From c03376096df8a382aeffe20f596930e03ba468c9 Mon Sep 17 00:00:00 2001
From: Brandon Casey <2381475+brandonocasey@users.noreply.github.com>
Date: Wed, 20 Jan 2021 10:12:38 -0500
Subject: [PATCH] feat: add support for #EXT-X-PART (#127)

https://developer.apple.com/documentation/http_live_streaming/enabling_low-latency_hls#3282436
https://tools.ietf.org/html/draft-pantos-hls-rfc8216bis-08#section-4.4.4.9
---
 src/parse-stream.js                |  34 ++++++++
 src/parser.js                      |   4 +
 test/fixtures/m3u8/llhls.json      | 116 ++++++++++++++++++++++++++++
 test/fixtures/m3u8/llhls.m3u8      |   4 +-
 test/fixtures/m3u8/llhlsDelta.json | 120 +++++++++++++++++++++++++++++
 test/fixtures/m3u8/llhlsDelta.m3u8 |   4 +-
 6 files changed, 278 insertions(+), 4 deletions(-)

diff --git a/src/parse-stream.js b/src/parse-stream.js
index 18f83e5..4374016 100644
--- a/src/parse-stream.js
+++ b/src/parse-stream.js
@@ -464,6 +464,40 @@ export default class ParseStream extends Stream {
         this.trigger('data', event);
         return;
       }
+      match = (/^#EXT-X-PART:(.*)$/).exec(newLine);
+      if (match && match[1]) {
+        event = {
+          type: 'tag',
+          tagType: 'part'
+        };
+        event.attributes = parseAttributes(match[1]);
+        ['DURATION'].forEach(function(key) {
+          if (event.attributes.hasOwnProperty(key)) {
+            event.attributes[key] = parseFloat(event.attributes[key]);
+          }
+        });
+
+        ['INDEPENDENT', 'GAP'].forEach(function(key) {
+          if (event.attributes.hasOwnProperty(key)) {
+            event.attributes[key] = (/YES/).test(event.attributes[key]);
+          }
+        });
+
+        if (event.attributes.hasOwnProperty('BYTERANGE')) {
+          const [length, offset] = event.attributes.BYTERANGE.split('@');
+
+          event.byterange = {};
+          if (length) {
+            event.byterange.length = parseInt(length, 10);
+          }
+          if (offset) {
+            event.byterange.offset = parseInt(offset, 10);
+          }
+        }
+
+        this.trigger('data', event);
+        return;
+      }
 
       // unknown tag type
       this.trigger('data', {
diff --git a/src/parser.js b/src/parser.js
index 1c4e36a..f74e2d9 100644
--- a/src/parser.js
+++ b/src/parser.js
@@ -386,6 +386,10 @@ export default class Parser extends Stream {
             },
             'skip'() {
               this.manifest.skip = entry.attributes;
+            },
+            'part'() {
+              this.manifest.parts = this.manifest.parts || [];
+              this.manifest.parts.push(entry.attributes);
             }
           })[entry.tagType] || noop).call(self);
         },
diff --git a/test/fixtures/m3u8/llhls.json b/test/fixtures/m3u8/llhls.json
index 3d82211..54b5846 100644
--- a/test/fixtures/m3u8/llhls.json
+++ b/test/fixtures/m3u8/llhls.json
@@ -5,6 +5,122 @@
   "discontinuitySequence": 0,
   "discontinuityStarts": [],
   "mediaSequence": 266,
+  "parts": [
+    {
+      "DURATION": 0.33334,
+      "URI": "filePart271.0.mp4"
+    },
+    {
+      "DURATION": 0.33334,
+      "URI": "filePart271.1.mp4"
+    },
+    {
+      "DURATION": 0.33334,
+      "URI": "filePart271.2.mp4"
+    },
+    {
+      "DURATION": 0.33334,
