Introduce new logic for HTMLMediaElement.buffered (#3159)

This new logic is aligned with upstream Chromium, and with the [HTML spec](https://html.spec.whatwg.org/#dom-media-buffered): * [HTMLMediaElement::BufferedInternal](https://source.chromium.org/chromium/chromium/src/+/main:third_party/blink/renderer/core/html/media/html_media_element.cc;l=3769-3772;drc=eb7475582501e654b3c0bb94be9fdbadfd6b83a0;bpv=0;bpt=0) * [MediaSource::SeekableInternal](https://source.chromium.org/chromium/chromium/src/+/main:third_party/blink/renderer/modules/mediasource/media_source.cc;l=882-883;drc=d911cdd7a76cdf8895915eae6b88e3bff02a3072;bpv=1;bpt=0) Because this is a potentially disruptive change, the code is gated behind a new H5VCC flag. Use `"MediaElement.EnableUsingMediaSourceBufferedRange"` to enable this change. b/338452286 Change-Id: I52052b2fc5a2c0a1a1c92552434cf53f3bf407e2
youtube · May 7, 2024 · a348ae2 · a348ae2
1 parent 5327e5f
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diff --git a/cobalt/dom/html_media_element.cc b/cobalt/dom/html_media_element.cc
@@ -126,6 +126,27 @@ bool OriginIsSafe(loader::RequestMode request_mode, const GURL& resource_url,
   return false;
 }
 
+const MediaSettings& GetMediaSettings(
+    const web::EnvironmentSettings* settings) {
+  DCHECK(settings);
+  DCHECK(settings->context());
+  DCHECK(settings->context()->web_settings());
+
+  const auto& web_settings = settings->context()->web_settings();
+  return web_settings->media_settings();
+}
+
+// If this function returns true, HTMLMediaElement::buffered() will attempt to
+// call MediaSource::GetBufferedRange() if available, and fallback to
+// WebMediaPlayer::UpdateBufferedTimeRanges().
+// The default value is false.
+bool IsMediaElementUsingMediaSourceBufferedRangeEnabled(
+    const web::EnvironmentSettings* settings) {
+  return GetMediaSettings(settings)
+      .IsMediaElementUsingMediaSourceBufferedRangeEnabled()
+      .value_or(false);
+}
+
 }  // namespace
 
 HTMLMediaElement::HTMLMediaElement(Document* document,
@@ -218,6 +239,17 @@ uint16_t HTMLMediaElement::network_state() const {
 scoped_refptr<TimeRanges> HTMLMediaElement::buffered() const {
   scoped_refptr<TimeRanges> buffered = new TimeRanges;
 
+  DCHECK(node_document());
+  DCHECK(node_document()->html_element_context());
+  DCHECK(node_document()->html_element_context()->environment_settings());
+  const auto* settings =
+      node_document()->html_element_context()->environment_settings();
+  if (IsMediaElementUsingMediaSourceBufferedRangeEnabled(settings)) {
+    if (media_source_) {
+      return media_source_->GetBufferedRange();
+    }
+  }
+
   if (!player_) {
     LOG(INFO) << "(empty)";
     return buffered;

diff --git a/cobalt/dom/media_settings.cc b/cobalt/dom/media_settings.cc
@@ -83,6 +83,12 @@ bool MediaSettingsImpl::Set(const std::string& name, int value) {
       LOG(INFO) << name << ": set to " << value;
       return true;
     }
+  } else if (name == "MediaElement.EnableUsingMediaSourceBufferedRange") {
+    if (value == 0 || value == 1) {
+      is_media_element_using_media_source_buffered_range_enabled_ = value != 0;
+      LOG(INFO) << name << ": set to " << value;
+      return true;
+    }
   } else {
     LOG(WARNING) << "Ignore unknown setting with name \"" << name << "\"";
     return false;

diff --git a/cobalt/dom/media_settings.h b/cobalt/dom/media_settings.h
@@ -42,6 +42,8 @@ class MediaSettings {
   virtual base::Optional<int>
   GetMediaElementTimeupdateEventIntervalInMilliseconds() const = 0;
   virtual base::Optional<bool> IsPaintingVideoBackgroundToBlack() const = 0;
+  virtual base::Optional<bool>
+  IsMediaElementUsingMediaSourceBufferedRangeEnabled() const = 0;
 
