fix(DASH): Clear streamMap when period is removed from the manifest (#…

…7202)

Related to #6239 and
#7148
Remove the reference to the stream when is no more needed.

---------

Co-authored-by: Wojciech Tyczyński <tykus160@gmail.com>

lib/dash/dash_parser.js

@@ -92,12 +92,19 @@ shaka.dash.DashParser = class {
 
     /**
      * A map of IDs to Stream objects.
-     * ID: Period@id,AdaptationSet@id,@Representation@id
-     * e.g.: '1,5,23'
+     * ID: Period@id,Representation@id
+     * e.g.: '1,23'
      * @private {!Object.<string, !shaka.extern.Stream>}
      */
     this.streamMap_ = {};
 
+    /**
+     * A map of Period IDs to Stream Map IDs.
+     * Use to have direct access to streamMap key.
+     * @private {!Object.<string, !Array<string>>}
+     */
+    this.indexStreamMap_ = {};
+
     /**
      * A map of period ids to their durations
      * @private {!Object.<string, number>}
@@ -235,6 +242,7 @@ shaka.dash.DashParser = class {
     this.manifestUris_ = [];
     this.manifest_ = null;
     this.streamMap_ = {};
+    this.indexStreamMap_ = {};
     this.contextCache_.clear();
     this.manifestPatchContext_ = {
       mpdId: '',
@@ -618,7 +626,7 @@ shaka.dash.DashParser = class {
     }
 
     this.manifestPatchContext_.type = mpdType;
-
+    this.cleanStreamMap_();
     /** @type {!shaka.media.PresentationTimeline} */
     let presentationTimeline;
     if (this.manifest_) {
@@ -697,7 +705,8 @@ shaka.dash.DashParser = class {
       profiles: profiles.split(','),
     };
 
-    const periodsAndDuration = this.parsePeriods_(context, getBaseUris, mpd);
+    const periodsAndDuration = this.parsePeriods_(
+        context, getBaseUris, mpd, /* newPeriod= */ false);
     const duration = periodsAndDuration.duration;
     const periods = periodsAndDuration.periods;
 
@@ -977,7 +986,7 @@ shaka.dash.DashParser = class {
     };
 
     const periodsAndDuration = this.parsePeriods_(context,
-        this.manifestPatchContext_.getBaseUris, periods);
+        this.manifestPatchContext_.getBaseUris, periods, /* newPeriod= */ true);
 
     return periodsAndDuration.periods;
   }
@@ -996,6 +1005,10 @@ shaka.dash.DashParser = class {
         this.contextCache_.delete(contextId);
       }
     }
+    const newPeriods = this.lastManifestUpdatePeriodIds_.filter((pID) => {
+      return pID !== periodId;
+    });
+    this.lastManifestUpdatePeriodIds_ = newPeriods;
   }
 
   /**
@@ -1237,14 +1250,15 @@ shaka.dash.DashParser = class {
    * @param {shaka.dash.DashParser.Context} context
    * @param {function():!Array.<string>} getBaseUris
    * @param {!shaka.extern.xml.Node} mpd
+   * @param {!boolean} newPeriod
    * @return {{
    *   periods: !Array.<shaka.extern.Period>,
    *   duration: ?number,
    *   durationDerivedFromPeriods: boolean
    * }}
    * @private
    */
-  parsePeriods_(context, getBaseUris, mpd) {
+  parsePeriods_(context, getBaseUris, mpd, newPeriod) {
     const TXml = shaka.util.TXml;
     let presentationDuration = context.mediaPresentationDuration;
 
@@ -1370,8 +1384,18 @@ shaka.dash.DashParser = class {
       prevEnd = start + periodDuration;
     } // end of period parsing loop
 
-    // Replace previous seen periods with the current one.
-    this.lastManifestUpdatePeriodIds_ = periods.map((el) => el.id);
+    if (newPeriod) {
+      // append new period from the patch manifest
+      for (const el of periods) {
+        const periodID = el.id;
+        if (!this.lastManifestUpdatePeriodIds_.includes(periodID)) {
+          this.lastManifestUpdatePeriodIds_.push(periodID);
+        }
+      }
+    } else {
+      // Replace previous seen periods with the current one.
+      this.lastManifestUpdatePeriodIds_ = periods.map((el) => el.id);
+    }
 
     if (presentationDuration != null) {
       if (prevEnd != null) {
@@ -1399,6 +1423,26 @@ shaka.dash.DashParser = class {
     }
   }
 
+  /**
+   * Clean StreamMap Object to remove reference of deleted Stream Object
+   * @private
+   */
+  cleanStreamMap_() {
+    const oldPeriodIds = Object.keys(this.indexStreamMap_);
+    if (oldPeriodIds.length === this.lastManifestUpdatePeriodIds_.length) {
+      return;
+    }
+    const diffPeriodsIDs = oldPeriodIds.filter((pId) => {
+      return !this.lastManifestUpdatePeriodIds_.includes(pId);
+    });
+    for (const pId of diffPeriodsIDs) {
+      for (const contextId of this.indexStreamMap_[pId]) {
+        delete this.streamMap_[contextId];
+      }
+      delete this.indexStreamMap_[pId];
+    }
+  }
+
   /**
    * Parses a Period XML element.  Unlike the other parse methods, this is not
    * given the Node; it is given a PeriodInfo structure.  Also, partial parsing
@@ -2184,7 +2228,12 @@ shaka.dash.DashParser = class {
     };
 
     if (contextId && context.dynamic && !this.streamMap_[contextId]) {
+      const periodId = context.period.id || '';
+      if (!this.indexStreamMap_[periodId]) {
+        this.indexStreamMap_[periodId] = [];
+      }
       this.streamMap_[contextId] = stream;
+      this.indexStreamMap_[periodId].push(contextId);
     }
 
     return stream;