Reland of "Change TWCC send interval to reduce overhead on low BW situations."
"Change TWCC send interval to reduce overhead on low BW situations." was first committed in https://codereview.webrtc.org/2381833003/
but was reverted in https://codereview.webrtc.org/2468413009/ due to "float-cast-overflow".
BUG=webrtc:6442, webrtc:6669
Review-Url: https://codereview.webrtc.org/2482823002
Cr-Commit-Position: refs/heads/master@{#14954}
diff --git a/webrtc/modules/congestion_controller/congestion_controller.cc b/webrtc/modules/congestion_controller/congestion_controller.cc
index f3ce2e5..0dafdf6 100644
--- a/webrtc/modules/congestion_controller/congestion_controller.cc
+++ b/webrtc/modules/congestion_controller/congestion_controller.cc
@@ -342,6 +342,7 @@
if (HasNetworkParametersToReportChanged(bitrate_bps, fraction_loss, rtt)) {
observer_->OnNetworkChanged(bitrate_bps, fraction_loss, rtt);
+ remote_estimator_proxy_.OnBitrateChanged(bitrate_bps);
}
}
diff --git a/webrtc/modules/remote_bitrate_estimator/remote_estimator_proxy.cc b/webrtc/modules/remote_bitrate_estimator/remote_estimator_proxy.cc
index b08b30a..5e7560a 100644
--- a/webrtc/modules/remote_bitrate_estimator/remote_estimator_proxy.cc
+++ b/webrtc/modules/remote_bitrate_estimator/remote_estimator_proxy.cc
@@ -11,6 +11,7 @@
#include "webrtc/modules/remote_bitrate_estimator/remote_estimator_proxy.h"
#include <limits>
+#include <algorithm>
#include "webrtc/base/checks.h"
#include "webrtc/base/logging.h"
@@ -22,8 +23,10 @@
namespace webrtc {
// TODO(sprang): Tune these!
-const int RemoteEstimatorProxy::kDefaultProcessIntervalMs = 50;
const int RemoteEstimatorProxy::kBackWindowMs = 500;
+const int RemoteEstimatorProxy::kMinSendIntervalMs = 50;
+const int RemoteEstimatorProxy::kMaxSendIntervalMs = 250;
+const int RemoteEstimatorProxy::kDefaultSendIntervalMs = 100;
// The maximum allowed value for a timestamp in milliseconds. This is lower
// than the numerical limit since we often convert to microseconds.
@@ -37,7 +40,8 @@
last_process_time_ms_(-1),
media_ssrc_(0),
feedback_sequence_(0),
- window_start_seq_(-1) {}
+ window_start_seq_(-1),
+ send_interval_ms_(kDefaultSendIntervalMs) {}
RemoteEstimatorProxy::~RemoteEstimatorProxy() {}
@@ -68,11 +72,12 @@
}
int64_t RemoteEstimatorProxy::TimeUntilNextProcess() {
- int64_t now = clock_->TimeInMilliseconds();
int64_t time_until_next = 0;
- if (last_process_time_ms_ != -1 &&
- now - last_process_time_ms_ < kDefaultProcessIntervalMs) {
- time_until_next = (last_process_time_ms_ + kDefaultProcessIntervalMs - now);
+ if (last_process_time_ms_ != -1) {
+ rtc::CritScope cs(&lock_);
+ int64_t now = clock_->TimeInMilliseconds();
+ if (now - last_process_time_ms_ < send_interval_ms_)
+ time_until_next = (last_process_time_ms_ + send_interval_ms_ - now);
}
return time_until_next;
}
@@ -92,6 +97,24 @@
}
}
+void RemoteEstimatorProxy::OnBitrateChanged(int bitrate_bps) {
+ // TwccReportSize = Ipv4(20B) + UDP(8B) + SRTP(10B) +
+ // AverageTwccReport(30B)
+ // TwccReport size at 50ms interval is 24 byte.
+ // TwccReport size at 250ms interval is 36 byte.
+ // AverageTwccReport = (TwccReport(50ms) + TwccReport(250ms)) / 2
+ constexpr int kTwccReportSize = 20 + 8 + 10 + 30;
+ constexpr double kMinTwccRate =
+ kTwccReportSize * 8.0 * 1000.0 / kMaxSendIntervalMs;
+ constexpr double kMaxTwccRate =
+ kTwccReportSize * 8.0 * 1000.0 / kMinSendIntervalMs;
+
+ // Let TWCC reports occupy 5% of total bandwidth.
