From 9e5bc3806f8913bbb715fcc84d0c3040f8565c83 Mon Sep 17 00:00:00 2001
From: scruzin <anoble@gmail.com>
Date: Fri, 12 Jul 2019 14:24:30 +0930
Subject: [PATCH] Added GetPTS.

---
 container/mts/mpegts.go | 15 +++++----------
 1 file changed, 5 insertions(+), 10 deletions(-)

diff --git a/container/mts/mpegts.go b/container/mts/mpegts.go
index ee898177..484254fe 100644
--- a/container/mts/mpegts.go
+++ b/container/mts/mpegts.go
@@ -424,9 +424,9 @@ var errNoPesPTS = errors.New("no PES PTS")
 var errInvalidPesHeader = errors.New("invalid PES header")
 var errInvalidPesPayload = errors.New("invalid PES payload")
 
-// GetPTS returns a PTS from an MTS packet that has PES payload, or an error otherwise.
+// GetPTS returns a PTS from a packet that has PES payload, or an error otherwise.
 func GetPTS(pkt []byte) (pts int64, err error) {
-	// Bail if packet does not contain a PES.
+	// Check the Payload Unit Start Indicator.
 	if pkt[1]&0x040 == 0 {
 		err = errNoPesPayload
 		return
@@ -435,27 +435,22 @@ func GetPTS(pkt []byte) (pts int64, err error) {
 	// Compute start of PES payload and check its length.
 	start := HeadSize
 	if pkt[3]&0x20 != 0 {
-		// Take into account length of the adaptation field.
+		// Adaptation field is present, so adjust start of payload accordingly.
 		start += 1 + int(pkt[4])
 	}
 	pes := pkt[start:]
 
-	if len(pes) < 9 {
+	if len(pes) < 14 {
 		err = errInvalidPesHeader
 		return
 	}
 
-	// Check that PES has a PTS.
+	// Check the PTS DTS indicator.
 	if pes[7]&0xc0 == 0 {
 		err = errNoPesPTS
 		return
 	}
 
-	// Extract the PTS.
-	if len(pes) < 14 {
-		err = errInvalidPesHeader
-		return
-	}
 	pts = extractPTS(pes[9:14])
 	return
 }