1 files changed, 148 insertions, 0 deletions
diff --git a/third_party/libwebrtc/modules/video_coding/utility/bandwidth_quality_scaler.cc b/third_party/libwebrtc/modules/video_coding/utility/bandwidth_quality_scaler.cc
new file mode 100644
index 0000000000..13502a142b
--- /dev/null
+++ b/third_party/libwebrtc/modules/video_coding/utility/bandwidth_quality_scaler.cc
@@ -0,0 +1,148 @@
+/*
+ *  Copyright (c) 2021 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 "modules/video_coding/utility/bandwidth_quality_scaler.h"
+
+#include <algorithm>
+#include <memory>
+#include <utility>
+#include <vector>
+
+#include "api/video/video_adaptation_reason.h"
+#include "api/video_codecs/video_encoder.h"
+#include "rtc_base/checks.h"
+#include "rtc_base/experiments/bandwidth_quality_scaler_settings.h"
+#include "rtc_base/logging.h"
+#include "rtc_base/numerics/exp_filter.h"
+#include "rtc_base/time_utils.h"
+#include "rtc_base/weak_ptr.h"
+
+namespace webrtc {
+
+namespace {
+
+constexpr int kDefaultMaxWindowSizeMs = 5000;
+constexpr float kHigherMaxBitrateTolerationFactor = 0.95;
+constexpr float kLowerMinBitrateTolerationFactor = 0.8;
+constexpr int kDefaultBitrateStateUpdateIntervalSeconds = 5;
+}  // namespace
+
+BandwidthQualityScaler::BandwidthQualityScaler(
+    BandwidthQualityScalerUsageHandlerInterface* handler)
+    : kBitrateStateUpdateInterval(TimeDelta::Seconds(
+          BandwidthQualityScalerSettings::ParseFromFieldTrials()
+              .BitrateStateUpdateInterval()
+              .value_or(kDefaultBitrateStateUpdateIntervalSeconds))),
+      handler_(handler),
+      encoded_bitrate_(kDefaultMaxWindowSizeMs, RateStatistics::kBpsScale),
+      weak_ptr_factory_(this) {
+  RTC_DCHECK_RUN_ON(&task_checker_);
+  RTC_DCHECK(handler_ != nullptr);
+
+  StartCheckForBitrate();
+}
+
+BandwidthQualityScaler::~BandwidthQualityScaler() {
+  RTC_DCHECK_RUN_ON(&task_checker_);
+}
+
+void BandwidthQualityScaler::StartCheckForBitrate() {
+  RTC_DCHECK_RUN_ON(&task_checker_);
+  TaskQueueBase::Current()->PostDelayedTask(
+      [this_weak_ptr = weak_ptr_factory_.GetWeakPtr(), this] {
+        if (!this_weak_ptr) {
+          // The caller BandwidthQualityScaler has been deleted.
+          return;
+        }
+        RTC_DCHECK_RUN_ON(&task_checker_);
+        switch (CheckBitrate()) {
+          case BandwidthQualityScaler::CheckBitrateResult::kHighBitRate: {
+            handler_->OnReportUsageBandwidthHigh();
+            last_frame_size_pixels_.reset();
+            break;
+          }
+          case BandwidthQualityScaler::CheckBitrateResult::kLowBitRate: {
+            handler_->OnReportUsageBandwidthLow();
+            last_frame_size_pixels_.reset();
+            break;
+          }
+          case BandwidthQualityScaler::CheckBitrateResult::kNormalBitrate: {
+            break;
+          }
+          case BandwidthQualityScaler::CheckBitrateResult::
+              kInsufficientSamples: {
+            break;
+          }
+        }
+        StartCheckForBitrate();
+      },
+      kBitrateStateUpdateInterval);
+}
+
+void BandwidthQualityScaler::ReportEncodeInfo(int frame_size_bytes,
+                                              int64_t time_sent_in_ms,
+                                              uint32_t encoded_width,
+                                              uint32_t encoded_height) {
+  RTC_DCHECK_RUN_ON(&task_checker_);
+  last_time_sent_in_ms_ = time_sent_in_ms;
+  last_frame_size_pixels_ = encoded_width * encoded_height;
+  encoded_bitrate_.Update(frame_size_bytes, time_sent_in_ms);
+}
+
+void BandwidthQualityScaler::SetResolutionBitrateLimits(
+    const std::vector<VideoEncoder::ResolutionBitrateLimits>&
+        resolution_bitrate_limits) {
+  if (resolution_bitrate_limits.empty()) {
+    resolution_bitrate_limits_ = EncoderInfoSettings::
+        GetDefaultSinglecastBitrateLimitsWhenQpIsUntrusted();
+  } else {
+    resolution_bitrate_limits_ = resolution_bitrate_limits;
+  }
+}
+
+BandwidthQualityScaler::CheckBitrateResult
+BandwidthQualityScaler::CheckBitrate() {
+  RTC_DCHECK_RUN_ON(&task_checker_);
+  if (!last_frame_size_pixels_.has_value() ||
+      !last_time_sent_in_ms_.has_value()) {
+    return BandwidthQualityScaler::CheckBitrateResult::kInsufficientSamples;
+  }
+
+  absl::optional<int64_t> current_bitrate_bps =
+      encoded_bitrate_.Rate(last_time_sent_in_ms_.value());
+  if (!current_bitrate_bps.has_value()) {
+    // We can't get a valid bitrate due to not enough data points.
+    return BandwidthQualityScaler::CheckBitrateResult::kInsufficientSamples;
+  }
+  absl::optional<VideoEncoder::ResolutionBitrateLimits> suitable_bitrate_limit =
+      EncoderInfoSettings::
+          GetSinglecastBitrateLimitForResolutionWhenQpIsUntrusted(
+              last_frame_size_pixels_, resolution_bitrate_limits_);
+
+  if (!suitable_bitrate_limit.has_value()) {
+    return BandwidthQualityScaler::CheckBitrateResult::kInsufficientSamples;
+  }
+
+  // Multiply by toleration factor to solve the frequent adaptation due to
+  // critical value.
+  if (current_bitrate_bps > suitable_bitrate_limit->max_bitrate_bps *
+                                kHigherMaxBitrateTolerationFactor) {
+    return BandwidthQualityScaler::CheckBitrateResult::kLowBitRate;
+  } else if (current_bitrate_bps <
+             suitable_bitrate_limit->min_start_bitrate_bps *
+                 kLowerMinBitrateTolerationFactor) {
+    return BandwidthQualityScaler::CheckBitrateResult::kHighBitRate;
+  }
+  return BandwidthQualityScaler::CheckBitrateResult::kNormalBitrate;
+}
+
+BandwidthQualityScalerUsageHandlerInterface::
+    ~BandwidthQualityScalerUsageHandlerInterface() {}
+}  // namespace webrtc