feat: request Content Steering manifest

src/dash-playlist-loader.js

@@ -313,6 +313,7 @@ export default class DashPlaylistLoader extends EventTarget {
     this.vhs_ = vhs;
     this.withCredentials = withCredentials;
     this.addMetadataToTextTrack = options.addMetadataToTextTrack;
+    this.contentSteering = options.contentSteering;
 
     if (!srcUrlOrPlaylist) {
       throw new Error('A non-empty playlist URL or object is required');
@@ -465,6 +466,7 @@ export default class DashPlaylistLoader extends EventTarget {
     this.mediaUpdateTimeout = null;
     this.mediaRequest_ = null;
     this.minimumUpdatePeriodTimeout_ = null;
+    this.contentSteering.dispose();
 
     if (this.mainPlaylistLoader_.createMupOnMedia_) {
       this.off('loadedmetadata', this.mainPlaylistLoader_.createMupOnMedia_);
@@ -776,6 +778,10 @@ export default class DashPlaylistLoader extends EventTarget {
 
     this.addEventStreamToMetadataTrack_(newMain);
 
+    if (this.main.contentSteering) {
+      this.contentSteering.handleContentSteeringTags(this.vhs_.xhr, this.main.uri, this.main.contentSteering);
+    }
+
     return Boolean(newMain);
   }
 

src/playlist-controller.js

@@ -27,6 +27,7 @@ import { createMediaTypes, setupMediaGroups } from './media-groups';
 import logger from './util/logger';
 import {merge, createTimeRanges} from './util/vjs-compat';
 import { addMetadata, createMetadataTrackIfNotExists, addDateRangeMetadata } from './util/text-tracks';
+import ContentSteering from './util/content-steering';
 
 const ABORT_EARLY_EXCLUSION_SECONDS = 10;
 
@@ -200,7 +201,9 @@ export class PlaylistController extends videojs.EventTarget {
     this.requestOptions_ = {
       withCredentials,
       maxPlaylistRetries,
-      timeout: null
+      timeout: null,
+      // pass content steering parsing down to both playlist loaders.
+      contentSteering: new ContentSteering()
     };
 
     this.on('error', this.pauseLoading);

src/playlist-loader.js

@@ -393,6 +393,7 @@ export default class PlaylistLoader extends EventTarget {
     this.vhs_ = vhs;
     this.withCredentials = withCredentials;
     this.addDateRangesToTextTrack_ = options.addDateRangesToTextTrack;
+    this.contentSteering = options.contentSteering;
 
     const vhsOptions = vhs.options_;
 
@@ -545,6 +546,10 @@ export default class PlaylistLoader extends EventTarget {
 
     this.updateMediaUpdateTimeout_(refreshDelay(this.media(), !!update));
 
+    if (this.main.contentSteering) {
+      this.contentSteering.handleContentSteeringTags(this.vhs_.xhr, this.main.uri, this.main.contentSteering);
+    }
+
     this.trigger('loadedplaylist');
   }
 
@@ -557,6 +562,7 @@ export default class PlaylistLoader extends EventTarget {
     window.clearTimeout(this.mediaUpdateTimeout);
     window.clearTimeout(this.finalRenditionTimeout);
     this.dateRangesStorage_ = new DateRangesStorage();
+    this.contentSteering.dispose();
 
