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/*
* Copyright 2016 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 "common_video/include/bitrate_adjuster.h"
#include "api/units/time_delta.h"
#include "rtc_base/fake_clock.h"
#include "test/gtest.h"
namespace webrtc {
class BitrateAdjusterTest : public ::testing::Test {
public:
BitrateAdjusterTest()
: adjuster_(kMinAdjustedBitratePct, kMaxAdjustedBitratePct) {}
// Simulate an output bitrate for one update cycle of BitrateAdjuster.
void SimulateBitrateBps(uint32_t bitrate_bps) {
const uint32_t update_interval_ms =
BitrateAdjuster::kBitrateUpdateIntervalMs;
const uint32_t update_frame_interval =
BitrateAdjuster::kBitrateUpdateFrameInterval;
// Round up frame interval so we get one cycle passes.
const uint32_t frame_interval_ms =
(update_interval_ms + update_frame_interval - 1) /
update_frame_interval;
const size_t frame_size_bytes =
(bitrate_bps * frame_interval_ms) / (8 * 1000);
for (size_t i = 0; i < update_frame_interval; ++i) {
clock_.AdvanceTime(webrtc::TimeDelta::Millis(frame_interval_ms));
adjuster_.Update(frame_size_bytes);
}
}
uint32_t GetTargetBitrateBpsPct(float pct) {
return pct * adjuster_.GetTargetBitrateBps();
}
void VerifyAdjustment() {
// The adjusted bitrate should be between the estimated bitrate and the
// target bitrate within clamp.
uint32_t target_bitrate_bps = adjuster_.GetTargetBitrateBps();
uint32_t adjusted_bitrate_bps = adjuster_.GetAdjustedBitrateBps();
uint32_t estimated_bitrate_bps =
adjuster_.GetEstimatedBitrateBps().value_or(target_bitrate_bps);
uint32_t adjusted_lower_bound_bps =
GetTargetBitrateBpsPct(kMinAdjustedBitratePct);
uint32_t adjusted_upper_bound_bps =
GetTargetBitrateBpsPct(kMaxAdjustedBitratePct);
EXPECT_LE(adjusted_bitrate_bps, adjusted_upper_bound_bps);
EXPECT_GE(adjusted_bitrate_bps, adjusted_lower_bound_bps);
if (estimated_bitrate_bps > target_bitrate_bps) {
EXPECT_LT(adjusted_bitrate_bps, target_bitrate_bps);
}
}
protected:
static const float kMinAdjustedBitratePct;
static const float kMaxAdjustedBitratePct;
rtc::ScopedFakeClock clock_;
BitrateAdjuster adjuster_;
};
const float BitrateAdjusterTest::kMinAdjustedBitratePct = .5f;
const float BitrateAdjusterTest::kMaxAdjustedBitratePct = .95f;
TEST_F(BitrateAdjusterTest, VaryingBitrates) {
const uint32_t target_bitrate_bps = 640000;
adjuster_.SetTargetBitrateBps(target_bitrate_bps);
// Grossly overshoot for a little while. Adjusted bitrate should decrease.
uint32_t actual_bitrate_bps = 2 * target_bitrate_bps;
uint32_t last_adjusted_bitrate_bps = 0;
uint32_t adjusted_bitrate_bps = 0;
SimulateBitrateBps(actual_bitrate_bps);
VerifyAdjustment();
last_adjusted_bitrate_bps = adjuster_.GetAdjustedBitrateBps();
SimulateBitrateBps(actual_bitrate_bps);
VerifyAdjustment();
adjusted_bitrate_bps = adjuster_.GetAdjustedBitrateBps();
EXPECT_LE(adjusted_bitrate_bps, last_adjusted_bitrate_bps);
last_adjusted_bitrate_bps = adjusted_bitrate_bps;
// After two cycles we should've stabilized and hit the lower bound.
EXPECT_EQ(GetTargetBitrateBpsPct(kMinAdjustedBitratePct),
adjusted_bitrate_bps);
// Simulate encoder settling down. Adjusted bitrate should increase.
