add: midi audio player

gs/game/audio_player.go

@@ -0,0 +1,91 @@
+package game
+
+import (
+	"time"
+
+	"hk4e/pkg/logger"
+
+	"gitlab.com/gomidi/midi/v2"
+	"gitlab.com/gomidi/midi/v2/smf"
+)
+
+const (
+	KeyOffset = -12 * 1 // 八度修正偏移
+)
+
+var AUDIO_CHAN chan uint32
+
+func init() {
+	AUDIO_CHAN = make(chan uint32, 1000)
+}
+
+func RunPlayAudio() {
+	audio, err := smf.ReadFile("./in.mid")
+	if err != nil {
+		logger.Error("read midi file error: %v", err)
+		return
+	}
+	tempoChangeList := audio.TempoChanges()
+	if len(tempoChangeList) != 1 {
+		logger.Error("midi file format not support")
+		return
+	}
+	tempoChange := tempoChangeList[0]
+	metricTicks := audio.TimeFormat.(smf.MetricTicks)
+	tickTime := ((60000000.0 / tempoChange.BPM) / float64(metricTicks.Resolution())) / 1000.0
+	for {
+		// 洗脑循环
+		logger.Debug("start play audio")
+		for _, track := range audio.Tracks {
+			// 全部轨道
+			totalTick := uint64(0)
+			for _, event := range track {
+				// 单个轨道
+				delay := uint32(float64(event.Delta) * tickTime)
+				busyPoolWaitMilliSecond(delay)
+				// interruptWaitMilliSecond(delay)
+				totalTick += uint64(delay)
+
+				msg := event.Message
+				if msg.Type() != midi.NoteOnMsg {
+					continue
+				}
+				midiMsg := midi.Message(msg)
+				var channel, key, velocity uint8
+				midiMsg.GetNoteOn(&channel, &key, &velocity)
+				// TODO 测试一下客户端是否支持更宽的音域
+				// 60 -> 中央C C4
+				// if key < 36 || key > 71 {
+				// 	continue
+				// }
+				note := int32(key) + int32(KeyOffset)
+				if note < 21 || note > 108 {
+					// 非88键钢琴音域
+					continue
+				}
+				if velocity == 0 {
+					// 可能是NoteOffMsg
+					continue
+				}
+
+				AUDIO_CHAN <- uint32(note)
+				// logger.Debug("send midi note: %v, delay: %v, totalTick: %v", note, delay, totalTick)
+			}
+		}
+	}
+}
+
+func interruptWaitMilliSecond(delay uint32) {
+	time.Sleep(time.Millisecond * time.Duration(delay))
+}
+
+func busyPoolWaitMilliSecond(delay uint32) {
+	start := time.Now()
+	end := start.Add(time.Millisecond * time.Duration(delay))
+	for {
+		now := time.Now()
+		if now.After(end) {
+			break
+		}
+	}
+}