				},
+			}, vst2.Dispatcher{
+				CanDoFunc: func(pcds vst2.PluginCanDoString) vst2.CanDoResponse {
+					switch pcds {
+					case vst2.PluginCanReceiveEvents, vst2.PluginCanReceiveMIDIEvent, vst2.PluginCanReceiveTimeInfo:
+						return vst2.YesCanDo
+					}
+					return vst2.NoCanDo
+				},
+				ProcessEventsFunc: func(ev *vst2.EventsPtr) {
+					for i := 0; i < ev.NumEvents(); i++ {
+						a := ev.Event(i)
+						switch v := a.(type) {
+						case *vst2.MIDIEvent:
+							context.events = append(context.events, *v)
+						}
+					}
+				},
+				CloseFunc: func() {
+					tracker.Quit(true)
+				},
+			}
+
+	}
+}
+
+func main() {}