     this.off();
   }

src/util/content-steering.js

@@ -0,0 +1,122 @@
+import resolveUrl from '../resolve-url';
+import window from 'global/window';
+
+// Content Steering manifest format
+//
+// VERSION: number (required)
+// TTL: number in seconds (optional), default is 300 seconds.
+// RELOAD-URI: string (optional)
+// SERVICE-LOCATION-PRIORITY or PATHWAY-PRIORITY array of strings (handle quoted and not quoted) (optional) default = false in DASH
+// TODO: add spec references.
+
+/**
+ * This class represents a content steering manifest and associated state.
+ */
+export default class ContentSteering {
+  constructor() {
+    this.version = null;
+    this.ttl = null;
+    this.reloadUri = null;
+    this.cdnPriority = null;
+    this.ttlTimeout = null;
+    this.currentCdn = null;
+    this.request = null;
+  }
+
+  /**
+   * This function will extract the content steering data from both DASH and HLS manifest objects.
+   *
+   * @param {Function} xhr the tech xhr function
+   * @param {string} manifestUri the uri of the main manifest for path resolution
+   * @param {Object} steeringTag the content steering tag from the manifest
+   */
+  handleContentSteeringTags(xhr, manifestUri, steeringTag) {
+    if (!xhr || !steeringTag) {
+      return;
+    }
+    // serverUri is HLS serverURL is DASH
+    const steeringUri = steeringTag.serverUri || steeringTag.serverURL;
+
+    // pathwayId is HLS defaultServiceLocation is DASH
+    this.currentCdn = steeringTag.pathwayId || steeringTag.defaultServiceLocation;
+    // resolve the URI to an absolute URI.
+    const uri = resolveUrl(manifestUri, steeringUri);
+
+    this.requestContentSteeringManifest_(uri, xhr);
+  }
+
+  /**
+   * Requests the steering manifest and parse response.
+   *
+   * @param {string} uri the uri to request the steering manifest from
+   * @param {Function} xhr the tech xhr function
+   */
+  requestContentSteeringManifest_(uri, xhr) {
+    // TODO: Handle steering query parameters.
+    this.request = xhr({
+      uri
+    }, (error) => {
+      if (error) {
+        // TODO: Add error handling.
+      }
+      const steeringManifestJson = JSON.parse(this.request.responseText);
+
+      this.assignSteeringProperties_(steeringManifestJson, uri);
+      this.startTTLTimeout_(uri, xhr);
+    });
+  }
+
+  /**
+   * Assigns the current steering manifest properties and to the ContentSteering class.
+   *
+   * @param {Object} steeringManifest the raw JSON steering manifest
+   * @param {string} baseUri the baseUri for url path resolution
+   */
+  assignSteeringProperties_(steeringManifest, baseUri) {
+    this.version = steeringManifest.VERSION;
+    // time-to-live default = 300 seconds
+    this.ttl = steeringManifest.TTL || 300;
+    // RELOAD-URI is optional and can be relative, if absent use current manifest uri.
+    this.reloadUri = steeringManifest['RELOAD-URI'] ? resolveUrl(baseUri, steeringManifest['RELOAD-URI']) : baseUri;
+    // HLS = PATHWAY-PRIORITY, DASH = SERVICE-LOCATION-PRIORITY default = false
+    this.cdnPriority = steeringManifest['PATHWAY-PRIORITY'] || steeringManifest['SERVICE-LOCATION-PRIORITY'] || false;
+  }
+
+  /**
+   * Start the timeout for re-requesting the steering manifest at the TTL interval.
+   *
+   * @param {string} uri the uri to request the steering manifest from after the ttl interval
+   * @param {Function} xhr the tech xhr function
+   */
+  startTTLTimeout_(uri, xhr) {
+    const ttlMS = this.ttl * 1000;
+
+    this.ttlTimeout = window.setTimeout(() => {
+      this.requestContentSteeringManifest_(uri, xhr);
+    }, ttlMS);
+  }
+
+  /**
+   * Clear the TTL timeout if necessary.
+   */
+  clearTTLTimeout_() {
+    window.clearTimeout(this.ttlTimeout);
+    this.ttlTimeout = null;
+  }
+
+  /**
+   * aborts any current steering xhr and sets the current request object to null
+   */
+  abort() {
+    this.request.abort();
+    this.request = null;
+  }
+
+  /**
+   * aborts and clears the timeout on any steering manifest requests.
+   */
+  dispose() {
+    this.abort();
+    this.clearTTLTimeout_();
+  }
+}