diff --git a/algo/common/dispatch.go b/algo/common/dispatch.go
index ff42fdf..faefa2a 100644
--- a/algo/common/dispatch.go
+++ b/algo/common/dispatch.go
@@ -7,12 +7,24 @@ import (
 
 type NewDecoderFunc func([]byte) Decoder
 
-var decoderRegistry = make(map[string][]NewDecoderFunc)
+type decoderItem struct {
+	noop    bool
+	decoder NewDecoderFunc
+}
 
-func RegisterDecoder(ext string, dispatchFunc NewDecoderFunc) {
-	decoderRegistry[ext] = append(decoderRegistry[ext], dispatchFunc)
+var decoderRegistry = make(map[string][]decoderItem)
+
+func RegisterDecoder(ext string, noop bool, dispatchFunc NewDecoderFunc) {
+	decoderRegistry[ext] = append(decoderRegistry[ext],
+		decoderItem{noop: noop, decoder: dispatchFunc})
 }
-func GetDecoder(filename string) []NewDecoderFunc {
+func GetDecoder(filename string, skipNoop bool) (rs []NewDecoderFunc) {
 	ext := strings.ToLower(strings.TrimLeft(filepath.Ext(filename), "."))
-	return decoderRegistry[ext]
+	for _, dec := range decoderRegistry[ext] {
+		if skipNoop && dec.noop {
+			continue
+		}
+		rs = append(rs, dec.decoder)
+	}
+	return
 }
diff --git a/algo/common/raw.go b/algo/common/raw.go
index 3bb8e0b..6f901b2 100644
--- a/algo/common/raw.go
+++ b/algo/common/raw.go
@@ -45,11 +45,11 @@ func (d RawDecoder) GetMeta() Meta {
 }
 
 func init() {
-	RegisterDecoder("mp3", NewRawDecoder)
-	RegisterDecoder("flac", NewRawDecoder)
-	RegisterDecoder("ogg", NewRawDecoder)
-	RegisterDecoder("m4a", NewRawDecoder)
-	RegisterDecoder("wav", NewRawDecoder)
-	RegisterDecoder("wma", NewRawDecoder)
-	RegisterDecoder("aac", NewRawDecoder)
+	RegisterDecoder("mp3", true, NewRawDecoder)
+	RegisterDecoder("flac", true, NewRawDecoder)
+	RegisterDecoder("ogg", true, NewRawDecoder)
+	RegisterDecoder("m4a", true, NewRawDecoder)
+	RegisterDecoder("wav", true, NewRawDecoder)
+	RegisterDecoder("wma", true, NewRawDecoder)
+	RegisterDecoder("aac", true, NewRawDecoder)
 }
diff --git a/algo/kgm/kgm.go b/algo/kgm/kgm.go
index 0a72f86..37595c0 100644
--- a/algo/kgm/kgm.go
+++ b/algo/kgm/kgm.go
@@ -87,8 +87,8 @@ func (d *Decoder) Decode() error {
 }
 func init() {
 	// Kugou
-	common.RegisterDecoder("kgm", NewDecoder)
-	common.RegisterDecoder("kgma", NewDecoder)
+	common.RegisterDecoder("kgm", false, NewDecoder)
+	common.RegisterDecoder("kgma", false, NewDecoder)
 	// Viper
-	common.RegisterDecoder("vpr", NewDecoder)
+	common.RegisterDecoder("vpr", false, NewDecoder)
 }
diff --git a/algo/kwm/kwm.go b/algo/kwm/kwm.go
index e846ac7..a9fa2d6 100644
--- a/algo/kwm/kwm.go
+++ b/algo/kwm/kwm.go
@@ -124,6 +124,6 @@ func padOrTruncate(raw string, length int) string {
 
 func init() {
 	// Kuwo Mp3/Flac
-	common.RegisterDecoder("kwm", NewDecoder)
-	common.RegisterDecoder("kwm", common.NewRawDecoder)
+	common.RegisterDecoder("kwm", false, NewDecoder)
+	common.RegisterDecoder("kwm", false, common.NewRawDecoder)
 }
diff --git a/algo/ncm/ncm.go b/algo/ncm/ncm.go
index 620cb18..80da8b3 100644
--- a/algo/ncm/ncm.go
+++ b/algo/ncm/ncm.go
@@ -246,5 +246,5 @@ func (d Decoder) GetMeta() common.Meta {
 
 func init() {
 	// Netease Mp3/Flac
-	common.RegisterDecoder("ncm", NewDecoder)
+	common.RegisterDecoder("ncm", false, NewDecoder)
 }
diff --git a/algo/qmc/qmc.go b/algo/qmc/qmc.go
index 6f6586e..ed284c5 100644
--- a/algo/qmc/qmc.go
+++ b/algo/qmc/qmc.go
@@ -102,27 +102,27 @@ func DecoderFuncWithExt(ext string) common.NewDecoderFunc {
 
