diff --git a/video/BUILD.gn b/video/BUILD.gn
index bc026d2..2ef8473 100644
--- a/video/BUILD.gn
+++ b/video/BUILD.gn
@@ -38,6 +38,8 @@
     "stream_synchronization.h",
     "transport_adapter.cc",
     "transport_adapter.h",
+    "video_quality_observer.cc",
+    "video_quality_observer.h",
     "video_receive_stream.cc",
     "video_receive_stream.h",
     "video_send_stream.cc",
diff --git a/video/receive_statistics_proxy.cc b/video/receive_statistics_proxy.cc
index 2cccd5a..2fd5d9b 100644
--- a/video/receive_statistics_proxy.cc
+++ b/video/receive_statistics_proxy.cc
@@ -106,11 +106,14 @@
       render_fps_tracker_(100, 10u),
       render_pixel_tracker_(100, 10u),
       total_byte_tracker_(100, 10u),  // bucket_interval_ms, bucket_count
+      video_quality_observer_(
+          new VideoQualityObserver(VideoContentType::UNSPECIFIED)),
       interframe_delay_max_moving_(kMovingMaxWindowMs),
       freq_offset_counter_(clock, nullptr, kFreqOffsetProcessIntervalMs),
       first_report_block_time_ms_(-1),
       avg_rtt_ms_(0),
       last_content_type_(VideoContentType::UNSPECIFIED),
+      last_codec_type_(kVideoCodecVP8),
       timing_frame_info_counter_(kMovingMaxWindowMs) {
   decode_thread_.DetachFromThread();
   network_thread_.DetachFromThread();
@@ -147,13 +150,14 @@
                << stream_duration_sec << '\n';
   }
 
-  log_stream << "Frames decoded " << stats_.frames_decoded;
+  log_stream << "Frames decoded " << stats_.frames_decoded << '\n';
 
   if (num_unique_frames_) {
     int num_dropped_frames = *num_unique_frames_ - stats_.frames_decoded;
     RTC_HISTOGRAM_COUNTS_1000("WebRTC.Video.DroppedFrames.Receiver",
                               num_dropped_frames);
-    log_stream << "WebRTC.Video.DroppedFrames.Receiver " << num_dropped_frames;
+    log_stream << "WebRTC.Video.DroppedFrames.Receiver " << num_dropped_frames
+               << '\n';
   }
 
   if (first_report_block_time_ms_ != -1 &&
@@ -680,12 +684,30 @@
     total_byte_tracker_.AddSamples(total_bytes - last_total_bytes);
 }
 
+// Deprecated. TODO(ilnik): remove once all depending projects are updated.
 void ReceiveStatisticsProxy::OnDecodedFrame(rtc::Optional<uint8_t> qp,
                                             VideoContentType content_type) {
+  OnDecodedFrame(qp, 0, 0, content_type);
+}
+
+void ReceiveStatisticsProxy::OnDecodedFrame(rtc::Optional<uint8_t> qp,
+                                            int width,
+                                            int height,
+                                            VideoContentType content_type) {
   rtc::CritScope lock(&crit_);
 
   uint64_t now = clock_->TimeInMilliseconds();
 
+  if (videocontenttypehelpers::IsScreenshare(content_type) !=
+      videocontenttypehelpers::IsScreenshare(last_content_type_)) {
+    // Reset the quality observer if content type is switched. This will
+    // report stats for the previous part of the call.
+    video_quality_observer_.reset(new VideoQualityObserver(content_type));
+  }
+
+  video_quality_observer_->OnDecodedFrame(qp, width, height, now,
+                                          last_codec_type_);
+
   ContentSpecificStats* content_specific_stats =
       &content_specific_stats_[content_type];
   ++stats_.frames_decoded;
@@ -809,9 +831,10 @@
   if (!codec_specific_info || encoded_image.qp_ == -1) {
     return;
   }
-  if (codec_specific_info->codecType == kVideoCodecVP8) {
+  rtc::CritScope lock(&crit_);
+  last_codec_type_ = codec_specific_info->codecType;
+  if (last_codec_type_ == kVideoCodecVP8) {
     qp_counters_.vp8.Add(encoded_image.qp_);
-    rtc::CritScope lock(&crit_);
     qp_sample_.Add(encoded_image.qp_);
   }
 }
@@ -822,6 +845,7 @@
   rtc::CritScope lock(&crit_);
   // Don't report inter-frame delay if stream was paused.
   last_decoded_frame_time_ms_.reset();
+  video_quality_observer_->OnStreamInactive();
 }
 
 void ReceiveStatisticsProxy::OnRttUpdate(int64_t avg_rtt_ms,
diff --git a/video/receive_statistics_proxy.h b/video/receive_statistics_proxy.h
index 9a2185e..72fd2b2 100644
--- a/video/receive_statistics_proxy.h
+++ b/video/receive_statistics_proxy.h
@@ -12,6 +12,7 @@
 #define VIDEO_RECEIVE_STATISTICS_PROXY_H_
 
 #include <map>
+#include <memory>
 #include <string>
 #include <vector>
 
@@ -31,6 +32,7 @@
 #include "video/quality_threshold.h"
 #include "video/report_block_stats.h"
 #include "video/stats_counter.h"
+#include "video/video_quality_observer.h"
 #include "video/video_stream_decoder.h"
 
 namespace webrtc {
@@ -50,7 +52,14 @@
 
   VideoReceiveStream::Stats GetStats() const;
 
