diff --git a/stream/mts/psi/psi.go b/stream/mts/psi/psi.go
index 5eb9ce6e..ba1daf58 100644
--- a/stream/mts/psi/psi.go
+++ b/stream/mts/psi/psi.go
@@ -1,8 +1,8 @@
 package psi
 
 const (
-	ESSDHeadLen       = 5
-	DescriptorHeadLen = 2
+	ESSDHeadLen = 5
+	DescHeadLen = 2
 )
 
 // Program specific information
@@ -40,18 +40,18 @@ type PAT struct {
 
 // Program mapping table, implements SD
 type PMT struct {
-	pcrpid uint16       // Program clock reference pid
-	pil    uint16       // Program info length
-	pd     []Descriptor // Program descriptors
-	essd   []ESSD       // Elementary stream specific data
+	pcrpid uint16 // Program clock reference pid
+	pil    uint16 // Program info length
+	pd     []Desc // Program descriptors
+	essd   []ESSD // Elementary stream specific data
 }
 
 // Elementary stream specific data
 type ESSD struct {
-	st   byte         // Stream type
-	epid byte         // Elementary pid
-	esil uint16       // Elementary stream
-	esd  []Descriptor // Elementary stream desriptors
+	st   byte   // Stream type
+	epid byte   // Elementary pid
+	esil uint16 // Elementary stream
+	esd  []Desc // Elementary stream desriptors
 }
 
 // Descriptor
@@ -82,8 +82,8 @@ func (p *PMT) Fill(space []byte) error {
 	return nil
 }
 
-func (d *Descriptor) Fill(space []byte) error {
-	checkSpace(space, DescriptorHeadLen+int(d.dl))
+func (d *Desc) Fill(space []byte) error {
+	checkSpace(space, DescHeadLen+int(d.dl))
 	space[0] = d.dt
 	space[1] = d.dl
 	copy(space[2:], d.dd)