Revert "Migrate RemoteNtpTimeEstimator to more precise time representations"

This reverts commit a154a15c978a0eae133d957dcad3581fd5f98c7b.

Reason for revert: breaks downstream tests

Original change's description:
> Migrate RemoteNtpTimeEstimator to more precise time representations
>
> Bug: webrtc:13757
> Change-Id: I880ab3cc6e4f72da587ae42ddca051332907c07f
> Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/261311
> Commit-Queue: Danil Chapovalov <danilchap@webrtc.org>
> Reviewed-by: Jakob Ivarsson‎ <jakobi@webrtc.org>
> Reviewed-by: Erik Språng <sprang@webrtc.org>
> Reviewed-by: Emil Lundmark <lndmrk@webrtc.org>
> Cr-Commit-Position: refs/heads/main@{#36817}

Bug: webrtc:13757
Change-Id: Id21edb1378e6e944b24955396250ddc33fa70663
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/261722
Reviewed-by: Tomas Gunnarsson <tommi@webrtc.org>
Bot-Commit: rubber-stamper@appspot.gserviceaccount.com <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: Danil Chapovalov <danilchap@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#36819}

9 files changed, 117 insertions, 171 deletions

diff --git a/audio/channel_receive.cc b/audio/channel_receive.cc
index d00a9a9469..93f534e0c4 100644
--- a/audio/channel_receive.cc
+++ b/audio/channel_receive.cc
@@ -748,13 +748,12 @@ void ChannelReceive::ReceivedRTCPPacket(const uint8_t* data, size_t length) {
 
   {
     MutexLock lock(&ts_stats_lock_);
-    ntp_estimator_.UpdateRtcpTimestamp(
-        TimeDelta::Millis(rtt), NtpTime(ntp_secs, ntp_frac), rtp_timestamp);
-    absl::optional<int64_t> remote_to_local_clock_offset =
-        ntp_estimator_.EstimateRemoteToLocalClockOffset();
-    if (remote_to_local_clock_offset.has_value()) {
+    ntp_estimator_.UpdateRtcpTimestamp(rtt, ntp_secs, ntp_frac, rtp_timestamp);
+    absl::optional<int64_t> remote_to_local_clock_offset_ms =
+        ntp_estimator_.EstimateRemoteToLocalClockOffsetMs();
+    if (remote_to_local_clock_offset_ms.has_value()) {
       capture_clock_offset_updater_.SetRemoteToLocalClockOffset(
-          *remote_to_local_clock_offset);
+          Int64MsToQ32x32(*remote_to_local_clock_offset_ms));
     }
   }
 }
diff --git a/audio/voip/audio_ingress.cc b/audio/voip/audio_ingress.cc
index 71026e84e0..8aa552bb28 100644
--- a/audio/voip/audio_ingress.cc
+++ b/audio/voip/audio_ingress.cc
@@ -226,8 +226,7 @@ void AudioIngress::ReceivedRTCPPacket(
 
   {
     MutexLock lock(&lock_);
-    ntp_estimator_.UpdateRtcpTimestamp(
-        TimeDelta::Millis(rtt), NtpTime(ntp_secs, ntp_frac), rtp_timestamp);
+    ntp_estimator_.UpdateRtcpTimestamp(rtt, ntp_secs, ntp_frac, rtp_timestamp);
   }
 }
 
diff --git a/modules/rtp_rtcp/include/remote_ntp_time_estimator.h b/modules/rtp_rtcp/include/remote_ntp_time_estimator.h
index 2c1eeb35af..f31503dc4e 100644
--- a/modules/rtp_rtcp/include/remote_ntp_time_estimator.h
+++ b/modules/rtp_rtcp/include/remote_ntp_time_estimator.h
@@ -13,10 +13,7 @@
 
 #include <stdint.h>
 
-#include "absl/base/attributes.h"
 #include "absl/types/optional.h"
-#include "api/units/time_delta.h"
-#include "api/units/timestamp.h"
 #include "rtc_base/numerics/moving_median_filter.h"
 #include "system_wrappers/include/rtp_to_ntp_estimator.h"
 