  protected:
   MediaSettings() = default;
@@ -93,6 +95,11 @@ class MediaSettingsImpl : public MediaSettings {
   base::Optional<bool> IsPaintingVideoBackgroundToBlack() const override {
     return is_painting_video_background_to_black_;
   }
+  base::Optional<bool> IsMediaElementUsingMediaSourceBufferedRangeEnabled()
+      const override {
+    base::AutoLock auto_lock(lock_);
+    return is_media_element_using_media_source_buffered_range_enabled_;
+  }
 
   // Returns true when the setting associated with `name` is set to `value`.
   // Returns false when `name` is not associated with any settings, or if
@@ -110,6 +117,8 @@ class MediaSettingsImpl : public MediaSettings {
   base::Optional<int> max_source_buffer_append_size_in_bytes_;
 
   base::Optional<int> media_element_timeupdate_event_interval_in_milliseconds_;
+  base::Optional<bool>
+      is_media_element_using_media_source_buffered_range_enabled_;
 
   base::Optional<bool> is_painting_video_background_to_black_;
 };

diff --git a/cobalt/dom/media_settings_test.cc b/cobalt/dom/media_settings_test.cc
@@ -48,6 +48,7 @@ TEST(MediaSettingsImplTest, SunnyDay) {
   ASSERT_TRUE(
       impl.Set("MediaElement.TimeupdateEventIntervalInMilliseconds", 100001));
   ASSERT_TRUE(impl.Set("MediaElement.PaintingVideoBackgroundToBlack", 1));
+  ASSERT_TRUE(impl.Set("MediaElement.EnableUsingMediaSourceBufferedRange", 1));
 
   EXPECT_EQ(impl.GetSourceBufferEvictExtraInBytes().value(), 100);
   EXPECT_EQ(impl.GetMinimumProcessorCountToOffloadAlgorithm().value(), 101);
@@ -59,6 +60,8 @@ TEST(MediaSettingsImplTest, SunnyDay) {
   EXPECT_EQ(impl.GetMediaElementTimeupdateEventIntervalInMilliseconds().value(),
             100001);
   EXPECT_TRUE(impl.IsPaintingVideoBackgroundToBlack().value());
+  EXPECT_TRUE(
+      impl.IsMediaElementUsingMediaSourceBufferedRangeEnabled().value());
 }
 
 TEST(MediaSettingsImplTest, RainyDay) {
@@ -75,6 +78,8 @@ TEST(MediaSettingsImplTest, RainyDay) {
   ASSERT_FALSE(
       impl.Set("MediaElement.TimeupdateEventIntervalInMilliseconds", 0));
   ASSERT_FALSE(impl.Set("MediaElement.PaintingVideoBackgroundToBlack", 2));
+  ASSERT_FALSE(
+      impl.Set("MediaElement.EnableUsingMediaSourceBufferedRange", -101));
 
   EXPECT_FALSE(impl.GetSourceBufferEvictExtraInBytes());
   EXPECT_FALSE(impl.GetMinimumProcessorCountToOffloadAlgorithm());
@@ -85,6 +90,7 @@ TEST(MediaSettingsImplTest, RainyDay) {
   EXPECT_FALSE(impl.GetMaxSourceBufferAppendSizeInBytes());
   EXPECT_FALSE(impl.GetMediaElementTimeupdateEventIntervalInMilliseconds());
   EXPECT_FALSE(impl.IsPaintingVideoBackgroundToBlack());
+  EXPECT_FALSE(impl.IsMediaElementUsingMediaSourceBufferedRangeEnabled());
 }
 
 TEST(MediaSettingsImplTest, ZeroValuesWork) {
@@ -101,6 +107,7 @@ TEST(MediaSettingsImplTest, ZeroValuesWork) {
   // O is an invalid value for
   // "MediaElement.TimeupdateEventIntervalInMilliseconds".
   ASSERT_TRUE(impl.Set("MediaElement.PaintingVideoBackgroundToBlack", 0));
+  ASSERT_TRUE(impl.Set("MediaElement.EnableUsingMediaSourceBufferedRange", 0));
 