 //goland:noinspection SpellCheckingInspection
 func init() {
-	common.RegisterDecoder("qmc0", DecoderFuncWithExt("mp3")) //QQ Music Mp3
-	common.RegisterDecoder("qmc3", DecoderFuncWithExt("mp3")) //QQ Music Mp3
+	common.RegisterDecoder("qmc0", false, DecoderFuncWithExt("mp3")) //QQ Music Mp3
+	common.RegisterDecoder("qmc3", false, DecoderFuncWithExt("mp3")) //QQ Music Mp3
 
-	common.RegisterDecoder("qmc2", DecoderFuncWithExt("m4a")) //QQ Music M4A
-	common.RegisterDecoder("qmc4", DecoderFuncWithExt("m4a")) //QQ Music M4A
-	common.RegisterDecoder("qmc6", DecoderFuncWithExt("m4a")) //QQ Music M4A
-	common.RegisterDecoder("qmc8", DecoderFuncWithExt("m4a")) //QQ Music M4A
+	common.RegisterDecoder("qmc2", false, DecoderFuncWithExt("m4a")) //QQ Music M4A
+	common.RegisterDecoder("qmc4", false, DecoderFuncWithExt("m4a")) //QQ Music M4A
+	common.RegisterDecoder("qmc6", false, DecoderFuncWithExt("m4a")) //QQ Music M4A
+	common.RegisterDecoder("qmc8", false, DecoderFuncWithExt("m4a")) //QQ Music M4A
 
-	common.RegisterDecoder("qmcflac", DecoderFuncWithExt("flac")) //QQ Music Flac
-	common.RegisterDecoder("qmcogg", DecoderFuncWithExt("ogg"))   //QQ Music Ogg
-	common.RegisterDecoder("tkm", DecoderFuncWithExt("m4a"))      //QQ Music Accompaniment M4a
+	common.RegisterDecoder("qmcflac", false, DecoderFuncWithExt("flac")) //QQ Music Flac
+	common.RegisterDecoder("qmcogg", false, DecoderFuncWithExt("ogg"))   //QQ Music Ogg
+	common.RegisterDecoder("tkm", false, DecoderFuncWithExt("m4a"))      //QQ Music Accompaniment M4a
 
-	common.RegisterDecoder("bkcmp3", DecoderFuncWithExt("mp3"))   //Moo Music Mp3
-	common.RegisterDecoder("bkcflac", DecoderFuncWithExt("flac")) //Moo Music Flac
+	common.RegisterDecoder("bkcmp3", false, DecoderFuncWithExt("mp3"))   //Moo Music Mp3
+	common.RegisterDecoder("bkcflac", false, DecoderFuncWithExt("flac")) //Moo Music Flac
 
-	common.RegisterDecoder("666c6163", DecoderFuncWithExt("flac")) //QQ Music Weiyun Flac
-	common.RegisterDecoder("6d7033", DecoderFuncWithExt("mp3"))    //QQ Music Weiyun Mp3
-	common.RegisterDecoder("6f6767", DecoderFuncWithExt("ogg"))    //QQ Music Weiyun Ogg
-	common.RegisterDecoder("6d3461", DecoderFuncWithExt("m4a"))    //QQ Music Weiyun M4a
-	common.RegisterDecoder("776176", DecoderFuncWithExt("wav"))    //QQ Music Weiyun Wav
+	common.RegisterDecoder("666c6163", false, DecoderFuncWithExt("flac")) //QQ Music Weiyun Flac
+	common.RegisterDecoder("6d7033", false, DecoderFuncWithExt("mp3"))    //QQ Music Weiyun Mp3
+	common.RegisterDecoder("6f6767", false, DecoderFuncWithExt("ogg"))    //QQ Music Weiyun Ogg
+	common.RegisterDecoder("6d3461", false, DecoderFuncWithExt("m4a"))    //QQ Music Weiyun M4a
+	common.RegisterDecoder("776176", false, DecoderFuncWithExt("wav"))    //QQ Music Weiyun Wav
 