@@ -31,63 +28,32 @@ class Clock;
 class RemoteNtpTimeEstimator {
  public:
   explicit RemoteNtpTimeEstimator(Clock* clock);
+
+  ~RemoteNtpTimeEstimator();
+
   RemoteNtpTimeEstimator(const RemoteNtpTimeEstimator&) = delete;
   RemoteNtpTimeEstimator& operator=(const RemoteNtpTimeEstimator&) = delete;
-  ~RemoteNtpTimeEstimator() = default;
 
   // Updates the estimator with round trip time `rtt`, NTP seconds `ntp_secs`,
   // NTP fraction `ntp_frac` and RTP timestamp `rtp_timestamp`.
-  ABSL_DEPRECATED(
-      "Use UpdateRtcpTimestamp with strict time types: TimeDelta and NtpTime.")
   bool UpdateRtcpTimestamp(int64_t rtt,
                            uint32_t ntp_secs,
                            uint32_t ntp_frac,
-                           uint32_t rtp_timestamp) {
-    return UpdateRtcpTimestamp(TimeDelta::Millis(rtt),
-                               NtpTime(ntp_secs, ntp_frac), rtp_timestamp);
-  }
-
-  bool UpdateRtcpTimestamp(TimeDelta rtt,
-                           NtpTime sender_send_time,
                            uint32_t rtp_timestamp);
 
   // Estimates the NTP timestamp in local timebase from `rtp_timestamp`.
   // Returns the NTP timestamp in ms when success. -1 if failed.
-  int64_t Estimate(uint32_t rtp_timestamp) {
-    NtpTime ntp_time = EstimateNtp(rtp_timestamp);
-    if (!ntp_time.Valid()) {
-      return -1;
-    }
-    return ntp_time.ToMs();
-  }
-
-  // Estimates the NTP timestamp in local timebase from `rtp_timestamp`.
-  // Returns invalid NtpTime (i.e. NtpTime(0)) on failure.
-  NtpTime EstimateNtp(uint32_t rtp_timestamp);
+  int64_t Estimate(uint32_t rtp_timestamp);
 
   // Estimates the offset, in milliseconds, between the remote clock and the
   // local one. This is equal to local NTP clock - remote NTP clock.
-  ABSL_DEPRECATED("Use EstimateRemoteToLocalClockOffset.")
-  absl::optional<int64_t> EstimateRemoteToLocalClockOffsetMs() {
-    if (absl::optional<int64_t> offset = EstimateRemoteToLocalClockOffset()) {
-      return (*offset * 1'000) / (int64_t{1} << 32);
-    }
-    return absl::nullopt;
-  }
-
-  // Estimates the offset between the remote clock and the
-  // local one. This is equal to local NTP clock - remote NTP clock.
-  // The offset is returned in ntp time resolution, i.e. 1/2^32 sec ~= 0.2 ns.
-  // Returns nullopt on failure.
-  absl::optional<int64_t> EstimateRemoteToLocalClockOffset();
+  absl::optional<int64_t> EstimateRemoteToLocalClockOffsetMs();
 
  private:
   Clock* clock_;
-  // Offset is measured with the same precision as NtpTime: in 1/2^32 seconds ~=
-  // 0.2 ns.
   MovingMedianFilter<int64_t> ntp_clocks_offset_estimator_;
   RtpToNtpEstimator rtp_to_ntp_;
-  Timestamp last_timing_log_ = Timestamp::MinusInfinity();
+  int64_t last_timing_log_ms_;
 };
 