+      "URI": "filePart271.3.mp4"
+    },
+    {
+      "DURATION": 0.33334,
+      "INDEPENDENT": true,
+      "URI": "filePart271.4.mp4"
+    },
+    {
+      "DURATION": 0.33334,
+      "URI": "filePart271.5.mp4"
+    },
+    {
+      "DURATION": 0.33334,
+      "URI": "filePart271.6.mp4"
+    },
+    {
+      "DURATION": 0.33334,
+      "URI": "filePart271.7.mp4"
+    },
+    {
+      "DURATION": 0.33334,
+      "INDEPENDENT": true,
+      "URI": "filePart271.8.mp4"
+    },
+    {
+      "DURATION": 0.33334,
+      "URI": "filePart271.9.mp4"
+    },
+    {
+      "DURATION": 0.33334,
+      "URI": "filePart271.10.mp4"
+    },
+    {
+      "BYTERANGE": "587500@522828",
+      "DURATION": 0.33334,
+      "URI": "filePart271.11.mp4"
+    },
+    {
+      "DURATION": 0.33334,
+      "GAP": true,
+      "URI": "filePart272.a.mp4"
+    },
+    {
+      "DURATION": 0.33334,
+      "URI": "filePart272.b.mp4"
+    },
+    {
+      "DURATION": 0.33334,
+      "URI": "filePart272.c.mp4"
+    },
+    {
+      "DURATION": 0.33334,
+      "URI": "filePart272.d.mp4"
+    },
+    {
+      "DURATION": 0.33334,
+      "URI": "filePart272.e.mp4"
+    },
+    {
+      "DURATION": 0.33334,
+      "INDEPENDENT": true,
+      "URI": "filePart272.f.mp4"
+    },
+    {
+      "DURATION": 0.33334,
+      "URI": "filePart272.g.mp4"
+    },
+    {
+      "DURATION": 0.33334,
+      "URI": "filePart272.h.mp4"
+    },
+    {
+      "DURATION": 0.33334,
+      "URI": "filePart272.i.mp4"
+    },
+    {
+      "DURATION": 0.33334,
+      "URI": "filePart272.j.mp4"
+    },
+    {
+      "DURATION": 0.33334,
+      "URI": "filePart272.k.mp4"
+    },
+    {
+      "DURATION": 0.33334,
+      "URI": "filePart272.l.mp4"
+    },
+    {
+      "DURATION": 0.33334,
+      "INDEPENDENT": true,
+      "URI": "filePart273.0.mp4"
+    },
+    {
+      "DURATION": 0.33334,
+      "URI": "filePart273.1.mp4"
+    },
+    {
+      "DURATION": 0.33334,
+      "URI": "filePart273.2.mp4"
+    }
+  ],
   "segments": [
     {
       "dateTimeObject": new Date("2019-02-14T02:13:36.106Z"),
diff --git a/test/fixtures/m3u8/llhls.m3u8 b/test/fixtures/m3u8/llhls.m3u8
index d48f0a0..dc208ee 100644
--- a/test/fixtures/m3u8/llhls.m3u8
+++ b/test/fixtures/m3u8/llhls.m3u8
@@ -28,11 +28,11 @@ fileSequence270.mp4
 #EXT-X-PART:DURATION=0.33334,URI="filePart271.8.mp4",INDEPENDENT=YES
 #EXT-X-PART:DURATION=0.33334,URI="filePart271.9.mp4"
 #EXT-X-PART:DURATION=0.33334,URI="filePart271.10.mp4"
-#EXT-X-PART:DURATION=0.33334,URI="filePart271.11.mp4"
+#EXT-X-PART:BYTERANGE=587500@522828,DURATION=0.33334,URI="filePart271.11.mp4"
 #EXTINF:4.00008,
 fileSequence271.mp4
 #EXT-X-PROGRAM-DATE-TIME:2019-02-14T02:14:00.106Z
-#EXT-X-PART:DURATION=0.33334,URI="filePart272.a.mp4"
+#EXT-X-PART:GAP=YES,DURATION=0.33334,URI="filePart272.a.mp4"
 #EXT-X-PART:DURATION=0.33334,URI="filePart272.b.mp4"
 #EXT-X-PART:DURATION=0.33334,URI="filePart272.c.mp4"
 #EXT-X-PART:DURATION=0.33334,URI="filePart272.d.mp4"
diff --git a/test/fixtures/m3u8/llhlsDelta.json b/test/fixtures/m3u8/llhlsDelta.json
index e68928e..5bf8560 100644
--- a/test/fixtures/m3u8/llhlsDelta.json
+++ b/test/fixtures/m3u8/llhlsDelta.json
@@ -5,6 +5,126 @@
   "discontinuitySequence": 0,
   "discontinuityStarts": [],
   "mediaSequence": 266,
+  "parts": [
+    {
