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/*
* Copyright (c) 2022 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/inter_frame_delay_variation_calculator.h"
#include <limits>
#include "absl/types/optional.h"
#include "api/units/frequency.h"
#include "api/units/time_delta.h"
#include "api/units/timestamp.h"
#include "system_wrappers/include/clock.h"
#include "test/gmock.h"
#include "test/gtest.h"
namespace webrtc {
namespace {
// Test is for frames at 30fps. At 30fps, RTP timestamps will increase by
// 90000 / 30 = 3000 ticks per frame.
constexpr Frequency k30Fps = Frequency::Hertz(30);
constexpr TimeDelta kFrameDelay = 1 / k30Fps;
constexpr uint32_t kRtpTicksPerFrame = Frequency::KiloHertz(90) / k30Fps;
constexpr Timestamp kStartTime = Timestamp::Millis(1337);
} // namespace
using ::testing::Eq;
using ::testing::Optional;
TEST(InterFrameDelayVariationCalculatorTest, OldRtpTimestamp) {
InterFrameDelayVariationCalculator ifdv_calculator;
EXPECT_THAT(ifdv_calculator.Calculate(180000, kStartTime),
Optional(TimeDelta::Zero()));
EXPECT_THAT(ifdv_calculator.Calculate(90000, kStartTime), Eq(absl::nullopt));
}
TEST(InterFrameDelayVariationCalculatorTest,
NegativeWrapAroundIsSameAsOldRtpTimestamp) {
InterFrameDelayVariationCalculator ifdv_calculator;
uint32_t rtp = 1500;
EXPECT_THAT(ifdv_calculator.Calculate(rtp, kStartTime),
Optional(TimeDelta::Zero()));
// RTP has wrapped around backwards.
rtp -= 3000;
EXPECT_THAT(ifdv_calculator.Calculate(rtp, kStartTime), Eq(absl::nullopt));
}
TEST(InterFrameDelayVariationCalculatorTest, CorrectDelayForFrames) {
InterFrameDelayVariationCalculator ifdv_calculator;
// Use a fake clock to simplify time keeping.
SimulatedClock clock(kStartTime);
// First frame is always delay variation 0.
uint32_t rtp = 90000;
EXPECT_THAT(ifdv_calculator.Calculate(rtp, clock.CurrentTime()),
Optional(TimeDelta::Zero()));
// Perfectly timed frame has 0 delay variation.
clock.AdvanceTime(kFrameDelay);
rtp += kRtpTicksPerFrame;
EXPECT_THAT(ifdv_calculator.Calculate(rtp, clock.CurrentTime()),
Optional(TimeDelta::Zero()));
// Slightly early frame will have a negative delay variation.
clock.AdvanceTime(kFrameDelay - TimeDelta::Millis(3));
rtp += kRtpTicksPerFrame;
EXPECT_THAT(ifdv_calculator.Calculate(rtp, clock.CurrentTime()),
Optional(-TimeDelta::Millis(3)));
// Slightly late frame will have positive delay variation.
clock.AdvanceTime(kFrameDelay + TimeDelta::Micros(5125));
rtp += kRtpTicksPerFrame;
EXPECT_THAT(ifdv_calculator.Calculate(rtp, clock.CurrentTime()),
Optional(TimeDelta::Micros(5125)));
// Simulate faster frame RTP at the same clock delay. The frame arrives late,
// since the RTP timestamp is faster than the delay, and thus is positive.
clock.AdvanceTime(kFrameDelay);
rtp += kRtpTicksPerFrame / 2;
EXPECT_THAT(ifdv_calculator.Calculate(rtp, clock.CurrentTime()),
Optional(kFrameDelay / 2.0));
// Simulate slower frame RTP at the same clock delay. The frame is early,
// since the RTP timestamp advanced more than the delay, and thus is negative.
clock.AdvanceTime(kFrameDelay);
rtp += 1.5 * kRtpTicksPerFrame;
EXPECT_THAT(ifdv_calculator.Calculate(rtp, clock.CurrentTime()),
Optional(-kFrameDelay / 2.0));
}
TEST(InterFrameDelayVariationCalculatorTest, PositiveWrapAround) {
InterFrameDelayVariationCalculator ifdv_calculator;
// Use a fake clock to simplify time keeping.