 }  // namespace webrtc
diff --git a/modules/rtp_rtcp/source/remote_ntp_time_estimator.cc b/modules/rtp_rtcp/source/remote_ntp_time_estimator.cc
index 6f90cd175c..b1602e5dcd 100644
--- a/modules/rtp_rtcp/source/remote_ntp_time_estimator.cc
+++ b/modules/rtp_rtcp/source/remote_ntp_time_estimator.cc
@@ -22,37 +22,25 @@ namespace webrtc {
 namespace {
 
 constexpr int kMinimumNumberOfSamples = 2;
-constexpr TimeDelta kTimingLogInterval = TimeDelta::Seconds(10);
+constexpr int kTimingLogIntervalMs = 10000;
 constexpr int kClocksOffsetSmoothingWindow = 100;
 
-// Subtracts two NtpTime values keeping maximum precision.
-int64_t Subtract(NtpTime minuend, NtpTime subtrahend) {
-  uint64_t a = static_cast<uint64_t>(minuend);
-  uint64_t b = static_cast<uint64_t>(subtrahend);
-  return a >= b ? static_cast<int64_t>(a - b) : -static_cast<int64_t>(b - a);
-}
-
-NtpTime Add(NtpTime lhs, int64_t rhs) {
-  uint64_t result = static_cast<uint64_t>(lhs);
-  if (rhs >= 0) {
-    result += static_cast<uint64_t>(rhs);
-  } else {
-    result -= static_cast<uint64_t>(-rhs);
-  }
-  return NtpTime(result);
-}
-
 }  // namespace
 
 // TODO(wu): Refactor this class so that it can be shared with
 // vie_sync_module.cc.
 RemoteNtpTimeEstimator::RemoteNtpTimeEstimator(Clock* clock)
     : clock_(clock),
-      ntp_clocks_offset_estimator_(kClocksOffsetSmoothingWindow) {}
+      ntp_clocks_offset_estimator_(kClocksOffsetSmoothingWindow),
+      last_timing_log_ms_(-1) {}
+
+RemoteNtpTimeEstimator::~RemoteNtpTimeEstimator() {}
 
-bool RemoteNtpTimeEstimator::UpdateRtcpTimestamp(TimeDelta rtt,
-                                                 NtpTime sender_send_time,
+bool RemoteNtpTimeEstimator::UpdateRtcpTimestamp(int64_t rtt,
+                                                 uint32_t ntp_secs,
+                                                 uint32_t ntp_frac,
                                                  uint32_t rtp_timestamp) {
+  NtpTime sender_send_time(ntp_secs, ntp_frac);
   switch (rtp_to_ntp_.UpdateMeasurements(sender_send_time, rtp_timestamp)) {
     case RtpToNtpEstimator::kInvalidMeasurement:
       return false;
@@ -63,42 +51,42 @@ bool RemoteNtpTimeEstimator::UpdateRtcpTimestamp(TimeDelta rtt,
       break;
   }
 
-  // Assume connection is symmetric and thus time to deliver the packet is half
-  // the round trip time.
-  int64_t deliver_time_ntp = ToNtpUnits(rtt) / 2;
-
   // Update extrapolator with the new arrival time.
-  NtpTime receiver_arrival_time = clock_->CurrentNtpTime();
+  // The extrapolator assumes the ntp time.
+  int64_t receiver_arrival_time_ms = clock_->CurrentNtpInMilliseconds();
+  int64_t sender_arrival_time_ms = sender_send_time.ToMs() + rtt / 2;
   int64_t remote_to_local_clocks_offset =
-      Subtract(receiver_arrival_time, sender_send_time) - deliver_time_ntp;
+      receiver_arrival_time_ms - sender_arrival_time_ms;
   ntp_clocks_offset_estimator_.Insert(remote_to_local_clocks_offset);
   return true;
 }
 
-NtpTime RemoteNtpTimeEstimator::EstimateNtp(uint32_t rtp_timestamp) {
+int64_t RemoteNtpTimeEstimator::Estimate(uint32_t rtp_timestamp) {
   NtpTime sender_capture = rtp_to_ntp_.Estimate(rtp_timestamp);
   if (!sender_capture.Valid()) {
-    return sender_capture;
+    return -1;
   }
+  int64_t sender_capture_ntp_ms = sender_capture.ToMs();
 
   int64_t remote_to_local_clocks_offset =
       ntp_clocks_offset_estimator_.GetFilteredValue();
-  NtpTime receiver_capture = Add(sender_capture, remote_to_local_clocks_offset);
+  int64_t receiver_capture_ntp_ms =
+      sender_capture_ntp_ms + remote_to_local_clocks_offset;
 
