Bug 1276184: [MSE] P2. Remove the need to scan the track buffer when frames are being removed. r=kamidphish

The index at which we are removing frames is always the one where we will be inserting the next ones.

MozReview-Commit-ID: DHeJDmwiMS9

--HG--
extra : rebase_source : 3730c0ed7fbdb4d9f8b4157f36aa7bb9d03a6517

dom/media/mediasource/TrackBuffersManager.cpp

@@ -1630,7 +1630,11 @@ TrackBuffersManager::InsertFrames(TrackBuffer& aSamples,
       // so the search for when to start our frames removal can be exhaustive.
       trackBuffer.mNextInsertionIndex.reset();
     }
-    RemoveFrames(aIntervals, trackBuffer, trackBuffer.mNextInsertionIndex.refOr(0));
+    size_t index =
+      RemoveFrames(aIntervals, trackBuffer, trackBuffer.mNextInsertionIndex.refOr(0));
+    if (index) {
+      trackBuffer.mNextInsertionIndex = Some(index);
+    }
   }
 
   // 16. Add the coded frame with the presentation timestamp, decode timestamp, and frame duration to the track buffer.
@@ -1667,7 +1671,7 @@ TrackBuffersManager::InsertFrames(TrackBuffer& aSamples,
   }
 }
 
-void
+size_t
 TrackBuffersManager::RemoveFrames(const TimeIntervals& aIntervals,
                                   TrackData& aTrackData,
                                   uint32_t aStartIndex)
@@ -1699,7 +1703,7 @@ TrackBuffersManager::RemoveFrames(const TimeIntervals& aIntervals,
   }
 
   if (firstRemovedIndex.isNothing()) {
-    return;
+    return 0;
   }
 
   // Remove decoding dependencies of the coded frames removed in the previous step:
@@ -1763,6 +1767,8 @@ TrackBuffersManager::RemoveFrames(const TimeIntervals& aIntervals,
 
   data.RemoveElementsAt(firstRemovedIndex.ref(),
                         lastRemovedIndex - firstRemovedIndex.ref() + 1);
+
+  return firstRemovedIndex.ref();
 }
 
 void

dom/media/mediasource/TrackBuffersManager.h

@@ -341,9 +341,12 @@ private:
   void InsertFrames(TrackBuffer& aSamples,
                     const media::TimeIntervals& aIntervals,
                     TrackData& aTrackData);
-  void RemoveFrames(const media::TimeIntervals& aIntervals,
-                    TrackData& aTrackData,
-                    uint32_t aStartIndex);
+  // Remove all frames and their dependencies contained in aIntervals.
+  // Return the index at which frames were first removed or 0 if no frames
+  // removed.
+  size_t RemoveFrames(const media::TimeIntervals& aIntervals,
+                      TrackData& aTrackData,
+                      uint32_t aStartIndex);
   // Find index of sample. Return a negative value if not found.
   uint32_t FindSampleIndex(const TrackBuffer& aTrackBuffer,
                            const media::TimeInterval& aInterval);