-  void OnDecodedFrame(rtc::Optional<uint8_t> qp, VideoContentType content_type);
+  // Deprecated. TODO(ilnik): remove once all depending projects are updated.
+  RTC_DEPRECATED void OnDecodedFrame(rtc::Optional<uint8_t> qp,
+                                     VideoContentType content_type);
+
+  void OnDecodedFrame(rtc::Optional<uint8_t> qp,
+                      int width,
+                      int height,
+                      VideoContentType content_type);
   void OnSyncOffsetUpdated(int64_t sync_offset_ms, double estimated_freq_khz);
   void OnRenderedFrame(const VideoFrame& frame);
   void OnIncomingPayloadType(int payload_type);
@@ -163,6 +172,8 @@
   rtc::SampleCounter target_delay_counter_ RTC_GUARDED_BY(crit_);
   rtc::SampleCounter current_delay_counter_ RTC_GUARDED_BY(crit_);
   rtc::SampleCounter delay_counter_ RTC_GUARDED_BY(crit_);
+  std::unique_ptr<VideoQualityObserver> video_quality_observer_
+      RTC_GUARDED_BY(crit_);
   mutable rtc::MovingMaxCounter<int> interframe_delay_max_moving_
       RTC_GUARDED_BY(crit_);
   std::map<VideoContentType, ContentSpecificStats> content_specific_stats_
@@ -175,6 +186,7 @@
   int64_t avg_rtt_ms_ RTC_GUARDED_BY(crit_);
   mutable std::map<int64_t, size_t> frame_window_ RTC_GUARDED_BY(&crit_);
   VideoContentType last_content_type_ RTC_GUARDED_BY(&crit_);
+  VideoCodecType last_codec_type_ RTC_GUARDED_BY(&crit_);
   rtc::Optional<int64_t> first_decoded_frame_time_ms_ RTC_GUARDED_BY(&crit_);
   rtc::Optional<int64_t> last_decoded_frame_time_ms_ RTC_GUARDED_BY(&crit_);
   // Mutable because calling Max() on MovingMaxCounter is not const. Yet it is
diff --git a/video/receive_statistics_proxy_unittest.cc b/video/receive_statistics_proxy_unittest.cc
index d604429..f61f086 100644
--- a/video/receive_statistics_proxy_unittest.cc
+++ b/video/receive_statistics_proxy_unittest.cc
@@ -28,6 +28,10 @@
 const uint32_t kLocalSsrc = 123;
 const uint32_t kRemoteSsrc = 456;
 const int kMinRequiredSamples = 200;
+
+const int kWidth = 1280;
+const int kHeight = 720;
+
 }  // namespace
 
 // TODO(sakal): ReceiveStatisticsProxy is lacking unittesting.
@@ -70,7 +74,7 @@
 TEST_F(ReceiveStatisticsProxyTest, OnDecodedFrameIncreasesFramesDecoded) {
   EXPECT_EQ(0u, statistics_proxy_->GetStats().frames_decoded);
   for (uint32_t i = 1; i <= 3; ++i) {
-    statistics_proxy_->OnDecodedFrame(rtc::nullopt,
+    statistics_proxy_->OnDecodedFrame(rtc::nullopt, kWidth, kHeight,
                                       VideoContentType::UNSPECIFIED);
     EXPECT_EQ(i, statistics_proxy_->GetStats().frames_decoded);
   }
@@ -80,7 +84,7 @@
   const int kFps = 20;
   const int kRequiredSamples = metrics::kMinRunTimeInSeconds * kFps;
   for (int i = 0; i < kRequiredSamples; ++i) {
-    statistics_proxy_->OnDecodedFrame(rtc::Optional<uint8_t>(),
+    statistics_proxy_->OnDecodedFrame(rtc::Optional<uint8_t>(), kWidth, kHeight,
                                       VideoContentType::UNSPECIFIED);
     fake_clock_.AdvanceTimeMilliseconds(1000 / kFps);
   }
@@ -93,7 +97,7 @@
   const int kFps = 20;
   const int kRequiredSamples = metrics::kMinRunTimeInSeconds * kFps;
   for (int i = 0; i < kRequiredSamples - 1; ++i) {
-    statistics_proxy_->OnDecodedFrame(rtc::Optional<uint8_t>(),
+    statistics_proxy_->OnDecodedFrame(rtc::Optional<uint8_t>(), kWidth, kHeight,
                                       VideoContentType::UNSPECIFIED);
     fake_clock_.AdvanceTimeMilliseconds(1000 / kFps);
   }
@@ -104,15 +108,15 @@
 TEST_F(ReceiveStatisticsProxyTest, DecodedFpsIsReportedWithQpReset) {
   const int kFps1 = 10;
   for (int i = 0; i < metrics::kMinRunTimeInSeconds * kFps1; ++i) {
-    statistics_proxy_->OnDecodedFrame(rtc::Optional<uint8_t>(),
+    statistics_proxy_->OnDecodedFrame(rtc::Optional<uint8_t>(), kWidth, kHeight,
                                       VideoContentType::UNSPECIFIED);
     fake_clock_.AdvanceTimeMilliseconds(1000 / kFps1);
   }
   // First QP value received, resets frames decoded.
   const int kFps2 = 20;
   for (int i = 0; i < metrics::kMinRunTimeInSeconds * kFps2; ++i) {
-    statistics_proxy_->OnDecodedFrame(rtc::Optional<uint8_t>(1u),
-                                      VideoContentType::UNSPECIFIED);
+    statistics_proxy_->OnDecodedFrame(rtc::Optional<uint8_t>(1u), kWidth,
+                                      kHeight, VideoContentType::UNSPECIFIED);
     fake_clock_.AdvanceTimeMilliseconds(1000 / kFps2);
   }
   statistics_proxy_.reset();
@@ -124,19 +128,22 @@
 TEST_F(ReceiveStatisticsProxyTest, OnDecodedFrameWithQpResetsFramesDecoded) {
   EXPECT_EQ(0u, statistics_proxy_->GetStats().frames_decoded);
   for (uint32_t i = 1; i <= 3; ++i) {
-    statistics_proxy_->OnDecodedFrame(rtc::nullopt,
+    statistics_proxy_->OnDecodedFrame(rtc::nullopt, kWidth, kHeight,
                                       VideoContentType::UNSPECIFIED);
     EXPECT_EQ(i, statistics_proxy_->GetStats().frames_decoded);
   }
-  statistics_proxy_->OnDecodedFrame(1u, VideoContentType::UNSPECIFIED);
+  statistics_proxy_->OnDecodedFrame(1u, kWidth, kHeight,
+                                    VideoContentType::UNSPECIFIED);
   EXPECT_EQ(1u, statistics_proxy_->GetStats().frames_decoded);
 }
 
