Remove Vp9VariableFramerateScreenshare experiment

Bug: webrtc:10310
Change-Id: Ibd31e111bccbbc61d9f3da63bfdf54448820fb80
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/347661
Reviewed-by: Philip Eliasson <philipel@webrtc.org>
Commit-Queue: Ilya Nikolaevskiy <ilnik@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#42109}

experiments/field_trials.py

@@ -814,9 +814,6 @@ POLICY_EXEMPT_FIELD_TRIALS: FrozenSet[FieldTrial] = frozenset([
     FieldTrial('WebRTC-VP9QualityScaler',
                'webrtc:11319',
                date(2024, 4, 1)),
-    FieldTrial('WebRTC-VP9VariableFramerateScreenshare',
-               'webrtc:10310',
-               date(2024, 4, 1)),
     FieldTrial('WebRTC-Video-BalancedDegradation',
                'webrtc:7607',
                INDEFINITE),
@@ -890,7 +887,7 @@ POLICY_EXEMPT_FIELD_TRIALS: FrozenSet[FieldTrial] = frozenset([
 ])  # yapf: disable
 
 POLICY_EXEMPT_FIELD_TRIALS_DIGEST: str = \
-    '5690e723f0ca378ceb708e02bf2334327c0f64b6'
+    '680deace2615186c4d3cf9ed3bd3595b7b6c8ae8'
 
 REGISTERED_FIELD_TRIALS: FrozenSet[FieldTrial] = ACTIVE_FIELD_TRIALS.union(
     POLICY_EXEMPT_FIELD_TRIALS)

modules/video_coding/codecs/vp9/libvpx_vp9_encoder.cc

@@ -63,6 +63,13 @@ uint8_t kUpdBufIdx[4] = {0, 0, 1, 0};
 // Maximum allowed PID difference for differnet per-layer frame-rate case.
 const int kMaxAllowedPidDiff = 30;
 
+namespace variable_framerate_screenshare {
+constexpr double kMinFps = 5.0;
+constexpr int kMinQP = 32;
+constexpr int kUndershootPct = 30;
+constexpr int kFramesBeforeSteadyState = 5;
+}  // namespace variable_framerate_screenshare
+
 // TODO(ilink): Tune these thresholds further.
 // Selected using ConverenceMotion_1280_720_50.yuv clip.
 // No toggling observed on any link capacity from 100-2000kbps.
@@ -250,10 +257,7 @@ LibvpxVp9Encoder::LibvpxVp9Encoder(const Environment& env,
       ss_info_needed_(false),
       force_all_active_layers_(false),
       is_flexible_mode_(false),
-      variable_framerate_experiment_(
-          ParseVariableFramerateConfig(env.field_trials())),
-      variable_framerate_controller_(
-          variable_framerate_experiment_.framerate_limit),
+      variable_framerate_controller_(variable_framerate_screenshare::kMinFps),
       quality_scaler_experiment_(ParseQualityScalerConfig(env.field_trials())),
       external_ref_ctrl_(
           !env.field_trials().IsDisabled("WebRTC-Vp9ExternalRefCtrl")),
@@ -1033,10 +1037,9 @@ int LibvpxVp9Encoder::Encode(const VideoFrame& input_image,
       // interfere, they must be queried in order of increasing limit.
 
       bool use_steady_state_limiter =
-          variable_framerate_experiment_.enabled &&
           input_image.update_rect().IsEmpty() &&
           num_steady_state_frames_ >=
-              variable_framerate_experiment_.frames_before_steady_state;
+              variable_framerate_screenshare::kFramesBeforeSteadyState;
 
