Enable quality scaling when allowed

Before this CL quality scaling was conditioned on scaling settings
provided by encoder. That should not be a requirement since encoder
may not be aware of quality scaling which is a WebRTC feature. In M90
chromium HW encoders do not provide scaling settings (chromium:1179020).
The default scaling settings provided by these encoders are not correct
(b/181537172).

This CL adds is_quality_scaling_allowed to VideoEncoderConfig. The flag
is set to true in singlecast with normal video feed (not screen sharing)
mode. If quality scaling is allowed it is enabled no matter whether
scaling settings are present in encoder info or not. Setting from
QualityScalingExperiment are used in case if not provided by encoder.

Bug: chromium:1179020, webrtc:12511
Change-Id: I83d55319ce4b9f4fb143187ced94a16a778b4de3
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/209184
Reviewed-by: Rasmus Brandt <brandtr@webrtc.org>
Reviewed-by: Ilya Nikolaevskiy <ilnik@webrtc.org>
Reviewed-by: Åsa Persson <asapersson@webrtc.org>
Commit-Queue: Sergey Silkin <ssilkin@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#33373}

api/video_codecs/video_encoder_config.cc

@@ -57,7 +57,8 @@ VideoEncoderConfig::VideoEncoderConfig()
       max_bitrate_bps(0),
       bitrate_priority(1.0),
       number_of_streams(0),
-      legacy_conference_mode(false) {}
+      legacy_conference_mode(false),
+      is_quality_scaling_allowed(false) {}
 
 VideoEncoderConfig::VideoEncoderConfig(VideoEncoderConfig&&) = default;
 

api/video_codecs/video_encoder_config.h

@@ -181,6 +181,9 @@ class VideoEncoderConfig {
   // Legacy Google conference mode flag for simulcast screenshare
   bool legacy_conference_mode;
 
+  // Indicates whether quality scaling can be used or not.
+  bool is_quality_scaling_allowed;
+
  private:
   // Access to the copy constructor is private to force use of the Copy()
   // method for those exceptional cases where we do use it.

media/engine/webrtc_video_engine.cc

@@ -2492,11 +2492,17 @@ WebRtcVideoChannel::WebRtcVideoSendStream::CreateVideoEncoderConfig(
 
   encoder_config.legacy_conference_mode = parameters_.conference_mode;
 
+  encoder_config.is_quality_scaling_allowed =
+      !disable_automatic_resize_ && !is_screencast &&
+      (parameters_.config.rtp.ssrcs.size() == 1 ||
+       NumActiveStreams(rtp_parameters_) == 1);
+
   int max_qp = kDefaultQpMax;
   codec.GetParam(kCodecParamMaxQuantization, &max_qp);
   encoder_config.video_stream_factory =
       new rtc::RefCountedObject<EncoderStreamFactory>(
           codec.name, max_qp, is_screencast, parameters_.conference_mode);
+
   return encoder_config;
 }
 

media/engine/webrtc_video_engine_unittest.cc

@@ -8302,6 +8302,48 @@ TEST_F(WebRtcVideoChannelTest, ConfiguresLocalSsrcOnExistingReceivers) {
   TestReceiverLocalSsrcConfiguration(true);
 }
 
+TEST_F(WebRtcVideoChannelTest, Simulcast_QualityScalingNotAllowed) {
+  FakeVideoSendStream* stream = SetUpSimulcast(true, true);
+  EXPECT_FALSE(stream->GetEncoderConfig().is_quality_scaling_allowed);
+}
+
+TEST_F(WebRtcVideoChannelTest, Singlecast_QualityScalingAllowed) {
+  FakeVideoSendStream* stream = SetUpSimulcast(false, true);
+  EXPECT_TRUE(stream->GetEncoderConfig().is_quality_scaling_allowed);
+}
+
+TEST_F(WebRtcVideoChannelTest,
+       SinglecastScreenSharing_QualityScalingNotAllowed) {
+  SetUpSimulcast(false, true);
+
+  webrtc::test::FrameForwarder frame_forwarder;
+  VideoOptions options;
+  options.is_screencast = true;
+  EXPECT_TRUE(channel_->SetVideoSend(last_ssrc_, &options, &frame_forwarder));
+  // Fetch the latest stream since SetVideoSend() may recreate it if the
+  // screen content setting is changed.
+  FakeVideoSendStream* stream = fake_call_->GetVideoSendStreams().front();
+
+  EXPECT_FALSE(stream->GetEncoderConfig().is_quality_scaling_allowed);
+  EXPECT_TRUE(channel_->SetVideoSend(last_ssrc_, nullptr, nullptr));
+}
+
+TEST_F(WebRtcVideoChannelTest,
+       SimulcastSingleActiveStream_QualityScalingAllowed) {
+  FakeVideoSendStream* stream = SetUpSimulcast(true, false);
+
+  webrtc::RtpParameters rtp_parameters =
+      channel_->GetRtpSendParameters(last_ssrc_);
+  ASSERT_EQ(3u, rtp_parameters.encodings.size());
+  ASSERT_TRUE(rtp_parameters.encodings[0].active);
+  ASSERT_TRUE(rtp_parameters.encodings[1].active);
+  ASSERT_TRUE(rtp_parameters.encodings[2].active);
+  rtp_parameters.encodings[0].active = false;
+  rtp_parameters.encodings[1].active = false;
+  EXPECT_TRUE(channel_->SetRtpSendParameters(last_ssrc_, rtp_parameters).ok());
+  EXPECT_TRUE(stream->GetEncoderConfig().is_quality_scaling_allowed);
+}
+
 class WebRtcVideoChannelSimulcastTest : public ::testing::Test {
  public:
   WebRtcVideoChannelSimulcastTest()