 TEST_F(ReceiveStatisticsProxyTest, OnDecodedFrameIncreasesQpSum) {
   EXPECT_EQ(rtc::nullopt, statistics_proxy_->GetStats().qp_sum);
-  statistics_proxy_->OnDecodedFrame(3u, VideoContentType::UNSPECIFIED);
+  statistics_proxy_->OnDecodedFrame(3u, kWidth, kHeight,
+                                    VideoContentType::UNSPECIFIED);
   EXPECT_EQ(3u, statistics_proxy_->GetStats().qp_sum);
-  statistics_proxy_->OnDecodedFrame(127u, VideoContentType::UNSPECIFIED);
+  statistics_proxy_->OnDecodedFrame(127u, kWidth, kHeight,
+                                    VideoContentType::UNSPECIFIED);
   EXPECT_EQ(130u, statistics_proxy_->GetStats().qp_sum);
 }
 
@@ -145,10 +152,12 @@
   const std::string kScreenshareString("screen");
   EXPECT_EQ(kRealtimeString, videocontenttypehelpers::ToString(
                             statistics_proxy_->GetStats().content_type));
-  statistics_proxy_->OnDecodedFrame(3u, VideoContentType::SCREENSHARE);
+  statistics_proxy_->OnDecodedFrame(3u, kWidth, kHeight,
+                                    VideoContentType::SCREENSHARE);
   EXPECT_EQ(kScreenshareString, videocontenttypehelpers::ToString(
                           statistics_proxy_->GetStats().content_type));
-  statistics_proxy_->OnDecodedFrame(3u, VideoContentType::UNSPECIFIED);
+  statistics_proxy_->OnDecodedFrame(3u, kWidth, kHeight,
+                                    VideoContentType::UNSPECIFIED);
   EXPECT_EQ(kRealtimeString, videocontenttypehelpers::ToString(
                             statistics_proxy_->GetStats().content_type));
 }
@@ -158,21 +167,25 @@
   const int64_t kInterframeDelayMs2 = 200;
   const int64_t kInterframeDelayMs3 = 100;
   EXPECT_EQ(-1, statistics_proxy_->GetStats().interframe_delay_max_ms);
-  statistics_proxy_->OnDecodedFrame(3u, VideoContentType::UNSPECIFIED);
+  statistics_proxy_->OnDecodedFrame(3u, kWidth, kHeight,
+                                    VideoContentType::UNSPECIFIED);
   EXPECT_EQ(-1, statistics_proxy_->GetStats().interframe_delay_max_ms);
 
   fake_clock_.AdvanceTimeMilliseconds(kInterframeDelayMs1);
-  statistics_proxy_->OnDecodedFrame(127u, VideoContentType::UNSPECIFIED);
+  statistics_proxy_->OnDecodedFrame(127u, kWidth, kHeight,
+                                    VideoContentType::UNSPECIFIED);
   EXPECT_EQ(kInterframeDelayMs1,
             statistics_proxy_->GetStats().interframe_delay_max_ms);
 
   fake_clock_.AdvanceTimeMilliseconds(kInterframeDelayMs2);
-  statistics_proxy_->OnDecodedFrame(127u, VideoContentType::UNSPECIFIED);
+  statistics_proxy_->OnDecodedFrame(127u, kWidth, kHeight,
+                                    VideoContentType::UNSPECIFIED);
   EXPECT_EQ(kInterframeDelayMs2,
             statistics_proxy_->GetStats().interframe_delay_max_ms);
 
   fake_clock_.AdvanceTimeMilliseconds(kInterframeDelayMs3);
-  statistics_proxy_->OnDecodedFrame(127u, VideoContentType::UNSPECIFIED);
+  statistics_proxy_->OnDecodedFrame(127u, kWidth, kHeight,
+                                    VideoContentType::UNSPECIFIED);
   // kInterframeDelayMs3 is smaller than kInterframeDelayMs2.
   EXPECT_EQ(kInterframeDelayMs2,
             statistics_proxy_->GetStats().interframe_delay_max_ms);
@@ -183,22 +196,26 @@
   const int64_t kInterframeDelayMs2 = 750;
   const int64_t kInterframeDelayMs3 = 700;
   EXPECT_EQ(-1, statistics_proxy_->GetStats().interframe_delay_max_ms);
-  statistics_proxy_->OnDecodedFrame(3u, VideoContentType::UNSPECIFIED);
+  statistics_proxy_->OnDecodedFrame(3u, kWidth, kHeight,
+                                    VideoContentType::UNSPECIFIED);
   EXPECT_EQ(-1, statistics_proxy_->GetStats().interframe_delay_max_ms);
 
   fake_clock_.AdvanceTimeMilliseconds(kInterframeDelayMs1);
-  statistics_proxy_->OnDecodedFrame(127u, VideoContentType::UNSPECIFIED);
+  statistics_proxy_->OnDecodedFrame(127u, kWidth, kHeight,
+                                    VideoContentType::UNSPECIFIED);
   EXPECT_EQ(kInterframeDelayMs1,
             statistics_proxy_->GetStats().interframe_delay_max_ms);
 
   fake_clock_.AdvanceTimeMilliseconds(kInterframeDelayMs2);
-  statistics_proxy_->OnDecodedFrame(127u, VideoContentType::UNSPECIFIED);
+  statistics_proxy_->OnDecodedFrame(127u, kWidth, kHeight,
+                                    VideoContentType::UNSPECIFIED);
   // Still first delay is the maximum
   EXPECT_EQ(kInterframeDelayMs1,
             statistics_proxy_->GetStats().interframe_delay_max_ms);
 
   fake_clock_.AdvanceTimeMilliseconds(kInterframeDelayMs3);
-  statistics_proxy_->OnDecodedFrame(127u, VideoContentType::UNSPECIFIED);
+  statistics_proxy_->OnDecodedFrame(127u, kWidth, kHeight,
+                                    VideoContentType::UNSPECIFIED);
   // Now the first sample is out of the window, so the second is the maximum.
   EXPECT_EQ(kInterframeDelayMs2,
             statistics_proxy_->GetStats().interframe_delay_max_ms);
@@ -206,16 +223,17 @@
 
