Feature enable low latency (#3684)

Enable low latency streaming automatically if availabilityTimeComplete is set to false
Dash-Industry-Forum · Sep 8, 2021 · ef00170 · ef00170
1 parent dcccdd3
commit ef00170
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Showing 15 changed files with 117 additions and 52 deletions.
diff --git a/index.d.ts b/index.d.ts
@@ -152,6 +152,7 @@ declare namespace dashjs {
             abandonLoadTimeout?: number,
             wallclockTimeUpdateInterval?: number,
             lowLatencyEnabled?: boolean,
+            lowLatencyEnabledByManifest?: boolean,
             manifestUpdateRetryInterval?: number,
             cacheInitSegments?: boolean,
             eventControllerRefreshDelay?: number,

diff --git a/samples/dash-if-reference-player/app/main.js b/samples/dash-if-reference-player/app/main.js
@@ -682,8 +682,16 @@ app.controller('DashController', ['$scope', '$window', 'sources', 'contributors'
 
     $scope.togglelowLatencyMode = function () {
         $scope.player.updateSettings({
-            'streaming': {
-                'lowLatencyEnabled': $scope.lowLatencyModeSelected
+            streaming: {
+                lowLatencyEnabled: $scope.lowLatencyModeSelected
+            }
+        });
+    };
+
+    $scope.toggleLowLatencyByManifestMode = function () {
+        $scope.player.updateSettings({
+            streaming: {
+                lowLatencyEnabledByManifest: $scope.lowLatencyEnabledByManifest
             }
         });
     };
@@ -776,16 +784,17 @@ app.controller('DashController', ['$scope', '$window', 'sources', 'contributors'
         }
 
         var config = {
-            'streaming': {
-                'buffer': {
-                    'stableBufferTime': $scope.defaultStableBufferDelay,
-                    'bufferTimeAtTopQuality': $scope.defaultBufferTimeAtTopQuality,
-                    'bufferTimeAtTopQualityLongForm': $scope.defaultBufferTimeAtTopQualityLongForm,
+            streaming: {
+                buffer: {
+                    stableBufferTime: $scope.defaultStableBufferDelay,
+                    bufferTimeAtTopQuality: $scope.defaultBufferTimeAtTopQuality,
+                    bufferTimeAtTopQualityLongForm: $scope.defaultBufferTimeAtTopQualityLongForm,
                 },
-                'delay': {
-                    'liveDelay': $scope.defaultLiveDelay
+                delay: {
+                    liveDelay: $scope.defaultLiveDelay
                 },
-                'lowLatencyEnabled': $scope.lowLatencyModeSelected,
+                lowLatencyEnabled: $scope.lowLatencyModeSelected,
+                lowLatencyEnabledByManifest: $scope.lowLatencyEnabledByManifest,
                 abr: {},
                 cmcd: {}
             }
@@ -1008,7 +1017,7 @@ app.controller('DashController', ['$scope', '$window', 'sources', 'contributors'
                             protectionData[input.drmKeySystem]['httpRequestHeaders'] = input.httpRequestHeaders;
                         }
                     } else {
-                        alert("Kid and Key must be specified!");
+                        alert('Kid and Key must be specified!');
                     }
 
                 } else {
@@ -1018,15 +1027,15 @@ app.controller('DashController', ['$scope', '$window', 'sources', 'contributors'
                         // Check if DRM-Priorisation is enabled
                         if (this.prioritiesEnabled) {
                             protectionData[input.drmKeySystem] = {
-                                "serverURL": input.licenseServerUrl,
-                                "priority": parseInt(input.priority)
+                                'serverURL': input.licenseServerUrl,
+                                'priority': parseInt(input.priority)
                             }
                             if (!angular.equals(input.httpRequestHeaders, {}))
                                 protectionData[input.drmKeySystem]['httpRequestHeaders'] = input.httpRequestHeaders;
 
                         } else {
                             protectionData[input.drmKeySystem] = {
-                                "serverURL": input.licenseServerUrl,
+                                'serverURL': input.licenseServerUrl,
                             }
                         }
 
