Adding field trials to control additional quality scaler settings

Bug: webrtc:11924
Change-Id: I98c7aa4bd4536770500fec7e8e8da9629fddd20f
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/183342
Reviewed-by: Henrik Boström <hbos@webrtc.org>
Reviewed-by: Åsa Persson <asapersson@webrtc.org>
Commit-Queue: Åsa Persson <asapersson@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#32103}

modules/video_coding/utility/quality_scaler.cc

@@ -189,13 +189,17 @@ QualityScaler::QualityScaler(QualityScalerQpUsageHandlerInterface* handler,
 // Protected ctor, should not be called directly.
 QualityScaler::QualityScaler(QualityScalerQpUsageHandlerInterface* handler,
                              VideoEncoder::QpThresholds thresholds,
-                             int64_t sampling_period_ms)
+                             int64_t default_sampling_period_ms)
     : handler_(handler),
       thresholds_(thresholds),
-      sampling_period_ms_(sampling_period_ms),
+      sampling_period_ms_(QualityScalerSettings::ParseFromFieldTrials()
+                              .SamplingPeriodMs()
+                              .value_or(default_sampling_period_ms)),
       fast_rampup_(true),
       // Arbitrarily choose size based on 30 fps for 5 seconds.
-      average_qp_(5 * 30),
+      average_qp_(QualityScalerSettings::ParseFromFieldTrials()
+                      .AverageQpWindow()
+                      .value_or(5 * 30)),
       framedrop_percent_media_opt_(5 * 30),
       framedrop_percent_all_(5 * 30),
       experiment_enabled_(QualityScalingExperiment::Enabled()),

rtc_base/experiments/quality_scaler_settings.cc

@@ -21,14 +21,17 @@ const double kMinScaleFactor = 0.01;
 
 QualityScalerSettings::QualityScalerSettings(
     const WebRtcKeyValueConfig* const key_value_config)
-    : min_frames_("min_frames"),
+    : sampling_period_ms_("sampling_period_ms"),
+      average_qp_window_("average_qp_window"),
+      min_frames_("min_frames"),
       initial_scale_factor_("initial_scale_factor"),
       scale_factor_("scale_factor"),
       initial_bitrate_interval_ms_("initial_bitrate_interval_ms"),
       initial_bitrate_factor_("initial_bitrate_factor") {
   ParseFieldTrial(
-      {&min_frames_, &initial_scale_factor_, &scale_factor_,
+      {&sampling_period_ms_, &average_qp_window_, &min_frames_,
-       &initial_bitrate_interval_ms_, &initial_bitrate_factor_},
+       &initial_scale_factor_, &scale_factor_, &initial_bitrate_interval_ms_,
+       &initial_bitrate_factor_},
       key_value_config->Lookup("WebRTC-Video-QualityScalerSettings"));
 }
 
@@ -37,6 +40,22 @@ QualityScalerSettings QualityScalerSettings::ParseFromFieldTrials() {
   return QualityScalerSettings(&field_trial_config);
 }
 
+absl::optional<int> QualityScalerSettings::SamplingPeriodMs() const {
+  if (sampling_period_ms_ && sampling_period_ms_.Value() <= 0) {
+    RTC_LOG(LS_WARNING) << "Unsupported sampling_period_ms value, ignored.";
+    return absl::nullopt;
+  }
+  return sampling_period_ms_.GetOptional();
+}
+
+absl::optional<int> QualityScalerSettings::AverageQpWindow() const {
+  if (average_qp_window_ && average_qp_window_.Value() <= 0) {
+    RTC_LOG(LS_WARNING) << "Unsupported average_qp_window value, ignored.";
+    return absl::nullopt;
+  }
+  return average_qp_window_.GetOptional();
+}
+
 absl::optional<int> QualityScalerSettings::MinFrames() const {
   if (min_frames_ && min_frames_.Value() < kMinFrames) {
     RTC_LOG(LS_WARNING) << "Unsupported min_frames value, ignored.";

rtc_base/experiments/quality_scaler_settings.h

@@ -21,6 +21,8 @@ class QualityScalerSettings final {
  public:
   static QualityScalerSettings ParseFromFieldTrials();
 
+  absl::optional<int> SamplingPeriodMs() const;
+  absl::optional<int> AverageQpWindow() const;
   absl::optional<int> MinFrames() const;
   absl::optional<double> InitialScaleFactor() const;
   absl::optional<double> ScaleFactor() const;
@@ -31,6 +33,8 @@ class QualityScalerSettings final {
   explicit QualityScalerSettings(
       const WebRtcKeyValueConfig* const key_value_config);
 
+  FieldTrialOptional<int> sampling_period_ms_;
+  FieldTrialOptional<int> average_qp_window_;
   FieldTrialOptional<int> min_frames_;
   FieldTrialOptional<double> initial_scale_factor_;
   FieldTrialOptional<double> scale_factor_;