1 files changed, 117 insertions, 0 deletions
diff --git a/third_party/libwebrtc/rtc_base/experiments/quality_scaling_experiment.cc b/third_party/libwebrtc/rtc_base/experiments/quality_scaling_experiment.cc
new file mode 100644
index 0000000000..ee3d7c0320
--- /dev/null
+++ b/third_party/libwebrtc/rtc_base/experiments/quality_scaling_experiment.cc
@@ -0,0 +1,117 @@
+/*
+ *  Copyright 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 "rtc_base/experiments/quality_scaling_experiment.h"
+
+#include <stdio.h>
+
+#include <string>
+
+#include "absl/strings/match.h"
+#include "api/field_trials_view.h"
+#include "api/transport/field_trial_based_config.h"
+#include "rtc_base/logging.h"
+
+namespace webrtc {
+namespace {
+constexpr char kFieldTrial[] = "WebRTC-Video-QualityScaling";
+constexpr int kMinQp = 1;
+constexpr int kMaxVp8Qp = 127;
+constexpr int kMaxVp9Qp = 255;
+constexpr int kMaxH264Qp = 51;
+constexpr int kMaxGenericQp = 255;
+
+#if !defined(WEBRTC_IOS)
+constexpr char kDefaultQualityScalingSetttings[] =
+    "Enabled-29,95,149,205,24,37,26,36,0.9995,0.9999,1";
+#endif
+
+absl::optional<VideoEncoder::QpThresholds> GetThresholds(int low,
+                                                         int high,
+                                                         int max) {
+  if (low < kMinQp || high > max || high < low)
+    return absl::nullopt;
+
+  RTC_LOG(LS_INFO) << "QP thresholds: low: " << low << ", high: " << high;
+  return absl::optional<VideoEncoder::QpThresholds>(
+      VideoEncoder::QpThresholds(low, high));
+}
+}  // namespace
+
+bool QualityScalingExperiment::Enabled(const FieldTrialsView& field_trials) {
+#if defined(WEBRTC_IOS)
+  return absl::StartsWith(field_trials.Lookup(kFieldTrial), "Enabled");
+#else
+  return !absl::StartsWith(field_trials.Lookup(kFieldTrial), "Disabled");
+#endif
+}
+
+absl::optional<QualityScalingExperiment::Settings>
+QualityScalingExperiment::ParseSettings(const FieldTrialsView& field_trials) {
+  std::string group = field_trials.Lookup(kFieldTrial);
+  // TODO(http://crbug.com/webrtc/12401): Completely remove the experiment code
+  // after few releases.
+#if !defined(WEBRTC_IOS)
+  if (group.empty())
+    group = kDefaultQualityScalingSetttings;
+#endif
+  Settings s;
+  if (sscanf(group.c_str(), "Enabled-%d,%d,%d,%d,%d,%d,%d,%d,%f,%f,%d",
+             &s.vp8_low, &s.vp8_high, &s.vp9_low, &s.vp9_high, &s.h264_low,
+             &s.h264_high, &s.generic_low, &s.generic_high, &s.alpha_high,
+             &s.alpha_low, &s.drop) != 11) {
+    RTC_LOG(LS_WARNING) << "Invalid number of parameters provided.";
+    return absl::nullopt;
+  }
+  return s;
+}
+
+absl::optional<VideoEncoder::QpThresholds>
+QualityScalingExperiment::GetQpThresholds(VideoCodecType codec_type,
+                                          const FieldTrialsView& field_trials) {
+  const auto settings = ParseSettings(field_trials);
+  if (!settings)
+    return absl::nullopt;
+
+  switch (codec_type) {
+    case kVideoCodecVP8:
+      return GetThresholds(settings->vp8_low, settings->vp8_high, kMaxVp8Qp);
+    case kVideoCodecVP9:
+      return GetThresholds(settings->vp9_low, settings->vp9_high, kMaxVp9Qp);
+    case kVideoCodecH265:
+    //  TODO(bugs.webrtc.org/13485): Use H264 QP thresholds for now.
+    case kVideoCodecH264:
+      return GetThresholds(settings->h264_low, settings->h264_high, kMaxH264Qp);
+    case kVideoCodecGeneric:
+      return GetThresholds(settings->generic_low, settings->generic_high,
+                           kMaxGenericQp);
+    default:
+      return absl::nullopt;
+  }
+}
+
+QualityScalingExperiment::Config QualityScalingExperiment::GetConfig(
+    const FieldTrialsView& field_trials) {
+  const auto settings = ParseSettings(field_trials);
+  if (!settings)
+    return Config();
+
+  Config config;
+  config.use_all_drop_reasons = settings->drop > 0;
+
+  if (settings->alpha_high < 0 || settings->alpha_low < settings->alpha_high) {
+    RTC_LOG(LS_WARNING) << "Invalid alpha value provided, using default.";
+    return config;
+  }
+  config.alpha_high = settings->alpha_high;
+  config.alpha_low = settings->alpha_low;
+  return config;
+}
+
+}  // namespace webrtc