@@ -1052,7 +1061,7 @@ app.controller('DashController', ['$scope', '$window', 'sources', 'contributors'
                         }
 
                     } else {
-                        console.log(input.licenseServerUrl, "is not a valid url!")
+                        console.log(input.licenseServerUrl, 'is not a valid url!')
                     }
 
                 }
@@ -1535,6 +1544,7 @@ app.controller('DashController', ['$scope', '$window', 'sources', 'contributors'
         $scope.defaultBufferTimeAtTopQuality = currentConfig.streaming.buffer.bufferTimeAtTopQuality;
         $scope.defaultBufferTimeAtTopQualityLongForm = currentConfig.streaming.buffer.bufferTimeAtTopQualityLongForm;
         $scope.lowLatencyModeSelected = currentConfig.streaming.lowLatencyEnabled;
+        $scope.lowLatencyEnabledByManifest = currentConfig.streaming.lowLatencyEnabledByManifest;
         $scope.liveCatchupEnabled = currentConfig.streaming.liveCatchup.enabled;
     }
 

diff --git a/samples/dash-if-reference-player/app/sources.json b/samples/dash-if-reference-player/app/sources.json
@@ -285,16 +285,15 @@
                     "url": "https://akamaibroadcasteruseast.akamaized.net/cmaf/live/657078/akasource/out.mpd",
                     "name": "Akamai Low Latency Stream (Single Rate)",
                     "bufferConfig": {
-                        "lowLatencyMode": true,
-                        "liveDelay": 3
+                        "liveDelay": 3,
+                        "lowLatencyMode": true
                     },
                     "provider": "akamai"
                 },
                 {
                     "url": "https://cmafref.akamaized.net/cmaf/live-ull/2006350/akambr/out.mpd",
                     "name": "Akamai Low Latency Stream (Multi Rate)",
                     "bufferConfig": {
-                        "lowLatencyMode": true,
                         "liveDelay": 3
                     },
                     "provider": "akamai"
@@ -303,7 +302,6 @@
                     "url": "https://livesim.dashif.org/livesim/chunkdur_1/ato_7/testpic4_8s/Manifest300.mpd",
                     "name": "Low Latency (Single-Rate) (livesim-chunked)",
                     "bufferConfig": {
-                        "lowLatencyMode": true,
                         "liveDelay": 4
                     },
                     "provider": "dashif"
@@ -312,7 +310,6 @@
                     "url": "https://livesim.dashif.org/livesim/chunkdur_1/ato_7/testpic4_8s/Manifest.mpd",
                     "name": "Low Latency (Multi-Rate) (livesim-chunked)",
                     "bufferConfig": {
-                        "lowLatencyMode": true,
                         "liveDelay": 4
                     },
                     "provider": "dashif"

diff --git a/samples/dash-if-reference-player/index.html b/samples/dash-if-reference-player/index.html
@@ -187,7 +187,13 @@
                        title="Enable low latency mode">
                     <input type="checkbox" id="lowLatencyModeCB" ng-model="lowLatencyModeSelected"
                            ng-change="togglelowLatencyMode()" ng-checked="lowLatencyModeSelected">
-                    Low Latency Mode
+                    Low latency mode
+                </label>             
+                <label class="topcoat-checkbox" data-toggle="tooltip" data-placement="right"
+                       title="Enable low latency mode by MPD attribute 'availabilityTimeComplete' ">
+                    <input type="checkbox" id="lowLatencyModeEnabledByManifestCB" ng-model="lowLatencyEnabledByManifest"
+                           ng-change="toggleLowLatencyByManifestMode()" ng-checked="lowLatencyEnabledByManifest">
+                    Enable low latency mode by MPD
                 </label>
                 <label class="topcoat-checkbox" data-toggle="tooltip" data-placement="right"
                        title="Enable catchup mode for non low latency streams">

