refactor: change decoder init parameter

algo/common/dispatch.go

@@ -6,7 +6,13 @@ import (
 	"strings"
 )
 
-type NewDecoderFunc func(rd io.ReadSeeker) Decoder
+type DecoderParams struct {
+	Reader    io.ReadSeeker // required
+	Extension string        // required, source extension, eg. ".mp3"
+
+	FilePath string // optional, source file path
+}
+type NewDecoderFunc func(p *DecoderParams) Decoder
 
 type decoderItem struct {
 	noop    bool

algo/common/raw.go

@@ -14,8 +14,8 @@ type RawDecoder struct {
 	audioExt string
 }
 
-func NewRawDecoder(rd io.ReadSeeker) Decoder {
-	return &RawDecoder{rd: rd}
+func NewRawDecoder(p *DecoderParams) Decoder {
+	return &RawDecoder{rd: p.Reader}
 }
 
 func (d *RawDecoder) Validate() error {