 TEST_F(ReceiveStatisticsProxyTest, OnDecodedFrameWithoutQpQpSumWontExist) {
   EXPECT_EQ(rtc::nullopt, statistics_proxy_->GetStats().qp_sum);
-  statistics_proxy_->OnDecodedFrame(rtc::nullopt,
+  statistics_proxy_->OnDecodedFrame(rtc::nullopt, kWidth, kHeight,
                                     VideoContentType::UNSPECIFIED);
   EXPECT_EQ(rtc::nullopt, statistics_proxy_->GetStats().qp_sum);
 }
 
 TEST_F(ReceiveStatisticsProxyTest, OnDecodedFrameWithoutQpResetsQpSum) {
   EXPECT_EQ(rtc::nullopt, statistics_proxy_->GetStats().qp_sum);
-  statistics_proxy_->OnDecodedFrame(3u, VideoContentType::UNSPECIFIED);
+  statistics_proxy_->OnDecodedFrame(3u, kWidth, kHeight,
+                                    VideoContentType::UNSPECIFIED);
   EXPECT_EQ(3u, statistics_proxy_->GetStats().qp_sum);
-  statistics_proxy_->OnDecodedFrame(rtc::nullopt,
+  statistics_proxy_->OnDecodedFrame(rtc::nullopt, kWidth, kHeight,
                                     VideoContentType::UNSPECIFIED);
   EXPECT_EQ(rtc::nullopt, statistics_proxy_->GetStats().qp_sum);
 }
@@ -718,7 +736,7 @@
     // Since OnRenderedFrame is never called the fps in each sample will be 0,
     // i.e. bad
     frame.set_ntp_time_ms(fake_clock_.CurrentNtpInMilliseconds());
-    statistics_proxy_->OnDecodedFrame(rtc::nullopt,
+    statistics_proxy_->OnDecodedFrame(rtc::nullopt, kWidth, kHeight,
                                       VideoContentType::UNSPECIFIED);
     statistics_proxy_->OnRenderedFrame(frame);
     fake_clock_.AdvanceTimeMilliseconds(1000 / kDefaultFps);
@@ -833,12 +851,14 @@
   const VideoContentType content_type = GetParam();
   const int kInterFrameDelayMs = 33;
   for (int i = 0; i < kMinRequiredSamples; ++i) {
-    statistics_proxy_->OnDecodedFrame(rtc::nullopt, content_type);
+    statistics_proxy_->OnDecodedFrame(rtc::nullopt, kWidth, kHeight,
+                                      content_type);
     fake_clock_.AdvanceTimeMilliseconds(kInterFrameDelayMs);
   }
   // One extra with double the interval.
   fake_clock_.AdvanceTimeMilliseconds(kInterFrameDelayMs);
-  statistics_proxy_->OnDecodedFrame(rtc::nullopt, content_type);
+  statistics_proxy_->OnDecodedFrame(rtc::nullopt, kWidth, kHeight,
+                                    content_type);
 
   statistics_proxy_.reset();
   const int kExpectedInterFrame =
@@ -866,16 +886,19 @@
   const int kLastFivePercentsSamples = kMinRequiredSamples * 5 / 100;
   for (int i = 0; i <= kMinRequiredSamples - kLastFivePercentsSamples; ++i) {
     fake_clock_.AdvanceTimeMilliseconds(kInterFrameDelayMs);
-    statistics_proxy_->OnDecodedFrame(rtc::nullopt, content_type);
+    statistics_proxy_->OnDecodedFrame(rtc::nullopt, kWidth, kHeight,
+                                      content_type);
   }
   // Last 5% of intervals are double in size.
   for (int i = 0; i < kLastFivePercentsSamples; ++i) {
     fake_clock_.AdvanceTimeMilliseconds(2 * kInterFrameDelayMs);
-    statistics_proxy_->OnDecodedFrame(rtc::nullopt, content_type);
+    statistics_proxy_->OnDecodedFrame(rtc::nullopt, kWidth, kHeight,
+                                      content_type);
   }
   // Final sample is outlier and 10 times as big.
   fake_clock_.AdvanceTimeMilliseconds(10 * kInterFrameDelayMs);
-  statistics_proxy_->OnDecodedFrame(rtc::nullopt, content_type);
+  statistics_proxy_->OnDecodedFrame(rtc::nullopt, kWidth, kHeight,
+                                    content_type);
 
   statistics_proxy_.reset();
   const int kExpectedInterFrame = kInterFrameDelayMs * 2;
@@ -894,7 +917,8 @@
   const VideoContentType content_type = GetParam();
   const int kInterFrameDelayMs = 33;
   for (int i = 0; i < kMinRequiredSamples; ++i) {
-    statistics_proxy_->OnDecodedFrame(rtc::nullopt, content_type);
+    statistics_proxy_->OnDecodedFrame(rtc::nullopt, kWidth, kHeight,
+                                      content_type);
     fake_clock_.AdvanceTimeMilliseconds(kInterFrameDelayMs);
   }
 