SimulateBitrateBps(target_bitrate_bps);
adjusted_bitrate_bps = adjuster_.GetAdjustedBitrateBps();
VerifyAdjustment();
EXPECT_GT(adjusted_bitrate_bps, last_adjusted_bitrate_bps);
last_adjusted_bitrate_bps = adjusted_bitrate_bps;
SimulateBitrateBps(target_bitrate_bps);
adjusted_bitrate_bps = adjuster_.GetAdjustedBitrateBps();
VerifyAdjustment();
EXPECT_GT(adjusted_bitrate_bps, last_adjusted_bitrate_bps);
last_adjusted_bitrate_bps = adjusted_bitrate_bps;
// After two cycles we should've stabilized and hit the upper bound.
EXPECT_EQ(GetTargetBitrateBpsPct(kMaxAdjustedBitratePct),
adjusted_bitrate_bps);
}
// Tests that large changes in target bitrate will result in immediate change
// in adjusted bitrate.
TEST_F(BitrateAdjusterTest, LargeTargetDelta) {
uint32_t target_bitrate_bps = 640000;
adjuster_.SetTargetBitrateBps(target_bitrate_bps);
EXPECT_EQ(target_bitrate_bps, adjuster_.GetAdjustedBitrateBps());
float delta_pct = BitrateAdjuster::kBitrateTolerancePct * 2;
target_bitrate_bps = (1 + delta_pct) * target_bitrate_bps;
adjuster_.SetTargetBitrateBps(target_bitrate_bps);
EXPECT_EQ(target_bitrate_bps, adjuster_.GetAdjustedBitrateBps());
target_bitrate_bps = (1 - delta_pct) * target_bitrate_bps;
adjuster_.SetTargetBitrateBps(target_bitrate_bps);
EXPECT_EQ(target_bitrate_bps, adjuster_.GetAdjustedBitrateBps());
}
// Tests that small changes in target bitrate within tolerance will not affect
// adjusted bitrate immediately.
TEST_F(BitrateAdjusterTest, SmallTargetDelta) {
const uint32_t initial_target_bitrate_bps = 640000;
uint32_t target_bitrate_bps = initial_target_bitrate_bps;
adjuster_.SetTargetBitrateBps(target_bitrate_bps);
EXPECT_EQ(initial_target_bitrate_bps, adjuster_.GetAdjustedBitrateBps());
float delta_pct = BitrateAdjuster::kBitrateTolerancePct / 2;
target_bitrate_bps = (1 + delta_pct) * target_bitrate_bps;
adjuster_.SetTargetBitrateBps(target_bitrate_bps);
EXPECT_EQ(initial_target_bitrate_bps, adjuster_.GetAdjustedBitrateBps());
target_bitrate_bps = (1 - delta_pct) * target_bitrate_bps;
adjuster_.SetTargetBitrateBps(target_bitrate_bps);
EXPECT_EQ(initial_target_bitrate_bps, adjuster_.GetAdjustedBitrateBps());
}
TEST_F(BitrateAdjusterTest, SmallTargetDeltaOverflow) {
const uint32_t initial_target_bitrate_bps = 640000;
uint32_t target_bitrate_bps = initial_target_bitrate_bps;
adjuster_.SetTargetBitrateBps(target_bitrate_bps);
EXPECT_EQ(initial_target_bitrate_bps, adjuster_.GetAdjustedBitrateBps());
float delta_pct = BitrateAdjuster::kBitrateTolerancePct / 2;
target_bitrate_bps = (1 + delta_pct) * target_bitrate_bps;
adjuster_.SetTargetBitrateBps(target_bitrate_bps);
EXPECT_EQ(initial_target_bitrate_bps, adjuster_.GetAdjustedBitrateBps());
// 1.05 * 1.05 is 1.1 which is greater than tolerance for the initial target
// bitrate. Since we didn't advance the clock the adjuster never updated.
target_bitrate_bps = (1 + delta_pct) * target_bitrate_bps;
adjuster_.SetTargetBitrateBps(target_bitrate_bps);
EXPECT_EQ(target_bitrate_bps, adjuster_.GetAdjustedBitrateBps());
}
} // namespace webrtc
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