fix: warn user if sample rate other than 44100 Hz

Closes #129.

cmd/sointu-vsti/main.go

@@ -5,8 +5,11 @@ package main
 import (
 	"crypto/rand"
 	"encoding/hex"
+	"fmt"
+	"math"
 	"os"
 	"path/filepath"
+	"time"
 
 	"github.com/vsariola/sointu"
 	"github.com/vsariola/sointu/cmd"
@@ -63,6 +66,13 @@ func init() {
 		model, player := tracker.NewModelPlayer(cmd.MainSynther, recoveryFile)
 		t := gioui.NewTracker(model)
 		tracker.Bool{BoolData: (*tracker.InstrEnlarged)(model)}.Set(true)
+		if s := h.GetSampleRate(); math.Abs(float64(h.GetSampleRate()-44100.0)) > 1e-6 {
+			model.Alerts().AddAlert(tracker.Alert{
+				Message:  fmt.Sprintf("VSTi host sample rate is %.0f Hz; sointu supports 44100 Hz only", s),
+				Priority: tracker.Error,
+				Duration: 10 * time.Second,
+			})
+		}
 		go t.Main()
 		context := VSTIProcessContext{host: h}
 		buf := make(sointu.AudioBuffer, 1024)