   EXPECT_EQ(impl.GetSourceBufferEvictExtraInBytes().value(), 0);
   EXPECT_EQ(impl.GetMinimumProcessorCountToOffloadAlgorithm().value(), 0);
@@ -109,6 +116,8 @@ TEST(MediaSettingsImplTest, ZeroValuesWork) {
   EXPECT_FALSE(impl.IsCallingEndedWhenClosedEnabled().value());
   EXPECT_EQ(impl.GetMaxSizeForImmediateJob().value(), 0);
   EXPECT_FALSE(impl.IsPaintingVideoBackgroundToBlack().value());
+  EXPECT_FALSE(
+      impl.IsMediaElementUsingMediaSourceBufferedRangeEnabled().value());
 }
 
 TEST(MediaSettingsImplTest, Updatable) {
@@ -125,6 +134,7 @@ TEST(MediaSettingsImplTest, Updatable) {
   ASSERT_TRUE(
       impl.Set("MediaElement.TimeupdateEventIntervalInMilliseconds", 1));
   ASSERT_TRUE(impl.Set("MediaElement.PaintingVideoBackgroundToBlack", 0));
+  ASSERT_TRUE(impl.Set("MediaElement.EnableUsingMediaSourceBufferedRange", 0));
 
   ASSERT_TRUE(impl.Set("MediaSource.SourceBufferEvictExtraInBytes", 1));
   ASSERT_TRUE(
@@ -137,6 +147,7 @@ TEST(MediaSettingsImplTest, Updatable) {
   ASSERT_TRUE(
       impl.Set("MediaElement.TimeupdateEventIntervalInMilliseconds", 2));
   ASSERT_TRUE(impl.Set("MediaElement.PaintingVideoBackgroundToBlack", 1));
+  ASSERT_TRUE(impl.Set("MediaElement.EnableUsingMediaSourceBufferedRange", 1));
 
   EXPECT_EQ(impl.GetSourceBufferEvictExtraInBytes().value(), 1);
   EXPECT_EQ(impl.GetMinimumProcessorCountToOffloadAlgorithm().value(), 1);
@@ -148,6 +159,8 @@ TEST(MediaSettingsImplTest, Updatable) {
   EXPECT_EQ(impl.GetMediaElementTimeupdateEventIntervalInMilliseconds().value(),
             2);
   EXPECT_TRUE(impl.IsPaintingVideoBackgroundToBlack().value());
+  EXPECT_TRUE(
+      impl.IsMediaElementUsingMediaSourceBufferedRangeEnabled().value());
 }
 
 TEST(MediaSettingsImplTest, InvalidSettingNames) {

diff --git a/cobalt/dom/media_source.cc b/cobalt/dom/media_source.cc
@@ -131,6 +131,18 @@ int GetMaxSizeForImmediateJob(web::EnvironmentSettings* settings) {
   return max_size;
 }
 
+// If this function returns true, MediaSource::GetSeekable() will short-circuit
+// getting the buffered range from HTMLMediaElement by directly calling to
+// MediaSource::GetBufferedRange(). This reduces potential cross-object,
+// cross-thread calls between MediaSource and HTMLMediaElement.
+// The default value is false.
+bool IsMediaElementUsingMediaSourceBufferedRangeEnabled(
+    web::EnvironmentSettings* settings) {
+  return GetMediaSettings(settings)
+      .IsMediaElementUsingMediaSourceBufferedRangeEnabled()
+      .value_or(false);
+}
+
 }  // namespace
 
 MediaSource::MediaSource(script::EnvironmentSettings* settings)
@@ -498,7 +510,13 @@ scoped_refptr<TimeRanges> MediaSource::GetSeekable() const {
   }
 
   if (source_duration == std::numeric_limits<double>::infinity()) {
-    scoped_refptr<TimeRanges> buffered = attached_element_->buffered();
+    scoped_refptr<TimeRanges> buffered = nullptr;
+    if (IsMediaElementUsingMediaSourceBufferedRangeEnabled(
+            environment_settings())) {
+      buffered = GetBufferedRange();
+    } else {
+      buffered = attached_element_->buffered();
+    }
 
     if (live_seekable_range_->length() != 0) {
       if (buffered->length() == 0) {