diff --git a/src/core/Settings.js b/src/core/Settings.js
@@ -60,6 +60,7 @@ import {HTTPRequest} from '../streaming/vo/metrics/HTTPRequest';
  *            abandonLoadTimeout: 10000,
  *            wallclockTimeUpdateInterval: 100,
  *            lowLatencyEnabled: false,
+ *            lowLatencyEnabledByManifest: true,
  *            manifestUpdateRetryInterval: 100,
  *            cacheInitSegments: true,
  *            eventControllerRefreshDelay: 100,
@@ -129,7 +130,7 @@ import {HTTPRequest} from '../streaming/vo/metrics/HTTPRequest';
  *            },
  *            liveCatchup: {
  *                minDrift: 0.02,
- *                maxDrift: 0,
+ *                maxDrift: 12,
  *                playbackRate: 0.5,
  *                latencyThreshold: 60,
  *                playbackBufferMin: 0.5,
@@ -377,6 +378,7 @@ import {HTTPRequest} from '../streaming/vo/metrics/HTTPRequest';
  * @property {boolean} [useManifestDateHeaderTimeSource=true]
  * Allows you to enable the use of the Date Header, if exposed with CORS, as a timing source for live edge detection.
  *
+ * The use of the date header will happen only after the other timing source that take precedence fail or are omitted as described.
  * @property {number} [backgroundAttempts=2]
  * Number of synchronization attempts to perform in the background after an initial synchronization request has been done. This is used to verify that the derived client-server offset is correct.
  *
@@ -434,7 +436,7 @@ import {HTTPRequest} from '../streaming/vo/metrics/HTTPRequest';
  * LowLatencyMinDrift should be provided in seconds, and it uses values between 0.0 and 0.5.
  *
  * Note: Catch-up mechanism is only applied when playing low latency live streams.
- * @property {number} [maxDrift=0]
+ * @property {number} [maxDrift=12]
  * Use this method to set the maximum latency deviation allowed before dash.js to do a seeking to live position.
  *
  * In low latency mode, when the difference between the measured latency and the target one, as an absolute number, is higher than the one sets with this method, then dash.js does a seek to live edge position minus the target live delay.
@@ -644,9 +646,11 @@ import {HTTPRequest} from '../streaming/vo/metrics/HTTPRequest';
  * @property {number} [wallclockTimeUpdateInterval=50]
  * How frequently the wallclockTimeUpdated internal event is triggered (in milliseconds).
  * @property {boolean} [lowLatencyEnabled=false]
- * Enable or disable low latency mode.
+ * Manually enable or disable low latency mode.
+ *
+ * @property {boolean} [lowLatencyEnabledByManifest=true]
+ * If this value is set to true we enable the low latency mode based on MPD attributes:  Specifically in case "availabilityTimeComplete" of the current representation is set to false.
  *
- * The use of the date header will happen only after the other timing source that take precedence fail or are omitted as described.
  * @property {number} [manifestUpdateRetryInterval=100]
  * For live streams, set the interval-frequency in milliseconds at which dash.js will check if the current manifest is still processed before downloading the next manifest once the minimumUpdatePeriod time has.
  * @property {boolean} [cacheInitSegments=true]
@@ -743,6 +747,7 @@ function Settings() {
             abandonLoadTimeout: 10000,
             wallclockTimeUpdateInterval: 100,
             lowLatencyEnabled: false,
+            lowLatencyEnabledByManifest: true,
             manifestUpdateRetryInterval: 100,
             cacheInitSegments: false,
             eventControllerRefreshDelay: 150,
@@ -812,7 +817,7 @@ function Settings() {
             },
             liveCatchup: {
                 minDrift: 0.02,
-                maxDrift: 0,
+                maxDrift: 12,
                 playbackRate: 0.5,
                 latencyThreshold: 60,
                 playbackBufferMin: 0.5,

diff --git a/src/dash/SegmentBaseLoader.js b/src/dash/SegmentBaseLoader.js
@@ -44,7 +44,6 @@ function SegmentBaseLoader() {
         boxParser,
         requestModifier,
         dashMetrics,
-        settings,
         mediaPlayerModel,
         urlLoader,
         errors,
@@ -62,7 +61,6 @@ function SegmentBaseLoader() {
             dashMetrics: dashMetrics,
             mediaPlayerModel: mediaPlayerModel,
             requestModifier: requestModifier,
-            useFetch: settings ? settings.get().streaming.lowLatencyEnabled : null,
             boxParser: boxParser,
             errors: errors,
             urlUtils: urlUtils,
@@ -88,10 +86,6 @@ function SegmentBaseLoader() {
             errHandler = config.errHandler;
         }
 
