From c6bd0f9236e77b36245505de6c5502adff023da9 Mon Sep 17 00:00:00 2001
From: Pierre-Etienne <pepoirot@users.noreply.github.com>
Date: Sat, 13 Apr 2024 03:40:36 +0200
Subject: [PATCH] Add support for EXT-X-GAP (#149)

---
 parse.ts                                      | 11 +++++
 .../4.4.4.7_EXT-X-GAP.spec.js                 | 40 +++++++++++++++++++
 .../7_EXT-X-VERSION.spec.js                   | 13 ++++++
 types.ts                                      |  5 ++-
 4 files changed, 68 insertions(+), 1 deletion(-)
 create mode 100644 test/spec/4_Playlists/4.3_Playlist-Tags/4.3.2_Media-Segment-Tags/4.4.4.7_EXT-X-GAP.spec.js

diff --git a/parse.ts b/parse.ts
index d8e54d9..0b909b8 100644
--- a/parse.ts
+++ b/parse.ts
@@ -49,6 +49,7 @@ function getTagCategory(tagName: string): TagCategory {
     case 'EXT-X-SCTE35':
     case 'EXT-X-PART':
     case 'EXT-X-PRELOAD-HINT':
+    case 'EXT-X-GAP':
       return 'Segment';
     case 'EXT-X-TARGETDURATION':
     case 'EXT-X-MEDIA-SEQUENCE':
@@ -214,6 +215,7 @@ function parseTagParam(name: string, param): TagParam {
     case 'EXT-X-I-FRAMES-ONLY':
     case 'EXT-X-INDEPENDENT-SEGMENTS':
     case 'EXT-X-CUE-IN':
+    case 'EXT-X-GAP':
       return [null, null];
     case 'EXT-X-VERSION':
     case 'EXT-X-TARGETDURATION':
@@ -508,6 +510,11 @@ function parseSegment(lines: Line[], uri: string, start: number, end: number, me
         utils.INVALIDPLAYLIST('EXT-X-DISCONTINUITY must appear before the first EXT-X-PART tag of the Parent Segment.');
       }
       segment.discontinuity = true;
+    } else if (name === 'EXT-X-GAP') {
+      if (params.compatibleVersion < 8) {
+        params.compatibleVersion = 8;
+      }
+      segment.gap = true;
     } else if (name === 'EXT-X-KEY') {
       if (segment.parts.length > 0) {
         utils.INVALIDPLAYLIST('EXT-X-KEY must appear before the first EXT-X-PART tag of the Parent Segment.');
@@ -604,6 +611,10 @@ function parseSegment(lines: Line[], uri: string, start: number, end: number, me
         independent: attributes['INDEPENDENT'],
         gap: attributes['GAP']
       });
+      if (segment.gap && !partialSegment.gap) {
+        // https://datatracker.ietf.org/doc/html/draft-pantos-hls-rfc8216bis#section-6.2.1
+        utils.INVALIDPLAYLIST('Partial segments must have GAP=YES if they are in a gap (EXT-X-GAP)');
+      }
       segment.parts.push(partialSegment);
     }
   }
diff --git a/test/spec/4_Playlists/4.3_Playlist-Tags/4.3.2_Media-Segment-Tags/4.4.4.7_EXT-X-GAP.spec.js b/test/spec/4_Playlists/4.3_Playlist-Tags/4.3.2_Media-Segment-Tags/4.4.4.7_EXT-X-GAP.spec.js
new file mode 100644
index 0000000..e8412e9
--- /dev/null
+++ b/test/spec/4_Playlists/4.3_Playlist-Tags/4.3.2_Media-Segment-Tags/4.4.4.7_EXT-X-GAP.spec.js
@@ -0,0 +1,40 @@
+const test = require("ava");
+const utils = require("../../../../helpers/utils");
+
+// https://datatracker.ietf.org/doc/html/draft-pantos-hls-rfc8216bis#section-4.4.4.7
+
+test('#EXT-X-TAG_01', t => {
+  utils.parseFail(t, `
+    #EXTM3U
+    #EXT-X-VERSION:8
+    #EXT-X-GAP
+    1.ts
+  `);
+  utils.parsePass(t, `
+    #EXTM3U
+    #EXT-X-VERSION:8
+    #EXT-X-TARGETDURATION:5
+    #EXT-X-GAP
+    #EXTINF:4,
+    1.ts
+  `);
+});
+
+test('#EXT-X-TAG_02', t => {
+  utils.parseFail(t, `
+    #EXTM3U
+    #EXT-X-VERSION:8
+    #EXT-X-TARGETDURATION:5
+    #EXT-X-GAP
+    #EXT-X-PART:DURATION=2,URI="1.ts"
+    #EXT-X-ENDLIST
+  `);
+  utils.parsePass(t, `
+    #EXTM3U
+    #EXT-X-VERSION:8
+    #EXT-X-TARGETDURATION:5
+    #EXT-X-GAP
+    #EXT-X-PART:DURATION=2,URI="1.ts",GAP=YES
+    #EXT-X-ENDLIST
+  `);
+});
diff --git a/test/spec/7_Protocol-version-compatibility/7_EXT-X-VERSION.spec.js b/test/spec/7_Protocol-version-compatibility/7_EXT-X-VERSION.spec.js
index 64fe071..1ea5032 100644
--- a/test/spec/7_Protocol-version-compatibility/7_EXT-X-VERSION.spec.js
+++ b/test/spec/7_Protocol-version-compatibility/7_EXT-X-VERSION.spec.js
@@ -274,3 +274,16 @@ test('#EXT-X-VERSION_11', t => {
     http://example.com
   `);
 });
+
+// A Media Playlist MUST indicate a EXT-X-VERSION of 8 or higher if it
+// contains:
+// - the "EXT-X-GAP" tag.
+test('#EXT-X-VERSION_12', t => {
+  utils.parseFail(t, `
+    #EXTM3U
+    #EXT-X-VERSION:1
+    #EXTINF:5
+    #EXT-X-GAP
+    http://example.com
+  `);
+});
diff --git a/types.ts b/types.ts
index a3867dd..8c7ce9b 100644
--- a/types.ts
+++ b/types.ts
@@ -367,6 +367,7 @@ class Segment extends Data {
   dateRange: DateRange;
   markers: SpliceInfo[];
   parts: PartialSegment[];
+  gap?: boolean;
 
   constructor({
     uri,
@@ -383,7 +384,8 @@ class Segment extends Data {
     programDateTime,
     dateRange,
     markers = [],
-    parts = []
+    parts = [],
+    gap
   }: any) {
     super('segment');
     // utils.PARAMCHECK(uri, mediaSequenceNumber, discontinuitySequence);
@@ -402,6 +404,7 @@ class Segment extends Data {
     this.dateRange = dateRange;
     this.markers = markers;
     this.parts = parts;
+    this.gap = gap;
   }
 }