[MSE] Reuse "fudge factor" when samples are removed

https://bugs.webkit.org/show_bug.cgi?id=258869

Reviewed by Xabier Rodriguez-Calvar.

Currently when TrackBuffer::removeSamples is called and erasedRanged is created from the samples,
removing small gaps between samples is not done. It causes that in some cases many separated ranges
are created which has impact on performance of removing samples.

Reusing "eliminate small gap" mechanism from SourceBufferPrivate::processMediaSample solves the problem.

* Source/WebCore/html/TimeRanges.cpp:
(WebCore::TimeRanges::add):
* Source/WebCore/html/TimeRanges.h:
* Source/WebCore/platform/graphics/PlatformTimeRanges.cpp:
(WebCore::PlatformTimeRanges::timeFudgeFactor):
(WebCore::PlatformTimeRanges::add):
* Source/WebCore/platform/graphics/PlatformTimeRanges.h:
* Source/WebCore/platform/graphics/SourceBufferPrivate.cpp:
(WebCore::SourceBufferPrivate::processMediaSample):
* Source/WebCore/platform/graphics/SourceBufferPrivate.h:
(WebCore::SourceBufferPrivate::timeFudgeFactor const):
* Source/WebCore/platform/graphics/TrackBuffer.cpp:
(WebCore::TrackBuffer::addBufferedRange):
(WebCore::TrackBuffer::removeSamples):
* Source/WebCore/platform/graphics/TrackBuffer.h:
* Tools/TestWebKitAPI/Tests/WebCore/TimeRanges.cpp:
(TestWebKitAPI::TEST):

Canonical link: https://commits.webkit.org/266357@main

Source/WebCore/html/TimeRanges.cpp

@@ -100,9 +100,9 @@ unsigned TimeRanges::length() const
     return m_ranges.length();
 }
 
-void TimeRanges::add(double start, double end)
+void TimeRanges::add(double start, double end, AddTimeRangeOption addTimeRangeOption)
 {
-    m_ranges.add(MediaTime::createWithDouble(start), MediaTime::createWithDouble(end));
+    m_ranges.add(MediaTime::createWithDouble(start), MediaTime::createWithDouble(end), addTimeRangeOption);
 }
 
 bool TimeRanges::contain(double time) const

Source/WebCore/html/TimeRanges.h

@@ -46,7 +46,7 @@ class TimeRanges : public RefCounted<TimeRanges> {
 
     WEBCORE_EXPORT unsigned length() const;
 
-    WEBCORE_EXPORT void add(double start, double end);
+    WEBCORE_EXPORT void add(double start, double end, AddTimeRangeOption = AddTimeRangeOption::None);
     bool contain(double time) const;
 
     size_t find(double time) const;

Source/WebCore/platform/graphics/PlatformTimeRanges.cpp

@@ -57,6 +57,11 @@ const PlatformTimeRanges& PlatformTimeRanges::emptyRanges()
     return emptyRanges.get();
 }
 
+MediaTime PlatformTimeRanges::timeFudgeFactor()
+{
+    return { 2002, 24000 };
+}
+
 void PlatformTimeRanges::invert()
 {
     PlatformTimeRanges inverted;
@@ -192,16 +197,29 @@ MediaTime PlatformTimeRanges::minimumBufferedTime() const
     return m_ranges[0].start;
 }
 
-void PlatformTimeRanges::add(const MediaTime& start, const MediaTime& end)
+void PlatformTimeRanges::add(const MediaTime& start, const MediaTime& end, AddTimeRangeOption addTimeRangeOption)
 {
 #if !PLATFORM(MAC) // https://bugs.webkit.org/show_bug.cgi?id=180253
     ASSERT(start.isValid());
     ASSERT(end.isValid());
 #endif
     ASSERT(start <= end);
 
+    auto startTime = start;
+    auto endTime = end;
+    if (addTimeRangeOption == AddTimeRangeOption::EliminateSmallGaps) {
+        // Eliminate small gaps between buffered ranges by coalescing
+        // disjoint ranges separated by less than a "fudge factor".
+        auto nearestToPresentationStartTime = nearest(startTime);
+        if (nearestToPresentationStartTime.isValid() && (startTime - nearestToPresentationStartTime).isBetween(MediaTime::zeroTime(), timeFudgeFactor()))
+            startTime = nearestToPresentationStartTime;
+
+        auto nearestToPresentationEndTime = nearest(endTime);
+        if (nearestToPresentationEndTime.isValid() && (nearestToPresentationEndTime - endTime).isBetween(MediaTime::zeroTime(), timeFudgeFactor()))
+            endTime = nearestToPresentationEndTime;
+    }
     size_t overlappingArcIndex;
-    Range addedRange { .start = start, .end = end };
+    Range addedRange { .start = startTime, .end = endTime };
 
     // For each present range check if we need to:
     // - merge with the added range, in case we are overlapping or contiguous

Source/WebCore/platform/graphics/PlatformTimeRanges.h

@@ -36,6 +36,11 @@ class PrintStream;
 
 namespace WebCore {
 
+enum class AddTimeRangeOption : uint8_t {
+    None,
+    EliminateSmallGaps,
+};
+
 class WEBCORE_EXPORT PlatformTimeRanges final {
     WTF_MAKE_FAST_ALLOCATED;
 public:
@@ -45,6 +50,7 @@ class WEBCORE_EXPORT PlatformTimeRanges final {
     PlatformTimeRanges copyWithEpsilon(const MediaTime&) const;
 
     static const PlatformTimeRanges& emptyRanges();
+    static MediaTime timeFudgeFactor();
 
