From 86260468e533a78814fa60af8b86530541c3caf2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Roman=20Koll=C3=A1r?=
 <10644651+rkollar@users.noreply.github.com>
Date: Fri, 20 Sep 2019 13:53:44 +0200
Subject: [PATCH] add INSTREAM-ID attribute for alternative renditions

---
 reader.go    | 2 ++
 structure.go | 1 +
 writer.go    | 5 +++++
 3 files changed, 8 insertions(+)

diff --git a/reader.go b/reader.go
index 86134762..7e670dc6 100644
--- a/reader.go
+++ b/reader.go
@@ -323,6 +323,8 @@ func decodeLineOfMasterPlaylist(p *MasterPlaylist, state *decodingState, line st
 				alt.Autoselect = v
 			case "FORCED":
 				alt.Forced = v
+			case "INSTREAM-ID":
+				alt.InstreamID = v
 			case "CHARACTERISTICS":
 				alt.Characteristics = v
 			case "SUBTITLES":
diff --git a/structure.go b/structure.go
index ea0d5c85..82bf94a6 100644
--- a/structure.go
+++ b/structure.go
@@ -192,6 +192,7 @@ type Alternative struct {
 	Default         bool
 	Autoselect      string
 	Forced          string
+	InstreamID      string
 	Characteristics string
 	Subtitles       string
 }
diff --git a/writer.go b/writer.go
index ae736067..050b5403 100644
--- a/writer.go
+++ b/writer.go
@@ -140,6 +140,11 @@ func (p *MasterPlaylist) Encode() *bytes.Buffer {
 					p.buf.WriteString(alt.Forced)
 					p.buf.WriteRune('"')
 				}
+				if alt.Type == "CLOSED-CAPTIONS" && alt.InstreamID != "" {
+					p.buf.WriteString(",INSTREAM-ID=\"")
+					p.buf.WriteString(alt.InstreamID)
+					p.buf.WriteRune('"')
+				}
 				if alt.Characteristics != "" {
 					p.buf.WriteString(",CHARACTERISTICS=\"")
 					p.buf.WriteString(alt.Characteristics)