+ rtc::CritScope cs(&lock_);
+ send_interval_ms_ = static_cast<int>(0.5 + kTwccReportSize * 8.0 * 1000.0 /
+ (std::max(std::min(0.05 * bitrate_bps, kMaxTwccRate), kMinTwccRate)));
+}
+
void RemoteEstimatorProxy::OnPacketArrival(uint16_t sequence_number,
int64_t arrival_time) {
if (arrival_time < 0 || arrival_time > kMaxTimeMs) {
diff --git a/webrtc/modules/remote_bitrate_estimator/remote_estimator_proxy.h b/webrtc/modules/remote_bitrate_estimator/remote_estimator_proxy.h
index 1278863..71099bf 100644
--- a/webrtc/modules/remote_bitrate_estimator/remote_estimator_proxy.h
+++ b/webrtc/modules/remote_bitrate_estimator/remote_estimator_proxy.h
@@ -47,8 +47,11 @@
void SetMinBitrate(int min_bitrate_bps) override {}
int64_t TimeUntilNextProcess() override;
void Process() override;
+ void OnBitrateChanged(int bitrate);
- static const int kDefaultProcessIntervalMs;
+ static const int kMinSendIntervalMs;
+ static const int kMaxSendIntervalMs;
+ static const int kDefaultSendIntervalMs;
static const int kBackWindowMs;
private:
@@ -68,6 +71,7 @@
int64_t window_start_seq_ GUARDED_BY(&lock_);
// Map unwrapped seq -> time.
std::map<int64_t, int64_t> packet_arrival_times_ GUARDED_BY(&lock_);
+ int64_t send_interval_ms_ GUARDED_BY(&lock_);
};
} // namespace webrtc
diff --git a/webrtc/modules/remote_bitrate_estimator/remote_estimator_proxy_unittest.cc b/webrtc/modules/remote_bitrate_estimator/remote_estimator_proxy_unittest.cc
index 9821568..dbb3eaa 100644
--- a/webrtc/modules/remote_bitrate_estimator/remote_estimator_proxy_unittest.cc
+++ b/webrtc/modules/remote_bitrate_estimator/remote_estimator_proxy_unittest.cc
@@ -42,7 +42,7 @@
void Process() {
clock_.AdvanceTimeMilliseconds(
- RemoteEstimatorProxy::kDefaultProcessIntervalMs);
+ RemoteEstimatorProxy::kDefaultSendIntervalMs);
proxy_.Process();
}
@@ -350,4 +350,45 @@
Process();
}
+TEST_F(RemoteEstimatorProxyTest, TimeUntilNextProcessIsZeroBeforeFirstProcess) {
+ EXPECT_EQ(0, proxy_.TimeUntilNextProcess());
+}
+
+TEST_F(RemoteEstimatorProxyTest, TimeUntilNextProcessIsDefaultOnUnkownBitrate) {
+ Process();
+ EXPECT_EQ(RemoteEstimatorProxy::kDefaultSendIntervalMs,
+ proxy_.TimeUntilNextProcess());
+}
+
+TEST_F(RemoteEstimatorProxyTest, TimeUntilNextProcessIsMinIntervalOn300kbps) {
+ Process();
+ proxy_.OnBitrateChanged(300000);
+ EXPECT_EQ(RemoteEstimatorProxy::kMinSendIntervalMs,
+ proxy_.TimeUntilNextProcess());
+}
+
+TEST_F(RemoteEstimatorProxyTest, TimeUntilNextProcessIsMaxIntervalOn0kbps) {
+ Process();
+ // TimeUntilNextProcess should be limited by |kMaxSendIntervalMs| when
+ // bitrate is small. We choose 0 bps as a special case, which also tests
+ // erroneous behaviors like division-by-zero.
+ proxy_.OnBitrateChanged(0);
+ EXPECT_EQ(RemoteEstimatorProxy::kMaxSendIntervalMs,
+ proxy_.TimeUntilNextProcess());
+}
+
+TEST_F(RemoteEstimatorProxyTest, TimeUntilNextProcessIsMaxIntervalOn20kbps) {
+ Process();
+ proxy_.OnBitrateChanged(20000);
+ EXPECT_EQ(RemoteEstimatorProxy::kMaxSendIntervalMs,
+ proxy_.TimeUntilNextProcess());
+}
+
+TEST_F(RemoteEstimatorProxyTest, TwccReportsUse5PercentOfAvailableBandwidth) {
+ Process();
+ proxy_.OnBitrateChanged(80000);
+ // 80kbps * 0.05 = TwccReportSize(68B * 8b/B) * 1000ms / SendInterval(136ms)
+ EXPECT_EQ(136, proxy_.TimeUntilNextProcess());
+}
+
} // namespace webrtc
