diff --git a/server/server.go b/server/server.go
index a348aad..a04af28 100644
--- a/server/server.go
+++ b/server/server.go
@@ -108,7 +108,6 @@ func (s *Server) handleWebSocket(c *gin.Context) {
 	go func() {
 		ticker := time.NewTicker(1 * time.Second)
 		for range ticker.C {
-			streamer.GlobalStreamer.TruncateOutput()
 			currentVideoPath, _ := streamer.GlobalStreamer.GetCurrentVideoPath()
 			s.Broadcast(mywebsocket.Date{
 				Timestamp:        time.Now().UnixMilli(),
diff --git a/streamer/streamer.go b/streamer/streamer.go
index 451a777..2033bf7 100644
--- a/streamer/streamer.go
+++ b/streamer/streamer.go
@@ -8,45 +8,55 @@ import (
 	"io"
 	"live-streamer/config"
 	"log"
-	"math"
 	"os/exec"
 	"strings"
 	"sync"
 	"time"
 )
 
-type Streamer struct {
-	videoList         []config.InputItem
+type playState struct {
 	currentVideoIndex int
+	manualControl     bool
 	cmd               *exec.Cmd
 	ctx               context.Context
 	cancel            context.CancelFunc
-	output            strings.Builder
-	manualControl     bool
-	mu                sync.Mutex
+}
+
+type Streamer struct {
+	playStateMu sync.RWMutex
+	playState   playState
+
+	videoMu   sync.RWMutex
+	videoList []config.InputItem
+
+	outputMu sync.RWMutex
+	output   strings.Builder
 }
 
 var GlobalStreamer *Streamer
 
 func NewStreamer(videoList []config.InputItem) *Streamer {
 	GlobalStreamer = &Streamer{
-		videoList:         videoList,
-		currentVideoIndex: 0,
-		cmd:               nil,
-		ctx:               nil,
+		videoList: videoList,
+		playState: playState{},
+		output:    strings.Builder{},
 	}
 	return GlobalStreamer
 }
 
 func (s *Streamer) start() {
-	s.mu.Lock()
-	s.ctx, s.cancel = context.WithCancel(context.Background())
-	currentVideo := s.videoList[s.currentVideoIndex]
+	s.playStateMu.Lock()
+	s.playState.ctx, s.playState.cancel = context.WithCancel(context.Background())
+	currentVideo := s.videoList[s.playState.currentVideoIndex]
 	videoPath := currentVideo.Path
-	s.cmd = exec.CommandContext(s.ctx, "ffmpeg", s.buildFFmpegArgs(currentVideo)...)
-	s.mu.Unlock()
+	s.playState.cmd = exec.CommandContext(s.playState.ctx, "ffmpeg", s.buildFFmpegArgs(currentVideo)...)
+	cmd := s.playState.cmd
+	ctx := s.playState.ctx
+	s.playStateMu.Unlock()
+
 	s.writeOutput(fmt.Sprintln("start stream: ", videoPath))
-	pipe, err := s.cmd.StderrPipe()
+
+	pipe, err := cmd.StderrPipe()
 	if err != nil {
 		log.Printf("failed to get pipe: %v", err)
 		return
@@ -54,25 +64,29 @@ func (s *Streamer) start() {
 
 	reader := bufio.NewReader(pipe)
 
-	if err := s.cmd.Start(); err != nil {
+	if err := cmd.Start(); err != nil {
 		s.writeOutput(fmt.Sprintf("starting ffmpeg error: %v\n", err))
 		return
 	}
 
 	go s.log(reader)
 
-	<-s.ctx.Done()
+	<-ctx.Done()
 	s.writeOutput(fmt.Sprintf("stop stream: %s\n", videoPath))
 