+      "DURATION": 0.33334,
+      "URI": "filePart271.0.mp4"
+    },
+    {
+      "DURATION": 0.33334,
+      "URI": "filePart271.1.mp4"
+    },
+    {
+      "DURATION": 0.33334,
+      "URI": "filePart271.2.mp4"
+    },
+    {
+      "DURATION": 0.33334,
+      "URI": "filePart271.3.mp4"
+    },
+    {
+      "DURATION": 0.33334,
+      "INDEPENDENT": true,
+      "URI": "filePart271.4.mp4"
+    },
+    {
+      "DURATION": 0.33334,
+      "URI": "filePart271.5.mp4"
+    },
+    {
+      "DURATION": 0.33334,
+      "URI": "filePart271.6.mp4"
+    },
+    {
+      "DURATION": 0.33334,
+      "URI": "filePart271.7.mp4"
+    },
+    {
+      "DURATION": 0.33334,
+      "INDEPENDENT": true,
+      "URI": "filePart271.8.mp4"
+    },
+    {
+      "DURATION": 0.33334,
+      "URI": "filePart271.9.mp4"
+    },
+    {
+      "DURATION": 0.33334,
+      "URI": "filePart271.10.mp4"
+    },
+    {
+      "BYTERANGE": "587500@522828",
+      "DURATION": 0.33334,
+      "URI": "filePart271.11.mp4"
+    },
+    {
+      "DURATION": 0.33334,
+      "GAP": true,
+      "URI": "filePart272.a.mp4"
+    },
+    {
+      "DURATION": 0.33334,
+      "URI": "filePart272.b.mp4"
+    },
+    {
+      "DURATION": 0.33334,
+      "URI": "filePart272.c.mp4"
+    },
+    {
+      "DURATION": 0.33334,
+      "URI": "filePart272.d.mp4"
+    },
+    {
+      "DURATION": 0.33334,
+      "URI": "filePart272.e.mp4"
+    },
+    {
+      "DURATION": 0.33334,
+      "INDEPENDENT": true,
+      "URI": "filePart272.f.mp4"
+    },
+    {
+      "DURATION": 0.33334,
+      "URI": "filePart272.g.mp4"
+    },
+    {
+      "DURATION": 0.33334,
+      "URI": "filePart272.h.mp4"
+    },
+    {
+      "DURATION": 0.33334,
+      "URI": "filePart272.i.mp4"
+    },
+    {
+      "DURATION": 0.33334,
+      "URI": "filePart272.j.mp4"
+    },
+    {
+      "DURATION": 0.33334,
+      "URI": "filePart272.k.mp4"
+    },
+    {
+      "DURATION": 0.33334,
+      "URI": "filePart272.l.mp4"
+    },
+    {
+      "DURATION": 0.33334,
+      "INDEPENDENT": true,
+      "URI": "filePart273.0.mp4"
+    },
+    {
+      "DURATION": 0.33334,
+      "URI": "filePart273.1.mp4"
+    },
+    {
+      "DURATION": 0.33334,
+      "URI": "filePart273.2.mp4"
+    },
+    {
+      "DURATION": 0.33334,
+      "URI": "filePart273.3.mp4"
+    }
+  ],
   "segments": [
     {
       "duration": 4.00008,
diff --git a/test/fixtures/m3u8/llhlsDelta.m3u8 b/test/fixtures/m3u8/llhlsDelta.m3u8
index 01e2336..85e3719 100644
--- a/test/fixtures/m3u8/llhlsDelta.m3u8
+++ b/test/fixtures/m3u8/llhlsDelta.m3u8
@@ -21,11 +21,11 @@ fileSequence270.mp4
 #EXT-X-PART:DURATION=0.33334,URI="filePart271.8.mp4",INDEPENDENT=YES
 #EXT-X-PART:DURATION=0.33334,URI="filePart271.9.mp4"
 #EXT-X-PART:DURATION=0.33334,URI="filePart271.10.mp4"
-#EXT-X-PART:DURATION=0.33334,URI="filePart271.11.mp4"
+#EXT-X-PART:BYTERANGE=587500@522828,DURATION=0.33334,URI="filePart271.11.mp4"
 #EXTINF:4.00008,
 fileSequence271.mp4
 #EXT-X-PROGRAM-DATE-TIME:2019-02-14T02:14:00.106Z
-#EXT-X-PART:DURATION=0.33334,URI="filePart272.a.mp4"
+#EXT-X-PART:GAP=YES,DURATION=0.33334,URI="filePart272.a.mp4"
 #EXT-X-PART:DURATION=0.33334,URI="filePart272.b.mp4"
 #EXT-X-PART:DURATION=0.33334,URI="filePart272.c.mp4"
 #EXT-X-PART:DURATION=0.33334,URI="filePart272.d.mp4"