       // Need to check all frame limiters, even if lower layers are disabled,
       // because variable frame-rate limiter should be checked after the first
@@ -1047,7 +1050,7 @@ int LibvpxVp9Encoder::Encode(const VideoFrame& input_image,
             framerate_controller_[layer_id.spatial_layer_id].GetTargetRate();
         // Use steady state rate-limiter at the correct place.
         if (use_steady_state_limiter &&
-            layer_fps > variable_framerate_experiment_.framerate_limit - 1e-9) {
+            layer_fps > variable_framerate_screenshare::kMinFps - 1e-9) {
           if (variable_framerate_controller_.DropFrame(frame_timestamp_ms)) {
             layer_id.spatial_layer_id = num_active_spatial_layers_;
           }
@@ -1794,9 +1797,8 @@ void LibvpxVp9Encoder::DeliverBufferedFrame(bool end_of_picture) {
       // Only frames on spatial layers, which may be limited in a steady state
       // are considered for steady state detection.
       if (framerate_controller_[spatial_idx].GetTargetRate() >
-          variable_framerate_experiment_.framerate_limit + 1e-9) {
-        if (encoded_image_.qp_ <=
-                variable_framerate_experiment_.steady_state_qp &&
+          variable_framerate_screenshare::kMinFps + 1e-9) {
+        if (encoded_image_.qp_ <= variable_framerate_screenshare::kMinQP &&
             encoded_image_.size() <= steady_state_size) {
           ++num_steady_state_frames_;
         } else {
@@ -1876,34 +1878,10 @@ size_t LibvpxVp9Encoder::SteadyStateSize(int sid, int tid) {
                         : codec_.maxFramerate;
   return static_cast<size_t>(
       bitrate_bps / (8 * fps) *
-          (100 -
-           variable_framerate_experiment_.steady_state_undershoot_percentage) /
-          100 +
+          (100 - variable_framerate_screenshare::kUndershootPct) / 100 +
       0.5);
 }
 
-// static
-LibvpxVp9Encoder::VariableFramerateExperiment
-LibvpxVp9Encoder::ParseVariableFramerateConfig(const FieldTrialsView& trials) {
-  FieldTrialFlag enabled = FieldTrialFlag("Enabled");
-  FieldTrialParameter<double> framerate_limit("min_fps", 5.0);
-  FieldTrialParameter<int> qp("min_qp", 32);
-  FieldTrialParameter<int> undershoot_percentage("undershoot", 30);
-  FieldTrialParameter<int> frames_before_steady_state(
-      "frames_before_steady_state", 5);
-  ParseFieldTrial({&enabled, &framerate_limit, &qp, &undershoot_percentage,
-                   &frames_before_steady_state},
-                  trials.Lookup("WebRTC-VP9VariableFramerateScreenshare"));
-  VariableFramerateExperiment config;
-  config.enabled = enabled.Get();
-  config.framerate_limit = framerate_limit.Get();
-  config.steady_state_qp = qp.Get();
-  config.steady_state_undershoot_percentage = undershoot_percentage.Get();
-  config.frames_before_steady_state = frames_before_steady_state.Get();
-
-  return config;
-}
-
 // static
 LibvpxVp9Encoder::QualityScalerExperiment
 LibvpxVp9Encoder::ParseQualityScalerConfig(const FieldTrialsView& trials) {

modules/video_coding/codecs/vp9/libvpx_vp9_encoder.h

@@ -169,22 +169,6 @@ class LibvpxVp9Encoder : public VideoEncoder {
   std::array<RefFrameBuffer, kNumVp9Buffers> ref_buf_;
   std::vector<ScalableVideoController::LayerFrameConfig> layer_frames_;
 
-  // Variable frame-rate related fields and methods.
-  const struct VariableFramerateExperiment {
-    bool enabled;
-    // Framerate is limited to this value in steady state.
-    float framerate_limit;
-    // This qp or below is considered a steady state.
-    int steady_state_qp;
-    // Frames of at least this percentage below ideal for configured bitrate are
-    // considered in a steady state.
-    int steady_state_undershoot_percentage;
-    // Number of consecutive frames with good QP and size required to detect
-    // the steady state.
-    int frames_before_steady_state;
-  } variable_framerate_experiment_;
-  static VariableFramerateExperiment ParseVariableFramerateConfig(
-      const FieldTrialsView& trials);
   FramerateControllerDeprecated variable_framerate_controller_;
 
   const struct QualityScalerExperiment {