diff --git a/TODO b/TODO
index 2c4d599..5d078b1 100644
--- a/TODO
+++ b/TODO
@@ -9,4 +9,7 @@
 2. qemu只在声卡初始化后才开始抓取声音
 
 # 2022-10-3
-1. 虚拟设备应当一直运行，无阻塞
\ No newline at end of file
+1. 虚拟设备应当一直运行，无阻塞
+
+# 2022-10-10
+1. 视频设备延迟过高
\ No newline at end of file
diff --git a/drivers/audio/wavfifo.go b/drivers/audio/wavfifo.go
index 5be1806..432b6e5 100644
--- a/drivers/audio/wavfifo.go
+++ b/drivers/audio/wavfifo.go
@@ -68,12 +68,14 @@ func (w *PCMStreamDriver) AudioRecord(p prop.Media) (audio.Reader, error) {
 
 	reader := func() (wave.Audio, func(), error) {
 		a := wave.NewInt16Interleaved(chunkInfo)
+		ticker := time.NewTicker(p.Latency)
+		defer ticker.Stop()
 		select {
 		case <-w.closed:
 			return nil, func() {}, io.EOF
 		case pcmData := <-w.PCM:
 			copy(a.Data, bytesTo16BitSamples(pcmData[:]))
-		case <-time.After(p.Latency):
+		case <-ticker.C:
 			// no stuck
 		}
 		return a, func() {}, nil
diff --git a/drivers/video/ppm.go b/drivers/video/ppm.go
index 76b76c2..7269ce4 100644
--- a/drivers/video/ppm.go
+++ b/drivers/video/ppm.go
@@ -59,6 +59,9 @@ func (v *PPMStreamDriver) VideoRecord(p prop.Media) (video.Reader, error) {
 		image.YCbCrSubsampleRatio420,
 	)
 	r := video.ReaderFunc(func() (img image.Image, release func(), err error) {
+		ticker := time.NewTicker(time.Second / time.Duration(p.FrameRate))
+		defer ticker.Stop()
+
 		select {
 		case <-v.closed:
 			return nil, func() {}, io.EOF
@@ -82,7 +85,7 @@ func (v *PPMStreamDriver) VideoRecord(p prop.Media) (video.Reader, error) {
 					canvas.Cr[canvas.COffset(x, y)] = Cr
 				}
 			}
-		case <-time.After(time.Second / time.Duration(p.FrameRate)):
+		case <-ticker.C:
 		}
 		return canvas, func() {}, nil
 	})
diff --git a/lib/webrtcconnection/connection.go b/lib/webrtcconnection/connection.go
index 48db210..605beb7 100644
--- a/lib/webrtcconnection/connection.go
+++ b/lib/webrtcconnection/connection.go
@@ -119,6 +119,7 @@ func setupCodec(videoBPS int) (*mediadevices.CodecSelector, error) {
 		return nil, err
 	}
 	x264Prarm.BitRate = videoBPS
+	x264Prarm.Preset = x264.PresetMedium
 
 	opusParam, err := opus.NewParams()
 	if err != nil {
diff --git a/lib/webrtcconnection/options.go b/lib/webrtcconnection/options.go
index d584926..d0d218e 100644
--- a/lib/webrtcconnection/options.go
+++ b/lib/webrtcconnection/options.go
@@ -11,7 +11,7 @@ func ExampleOptions() *Options {
 			"stun:stun.l.google.com:19302",
 			"stun:wetofu.me:3478",
 		},
-		VideoBPS: 500_000,
+		VideoBPS: 2_048_000,
 	}
 	return options
 }
diff --git a/servers/qemuserver/server.go b/servers/qemuserver/server.go
index d977179..ef0b4d4 100644
--- a/servers/qemuserver/server.go
+++ b/servers/qemuserver/server.go
@@ -39,7 +39,7 @@ func NewServer(o *Options) (*Server, error) {
 		options:     o,
 		audioHeader: make(chan *audio.WavHeader, 1),
 		pcm:         make(chan []byte),
-		ppm:         make(chan io.ReadCloser, 60), // to be configured
+		ppm:         make(chan io.ReadCloser, int(o.Video.FPS)), // to be configured
 	}
 
 	u, err := url.Parse(o.QmpAddress)
@@ -115,13 +115,22 @@ func (s *Server) Run() error {
 	go func() {
 		logrus.Debug("screen capture start")
 		defer close(s.ppm)
-		for range time.Tick(time.Second / time.Duration(s.options.Video.FPS)) { // to be configured
+
+		ticker := time.NewTicker(time.Second / time.Duration(s.options.Video.FPS))
+		defer ticker.Stop()
+
+		for { // to be configured
 			ppm, err := s.qemu.ScreenDump()
 			if err != nil {
 				logrus.Error(err)
 				continue
 			}
-			s.ppm <- ppm
+			select {
+			case s.ppm <- ppm:
+			case <-ticker.C:
+				continue
+			}
+			//<-ticker.C
 		}
 	}()
 
@@ -144,6 +153,8 @@ func (s *Server) Run() error {
 
 		logrus.Debug("start reading PCM")
 		defer close(s.pcm)
+		ticker := time.NewTicker(waveHeader.GetLatnecy(s.options.Audio.BufferSize))
+		defer ticker.Stop()
 		for {
 			b := make([]byte, s.options.Audio.BufferSize) // to be configured
 			if _, err := f.Read(b[:]); err != nil {
@@ -151,7 +162,7 @@ func (s *Server) Run() error {
 			}
 			select {
 			case s.pcm <- b:
-			case <-time.After(waveHeader.GetLatnecy(s.options.Audio.BufferSize)):
+			case <-ticker.C:
 			}
 		}
 	}()