video/adaptation/video_stream_encoder_resource_manager.cc

@@ -521,7 +521,9 @@ void VideoStreamEncoderResourceManager::ConfigureQualityScaler(
   const auto scaling_settings = encoder_info.scaling_settings;
   const bool quality_scaling_allowed =
       IsResolutionScalingEnabled(degradation_preference_) &&
-      scaling_settings.thresholds;
+      (scaling_settings.thresholds.has_value() ||
+       (encoder_settings_.has_value() &&
+        encoder_settings_->encoder_config().is_quality_scaling_allowed));
 
   // TODO(https://crbug.com/webrtc/11222): Should this move to
   // QualityScalerResource?
@@ -535,9 +537,9 @@ void VideoStreamEncoderResourceManager::ConfigureQualityScaler(
         experimental_thresholds = QualityScalingExperiment::GetQpThresholds(
             GetVideoCodecTypeOrGeneric(encoder_settings_));
       }
-      UpdateQualityScalerSettings(experimental_thresholds
-                                      ? *experimental_thresholds
-                                      : *(scaling_settings.thresholds));
+      UpdateQualityScalerSettings(experimental_thresholds.has_value()
+                                      ? experimental_thresholds
+                                      : scaling_settings.thresholds);
     }
   } else {
     UpdateQualityScalerSettings(absl::nullopt);

video/video_stream_encoder_unittest.cc

@@ -7923,4 +7923,61 @@ TEST_F(VideoStreamEncoderTest, EncoderResolutionsExposedInSimulcast) {
   video_stream_encoder_->Stop();
 }
 
+TEST_F(VideoStreamEncoderTest,
+       QualityScalingNotAllowed_QualityScalingDisabled) {
+  VideoEncoderConfig video_encoder_config = video_encoder_config_.Copy();
+
+  // Disable scaling settings in encoder info.
+  fake_encoder_.SetQualityScaling(false);
+  // Disable quality scaling in encoder config.
+  video_encoder_config.is_quality_scaling_allowed = false;
+  ConfigureEncoder(std::move(video_encoder_config));
+
+  video_stream_encoder_->OnBitrateUpdatedAndWaitForManagedResources(
+      DataRate::BitsPerSec(kTargetBitrateBps),
+      DataRate::BitsPerSec(kTargetBitrateBps),
+      DataRate::BitsPerSec(kTargetBitrateBps), 0, 0, 0);
+
+  test::FrameForwarder source;
+  video_stream_encoder_->SetSource(
+      &source, webrtc::DegradationPreference::MAINTAIN_FRAMERATE);
+  EXPECT_THAT(source.sink_wants(), UnlimitedSinkWants());
+  EXPECT_FALSE(stats_proxy_->GetStats().bw_limited_resolution);
+
+  source.IncomingCapturedFrame(CreateFrame(1, 1280, 720));
+  WaitForEncodedFrame(1);
+  video_stream_encoder_->TriggerQualityLow();
+  EXPECT_FALSE(stats_proxy_->GetStats().bw_limited_resolution);
+
+  video_stream_encoder_->Stop();
+}
+
+TEST_F(VideoStreamEncoderTest, QualityScalingAllowed_QualityScalingEnabled) {
+  VideoEncoderConfig video_encoder_config = video_encoder_config_.Copy();
+
+  // Disable scaling settings in encoder info.
+  fake_encoder_.SetQualityScaling(false);
+  // Enable quality scaling in encoder config.
+  video_encoder_config.is_quality_scaling_allowed = true;
+  ConfigureEncoder(std::move(video_encoder_config));
+
+  video_stream_encoder_->OnBitrateUpdatedAndWaitForManagedResources(
+      DataRate::BitsPerSec(kTargetBitrateBps),
+      DataRate::BitsPerSec(kTargetBitrateBps),
+      DataRate::BitsPerSec(kTargetBitrateBps), 0, 0, 0);
+
+  test::FrameForwarder source;
+  video_stream_encoder_->SetSource(
+      &source, webrtc::DegradationPreference::MAINTAIN_FRAMERATE);
+  EXPECT_THAT(source.sink_wants(), UnlimitedSinkWants());
+  EXPECT_FALSE(stats_proxy_->GetStats().bw_limited_resolution);
+
+  source.IncomingCapturedFrame(CreateFrame(1, 1280, 720));
+  WaitForEncodedFrame(1);
+  video_stream_encoder_->TriggerQualityLow();
+  EXPECT_TRUE(stats_proxy_->GetStats().bw_limited_resolution);
+
+  video_stream_encoder_->Stop();
+}
+
 }  // namespace webrtc