-  Timestamp now = clock_->CurrentTime();
-  if (now - last_timing_log_ > kTimingLogInterval) {
+  int64_t now_ms = clock_->TimeInMilliseconds();
+  if (now_ms - last_timing_log_ms_ > kTimingLogIntervalMs) {
     RTC_LOG(LS_INFO) << "RTP timestamp: " << rtp_timestamp
-                     << " in NTP clock: " << sender_capture.ToMs()
+                     << " in NTP clock: " << sender_capture_ntp_ms
                      << " estimated time in receiver NTP clock: "
-                     << receiver_capture.ToMs();
-    last_timing_log_ = now;
+                     << receiver_capture_ntp_ms;
+    last_timing_log_ms_ = now_ms;
   }
 
-  return receiver_capture;
+  return receiver_capture_ntp_ms;
 }
 
 absl::optional<int64_t>
-RemoteNtpTimeEstimator::EstimateRemoteToLocalClockOffset() {
+RemoteNtpTimeEstimator::EstimateRemoteToLocalClockOffsetMs() {
   if (ntp_clocks_offset_estimator_.GetNumberOfSamplesStored() <
       kMinimumNumberOfSamples) {
     return absl::nullopt;
diff --git a/modules/rtp_rtcp/source/remote_ntp_time_estimator_unittest.cc b/modules/rtp_rtcp/source/remote_ntp_time_estimator_unittest.cc
index 8dbfaec940..73c3e9b9b8 100644
--- a/modules/rtp_rtcp/source/remote_ntp_time_estimator_unittest.cc
+++ b/modules/rtp_rtcp/source/remote_ntp_time_estimator_unittest.cc
@@ -9,29 +9,32 @@
  */
 
 #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 int64_t kTestRtt = 10;
+constexpr int64_t kLocalClockInitialTimeMs = 123;
+constexpr int64_t kRemoteClockInitialTimeMs = 345;
 constexpr uint32_t kTimestampOffset = 567;
-constexpr int64_t kRemoteToLocalClockOffsetNtp =
-    ToNtpUnits(kLocalClockInitialTime - kRemoteClockInitialTime);
+constexpr int64_t kRemoteToLocalClockOffsetMs =
+    kLocalClockInitialTimeMs - kRemoteClockInitialTimeMs;
 
 class RemoteNtpTimeEstimatorTest : public ::testing::Test {
  protected:
-  void AdvanceTime(TimeDelta delta) {
-    local_clock_.AdvanceTime(delta);
-    remote_clock_.AdvanceTime(delta);
+  RemoteNtpTimeEstimatorTest()
+      : local_clock_(kLocalClockInitialTimeMs * 1000),
+        remote_clock_(kRemoteClockInitialTimeMs * 1000),
+        estimator_(new RemoteNtpTimeEstimator(&local_clock_)) {}
+  ~RemoteNtpTimeEstimatorTest() override = default;
+
+  void AdvanceTimeMilliseconds(int64_t ms) {
+    local_clock_.AdvanceTimeMilliseconds(ms);
+    remote_clock_.AdvanceTimeMilliseconds(ms);
   }
 
   uint32_t GetRemoteTimestamp() {
@@ -39,90 +42,107 @@ class RemoteNtpTimeEstimatorTest : public ::testing::Test {
            kTimestampOffset;
   }
 
+  NtpTime GetRemoteNtpTime() { return remote_clock_.CurrentNtpTime(); }
+
   void SendRtcpSr() {
     uint32_t rtcp_timestamp = GetRemoteTimestamp();
-    NtpTime ntp = remote_clock_.CurrentNtpTime();
+    NtpTime ntp = GetRemoteNtpTime();
 