-	if s.manualControl {
-		s.manualControl = false
+	s.playStateMu.Lock()
+	if s.playState.manualControl {
+		// manualing change video, don't increase currentVideoIndex
+		s.playState.manualControl = false
 	} else {
-		// stream next video
-		s.currentVideoIndex++
-		if s.currentVideoIndex >= len(s.videoList) {
-			s.currentVideoIndex = 0
+		s.playState.currentVideoIndex++
+		s.videoMu.RLock()
+		if s.playState.currentVideoIndex >= len(s.videoList) {
+			s.playState.currentVideoIndex = 0
 		}
+		s.videoMu.RUnlock()
 	}
+	s.playStateMu.Unlock()
 }
 
 func (s *Streamer) Stream() {
@@ -86,83 +100,123 @@ func (s *Streamer) Stream() {
 }
 
 func (s *Streamer) Stop() {
-	s.mu.Lock()
-	defer s.mu.Unlock()
-	if s.cancel != nil {
-		stopped := make(chan error)
-		go func() {
-			if s.cmd != nil {
-				stopped <- s.cmd.Wait()
-			}
-		}()
-		s.cancel()
-		if s.cmd != nil && s.cmd.Process != nil {
-			select {
-			case <-stopped:
-				break
-			case <-time.After(3 * time.Second):
-				_ = s.cmd.Process.Kill()
-				break
-			}
-			s.cmd = nil
+	s.playStateMu.Lock()
+	cancel := s.playState.cancel
+	cmd := s.playState.cmd
+	s.playState.cancel = nil
+	s.playState.cmd = nil
+	s.playStateMu.Unlock()
+
+	if cancel == nil || cmd == nil {
+		return
+	}
+
+	stopped := make(chan error, 1)
+	go func() {
+		if cmd.Process != nil {
+			stopped <- cmd.Wait()
+		} else {
+			stopped <- nil
 		}
+	}()
+
+	cancel()
+
+	if cmd.Process != nil {
+		select {
+		case <-stopped:
+		case <-time.After(3 * time.Second):
+			_ = cmd.Process.Kill()
+		}
+		close(stopped)
 	}
 }
 
-func (s *Streamer) writeOutput(str string) {
-	s.mu.Lock()
-	defer s.mu.Unlock()
-	s.output.WriteString(str)
-}
-
 func (s *Streamer) Add(videoPath string) {
-	s.mu.Lock()
-	defer s.mu.Unlock()
+	s.videoMu.Lock()
+	defer s.videoMu.Unlock()
 	s.videoList = append(s.videoList, config.InputItem{Path: videoPath})
 }
 
 func (s *Streamer) Remove(videoPath string) {
-	s.mu.Lock()
-	defer s.mu.Unlock()
+	var needStop bool // removed video is current playing
+	var removeIndex int = -1
+
+	s.videoMu.Lock()
 	for i, item := range s.videoList {
 		if item.Path == videoPath {
-			s.videoList = append(s.videoList[:i], s.videoList[i+1:]...)
-			if s.currentVideoIndex >= len(s.videoList) {
-				s.currentVideoIndex = 0
-			}
-			if s.currentVideoIndex == i {
-				s.Stop()
-			}
+			removeIndex = i
+
+			s.playStateMu.RLock()
+			needStop = (s.playState.currentVideoIndex == i)
+			s.playStateMu.RUnlock()
+
 			break
 		}
 	}
+
+	if removeIndex >= 0 && removeIndex < len(s.videoList) {
+		oldLen := len(s.videoList)
+		s.videoList = append(s.videoList[:removeIndex], s.videoList[removeIndex+1:]...)
+
+		s.playStateMu.Lock()
+		if s.playState.currentVideoIndex >= oldLen-1 {
+			s.playState.currentVideoIndex = 0
+		}
+		s.playStateMu.Unlock()
+	}
+	s.videoMu.Unlock()
+
+	if needStop {
+		s.Stop()
+	}
 }
 