@@ -913,7 +937,8 @@
   const VideoContentType content_type = GetParam();
   const int kInterFrameDelayMs = 33;
   for (int i = 0; i <= kMinRequiredSamples; ++i) {
-    statistics_proxy_->OnDecodedFrame(rtc::nullopt, content_type);
+    statistics_proxy_->OnDecodedFrame(rtc::nullopt, kWidth, kHeight,
+                                      content_type);
     fake_clock_.AdvanceTimeMilliseconds(kInterFrameDelayMs);
   }
 
@@ -924,9 +949,11 @@
 
   // Insert two more frames. The interval during the pause should be disregarded
   // in the stats.
-  statistics_proxy_->OnDecodedFrame(rtc::nullopt, content_type);
+  statistics_proxy_->OnDecodedFrame(rtc::nullopt, kWidth, kHeight,
+                                    content_type);
   fake_clock_.AdvanceTimeMilliseconds(kInterFrameDelayMs);
-  statistics_proxy_->OnDecodedFrame(rtc::nullopt, content_type);
+  statistics_proxy_->OnDecodedFrame(rtc::nullopt, kWidth, kHeight,
+                                    content_type);
 
   statistics_proxy_.reset();
   if (videocontenttypehelpers::IsScreenshare(content_type)) {
@@ -950,6 +977,174 @@
   }
 }
 