     MediaTime start(unsigned index) const;
     MediaTime start(unsigned index, bool& valid) const;
@@ -62,7 +68,7 @@ class WEBCORE_EXPORT PlatformTimeRanges final {
 
     unsigned length() const { return m_ranges.size(); }
 
-    void add(const MediaTime& start, const MediaTime& end);
+    void add(const MediaTime& start, const MediaTime& end, AddTimeRangeOption = AddTimeRangeOption::None);
     void clear();
 
     bool contain(const MediaTime&) const;

Source/WebCore/platform/graphics/SourceBufferPrivate.cpp

@@ -1218,18 +1218,8 @@ void SourceBufferPrivate::processMediaSample(Ref<MediaSample>&& sample)
             resetTimestampOffsetInTrackBuffers();
         }
 
-        // Eliminate small gaps between buffered ranges by coalescing
-        // disjoint ranges separated by less than a "fudge factor".
         auto presentationEndTime = presentationTimestamp + frameDuration;
-        auto nearestToPresentationStartTime = trackBuffer.buffered().nearest(presentationTimestamp);
-        if (nearestToPresentationStartTime.isValid() && (presentationTimestamp - nearestToPresentationStartTime).isBetween(MediaTime::zeroTime(), timeFudgeFactor()))
-            presentationTimestamp = nearestToPresentationStartTime;
-
-        auto nearestToPresentationEndTime = trackBuffer.buffered().nearest(presentationEndTime);
-        if (nearestToPresentationEndTime.isValid() && (nearestToPresentationEndTime - presentationEndTime).isBetween(MediaTime::zeroTime(), timeFudgeFactor()))
-            presentationEndTime = nearestToPresentationEndTime;
-
-        trackBuffer.addBufferedRange(presentationTimestamp, presentationEndTime);
+        trackBuffer.addBufferedRange(presentationTimestamp, presentationEndTime, AddTimeRangeOption::EliminateSmallGaps);
         m_client->sourceBufferPrivateDidParseSample(frameDuration.toDouble());
 
         break;

Source/WebCore/platform/graphics/SourceBufferPrivate.h

@@ -162,7 +162,7 @@ class SourceBufferPrivate
 
     virtual void appendInternal(Ref<SharedBuffer>&&) = 0;
     virtual void resetParserStateInternal() = 0;
-    virtual MediaTime timeFudgeFactor() const { return { 2002, 24000 }; }
+    virtual MediaTime timeFudgeFactor() const { return PlatformTimeRanges::timeFudgeFactor(); }
     virtual bool isActive() const { return false; }
     virtual bool isSeeking() const { return false; }
     virtual MediaTime currentMediaTime() const { return { }; }

Source/WebCore/platform/graphics/TrackBuffer.cpp

@@ -67,9 +67,9 @@ MediaTime TrackBuffer::maximumBufferedTime() const
     return m_buffered.maximumBufferedTime();
 }
 
-void TrackBuffer::addBufferedRange(const MediaTime& start, const MediaTime& end)
+void TrackBuffer::addBufferedRange(const MediaTime& start, const MediaTime& end, AddTimeRangeOption addTimeRangeOption)
 {
-    m_buffered.add(start, end);
+    m_buffered.add(start, end, addTimeRangeOption);
 }
 
 void TrackBuffer::addSample(MediaSample& sample)
@@ -198,7 +198,7 @@ PlatformTimeRanges TrackBuffer::removeSamples(const DecodeOrderSampleMap::MapTyp
 
         auto startTime = sample->presentationTime();
         auto endTime = startTime + sample->duration();
-        erasedRanges.add(startTime, endTime);
+        erasedRanges.add(startTime, endTime, AddTimeRangeOption::EliminateSmallGaps);
 
 #if !RELEASE_LOG_DISABLED
         bytesRemoved += startBufferSize - m_samples.sizeInBytes();

Source/WebCore/platform/graphics/TrackBuffer.h

@@ -49,7 +49,7 @@ class TrackBuffer final
     static UniqueRef<TrackBuffer> create(RefPtr<MediaDescription>&&, const MediaTime&);
 
     MediaTime maximumBufferedTime() const;
-    void addBufferedRange(const MediaTime& start, const MediaTime& end);
+    void addBufferedRange(const MediaTime& start, const MediaTime& end, AddTimeRangeOption = AddTimeRangeOption::None);
     void addSample(MediaSample&);
 
     bool updateMinimumUpcomingPresentationTime();

Tools/TestWebKitAPI/Tests/WebCore/TimeRanges.cpp

@@ -287,5 +287,34 @@ TEST(TimeRanges, IntersectWith_Gaps3)
     ASSERT_RANGE("{ [1,5) [6,9) }", rangesB);
 }
 
+TEST(TimeRanges, Add_SmallGaps)
+{
+    RefPtr<TimeRanges> ranges = TimeRanges::create();
+
+    const MediaTime duration { MediaTime::createWithDouble(1.0) };
+    const double smallGap { 0.001 };
+    const unsigned numberOfSamples { 10 };
+
+    for (unsigned i = 0; i < numberOfSamples; ++i) {
+        const double start = duration.toDouble() * i;
+        const double end = start + duration.toDouble() - smallGap;
+
+        ranges->add(start, end, AddTimeRangeOption::None);
+    }
+
+    EXPECT_EQ(numberOfSamples, ranges->length());
+
+    ranges = TimeRanges::create();
+
+    for (unsigned i = 0; i < numberOfSamples; ++i) {
+        const double start = duration.toDouble() * i;
+        const double end = start + duration.toDouble() - smallGap;
+
+        ranges->add(start, end, AddTimeRangeOption::EliminateSmallGaps);
+    }
+
+    EXPECT_EQ(1u, ranges->length());
+}
+
 }