-    AdvanceTime(kTestRtt / 2);
-    RTC_DCHECK(estimator_.UpdateRtcpTimestamp(kTestRtt, ntp, rtcp_timestamp));
+    AdvanceTimeMilliseconds(kTestRtt / 2);
+    ReceiveRtcpSr(kTestRtt, rtcp_timestamp, ntp.seconds(), ntp.fractions());
   }
 
-  void SendRtcpSrInaccurately(TimeDelta ntp_error, TimeDelta networking_delay) {
+  void SendRtcpSrInaccurately(int64_t ntp_error_ms,
+                              int64_t networking_delay_ms) {
     uint32_t rtcp_timestamp = GetRemoteTimestamp();
-    int64_t ntp_error_fractions = ToNtpUnits(ntp_error);
-    NtpTime ntp(static_cast<uint64_t>(remote_clock_.CurrentNtpTime()) +
+    int64_t ntp_error_fractions =
+        ntp_error_ms * static_cast<int64_t>(NtpTime::kFractionsPerSecond) /
+        1000;
+    NtpTime ntp(static_cast<uint64_t>(GetRemoteNtpTime()) +
                 ntp_error_fractions);
-    AdvanceTime(kTestRtt / 2 + networking_delay);
-    RTC_DCHECK(estimator_.UpdateRtcpTimestamp(kTestRtt, ntp, rtcp_timestamp));
+    AdvanceTimeMilliseconds(kTestRtt / 2 + networking_delay_ms);
+    ReceiveRtcpSr(kTestRtt, rtcp_timestamp, ntp.seconds(), ntp.fractions());
   }
 
-  SimulatedClock local_clock_{kLocalClockInitialTime};
-  SimulatedClock remote_clock_{kRemoteClockInitialTime};
-  RemoteNtpTimeEstimator estimator_{&local_clock_};
-};
+  void UpdateRtcpTimestamp(int64_t rtt,
+                           uint32_t ntp_secs,
+                           uint32_t ntp_frac,
+                           uint32_t rtp_timestamp,
+                           bool expected_result) {
+    EXPECT_EQ(expected_result, estimator_->UpdateRtcpTimestamp(
+                                   rtt, ntp_secs, ntp_frac, rtp_timestamp));
+  }
 
-TEST_F(RemoteNtpTimeEstimatorTest, FailsWithoutValidNtpTime) {
-  EXPECT_FALSE(
-      estimator_.UpdateRtcpTimestamp(kTestRtt, NtpTime(), /*rtp_timestamp=*/0));
-}
+  void ReceiveRtcpSr(int64_t rtt,
+                     uint32_t rtcp_timestamp,
+                     uint32_t ntp_seconds,
+                     uint32_t ntp_fractions) {
+    UpdateRtcpTimestamp(rtt, ntp_seconds, ntp_fractions, rtcp_timestamp, true);
+  }
+
+  SimulatedClock local_clock_;
+  SimulatedClock remote_clock_;
+  std::unique_ptr<RemoteNtpTimeEstimator> estimator_;
+};
 
 TEST_F(RemoteNtpTimeEstimatorTest, Estimate) {
+  // Failed without valid NTP.
+  UpdateRtcpTimestamp(kTestRtt, 0, 0, 0, false);
+
+  AdvanceTimeMilliseconds(1000);
   // Remote peer sends first RTCP SR.
   SendRtcpSr();
 
   // Remote sends a RTP packet.
-  AdvanceTime(TimeDelta::Millis(15));
+  AdvanceTimeMilliseconds(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);
+  EXPECT_EQ(kNotEnoughRtcpSr, estimator_->Estimate(rtp_timestamp));
+  EXPECT_EQ(absl::nullopt, estimator_->EstimateRemoteToLocalClockOffsetMs());
 
