diff --git a/stream/mts/psi/psi.go b/stream/mts/psi/psi.go
index 7366ee3b..7f9569e6 100644
--- a/stream/mts/psi/psi.go
+++ b/stream/mts/psi/psi.go
@@ -1,6 +1,7 @@
 package psi
 
 import (
+	"errors"
 	"hash/crc32"
 	"math/bits"
 )
@@ -63,7 +64,7 @@ type PMT struct {
 	Pcrpid uint16 // Program clock reference pid
 	Pil    uint16 // Program info length
 	Pd     []Desc // Program descriptors
-	Essd   ESSD   // Elementary stream specific data
+	Essd   *ESSD  // Elementary stream specific data
 }
 
 // Elementary stream specific data
@@ -177,6 +178,13 @@ func readEssd(data []byte) *ESSD {
 	essd := ESSD{}
 	pos := 0
 	essd.St = data[pos]
+	pos++
+	essd.Epid = uint16(data[pos]&0x1f)<<8 | uint16(data[pos+1])
+	pos += 2
+	essd.Esil = uint16(data[pos]&0x03)<<8 | uint16(data[pos+1])
+	pos += 2
+	essd.Esd = readDescs(data[pos:], int(essd.Esil))
+	return &essd
 }
 
 // Bytes outputs a byte slice representation of the PSI
@@ -295,3 +303,12 @@ func crc32_Update(crc uint32, tab *crc32.Table, p []byte) uint32 {
 	}
 	return crc
 }
+
+// UpdateTimestamp
+func UpdateTimestamp(data []byte, t int) error {
+	psi := ReadPSI(data)
+	if psi.Tid != PATTableID {
+		return errors.New("Timestamp update failed because psi is not a PMT")
+	}
+	return nil
+}
diff --git a/stream/mts/psi/psi_test.go b/stream/mts/psi/psi_test.go
new file mode 100644
index 00000000..7ec1a3b2
--- /dev/null
+++ b/stream/mts/psi/psi_test.go
@@ -0,0 +1,9 @@
+package psi
+
+import (
+	"testing"
+)
+
+func TestReadPSI1(t *testing.T) {
+
+}