+TEST_P(ReceiveStatisticsProxyTest, FreezesAreReported) {
+  const VideoContentType content_type = GetParam();
+  const int kInterFrameDelayMs = 33;
+  const int kFreezeDelayMs = 200;
+  for (int i = 0; i < kMinRequiredSamples; ++i) {
+    statistics_proxy_->OnDecodedFrame(rtc::nullopt, kWidth, kHeight,
+                                      content_type);
+    fake_clock_.AdvanceTimeMilliseconds(kInterFrameDelayMs);
+  }
+  // Add extra freeze.
+  fake_clock_.AdvanceTimeMilliseconds(kFreezeDelayMs);
+  statistics_proxy_->OnDecodedFrame(rtc::nullopt, kWidth, kHeight,
+                                    content_type);
+
+  statistics_proxy_.reset();
+  const int kExpectedTimeBetweenFreezes =
+      kInterFrameDelayMs * (kMinRequiredSamples - 1);
+  if (videocontenttypehelpers::IsScreenshare(content_type)) {
+    EXPECT_EQ(
+        kFreezeDelayMs + kInterFrameDelayMs,
+        metrics::MinSample("WebRTC.Video.Screenshare.MeanFreezeDurationMs"));
+    EXPECT_EQ(kExpectedTimeBetweenFreezes,
+              metrics::MinSample(
+                  "WebRTC.Video.Screenshare.MeanTimeBetweenFreezesMs"));
+  } else {
+    EXPECT_EQ(kFreezeDelayMs + kInterFrameDelayMs,
+              metrics::MinSample("WebRTC.Video.MeanFreezeDurationMs"));
+    EXPECT_EQ(kExpectedTimeBetweenFreezes,
+              metrics::MinSample("WebRTC.Video.MeanTimeBetweenFreezesMs"));
+  }
+}
+
+TEST_P(ReceiveStatisticsProxyTest, PausesAreIgnored) {
+  const VideoContentType content_type = GetParam();
+  const int kInterFrameDelayMs = 33;
+  const int kPauseDurationMs = 10000;
+  for (int i = 0; i <= kMinRequiredSamples; ++i) {
+    statistics_proxy_->OnDecodedFrame(rtc::nullopt, kWidth, kHeight,
+                                      content_type);
+    fake_clock_.AdvanceTimeMilliseconds(kInterFrameDelayMs);
+  }
+  // Add a pause.
+  fake_clock_.AdvanceTimeMilliseconds(kPauseDurationMs);
+  statistics_proxy_->OnStreamInactive();
+
+  // Second playback interval with triple the length.
+  for (int i = 0; i <= kMinRequiredSamples * 3; ++i) {
+    statistics_proxy_->OnDecodedFrame(rtc::nullopt, kWidth, kHeight,
+                                      content_type);
+    fake_clock_.AdvanceTimeMilliseconds(kInterFrameDelayMs);
+  }
+
+  statistics_proxy_.reset();
+  // Average of two playback intervals.
+  const int kExpectedTimeBetweenFreezes =
+      kInterFrameDelayMs * kMinRequiredSamples * 2;
+  if (videocontenttypehelpers::IsScreenshare(content_type)) {
+    EXPECT_EQ(-1, metrics::MinSample(
+                      "WebRTC.Video.Screenshare.MeanFreezeDurationMs"));
+    EXPECT_EQ(kExpectedTimeBetweenFreezes,
+              metrics::MinSample(
+                  "WebRTC.Video.Screenshare.MeanTimeBetweenFreezesMs"));
+  } else {
+    EXPECT_EQ(-1, metrics::MinSample("WebRTC.Video.MeanFreezeDurationMs"));
+    EXPECT_EQ(kExpectedTimeBetweenFreezes,
+              metrics::MinSample("WebRTC.Video.MeanTimeBetweenFreezesMs"));
+  }
+}
+
+TEST_P(ReceiveStatisticsProxyTest, TimeInHdReported) {
+  const VideoContentType content_type = GetParam();
+  const int kInterFrameDelayMs = 20;
+  // HD frames.
+  for (int i = 0; i < kMinRequiredSamples; ++i) {
+    statistics_proxy_->OnDecodedFrame(rtc::nullopt, kWidth, kHeight,
+                                      content_type);
+    fake_clock_.AdvanceTimeMilliseconds(kInterFrameDelayMs);
+  }
+  // SD frames.
+  for (int i = 0; i < 2 * kMinRequiredSamples; ++i) {
+    statistics_proxy_->OnDecodedFrame(rtc::nullopt, kWidth / 2, kHeight / 2,
+                                      content_type);
+    fake_clock_.AdvanceTimeMilliseconds(kInterFrameDelayMs);
+  }
+  // Extra last frame.
+  statistics_proxy_->OnDecodedFrame(rtc::nullopt, kWidth / 2, kHeight / 2,
+                                    content_type);
+  statistics_proxy_.reset();
+  const int kExpectedTimeInHdPercents = 33;
+  if (videocontenttypehelpers::IsScreenshare(content_type)) {
+    EXPECT_EQ(
+        kExpectedTimeInHdPercents,
+        metrics::MinSample("WebRTC.Video.Screenshare.TimeInHdPercentage"));
+  } else {
+    EXPECT_EQ(kExpectedTimeInHdPercents,
+              metrics::MinSample("WebRTC.Video.TimeInHdPercentage"));
+  }
+}
+
+TEST_P(ReceiveStatisticsProxyTest, TimeInBlockyVideoReported) {
+  const VideoContentType content_type = GetParam();
+  const int kInterFrameDelayMs = 20;
+  const int kHighQp = 80;
+  const int kLowQp = 30;
+  // High quality frames.
+  for (int i = 0; i < kMinRequiredSamples; ++i) {
+    statistics_proxy_->OnDecodedFrame(kLowQp, kWidth, kHeight, content_type);
+    fake_clock_.AdvanceTimeMilliseconds(kInterFrameDelayMs);
+  }
+  // Blocky frames.
+  for (int i = 0; i < 2 * kMinRequiredSamples; ++i) {
+    statistics_proxy_->OnDecodedFrame(kHighQp, kWidth, kHeight, content_type);
+    fake_clock_.AdvanceTimeMilliseconds(kInterFrameDelayMs);
+  }
+  // Extra last frame.
+  statistics_proxy_->OnDecodedFrame(kHighQp, kWidth, kHeight, content_type);
+  statistics_proxy_.reset();
+  const int kExpectedTimeInHdPercents = 66;
+  if (videocontenttypehelpers::IsScreenshare(content_type)) {
+    EXPECT_EQ(kExpectedTimeInHdPercents,
+              metrics::MinSample(
+                  "WebRTC.Video.Screenshare.TimeInBlockyVideoPercentage"));
+  } else {
+    EXPECT_EQ(kExpectedTimeInHdPercents,
+              metrics::MinSample("WebRTC.Video.TimeInBlockyVideoPercentage"));
+  }
+}
+
+TEST_P(ReceiveStatisticsProxyTest, DownscalesReported) {
+  const VideoContentType content_type = GetParam();
+  const int kInterFrameDelayMs = 1000;  // To ensure long enough call duration.
+  const int kLowQp = 30;
+
+  statistics_proxy_->OnDecodedFrame(kLowQp, kWidth / 2, kHeight / 2,
+                                    content_type);
+  fake_clock_.AdvanceTimeMilliseconds(kInterFrameDelayMs);
+
+  // Downscale.
+  statistics_proxy_->OnDecodedFrame(kLowQp, kWidth, kHeight, content_type);
+  fake_clock_.AdvanceTimeMilliseconds(kInterFrameDelayMs);
+
+  statistics_proxy_->OnDecodedFrame(kLowQp, kWidth / 2, kHeight / 2,
+                                    content_type);
+  fake_clock_.AdvanceTimeMilliseconds(kInterFrameDelayMs);
+
+  statistics_proxy_->OnDecodedFrame(kLowQp, kWidth / 2, kHeight / 2,
+                                    content_type);
+  fake_clock_.AdvanceTimeMilliseconds(kInterFrameDelayMs);
+
+  // Downscale.
+  statistics_proxy_->OnDecodedFrame(kLowQp, kWidth / 4, kHeight / 4,
+                                    content_type);
+  fake_clock_.AdvanceTimeMilliseconds(kInterFrameDelayMs);
+
+  statistics_proxy_.reset();
+  const int kExpectedDownscales = 30;  // 2 per 5 seconds = 30 per minute.
+  if (videocontenttypehelpers::IsScreenshare(content_type)) {
+    EXPECT_EQ(
+        kExpectedDownscales,
+        metrics::MinSample(
+            "WebRTC.Video.Screenshare.NumberResolutionDownswitchesPerMinute"));
+  } else {
+    EXPECT_EQ(kExpectedDownscales,
+              metrics::MinSample(
+                  "WebRTC.Video.NumberResolutionDownswitchesPerMinute"));
+  }
+}
+
 TEST_P(ReceiveStatisticsProxyTest, StatsAreSlicedOnSimulcastAndExperiment) {
   VideoContentType content_type = GetParam();
   const uint8_t experiment_id = 1;
@@ -960,13 +1155,15 @@
   videocontenttypehelpers::SetSimulcastId(&content_type, 1);
   for (int i = 0; i <= kMinRequiredSamples; ++i) {
     fake_clock_.AdvanceTimeMilliseconds(kInterFrameDelayMs1);
-    statistics_proxy_->OnDecodedFrame(rtc::nullopt, content_type);
+    statistics_proxy_->OnDecodedFrame(rtc::nullopt, kWidth, kHeight,
+                                      content_type);
   }
 
   videocontenttypehelpers::SetSimulcastId(&content_type, 2);
   for (int i = 0; i <= kMinRequiredSamples; ++i) {
     fake_clock_.AdvanceTimeMilliseconds(kInterFrameDelayMs2);
-    statistics_proxy_->OnDecodedFrame(rtc::nullopt, content_type);
+    statistics_proxy_->OnDecodedFrame(rtc::nullopt, kWidth, kHeight,
+                                      content_type);
   }
   statistics_proxy_.reset();
 