-  AdvanceTime(TimeDelta::Millis(800));
+  AdvanceTimeMilliseconds(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);
+  EXPECT_EQ(capture_ntp_time_ms, estimator_->Estimate(rtp_timestamp));
+  EXPECT_EQ(kRemoteToLocalClockOffsetMs,
+            estimator_->EstimateRemoteToLocalClockOffsetMs());
 }
 
 TEST_F(RemoteNtpTimeEstimatorTest, AveragesErrorsOut) {
   // Remote peer sends first 10 RTCP SR without errors.
   for (int i = 0; i < 10; ++i) {
-    AdvanceTime(TimeDelta::Seconds(1));
+    AdvanceTimeMilliseconds(1000);
     SendRtcpSr();
   }
 
-  AdvanceTime(TimeDelta::Millis(150));
+  AdvanceTimeMilliseconds(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());
+  EXPECT_EQ(capture_ntp_time_ms, estimator_->Estimate(rtp_timestamp));
+  EXPECT_EQ(kRemoteToLocalClockOffsetMs,
+            estimator_->EstimateRemoteToLocalClockOffsetMs());
 
   // 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));
+  AdvanceTimeMilliseconds(1000);
+  SendRtcpSrInaccurately(/*ntp_error_ms=*/2, /*networking_delay_ms=*/-1);
+  AdvanceTimeMilliseconds(1000);
+  SendRtcpSrInaccurately(/*ntp_error_ms=*/-2, /*networking_delay_ms=*/1);
 
   // New RTP packet to estimate timestamp.
-  AdvanceTime(TimeDelta::Millis(150));
+  AdvanceTimeMilliseconds(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());
+  EXPECT_EQ(capture_ntp_time_ms, estimator_->Estimate(rtp_timestamp));
+  EXPECT_EQ(kRemoteToLocalClockOffsetMs,
+            estimator_->EstimateRemoteToLocalClockOffsetMs());
 }
 
-}  // namespace
 }  // namespace webrtc
diff --git a/modules/rtp_rtcp/source/time_util.h b/modules/rtp_rtcp/source/time_util.h
index 5e72bba3b9..fba2dd9ff4 100644
--- a/modules/rtp_rtcp/source/time_util.h
+++ b/modules/rtp_rtcp/source/time_util.h
@@ -34,14 +34,6 @@ inline uint32_t CompactNtp(NtpTime ntp) {
 // Negative values converted to 0, Overlarge values converted to max uint32_t.
 uint32_t SaturatedToCompactNtp(TimeDelta delta);
 
-// Convert interval to the NTP time resolution (1/2^32 seconds ~= 0.2 ns).
-inline constexpr int64_t ToNtpUnits(TimeDelta delta) {
-  // For better precision `delta` is taken with best TimeDelta precision (us),
-  // then multiplaction and conversion to seconds are swapped to avoid float
-  // arithmetic.
-  return (delta.us() * (int64_t{1} << 32)) / 1'000'000;
-}
-
 // Converts interval from compact ntp (1/2^16 seconds) resolution to TimeDelta.
 // This interval can be up to ~9.1 hours (2^15 seconds).
 // Values close to 2^16 seconds are considered negative and are converted to
diff --git a/modules/rtp_rtcp/source/time_util_unittest.cc b/modules/rtp_rtcp/source/time_util_unittest.cc
index f77c3c6e5d..983155e8a3 100644
--- a/modules/rtp_rtcp/source/time_util_unittest.cc
+++ b/modules/rtp_rtcp/source/time_util_unittest.cc
@@ -95,20 +95,4 @@ TEST(TimeUtilTest, SaturatedToCompactNtp) {
       5'515, 16);
 }
 
