diff --git a/algo/kgm/kgm.go b/algo/kgm/kgm.go
index 71b9526..9a039cb 100644
--- a/algo/kgm/kgm.go
+++ b/algo/kgm/kgm.go
@@ -40,7 +40,7 @@ func (d Decoder) GetAudioData() []byte {
 }
 
 func (d Decoder) GetAudioExt() string {
-	return ""
+	return "" // use sniffer
 }
 
 func (d Decoder) GetMeta() common.Meta {
@@ -58,9 +58,8 @@ func (d *Decoder) Validate() error {
 
 	d.key = d.file[0x1c:0x2c]
 	d.key = append(d.key, 0x00)
-	_ = d.file[0x2c:0x3c] //key2
+	_ = d.file[0x2c:0x3c] //todo: key2
 	return nil
-
 }
 
 func (d *Decoder) Decode() error {
@@ -69,7 +68,8 @@ func (d *Decoder) Decode() error {
 	lenData := len(dataEncrypted)
 	initMask()
 	if fullMaskLen < lenData {
-		logging.Log().Warn("文件过大，处理后的音频不完整,请向我们报告此文件的信息")
+		logging.Log().Warn("The file is too large and the processed audio is incomplete, " +
+			"please report to us about this file at https://github.com/unlock-music/cli/issues")
 		lenData = fullMaskLen
 	}
 	d.audio = make([]byte, lenData)
diff --git a/algo/kgm/mask.go b/algo/kgm/mask.go
index ee355dc..9ac2abf 100644
--- a/algo/kgm/mask.go
+++ b/algo/kgm/mask.go
@@ -41,7 +41,7 @@ var maskV2 []byte
 var fullMaskLen int
 var initMaskOK = false
 
-//todo: 根据需求解压Mask大小
+//todo: decompress mask on demand
 func initMask() {
 	if initMaskOK {
 		return
diff --git a/algo/ncm/ncm.go b/algo/ncm/ncm.go
index 9b4334a..620cb18 100644
--- a/algo/ncm/ncm.go
+++ b/algo/ncm/ncm.go
@@ -61,7 +61,6 @@ func (d *Decoder) Validate() error {
 	return nil
 }
 
-//todo: 读取前进行检查长度，防止越界
 func (d *Decoder) readKeyData() error {
 	if d.offsetKey == 0 || d.offsetKey+4 > d.fileLen {
 		return errors.New("invalid cover file offset")