SimulatedClock clock(kStartTime);
// First frame is behind the max RTP by 1500.
uint32_t rtp = std::numeric_limits<uint32_t>::max() - 1500;
EXPECT_THAT(ifdv_calculator.Calculate(rtp, clock.CurrentTime()),
Optional(TimeDelta::Zero()));
// Rtp wraps around, now 1499.
rtp += kRtpTicksPerFrame;
// Frame delay should be as normal, in this case simulated as 1ms late.
clock.AdvanceTime(kFrameDelay + TimeDelta::Millis(1));
EXPECT_THAT(ifdv_calculator.Calculate(rtp, clock.CurrentTime()),
Optional(TimeDelta::Millis(1)));
}
TEST(InterFrameDelayVariationCalculatorTest, MultipleWrapArounds) {
// Simulate a long pauses which cause wrap arounds multiple times.
constexpr Frequency k90Khz = Frequency::KiloHertz(90);
constexpr uint32_t kHalfRtp = std::numeric_limits<uint32_t>::max() / 2;
constexpr TimeDelta kWrapAroundDelay = kHalfRtp / k90Khz;
InterFrameDelayVariationCalculator ifdv_calculator;
// Use a fake clock to simplify time keeping.
SimulatedClock clock(kStartTime);
uint32_t rtp = 0;
EXPECT_THAT(ifdv_calculator.Calculate(rtp, clock.CurrentTime()),
Optional(TimeDelta::Zero()));
rtp += kHalfRtp;
clock.AdvanceTime(kWrapAroundDelay);
EXPECT_THAT(ifdv_calculator.Calculate(rtp, clock.CurrentTime()),
Optional(TimeDelta::Zero()));
// 1st wrap around.
rtp += kHalfRtp + 1;
clock.AdvanceTime(kWrapAroundDelay + TimeDelta::Millis(1));
EXPECT_THAT(ifdv_calculator.Calculate(rtp, clock.CurrentTime()),
Optional(TimeDelta::Millis(1) - (1 / k90Khz)));
rtp += kHalfRtp;
clock.AdvanceTime(kWrapAroundDelay);
EXPECT_THAT(ifdv_calculator.Calculate(rtp, clock.CurrentTime()),
Optional(TimeDelta::Zero()));
// 2nd wrap arounds.
rtp += kHalfRtp + 1;
clock.AdvanceTime(kWrapAroundDelay - TimeDelta::Millis(1));
EXPECT_THAT(ifdv_calculator.Calculate(rtp, clock.CurrentTime()),
Optional(-TimeDelta::Millis(1) - (1 / k90Khz)));
// Ensure short delay (large RTP delay) between wrap-arounds has correct
// jitter.
rtp += kHalfRtp;
clock.AdvanceTime(TimeDelta::Millis(10));
EXPECT_THAT(ifdv_calculator.Calculate(rtp, clock.CurrentTime()),
Optional(-(kWrapAroundDelay - TimeDelta::Millis(10))));
// 3nd wrap arounds, this time with large RTP delay.
rtp += kHalfRtp + 1;
clock.AdvanceTime(TimeDelta::Millis(10));
EXPECT_THAT(
ifdv_calculator.Calculate(rtp, clock.CurrentTime()),
Optional(-(kWrapAroundDelay - TimeDelta::Millis(10) + (1 / k90Khz))));
}
TEST(InterFrameDelayVariationCalculatorTest,
NegativeWrapAroundAfterPositiveWrapAround) {
InterFrameDelayVariationCalculator ifdv_calculator;
// Use a fake clock to simplify time keeping.
SimulatedClock clock(kStartTime);
uint32_t rtp = std::numeric_limits<uint32_t>::max() - 1500;
EXPECT_THAT(ifdv_calculator.Calculate(rtp, clock.CurrentTime()),
Optional(TimeDelta::Zero()));
// Rtp wraps around, now 1499.
rtp += kRtpTicksPerFrame;
// Frame delay should be as normal, in this case simulated as 1ms late.
clock.AdvanceTime(kFrameDelay);
EXPECT_THAT(ifdv_calculator.Calculate(rtp, clock.CurrentTime()),
Optional(TimeDelta::Zero()));
// Wrap back.
rtp -= kRtpTicksPerFrame;
// Frame delay should be as normal, in this case simulated as 1ms late.
clock.AdvanceTime(kFrameDelay);
EXPECT_THAT(ifdv_calculator.Calculate(rtp, clock.CurrentTime()),
Eq(absl::nullopt));
}
} // namespace webrtc
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