-	common.RegisterDecoder("mgg", NewMgg256Decoder)     //QQ Music New Ogg
-	common.RegisterDecoder("mflac", NewMflac256Decoder) //QQ Music New Flac
+	common.RegisterDecoder("mgg", false, NewMgg256Decoder)     //QQ Music New Ogg
+	common.RegisterDecoder("mflac", false, NewMflac256Decoder) //QQ Music New Flac
 }
diff --git a/algo/tm/tm.go b/algo/tm/tm.go
index 40c6ab4..d1ccc18 100644
--- a/algo/tm/tm.go
+++ b/algo/tm/tm.go
@@ -70,10 +70,10 @@ func DecoderFuncWithExt(ext string) common.NewDecoderFunc {
 
 func init() {
 	// QQ Music IOS M4a
-	common.RegisterDecoder("tm2", DecoderFuncWithExt("m4a"))
-	common.RegisterDecoder("tm6", DecoderFuncWithExt("m4a"))
+	common.RegisterDecoder("tm2", false, DecoderFuncWithExt("m4a"))
+	common.RegisterDecoder("tm6", false, DecoderFuncWithExt("m4a"))
 	// QQ Music IOS Mp3
-	common.RegisterDecoder("tm0", common.NewRawDecoder)
-	common.RegisterDecoder("tm3", common.NewRawDecoder)
+	common.RegisterDecoder("tm0", false, common.NewRawDecoder)
+	common.RegisterDecoder("tm3", false, common.NewRawDecoder)
 
 }
diff --git a/algo/xm/xm.go b/algo/xm/xm.go
index de5bbcb..42a88ba 100644
--- a/algo/xm/xm.go
+++ b/algo/xm/xm.go
@@ -97,10 +97,10 @@ func DecoderFuncWithExt(ext string) common.NewDecoderFunc {
 
 func init() {
 	// Xiami Wav/M4a/Mp3/Flac
-	common.RegisterDecoder("xm", NewDecoder)
+	common.RegisterDecoder("xm", false, NewDecoder)
 	// Xiami Typed Format
-	common.RegisterDecoder("wav", DecoderFuncWithExt("wav"))
-	common.RegisterDecoder("mp3", DecoderFuncWithExt("mp3"))
-	common.RegisterDecoder("flac", DecoderFuncWithExt("flac"))
-	common.RegisterDecoder("m4a", DecoderFuncWithExt("m4a"))
+	common.RegisterDecoder("wav", false, DecoderFuncWithExt("wav"))
+	common.RegisterDecoder("mp3", false, DecoderFuncWithExt("mp3"))
+	common.RegisterDecoder("flac", false, DecoderFuncWithExt("flac"))
+	common.RegisterDecoder("m4a", false, DecoderFuncWithExt("m4a"))
 }
diff --git a/cmd/um/main.go b/cmd/um/main.go
index 4c59a08..c768cc5 100644
--- a/cmd/um/main.go
+++ b/cmd/um/main.go
@@ -28,12 +28,13 @@ func main() {
 		Flags: []cli.Flag{
 			&cli.StringFlag{Name: "input", Aliases: []string{"i"}, Usage: "path to input file or dir", Required: false},
 			&cli.StringFlag{Name: "output", Aliases: []string{"o"}, Usage: "path to output dir", Required: false},
+			&cli.BoolFlag{Name: "skip-noop", Aliases: []string{"n"}, Usage: "skip noop decoder", Required: false, Value: true},
 		},
 
 		Action:          appMain,
 		Copyright:       "Copyright (c) 2020 - 2021 Unlock Music https://github.com/unlock-music/cli/blob/master/LICENSE",
 		HideHelpCommand: true,
-		UsageText:       "um [-o /path/to/output/dir] [-i] /path/to/input",
+		UsageText:       "um [-o /path/to/output/dir] [--extra-flags] [-i] /path/to/input",
 	}
 	err := app.Run(os.Args)
 	if err != nil {
@@ -56,6 +57,8 @@ func appMain(c *cli.Context) error {
 		}
 	}
 
+	skipNoop := c.Bool("skip-noop")
+
 	inputStat, err := os.Stat(input)
 	if err != nil {
 		return err
@@ -74,9 +77,9 @@ func appMain(c *cli.Context) error {
 	}
 
 	if inputStat.IsDir() {
-		return dealDirectory(input, output)
+		return dealDirectory(input, output, skipNoop)
 	} else {
-		allDec := common.GetDecoder(inputStat.Name())
+		allDec := common.GetDecoder(inputStat.Name(), skipNoop)
 		if len(allDec) == 0 {
 			logging.Log().Fatal("skipping while no suitable decoder")
 		}
@@ -84,7 +87,7 @@ func appMain(c *cli.Context) error {
 	}
 
 }
-func dealDirectory(inputDir string, outputDir string) error {
+func dealDirectory(inputDir string, outputDir string, skipNoop bool) error {
 	items, err := os.ReadDir(inputDir)
 	if err != nil {
 		return err
@@ -93,7 +96,7 @@ func dealDirectory(inputDir string, outputDir string) error {
 		if item.IsDir() {
 			continue
 		}
-		allDec := common.GetDecoder(item.Name())
+		allDec := common.GetDecoder(item.Name(), skipNoop)
 		if len(allDec) == 0 {
 			logging.Log().Info("skipping while no suitable decoder", zap.String("file", item.Name()))
 			continue