-        if (config.settings) {
-            settings = config.settings;
-        }
-
         if (config.boxParser) {
             boxParser = config.boxParser;
         }

diff --git a/src/dash/WebmSegmentBaseLoader.js b/src/dash/WebmSegmentBaseLoader.js
@@ -18,7 +18,6 @@ function WebmSegmentBaseLoader() {
         dashMetrics,
         mediaPlayerModel,
         urlLoader,
-        settings,
         errors,
         baseURLController;
 
@@ -94,7 +93,6 @@ function WebmSegmentBaseLoader() {
             dashMetrics: dashMetrics,
             mediaPlayerModel: mediaPlayerModel,
             requestModifier: requestModifier,
-            useFetch: settings ? settings.get().streaming.lowLatencyEnabled : null,
             errors: errors
         });
     }
@@ -107,7 +105,6 @@ function WebmSegmentBaseLoader() {
         dashMetrics = config.dashMetrics;
         mediaPlayerModel = config.mediaPlayerModel;
         errHandler = config.errHandler;
-        settings = config.settings;
         errors = config.errors;
         logger = config.debug.getLogger(instance);
         requestModifier = config.requestModifier;

diff --git a/src/dash/controllers/RepresentationController.js b/src/dash/controllers/RepresentationController.js
@@ -105,7 +105,8 @@ function RepresentationController(config) {
 
         voAvailableRepresentations = availableRepresentations;
 
-        currentVoRepresentation = getRepresentationForQuality(quality);
+        const rep = getRepresentationForQuality(quality)
+        _setCurrentVoRepresentation(rep);
         realAdaptation = newRealAdaptation;
 
         if (type !== Constants.VIDEO && type !== Constants.AUDIO && (type !== Constants.TEXT || !isFragmented)) {
@@ -203,7 +204,7 @@ function RepresentationController(config) {
         return representation;
     }
 
-    function addRepresentationSwitch() {
+    function _addRepresentationSwitch() {
         checkConfig();
         const now = new Date();
         const currentRepresentation = getCurrentRepresentation();
@@ -214,9 +215,10 @@ function RepresentationController(config) {
 
         eventBus.trigger(MediaPlayerEvents.REPRESENTATION_SWITCH, {
             mediaType: type,
+            streamId: streamInfo.id,
             currentRepresentation,
             numberOfRepresentations: voAvailableRepresentations.length
-        })
+        }, { streamId: streamInfo.id, mediaType: type })
     }
 
     function getRepresentationForQuality(quality) {
@@ -285,15 +287,20 @@ function RepresentationController(config) {
             repSwitch = dashMetrics.getCurrentRepresentationSwitch(getCurrentRepresentation().adaptation.type);
 
             if (!repSwitch) {
-                addRepresentationSwitch();
+                _addRepresentationSwitch();
             }
             endDataUpdate();
         }
     }
 
     function prepareQualityChange(newQuality) {
-        currentVoRepresentation = getRepresentationForQuality(newQuality);
-        addRepresentationSwitch();
+        const newRep = getRepresentationForQuality(newQuality)
+        _setCurrentVoRepresentation(newRep);
+        _addRepresentationSwitch();
+    }
+
+    function _setCurrentVoRepresentation(value) {
+        currentVoRepresentation = value;
     }
 
