1 files changed, 128 insertions, 0 deletions
diff --git a/third_party/libwebrtc/modules/rtp_rtcp/source/remote_ntp_time_estimator_unittest.cc b/third_party/libwebrtc/modules/rtp_rtcp/source/remote_ntp_time_estimator_unittest.cc
new file mode 100644
index 0000000000..3737d66f07
--- /dev/null
+++ b/third_party/libwebrtc/modules/rtp_rtcp/source/remote_ntp_time_estimator_unittest.cc
@@ -0,0 +1,128 @@
+/*
+ *  Copyright (c) 2014 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/rtp_rtcp/include/remote_ntp_time_estimator.h"
+
+#include "absl/types/optional.h"
+#include "modules/rtp_rtcp/source/time_util.h"
+#include "system_wrappers/include/clock.h"
+#include "system_wrappers/include/ntp_time.h"
+#include "test/gmock.h"
+#include "test/gtest.h"
+
+namespace webrtc {
+namespace {
+
+constexpr TimeDelta kTestRtt = TimeDelta::Millis(10);
+constexpr Timestamp kLocalClockInitialTime = Timestamp::Millis(123);
+constexpr Timestamp kRemoteClockInitialTime = Timestamp::Millis(373);
+constexpr uint32_t kTimestampOffset = 567;
+constexpr int64_t kRemoteToLocalClockOffsetNtp =
+    ToNtpUnits(kLocalClockInitialTime - kRemoteClockInitialTime);
+
+class RemoteNtpTimeEstimatorTest : public ::testing::Test {
+ protected:
+  void AdvanceTime(TimeDelta delta) {
+    local_clock_.AdvanceTime(delta);
+    remote_clock_.AdvanceTime(delta);
+  }
+
+  uint32_t GetRemoteTimestamp() {
+    return static_cast<uint32_t>(remote_clock_.TimeInMilliseconds()) * 90 +
+           kTimestampOffset;
+  }
+
+  void SendRtcpSr() {
+    uint32_t rtcp_timestamp = GetRemoteTimestamp();
+    NtpTime ntp = remote_clock_.CurrentNtpTime();
+
+    AdvanceTime(kTestRtt / 2);
+    EXPECT_TRUE(estimator_.UpdateRtcpTimestamp(kTestRtt, ntp, rtcp_timestamp));
+  }
+
+  void SendRtcpSrInaccurately(TimeDelta ntp_error, TimeDelta networking_delay) {
+    uint32_t rtcp_timestamp = GetRemoteTimestamp();
+    int64_t ntp_error_fractions = ToNtpUnits(ntp_error);
+    NtpTime ntp(static_cast<uint64_t>(remote_clock_.CurrentNtpTime()) +
+                ntp_error_fractions);
+    AdvanceTime(kTestRtt / 2 + networking_delay);
+    EXPECT_TRUE(estimator_.UpdateRtcpTimestamp(kTestRtt, ntp, rtcp_timestamp));
+  }
+
+  SimulatedClock local_clock_{kLocalClockInitialTime};
+  SimulatedClock remote_clock_{kRemoteClockInitialTime};
+  RemoteNtpTimeEstimator estimator_{&local_clock_};
+};
+
+TEST_F(RemoteNtpTimeEstimatorTest, FailsWithoutValidNtpTime) {
+  EXPECT_FALSE(
+      estimator_.UpdateRtcpTimestamp(kTestRtt, NtpTime(), /*rtp_timestamp=*/0));
+}
+
+TEST_F(RemoteNtpTimeEstimatorTest, Estimate) {
+  // Remote peer sends first RTCP SR.
+  SendRtcpSr();
+
+  // Remote sends a RTP packet.
+  AdvanceTime(TimeDelta::Millis(15));
+  uint32_t rtp_timestamp = GetRemoteTimestamp();
+  int64_t capture_ntp_time_ms = local_clock_.CurrentNtpInMilliseconds();
+
+  // Local peer needs at least 2 RTCP SR to calculate the capture time.
+  const int64_t kNotEnoughRtcpSr = -1;
+  EXPECT_EQ(kNotEnoughRtcpSr, estimator_.Estimate(rtp_timestamp));
+  EXPECT_EQ(estimator_.EstimateRemoteToLocalClockOffset(), absl::nullopt);
+
+  AdvanceTime(TimeDelta::Millis(800));
+  // Remote sends second RTCP SR.
+  SendRtcpSr();
+
+  // Local peer gets enough RTCP SR to calculate the capture time.
+  EXPECT_EQ(capture_ntp_time_ms, estimator_.Estimate(rtp_timestamp));
+  EXPECT_EQ(estimator_.EstimateRemoteToLocalClockOffset(),
+            kRemoteToLocalClockOffsetNtp);
+}
+
+TEST_F(RemoteNtpTimeEstimatorTest, AveragesErrorsOut) {
+  // Remote peer sends first 10 RTCP SR without errors.
+  for (int i = 0; i < 10; ++i) {
+    AdvanceTime(TimeDelta::Seconds(1));
+    SendRtcpSr();
+  }
+
+  AdvanceTime(TimeDelta::Millis(150));
+  uint32_t rtp_timestamp = GetRemoteTimestamp();
+  int64_t capture_ntp_time_ms = local_clock_.CurrentNtpInMilliseconds();
+  // Local peer gets enough RTCP SR to calculate the capture time.
+  EXPECT_EQ(capture_ntp_time_ms, estimator_.Estimate(rtp_timestamp));
+  EXPECT_EQ(kRemoteToLocalClockOffsetNtp,
+            estimator_.EstimateRemoteToLocalClockOffset());
+
+  // Remote sends corrupted RTCP SRs
+  AdvanceTime(TimeDelta::Seconds(1));
+  SendRtcpSrInaccurately(/*ntp_error=*/TimeDelta::Millis(2),
+                         /*networking_delay=*/TimeDelta::Millis(-1));
+  AdvanceTime(TimeDelta::Seconds(1));
+  SendRtcpSrInaccurately(/*ntp_error=*/TimeDelta::Millis(-2),
+                         /*networking_delay=*/TimeDelta::Millis(1));
+
+  // New RTP packet to estimate timestamp.
+  AdvanceTime(TimeDelta::Millis(150));
+  rtp_timestamp = GetRemoteTimestamp();
+  capture_ntp_time_ms = local_clock_.CurrentNtpInMilliseconds();
+
+  // Errors should be averaged out.
+  EXPECT_EQ(capture_ntp_time_ms, estimator_.Estimate(rtp_timestamp));
+  EXPECT_EQ(kRemoteToLocalClockOffsetNtp,
+            estimator_.EstimateRemoteToLocalClockOffset());
+}
+
+}  // namespace
+}  // namespace webrtc