-TEST(TimeUtilTest, ToNtpUnits) {
-  EXPECT_EQ(ToNtpUnits(TimeDelta::Zero()), 0);
-  EXPECT_EQ(ToNtpUnits(TimeDelta::Seconds(1)), int64_t{1} << 32);
-  EXPECT_EQ(ToNtpUnits(TimeDelta::Seconds(-1)), -(int64_t{1} << 32));
-
-  EXPECT_EQ(ToNtpUnits(TimeDelta::Millis(500)), int64_t{1} << 31);
-  EXPECT_EQ(ToNtpUnits(TimeDelta::Millis(-1'500)), -(int64_t{3} << 31));
-
-  // Smallest TimeDelta that can be converted without precision loss.
-  EXPECT_EQ(ToNtpUnits(TimeDelta::Micros(15'625)), int64_t{1} << 26);
-
-  // 1 us ~= 4'294.97 NTP units. ToNtpUnits makes no rounding promises.
-  EXPECT_GE(ToNtpUnits(TimeDelta::Micros(1)), 4'294);
-  EXPECT_LE(ToNtpUnits(TimeDelta::Micros(1)), 4'295);
-}
-
 }  // namespace webrtc
diff --git a/video/rtp_video_stream_receiver.cc b/video/rtp_video_stream_receiver.cc
index 5a268398f7..04484b91cc 100644
--- a/video/rtp_video_stream_receiver.cc
+++ b/video/rtp_video_stream_receiver.cc
@@ -1122,13 +1122,12 @@ bool RtpVideoStreamReceiver::DeliverRtcp(const uint8_t* rtcp_packet,
       clock_->CurrentNtpInMilliseconds() - received_ntp.ToMs();
   // Don't use old SRs to estimate time.
   if (time_since_received <= 1) {
-    ntp_estimator_.UpdateRtcpTimestamp(
-        TimeDelta::Millis(rtt), NtpTime(ntp_secs, ntp_frac), rtp_timestamp);
-    absl::optional<int64_t> remote_to_local_clock_offset =
-        ntp_estimator_.EstimateRemoteToLocalClockOffset();
-    if (remote_to_local_clock_offset.has_value()) {
+    ntp_estimator_.UpdateRtcpTimestamp(rtt, ntp_secs, ntp_frac, rtp_timestamp);
+    absl::optional<int64_t> remote_to_local_clock_offset_ms =
+        ntp_estimator_.EstimateRemoteToLocalClockOffsetMs();
+    if (remote_to_local_clock_offset_ms.has_value()) {
       capture_clock_offset_updater_.SetRemoteToLocalClockOffset(
-          *remote_to_local_clock_offset);
+          Int64MsToQ32x32(*remote_to_local_clock_offset_ms));
     }
   }
 
diff --git a/video/rtp_video_stream_receiver2.cc b/video/rtp_video_stream_receiver2.cc
index 46fa2d94e7..9956760c3b 100644
--- a/video/rtp_video_stream_receiver2.cc
+++ b/video/rtp_video_stream_receiver2.cc
@@ -1042,13 +1042,12 @@ bool RtpVideoStreamReceiver2::DeliverRtcp(const uint8_t* rtcp_packet,
       clock_->CurrentNtpInMilliseconds() - received_ntp.ToMs();
   // Don't use old SRs to estimate time.
   if (time_since_received <= 1) {
-    ntp_estimator_.UpdateRtcpTimestamp(
-        TimeDelta::Millis(rtt), NtpTime(ntp_secs, ntp_frac), rtp_timestamp);
-    absl::optional<int64_t> remote_to_local_clock_offset =
-        ntp_estimator_.EstimateRemoteToLocalClockOffset();
-    if (remote_to_local_clock_offset.has_value()) {
+    ntp_estimator_.UpdateRtcpTimestamp(rtt, ntp_secs, ntp_frac, rtp_timestamp);
+    absl::optional<int64_t> remote_to_local_clock_offset_ms =
+        ntp_estimator_.EstimateRemoteToLocalClockOffsetMs();
+    if (remote_to_local_clock_offset_ms.has_value()) {
       capture_clock_offset_updater_.SetRemoteToLocalClockOffset(
-          *remote_to_local_clock_offset);
+          Int64MsToQ32x32(*remote_to_local_clock_offset_ms));
     }
   }