     function onManifestValidityChanged(e) {

diff --git a/src/streaming/FragmentLoader.js b/src/streaming/FragmentLoader.js
@@ -54,7 +54,6 @@ function FragmentLoader(config) {
             dashMetrics: config.dashMetrics,
             mediaPlayerModel: config.mediaPlayerModel,
             requestModifier: config.requestModifier,
-            useFetch: config.settings.get().streaming.lowLatencyEnabled,
             urlUtils: urlUtils,
             constants: Constants,
             boxParser: config.boxParser,

diff --git a/src/streaming/ManifestLoader.js b/src/streaming/ManifestLoader.js
@@ -68,7 +68,6 @@ function ManifestLoader(config) {
             dashMetrics: config.dashMetrics,
             mediaPlayerModel: config.mediaPlayerModel,
             requestModifier: config.requestModifier,
-            useFetch: config.settings.get().streaming.lowLatencyEnabled,
             urlUtils: urlUtils,
             constants: Constants,
             dashConstants: DashConstants,

diff --git a/src/streaming/XlinkLoader.js b/src/streaming/XlinkLoader.js
@@ -50,7 +50,6 @@ function XlinkLoader(config) {
         dashMetrics: config.dashMetrics,
         mediaPlayerModel: config.mediaPlayerModel,
         requestModifier: config.requestModifier,
-        useFetch: config.settings ? config.settings.get().streaming.lowLatencyEnabled : null,
         errors: Errors
     });
 

diff --git a/src/streaming/controllers/PlaybackController.js b/src/streaming/controllers/PlaybackController.js
@@ -109,6 +109,7 @@ function PlaybackController() {
         eventBus.on(MediaPlayerEvents.PLAYBACK_TIME_UPDATED, _onPlaybackProgression, this);
         eventBus.on(MediaPlayerEvents.PLAYBACK_ENDED, _onPlaybackEnded, this, { priority: EventBus.EVENT_PRIORITY_HIGH });
         eventBus.on(MediaPlayerEvents.STREAM_INITIALIZING, _onStreamInitializing, this);
+        eventBus.on(MediaPlayerEvents.REPRESENTATION_SWITCH, _onRepresentationSwitch, this);
 
         if (playOnceInitialized) {
             playOnceInitialized = false;
@@ -353,6 +354,7 @@ function PlaybackController() {
             eventBus.off(MediaPlayerEvents.PLAYBACK_TIME_UPDATED, _onPlaybackProgression, this);
             eventBus.off(MediaPlayerEvents.PLAYBACK_ENDED, _onPlaybackEnded, this);
             eventBus.off(MediaPlayerEvents.STREAM_INITIALIZING, _onStreamInitializing, this);
+            eventBus.off(MediaPlayerEvents.REPRESENTATION_SWITCH, _onRepresentationSwitch, this);
             videoModel.setPlaybackRate(1.0, true);
             stopUpdatingWallclockTime();
             removeAllListeners();
@@ -916,6 +918,29 @@ function PlaybackController() {
         _checkEnableLowLatency(e.mediaInfo);
     }
 
+    /**
+     * We enable low latency playback if for the current representation availabilityTimeComplete is set to false
+     * @param e
+     * @private
+     */
+    function _onRepresentationSwitch(e) {
+        const activeStreamInfo = streamController.getActiveStreamInfo();
+        if (!settings.get().streaming.lowLatencyEnabledByManifest || !e || !activeStreamInfo || !e.currentRepresentation || !e.streamId || e.streamId !== activeStreamInfo.id || !e.mediaType || (e.mediaType !== Constants.VIDEO && e.mediaType !== Constants.AUDIO)) {
+            return;
+        }
+
+        const lowLatencyEnabled = !e.currentRepresentation.availabilityTimeComplete;
+
+        if (lowLatencyEnabled) {
+            settings.update({
+                streaming: {
+                    lowLatencyEnabled: lowLatencyEnabled
+                }
+            });
+        }
+    }
+
+
     function _checkEnableLowLatency(mediaInfo) {
         if (mediaInfo && mediaInfo.supplementalProperties &&
             mediaInfo.supplementalProperties[Constants.SUPPLEMENTAL_PROPERTY_LL_SCHEME] === 'true') {