diff --git a/video/video_quality_observer.cc b/video/video_quality_observer.cc
new file mode 100644
index 0000000..bcadb64
--- /dev/null
+++ b/video/video_quality_observer.cc
@@ -0,0 +1,194 @@
+/*
+ *  Copyright (c) 2018 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "video/video_quality_observer.h"
+
+#include <algorithm>
+#include <string>
+
+#include "rtc_base/checks.h"
+#include "rtc_base/logging.h"
+#include "rtc_base/strings/string_builder.h"
+#include "system_wrappers/include/metrics.h"
+
+namespace webrtc {
+
+namespace {
+const int kMinFrameSamplesToDetectFreeze = 5;
+const int kMinCallDurationMs = 3000;
+const int kMinRequiredSamples = 1;
+const int kMinIncreaseForFreezeMs = 150;
+const int kPixelsInHighResolution = 960 * 540;  // CPU-adapted HD still counts.
+const int kPixelsInMediumResolution = 640 * 360;
+const int kBlockyQpThresholdVp8 = 70;
+const int kBlockyQpThresholdVp9 = 60;  // TODO(ilnik): tune this value.
+// TODO(ilnik): Add H264/HEVC thresholds.
+}  // namespace
+
+VideoQualityObserver::VideoQualityObserver(VideoContentType content_type)
+    : last_frame_decoded_ms_(-1),
+      num_frames_decoded_(0),
+      first_frame_decoded_ms_(-1),
+      last_frame_pixels_(0),
+      last_frame_qp_(0),
+      last_unfreeze_time_(0),
+      time_in_resolution_ms_(3, 0),
+      current_resolution_(Resolution::Low),
+      num_resolution_downgrades_(0),
+      time_in_blocky_video_ms_(0),
+      content_type_(content_type),
+      is_paused_(false) {}
+
+VideoQualityObserver::~VideoQualityObserver() {
+  UpdateHistograms();
+}
+
+void VideoQualityObserver::UpdateHistograms() {
+  // Don't report anything on an empty video stream.
+  if (num_frames_decoded_ == 0) {
+    return;
+  }
+
+  char log_stream_buf[2 * 1024];
+  rtc::SimpleStringBuilder log_stream(log_stream_buf);
+
+  if (last_frame_decoded_ms_ > last_unfreeze_time_) {
+    smooth_playback_durations_.Add(last_frame_decoded_ms_ -
+                                   last_unfreeze_time_);
+  }
+
+  std::string uma_prefix = videocontenttypehelpers::IsScreenshare(content_type_)
+                               ? "WebRTC.Video.Screenshare"
+                               : "WebRTC.Video";
+
+  auto mean_time_between_freezes =
+      smooth_playback_durations_.Avg(kMinRequiredSamples);
+  if (mean_time_between_freezes) {
+    RTC_HISTOGRAM_COUNTS_SPARSE_100000(uma_prefix + ".MeanTimeBetweenFreezesMs",
+                                       *mean_time_between_freezes);
+    log_stream << uma_prefix << ".MeanTimeBetweenFreezesMs "
+               << *mean_time_between_freezes << "\n";
+  }
+  auto avg_freeze_length = freezes_durations_.Avg(kMinRequiredSamples);
+  if (avg_freeze_length) {
+    RTC_HISTOGRAM_COUNTS_SPARSE_100000(uma_prefix + ".MeanFreezeDurationMs",
+                                       *avg_freeze_length);
+    log_stream << uma_prefix << ".MeanFreezeDurationMs " << *avg_freeze_length
+               << "\n";
+  }
+
+  int64_t call_duration_ms = last_frame_decoded_ms_ - first_frame_decoded_ms_;
+
+  if (call_duration_ms >= kMinCallDurationMs) {
+    int time_spent_in_hd_percentage = static_cast<int>(
+        time_in_resolution_ms_[Resolution::High] * 100 / call_duration_ms);
+    int time_with_blocky_video_percentage =
+        static_cast<int>(time_in_blocky_video_ms_ * 100 / call_duration_ms);
+
+    RTC_HISTOGRAM_COUNTS_SPARSE_100(uma_prefix + ".TimeInHdPercentage",
+                                    time_spent_in_hd_percentage);
+    log_stream << uma_prefix << ".TimeInHdPercentage "
+               << time_spent_in_hd_percentage << "\n";
+    RTC_HISTOGRAM_COUNTS_SPARSE_100(uma_prefix + ".TimeInBlockyVideoPercentage",
+                                    time_with_blocky_video_percentage);
+    log_stream << uma_prefix << ".TimeInBlockyVideoPercentage "
+               << time_with_blocky_video_percentage << "\n";
+    RTC_HISTOGRAM_COUNTS_SPARSE_100(
+        uma_prefix + ".NumberResolutionDownswitchesPerMinute",
+        num_resolution_downgrades_ * 60000 / call_duration_ms);
+    log_stream << uma_prefix << ".NumberResolutionDownswitchesPerMinute "
+               << num_resolution_downgrades_ * 60000 / call_duration_ms << "\n";
+  }
+  RTC_LOG(LS_INFO) << log_stream.str();
+}
+
+void VideoQualityObserver::OnDecodedFrame(rtc::Optional<uint8_t> qp,
+                                          int width,
+                                          int height,
+                                          int64_t now_ms,
+                                          VideoCodecType codec) {
+  if (num_frames_decoded_ == 0) {
+    first_frame_decoded_ms_ = now_ms;
+    last_unfreeze_time_ = now_ms;
+  }
+
+  ++num_frames_decoded_;
+
+  if (!is_paused_ && num_frames_decoded_ > 1) {
+    // Process inter-frame delay.
+    int64_t interframe_delay_ms = now_ms - last_frame_decoded_ms_;
+    interframe_delays_.Add(interframe_delay_ms);
+    rtc::Optional<int> avg_interframe_delay =
+        interframe_delays_.Avg(kMinFrameSamplesToDetectFreeze);
+    // Check if it was a freeze.
+    if (num_frames_decoded_ > kMinFrameSamplesToDetectFreeze &&
+        interframe_delay_ms >=
+            std::max(3 * *avg_interframe_delay,