 func (s *Streamer) Prev() {
-	s.mu.Lock()
-	s.manualControl = true
-	s.currentVideoIndex--
-	if s.currentVideoIndex < 0 {
-		s.currentVideoIndex = len(s.videoList) - 1
+	s.videoMu.RLock()
+	videoLen := len(s.videoList)
+	if videoLen == 0 {
+		return
 	}
-	s.mu.Unlock()
+	s.videoMu.RUnlock()
+
+	s.playStateMu.Lock()
+	s.playState.manualControl = true
+	s.playState.currentVideoIndex--
+	if s.playState.currentVideoIndex < 0 {
+		s.playState.currentVideoIndex = videoLen - 1
+	}
+	s.playStateMu.Unlock()
+
 	s.Stop()
 }
 
 func (s *Streamer) Next() {
-	s.mu.Lock()
-	s.manualControl = true
-	s.currentVideoIndex++
-	if s.currentVideoIndex >= len(s.videoList) {
-		s.currentVideoIndex = 0
+	s.videoMu.RLock()
+	videoLen := len(s.videoList)
+	if videoLen == 0 {
+		return
 	}
-	s.mu.Unlock()
+	s.videoMu.RUnlock()
+
+	s.playStateMu.Lock()
+	s.playState.manualControl = true
+	s.playState.currentVideoIndex++
+	if s.playState.currentVideoIndex >= videoLen {
+		s.playState.currentVideoIndex = 0
+	}
+	s.playStateMu.Unlock()
+
 	s.Stop()
 }
 
 func (s *Streamer) log(reader *bufio.Reader) {
+	s.playStateMu.RLock()
+	ctx := s.playState.ctx
+	s.playStateMu.RUnlock()
+
 	select {
-	case <-s.ctx.Done():
+	case <-ctx.Done():
 		return
 	default:
 		if !config.GlobalConfig.Log.PlayState {
@@ -187,23 +241,23 @@ func (s *Streamer) log(reader *bufio.Reader) {
 }
 
 func (s *Streamer) GetCurrentVideoPath() (string, error) {
-	s.mu.Lock()
-	defer s.mu.Unlock()
+	s.videoMu.RLock()
+	defer s.videoMu.RUnlock()
 	if len(s.videoList) == 0 {
 		return "", errors.New("no video streaming")
 	}
-	return s.videoList[s.currentVideoIndex].Path, nil
+	return s.videoList[s.GetCurrentIndex()].Path, nil
 }
 
 func (s *Streamer) GetVideoList() []config.InputItem {
-	s.mu.Lock()
-	defer s.mu.Unlock()
+	s.videoMu.RLock()
+	defer s.videoMu.RUnlock()
 	return s.videoList
 }
 
 func (s *Streamer) GetVideoListPath() []string {
-	s.mu.Lock()
-	defer s.mu.Unlock()
+	s.videoMu.RLock()
+	defer s.videoMu.RUnlock()
 	var videoList []string
 	for _, item := range s.videoList {
 		videoList = append(videoList, item.Path)
@@ -212,30 +266,23 @@ func (s *Streamer) GetVideoListPath() []string {
 }
 
 func (s *Streamer) GetCurrentIndex() int {
-	s.mu.Lock()
-	defer s.mu.Unlock()
-	return s.currentVideoIndex
+	s.playStateMu.RLock()
+	defer s.playStateMu.RUnlock()
+	return s.playState.currentVideoIndex
+}
+
+func (s *Streamer) writeOutput(str string) {
+	s.outputMu.Lock()
+	defer s.outputMu.Unlock()
+	s.output.WriteString(str)
 }
 
 func (s *Streamer) GetOutput() string {
-	s.mu.Lock()
-	defer s.mu.Unlock()
+	s.outputMu.RLock()
+	defer s.outputMu.RUnlock()
 	return s.output.String()
 }
 
-func (s *Streamer) TruncateOutput() int {
-	s.mu.Lock()
-	defer s.mu.Unlock()
-	currentSize := s.output.Len()
-	if currentSize > math.MaxInt {
-		newStart := currentSize - math.MaxInt
-		trimmedOutput := s.output.String()[newStart:]
-		s.output.Reset()
-		s.output.WriteString(trimmedOutput)
-	}
-	return currentSize
-}
-
 func (s *Streamer) Close() {
 	s.Stop()
 }