1 files changed, 135 insertions, 0 deletions
diff --git a/third_party/libwebrtc/call/rtp_bitrate_configurator.cc b/third_party/libwebrtc/call/rtp_bitrate_configurator.cc
new file mode 100644
index 0000000000..264dcdcb81
--- /dev/null
+++ b/third_party/libwebrtc/call/rtp_bitrate_configurator.cc
@@ -0,0 +1,135 @@
+/*
+ *  Copyright (c) 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 "call/rtp_bitrate_configurator.h"
+
+#include <algorithm>
+
+#include "rtc_base/checks.h"
+
+namespace {
+
+// Returns its smallest positive argument. If neither argument is positive,
+// returns an arbitrary nonpositive value.
+int MinPositive(int a, int b) {
+  if (a <= 0) {
+    return b;
+  }
+  if (b <= 0) {
+    return a;
+  }
+  return std::min(a, b);
+}
+
+}  // namespace
+
+namespace webrtc {
+RtpBitrateConfigurator::RtpBitrateConfigurator(
+    const BitrateConstraints& bitrate_config)
+    : bitrate_config_(bitrate_config), base_bitrate_config_(bitrate_config) {
+  RTC_DCHECK_GE(bitrate_config.min_bitrate_bps, 0);
+  RTC_DCHECK_GE(bitrate_config.start_bitrate_bps,
+                bitrate_config.min_bitrate_bps);
+  if (bitrate_config.max_bitrate_bps != -1) {
+    RTC_DCHECK_GE(bitrate_config.max_bitrate_bps,
+                  bitrate_config.start_bitrate_bps);
+  }
+}
+
+RtpBitrateConfigurator::~RtpBitrateConfigurator() = default;
+
+BitrateConstraints RtpBitrateConfigurator::GetConfig() const {
+  return bitrate_config_;
+}
+
+absl::optional<BitrateConstraints>
+RtpBitrateConfigurator::UpdateWithSdpParameters(
+    const BitrateConstraints& bitrate_config) {
+  RTC_DCHECK_GE(bitrate_config.min_bitrate_bps, 0);
+  RTC_DCHECK_NE(bitrate_config.start_bitrate_bps, 0);
+  if (bitrate_config.max_bitrate_bps != -1) {
+    RTC_DCHECK_GT(bitrate_config.max_bitrate_bps, 0);
+  }
+
+  absl::optional<int> new_start;
+  // Only update the "start" bitrate if it's set, and different from the old
+  // value. In practice, this value comes from the x-google-start-bitrate codec
+  // parameter in SDP, and setting the same remote description twice shouldn't
+  // restart bandwidth estimation.
+  if (bitrate_config.start_bitrate_bps != -1 &&
+      bitrate_config.start_bitrate_bps !=
+          base_bitrate_config_.start_bitrate_bps) {
+    new_start.emplace(bitrate_config.start_bitrate_bps);
+  }
+  base_bitrate_config_ = bitrate_config;
+  return UpdateConstraints(new_start);
+}
+
+absl::optional<BitrateConstraints>
+RtpBitrateConfigurator::UpdateWithClientPreferences(
+    const BitrateSettings& bitrate_mask) {
+  bitrate_config_mask_ = bitrate_mask;
+  return UpdateConstraints(bitrate_mask.start_bitrate_bps);
+}
+
+// Relay cap can change only max bitrate.
+absl::optional<BitrateConstraints> RtpBitrateConfigurator::UpdateWithRelayCap(
+    DataRate cap) {
+  if (cap.IsFinite()) {
+    RTC_DCHECK(!cap.IsZero());
+  }
+  max_bitrate_over_relay_ = cap;
+  return UpdateConstraints(absl::nullopt);
+}
+
+absl::optional<BitrateConstraints> RtpBitrateConfigurator::UpdateConstraints(
+    const absl::optional<int>& new_start) {
+  BitrateConstraints updated;
+  updated.min_bitrate_bps =
+      std::max(bitrate_config_mask_.min_bitrate_bps.value_or(0),
+               base_bitrate_config_.min_bitrate_bps);
+
+  updated.max_bitrate_bps =
+      MinPositive(bitrate_config_mask_.max_bitrate_bps.value_or(-1),
+                  base_bitrate_config_.max_bitrate_bps);
+  updated.max_bitrate_bps =
+      MinPositive(updated.max_bitrate_bps, max_bitrate_over_relay_.bps_or(-1));
+
+  // If the combined min ends up greater than the combined max, the max takes
+  // priority.
+  if (updated.max_bitrate_bps != -1 &&
+      updated.min_bitrate_bps > updated.max_bitrate_bps) {
+    updated.min_bitrate_bps = updated.max_bitrate_bps;
+  }
+
+  // If there is nothing to update (min/max unchanged, no new bandwidth
+  // estimation start value), return early.
+  if (updated.min_bitrate_bps == bitrate_config_.min_bitrate_bps &&
+      updated.max_bitrate_bps == bitrate_config_.max_bitrate_bps &&
+      !new_start) {
+    return absl::nullopt;
+  }
+
+  if (new_start) {
+    // Clamp start by min and max.
+    updated.start_bitrate_bps = MinPositive(
+        std::max(*new_start, updated.min_bitrate_bps), updated.max_bitrate_bps);
+  } else {
+    updated.start_bitrate_bps = -1;
+  }
+  BitrateConstraints config_to_return = updated;
+  if (!new_start) {
+    updated.start_bitrate_bps = bitrate_config_.start_bitrate_bps;
+  }
+  bitrate_config_ = updated;
+  return config_to_return;
+}
+
+}  // namespace webrtc