+                     *avg_interframe_delay + kMinIncreaseForFreezeMs)) {
+      freezes_durations_.Add(interframe_delay_ms);
+      smooth_playback_durations_.Add(last_frame_decoded_ms_ -
+                                     last_unfreeze_time_);
+      last_unfreeze_time_ = now_ms;
+    } else {
+      // Only count inter-frame delay as playback time if there
+      // was no freeze.
+      time_in_resolution_ms_[current_resolution_] += interframe_delay_ms;
+      rtc::Optional<int> qp_blocky_threshold;
+      // TODO(ilnik): add other codec types when we have QP for them.
+      switch (codec) {
+        case kVideoCodecVP8:
+          qp_blocky_threshold = kBlockyQpThresholdVp8;
+          break;
+        case kVideoCodecVP9:
+          qp_blocky_threshold = kBlockyQpThresholdVp9;
+          break;
+        default:
+          qp_blocky_threshold = rtc::nullopt;
+      }
+      if (qp_blocky_threshold && qp.value_or(0) > *qp_blocky_threshold) {
+        time_in_blocky_video_ms_ += interframe_delay_ms;
+      }
+    }
+  }
+
+  if (is_paused_) {
+    // If the stream was paused since the previous frame, do not count the
+    // pause toward smooth playback. Explicitly count the part before it and
+    // start the new smooth playback interval from this frame.
+    is_paused_ = false;
+    if (last_frame_decoded_ms_ > last_unfreeze_time_) {
+      smooth_playback_durations_.Add(last_frame_decoded_ms_ -
+                                     last_unfreeze_time_);
+    }
+    last_unfreeze_time_ = now_ms;
+  }
+
+  int64_t pixels = width * height;
+  if (pixels >= kPixelsInHighResolution) {
+    current_resolution_ = Resolution::High;
+  } else if (pixels >= kPixelsInMediumResolution) {
+    current_resolution_ = Resolution::Medium;
+  } else {
+    current_resolution_ = Resolution::Low;
+  }
+
+  if (pixels < last_frame_pixels_) {
+    ++num_resolution_downgrades_;
+  }
+
+  last_frame_decoded_ms_ = now_ms;
+  last_frame_qp_ = qp.value_or(0);
+  last_frame_pixels_ = pixels;
+}
+
+void VideoQualityObserver::OnStreamInactive() {
+  is_paused_ = true;
+}
+}  // namespace webrtc
diff --git a/video/video_quality_observer.h b/video/video_quality_observer.h
new file mode 100644
index 0000000..cbeab43
--- /dev/null
+++ b/video/video_quality_observer.h
@@ -0,0 +1,79 @@
+/*
+ *  Copyright (c) 2018 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef VIDEO_VIDEO_QUALITY_OBSERVER_H_
+#define VIDEO_VIDEO_QUALITY_OBSERVER_H_
+
+#include <stdint.h>
+#include <vector>
+
+#include "api/optional.h"
+#include "api/video/video_content_type.h"
+#include "common_types.h"  // NOLINT(build/include)
+#include "rtc_base/numerics/sample_counter.h"
+
+namespace webrtc {
+
+// Calculates spatial and temporal quality metrics and reports them to UMA
+// stats.
+class VideoQualityObserver {
+ public:
+  // Use either VideoQualityObserver::kBlockyQpThresholdVp8 or
+  // VideoQualityObserver::kBlockyQpThresholdVp9.
+  explicit VideoQualityObserver(VideoContentType content_type);
+  ~VideoQualityObserver();
+
+  void OnDecodedFrame(rtc::Optional<uint8_t> qp,
+                      int width,
+                      int height,
+                      int64_t now_ms,
+                      VideoCodecType codec);
+
+  void OnStreamInactive();
+
+ private:
+  void UpdateHistograms();
+
+  enum Resolution {
+    Low = 0,
+    Medium = 1,
+    High = 2,
+  };
+
+  int64_t last_frame_decoded_ms_;
+  int64_t num_frames_decoded_;
+  int64_t first_frame_decoded_ms_;
+  int64_t last_frame_pixels_;
+  uint8_t last_frame_qp_;
+  // Decoded timestamp of the last delayed frame.
+  int64_t last_unfreeze_time_;
+  rtc::SampleCounter interframe_delays_;
+  // An inter-frame delay is counted as a freeze if it's significantly longer
+  // than average inter-frame delay.
+  rtc::SampleCounter freezes_durations_;
+  // Time between freezes.
+  rtc::SampleCounter smooth_playback_durations_;
+  // Counters for time spent in different resolutions. Time between each two
+  // Consecutive frames is counted to bin corresponding to the first frame
+  // resolution.
+  std::vector<int64_t> time_in_resolution_ms_;
+  // Resolution of the last decoded frame. Resolution enum is used as an index.
+  Resolution current_resolution_;
+  int num_resolution_downgrades_;
+  // Similar to resolution, time spent in high-QP video.
+  int64_t time_in_blocky_video_ms_;
+  // Content type of the last decoded frame.
+  VideoContentType content_type_;
+  bool is_paused_;
+};
+
+}  // namespace webrtc
+
+#endif  // VIDEO_VIDEO_QUALITY_OBSERVER_H_
diff --git a/video/video_stream_decoder.cc b/video/video_stream_decoder.cc
index e766767c..5557c6c 100644
--- a/video/video_stream_decoder.cc
+++ b/video/video_stream_decoder.cc
@@ -77,7 +77,8 @@
 int32_t VideoStreamDecoder::FrameToRender(VideoFrame& video_frame,
                                           rtc::Optional<uint8_t> qp,
                                           VideoContentType content_type) {
-  receive_stats_callback_->OnDecodedFrame(qp, content_type);
+  receive_stats_callback_->OnDecodedFrame(qp, video_frame.width(),
+                                          video_frame.height(), content_type);
   incoming_video_stream_->OnFrame(video_frame);
   return 0;
 }