feat(HLS): allow customize live segments delay (shaka-project#4585)

joeyparrish · Oct 17, 2022 · 1f558a8 · 1f558a8
1 parent 7a039c5
commit 1f558a8
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Showing 7 changed files with 17 additions and 2 deletions.
diff --git a/demo/common/message_ids.js b/demo/common/message_ids.js
@@ -210,6 +210,7 @@ shakaDemo.MessageIds = {
   LCEVC_DYNAMIC_PERFORMANCE_SCALING: 'DEMO_LCEVC_DYNAMIC_PERFORMANCE_SCALING',
   LCEVC_LOG_LEVEL: 'DEMO_LCEVC_LOG_LEVEL',
   LCEVC_SECTION_HEADER: 'DEMO_LCEVC_SECTION_HEADER',
+  LIVE_SEGMENTS_DELAY: 'DEMO_LIVE_SEGMENTS_DELAY',
   LOG_LEVEL: 'DEMO_LOG_LEVEL',
   LOG_LEVEL_DEBUG: 'DEMO_LOG_LEVEL_DEBUG',
   LOG_LEVEL_INFO: 'DEMO_LOG_LEVEL_INFO',

diff --git a/demo/config.js b/demo/config.js
@@ -220,6 +220,8 @@ shakaDemo.Config = class {
             'manifest.hls.ignoreManifestProgramDateTime')
         .addBoolInput_(MessageIds.USE_SAFARI_BEHAVIOR_FOR_LIVE,
             'manifest.hls.useSafariBehaviorForLive')
+        .addNumberInput_(MessageIds.LIVE_SEGMENTS_DELAY,
+            'manifest.hls.liveSegmentsDelay')
         .addNumberInput_(MessageIds.AVAILABILITY_WINDOW_OVERRIDE,
             'manifest.availabilityWindowOverride',
             /* canBeDecimal= */ true,

diff --git a/demo/locales/en.json b/demo/locales/en.json
@@ -128,6 +128,7 @@
   "DEMO_LICENSE_SERVER_URL": "Custom License Server URL",
   "DEMO_LIVE": "Live",
   "DEMO_LIVE_SEARCH": "Live",
+  "DEMO_LIVE_SEGMENTS_DELAY": "Live segments delay",
   "DEMO_LOG_LEVEL": "Log Level",
   "DEMO_LOG_LEVEL_DEBUG": "Debug",
   "DEMO_LOG_LEVEL_INFO": "Info",

diff --git a/demo/locales/source.json b/demo/locales/source.json
@@ -515,6 +515,10 @@
     "description": "A header on a search field that filters by whether the asset is live or not.",
     "message": "Live"
   },
+  "DEMO_LIVE_SEGMENTS_DELAY": {
+    "description": "The name of a configuration value.",
+    "message": "Live segments delay"
+  },
   "DEMO_LOG_LEVEL": {
     "description": "The name of a configuration value.",
     "message": "Log Level"

diff --git a/externs/shaka/player.js b/externs/shaka/player.js
@@ -828,7 +828,8 @@ shaka.extern.DashManifestConfiguration;
  *   defaultVideoCodec: string,
  *   ignoreManifestProgramDateTime: boolean,
  *   mediaPlaylistFullMimeType: string,
- *   useSafariBehaviorForLive: boolean
+ *   useSafariBehaviorForLive: boolean,
+ *   liveSegmentsDelay: number
  * }}
  *
  * @property {boolean} ignoreTextStreamFailures
@@ -865,6 +866,10 @@ shaka.extern.DashManifestConfiguration;
  *   segments, but the seek window will be zero-sized, to be consistent with
  *   Safari. If this is false, the seek window will be the entire duration.
  *   <i>Defaults to <code>true</code>.</i>
+ * @property {number} liveSegmentsDelay
+ *   The default presentation delay will be calculated as a number of segments.
+ *   This is the number of segments for this calculation..
+ *   <i>Defaults to <code>3</code>.</i>
  * @exportDoc
  */
 shaka.extern.HlsManifestConfiguration;

diff --git a/lib/hls/hls_parser.js b/lib/hls/hls_parser.js
@@ -2123,7 +2123,8 @@ shaka.hls.HlsParser = class {
     } else if (this.lowLatencyPresentationDelay_) {
       presentationDelay = this.lowLatencyPresentationDelay_;
     } else {
-      presentationDelay = this.maxTargetDuration_ * 3;
+      const numberOfSegments = this.config_.hls.liveSegmentsDelay;
+      presentationDelay = this.maxTargetDuration_ * numberOfSegments;
     }
 
     this.presentationTimeline_.setPresentationStartTime(0);

diff --git a/lib/util/player_configuration.js b/lib/util/player_configuration.js
@@ -131,6 +131,7 @@ shaka.util.PlayerConfiguration = class {
         mediaPlaylistFullMimeType:
             'video/mp2t; codecs="avc1.42E01E, mp4a.40.2"',
         useSafariBehaviorForLive: true,
+        liveSegmentsDelay: 3,
       },
     };