modules/video_coding/timing/default_video_jitter_timing_unittest.cc

/*
 *  Copyright (c) 2026 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/timing/default_video_jitter_timing.h"

#include <cstdint>
#include <optional>

#include "api/environment/environment.h"
#include "api/field_trials.h"
#include "api/units/data_size.h"
#include "api/units/time_delta.h"
#include "api/units/timestamp.h"
#include "system_wrappers/include/clock.h"
#include "test/create_test_environment.h"
#include "test/create_test_field_trials.h"
#include "test/gtest.h"

namespace webrtc {
namespace {

constexpr uint32_t kRtpTimestamp = 12345;
constexpr Timestamp kInitialTime = Timestamp::Millis(789);
constexpr DataSize kFrameSize = DataSize::Bytes(1000);
constexpr TimeDelta kRtt = TimeDelta::Millis(100);

TEST(DefaultVideoJitterTimingTest, ExtrapolatorReturnsNulloptInitially) {
  SimulatedClock clock(kInitialTime);
  Environment env = CreateTestEnvironment({.time = &clock});
  DefaultVideoJitterTiming timing(env);

  EXPECT_EQ(timing.ExtrapolateLocalTime(kRtpTimestamp), std::nullopt);
}

TEST(DefaultVideoJitterTimingTest, ExtrapolatorReturnsTimeAfterUpdate) {
  SimulatedClock clock(kInitialTime);
  Environment env = CreateTestEnvironment({.time = &clock});
  DefaultVideoJitterTiming timing(env);

  timing.OnCompleteTemporalUnit(kRtpTimestamp, clock.CurrentTime());
  EXPECT_EQ(timing.ExtrapolateLocalTime(kRtpTimestamp), clock.CurrentTime());
}

TEST(DefaultVideoJitterTimingTest, ExtrapolatorReturnsNulloptAfterReset) {
  SimulatedClock clock(kInitialTime);
  Environment env = CreateTestEnvironment({.time = &clock});
  DefaultVideoJitterTiming timing(env);

  timing.OnCompleteTemporalUnit(kRtpTimestamp, clock.CurrentTime());
  EXPECT_EQ(timing.ExtrapolateLocalTime(kRtpTimestamp), clock.CurrentTime());

  timing.Reset();
  EXPECT_EQ(timing.ExtrapolateLocalTime(kRtpTimestamp), std::nullopt);
}

TEST(DefaultVideoJitterTimingTest, OnDecodableTemporalUnitReturnsEstimate) {
  SimulatedClock clock(kInitialTime);
  Environment env = CreateTestEnvironment({.time = &clock});
  DefaultVideoJitterTiming timing(env);

  EXPECT_NE(timing.OnDecodableTemporalUnit(kRtpTimestamp, kFrameSize,
                                           clock.CurrentTime(),
                                           /*was_retransmitted=*/false),
            std::nullopt);
}

TEST(DefaultVideoJitterTimingTest,
     OnDecodableTemporalUnitReturnsNulloptOnRetransmission) {
  SimulatedClock clock(kInitialTime);
  Environment env = CreateTestEnvironment({.time = &clock});
  DefaultVideoJitterTiming timing(env);

  EXPECT_EQ(timing.OnDecodableTemporalUnit(kRtpTimestamp, kFrameSize,
                                           clock.CurrentTime(),
                                           /*was_retransmitted=*/true),
            std::nullopt);
}

TEST(DefaultVideoJitterTimingTest, EstimateIncludesRttAfterRetransmission) {
  constexpr double kMargin = 0.8;
  FieldTrials field_trials =
      CreateTestFieldTrials("WebRTC-JitterEstimatorConfig/nack_limit:1/");
  SimulatedClock clock(kInitialTime);
  Environment env =
      CreateTestEnvironment({.field_trials = field_trials, .time = &clock});
  DefaultVideoJitterTiming timing(env);

  timing.UpdateRtt(kRtt);

  std::optional<TimeDelta> initial_estimate = timing.OnDecodableTemporalUnit(
      /*rtp_timestamp=*/3000, kFrameSize, clock.CurrentTime(),
      /*was_retransmitted=*/false);
  ASSERT_TRUE(initial_estimate.has_value());

  // Retransmitted frame.
  clock.AdvanceTime(TimeDelta::Millis(33));
  EXPECT_EQ(timing.OnDecodableTemporalUnit(/*rtp_timestamp=*/6000, kFrameSize,
                                           clock.CurrentTime(),
                                           /*was_retransmitted=*/true),
            std::nullopt);

  // Get estimate after retransmission.
  clock.AdvanceTime(TimeDelta::Millis(33));
  EXPECT_GT(timing.OnDecodableTemporalUnit(/*rtp_timestamp=*/9000, kFrameSize,
                                           clock.CurrentTime(),
                                           /*was_retransmitted=*/false),
            *initial_estimate + kMargin * kRtt);
}

TEST(DefaultVideoJitterTimingTest, ResetClearsJitterEstimator) {
  constexpr double kMargin = 0.5;
  FieldTrials field_trials =
      CreateTestFieldTrials("WebRTC-JitterEstimatorConfig/nack_limit:1/");
  SimulatedClock clock(kInitialTime);
  Environment env =
      CreateTestEnvironment({.field_trials = field_trials, .time = &clock});
  DefaultVideoJitterTiming timing(env);

  timing.UpdateRtt(kRtt);

  std::optional<TimeDelta> initial_estimate = timing.OnDecodableTemporalUnit(
      /*rtp_timestamp=*/3000, kFrameSize, clock.CurrentTime(),
      /*was_retransmitted=*/false);
  ASSERT_TRUE(initial_estimate.has_value());

  // Retransmitted frame.
  clock.AdvanceTime(TimeDelta::Millis(33));
  EXPECT_EQ(timing.OnDecodableTemporalUnit(/*rtp_timestamp=*/6000, kFrameSize,
                                           clock.CurrentTime(),
                                           /*was_retransmitted=*/true),
            std::nullopt);

  timing.Reset();

  // Get estimate after retransmission and reset, should not include RTT.
  clock.AdvanceTime(TimeDelta::Millis(33));
  EXPECT_LT(timing.OnDecodableTemporalUnit(/*rtp_timestamp=*/9000, kFrameSize,
                                           clock.CurrentTime(),
                                           /*was_retransmitted=*/false),
            *initial_estimate + kMargin * kRtt);
}

}  // namespace
}  // namespace webrtc