diff --git a/audio/audio.go b/audio/audio.go
index fbee8d9..50b794f 100644
--- a/audio/audio.go
+++ b/audio/audio.go
@@ -2,6 +2,7 @@ package audio
 
 import (
 	"fmt"
+	"os"
 	"xyosc/config"
 	"xyosc/utils"
 
@@ -15,10 +16,8 @@ var SampleSizeInBytes uint32
 const format = malgo.FormatF32
 
 func Init() {
-	deviceConfig := malgo.DefaultDeviceConfig(malgo.Duplex)
 	SampleRingBuffer = ringbuffer.New(int(config.Config.RingBufferSize))
-	deviceConfig.Capture.Format = format
-	SampleSizeInBytes = uint32(malgo.SampleSizeInBytes(deviceConfig.Capture.Format))
+	SampleSizeInBytes = uint32(malgo.SampleSizeInBytes(format))
 }
 
 func Start() {
@@ -31,11 +30,31 @@ func Start() {
 		ctx.Free()
 	}()
 
-	deviceConfig := malgo.DefaultDeviceConfig(malgo.Duplex)
+	// Capture devices.
+	infos, err := ctx.Devices(malgo.Capture)
+	if err != nil {
+		fmt.Println(err)
+		os.Exit(1)
+	}
+
+	fmt.Println("Capture Devices")
+	for i, info := range infos {
+		e := "ok"
+		full, err := ctx.DeviceInfo(malgo.Capture, info.ID, malgo.Shared)
+		if err != nil {
+			e = err.Error()
+		}
+		fmt.Printf("    %d: %v, %s, [%s], formats: %+v\n",
+			i, info.ID, info.Name(), e, full.Formats)
+	}
+
+	deviceConfig := malgo.DefaultDeviceConfig(malgo.Capture)
 	deviceConfig.Capture.Format = format
 	deviceConfig.Capture.Channels = 2
+	deviceConfig.Capture.DeviceID = infos[config.Config.CaptureDeviceIndex].ID.Pointer()
 	deviceConfig.SampleRate = config.Config.SampleRate
 	deviceConfig.Alsa.NoMMap = 1
+
 	onRecvFrames := func(pSample2, pSample []byte, framecount uint32) {
 		SampleRingBuffer.Write(pSample)
 	}
@@ -49,7 +68,6 @@ func Start() {
 	err = device.Start()
 
 	utils.CheckError(err)
-	for {
-	}
+	select {}
 	//device.Uninit()
 }
diff --git a/config/config.go b/config/config.go
index 72dec39..ac9a3d3 100644
--- a/config/config.go
+++ b/config/config.go
@@ -13,29 +13,33 @@ import (
 )
 
 type ConfigS struct {
-	FPSCounter     bool
-	TargetFPS      int32
-	WindowWidth    int32
-	WindowHeight   int32
-	SampleRate     uint32
-	RingBufferSize uint32
-	ReadBufferSize uint32
-	Gain           float32
-	LineOpacity    uint8
-	LineThickness  float32
+	FPSCounter         bool
+	TargetFPS          int32
+	WindowWidth        int32
+	WindowHeight       int32
+	WindowOpacity      float32
+	CaptureDeviceIndex int
+	SampleRate         uint32
+	RingBufferSize     uint32
+	ReadBufferSize     uint32
+	Gain               float32
+	LineOpacity        uint8
+	LineThickness      float32
 }
 
 var DefaultConfig = ConfigS{
-	FPSCounter:     false,
-	TargetFPS:      60,
-	WindowWidth:    800,
-	WindowHeight:   800,
-	SampleRate:     192000,
-	RingBufferSize: 192000 * 4,
-	ReadBufferSize: 192000,
-	Gain:           1,
-	LineOpacity:    50,
-	LineThickness:  2,
+	FPSCounter:         false,
+	TargetFPS:          60,
+	WindowWidth:        800,
+	WindowHeight:       800,
+	WindowOpacity:      0.9,
+	CaptureDeviceIndex: 0,
+	SampleRate:         192000,
+	RingBufferSize:     192000,
+	ReadBufferSize:     192000,
+	Gain:               1,
+	LineOpacity:        50,
+	LineThickness:      2,
 }
 
 var Config ConfigS
diff --git a/main.go b/main.go
index 12b59c2..cd8c26b 100644
--- a/main.go
+++ b/main.go
@@ -16,7 +16,7 @@ func main() {
 	scale := min(config.Config.WindowWidth, config.Config.WindowHeight) / 2
 	rl.InitWindow(config.Config.WindowWidth, config.Config.WindowHeight, "xyosc")
 	defer rl.CloseWindow()
-	rl.SetWindowOpacity(0.5)
+	rl.SetWindowOpacity(config.Config.WindowOpacity)
 	rl.SetConfigFlags(rl.FlagWindowTransparent)
 	rl.SetConfigFlags(rl.FlagMsaa4xHint)
 	rl.SetWindowState(rl.FlagWindowUndecorated)