Add support for Luckfox PicoKVM

Signed-off-by: luckfox-eng29 <eng29@luckfox.com>

audio.go

@@ -0,0 +1,170 @@
+package kvm
+
+import (
+	"encoding/json"
+	"fmt"
+	"net"
+	"sync"
+	"time"
+
+	"github.com/pion/rtp"
+)
+
+var (
+	audioListener *net.UDPConn
+	currentPort   int
+	mutex         sync.Mutex
+	portList      = []int{3333}
+	portIndex     = 0
+)
+
+const (
+	maxAudioFrameSize = 1500
+	frameDurationMs   = 20
+	timestampRate     = 48000
+	timestampStep     = timestampRate * frameDurationMs / 1000
+)
+
+func waitUDPPortReleased(port int, retries int, delay time.Duration) error {
+	addr := fmt.Sprintf("127.0.0.1:%d", port)
+	for i := 0; i < retries; i++ {
+		conn, err := net.ListenPacket("udp", addr)
+		if err == nil {
+			conn.Close()
+			return nil
+		}
+		time.Sleep(delay)
+	}
+	return fmt.Errorf("port %d still in use after %d retries", port, retries)
+}
+
+func getNextAvailablePort() int {
+	for i := 0; i < len(portList); i++ {
+		port := portList[portIndex]
+		portIndex = (portIndex + 1) % len(portList)
+		addr := fmt.Sprintf("127.0.0.1:%d", port)
+		conn, err := net.ListenPacket("udp", addr)
+		if err == nil {
+			conn.Close()
+			return port
+		}
+	}
+	return 0
+}
+
+func StartNtpAudioServer(handleClient func(net.Conn)) {
+	mutex.Lock()
+	defer mutex.Unlock()
+
+	if audioListener != nil || lastAudioState.Ready {
+		StopNtpAudioServer()
+	}
+
+	port := getNextAvailablePort()
+	if port == 0 {
+		audioLogger.Error().Msg("no available ports to start audio server")
+		return
+	}
+
+	listener, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.ParseIP("127.0.0.1"), Port: port})
+	if err != nil {
+		audioLogger.Error().Err(err).Msg("failed to start server on port %d")
+		return
+	}
+
+	audioListener = listener
+	currentPort = port
+
+	if config.AudioMode == "usb" {
+		_, err := CallAudioCtrlAction("set_audio_mode", map[string]interface{}{"audio_mode": "usb", "rtp_port": port})
+		if err != nil {
+			audioLogger.Error().Err(err).Msg("failed to set audio mode")
+		}
+		_, err = CallAudioCtrlAction("set_audio_enable", map[string]interface{}{"audio_enable": true})
+		if err != nil {
+			audioLogger.Error().Err(err).Msg("failed to set audio enable")
+		}
+	} else {
+		_, err := CallAudioCtrlAction("set_audio_mode", map[string]interface{}{"audio_mode": "hdmi", "rtp_port": port})
+		if err != nil {
+			audioLogger.Error().Err(err).Msg("failed to set audio mode")
+		}
+		_, err = CallAudioCtrlAction("set_audio_enable", map[string]interface{}{"audio_enable": true})
+		if err != nil {
+			audioLogger.Error().Err(err).Msg("failed to set audio enable")
+		}
+	}
+
+	go handleClient(listener)
+}
+
+func StopNtpAudioServer() {
+	CallAudioCtrlAction("set_audio_enable", map[string]interface{}{"audio_enable": false})
+
+	if audioListener != nil {
+		audioListener.Close()
+		audioListener = nil
+	}
+
+	if currentPort != 0 {
+		if err := waitUDPPortReleased(currentPort, 10, 200*time.Millisecond); err != nil {
+			audioLogger.Error().Err(err).Msg("port not released")
+		}
+		currentPort = 0
+	}
+
+	audioLogger.Info().Msg("audio server stopped")
+}
+
+func handleAudioClient(conn net.Conn) {
+	defer conn.Close()
+
+	audioLogger.Info().Msg("native audio socket client connected")
+	inboundPacket := make([]byte, maxAudioFrameSize)
+	var timestamp uint32
+	var packet rtp.Packet
+
+	for {
+		n, err := conn.Read(inboundPacket)
+		if err != nil {
+			audioLogger.Warn().Err(err).Msg("error during read")
+			return
+		}
+
+		if currentSession != nil {
+			if err := packet.Unmarshal(inboundPacket[:n]); err != nil {
+				audioLogger.Warn().Err(err).Msg("error unmarshalling audio socket packet")
+				continue
+			}
+
+			timestamp += timestampStep
+			packet.Header.Timestamp = timestamp
+			buf, err := packet.Marshal()
+			if err != nil {
+				audioLogger.Warn().Err(err).Msg("error marshalling packet")
+				continue
+			}
+
+			if _, err := currentSession.AudioTrack.Write(buf); err != nil {
+				audioLogger.Warn().Err(err).Msg("error writing sample")
+			}
+		}
+	}
+}
+
+type AudioInputState struct {
+	Ready bool   `json:"ready"`
+	Error string `json:"error,omitempty"` //no_signal, no_lock, out_of_range
+}
+
+var lastAudioState AudioInputState
+
+func HandleAudioStateMessage(event CtrlResponse) {
+	audioState := AudioInputState{}
+	err := json.Unmarshal(event.Data, &audioState)
+	if err != nil {
+		audioLogger.Warn().Err(err).Msg("Error parsing audio state json")
+		return
+	}
+	lastAudioState = audioState
+}