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/*
* Copyright (c) 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 "modules/video_coding/utility/frame_dropper.h"
#include "rtc_base/logging.h"
#include "test/gtest.h"
namespace webrtc {
namespace {
const float kTargetBitRateKbps = 300;
const float kIncomingFrameRate = 30;
const size_t kFrameSizeBytes = 1250;
const size_t kLargeFrameSizeBytes = 25000;
const bool kIncludeKeyFrame = true;
const bool kDoNotIncludeKeyFrame = false;
} // namespace
class FrameDropperTest : public ::testing::Test {
protected:
void SetUp() override {
frame_dropper_.SetRates(kTargetBitRateKbps, kIncomingFrameRate);
}
void OverflowLeakyBucket() {
// Overflow bucket in frame dropper.
for (int i = 0; i < kIncomingFrameRate; ++i) {
frame_dropper_.Fill(kFrameSizeBytes, true);
}
frame_dropper_.Leak(kIncomingFrameRate);
}
void ValidateNoDropsAtTargetBitrate(int large_frame_size_bytes,
int large_frame_rate,
bool is_large_frame_delta) {
// Smaller frame size is computed to meet |kTargetBitRateKbps|.
int small_frame_size_bytes =
kFrameSizeBytes -
(large_frame_size_bytes * large_frame_rate) / kIncomingFrameRate;
for (int i = 1; i <= 5 * large_frame_rate; ++i) {
// Large frame. First frame is always a key frame.
frame_dropper_.Fill(large_frame_size_bytes,
(i == 1) ? false : is_large_frame_delta);
frame_dropper_.Leak(kIncomingFrameRate);
EXPECT_FALSE(frame_dropper_.DropFrame());
// Smaller frames.
for (int j = 1; j < kIncomingFrameRate / large_frame_rate; ++j) {
frame_dropper_.Fill(small_frame_size_bytes, true);
frame_dropper_.Leak(kIncomingFrameRate);
EXPECT_FALSE(frame_dropper_.DropFrame());
}
}
}
void ValidateThroughputMatchesTargetBitrate(int bitrate_kbps,
bool include_keyframe) {
int delta_frame_size;
int total_bytes = 0;
if (include_keyframe) {
delta_frame_size = ((1000.0 / 8 * bitrate_kbps) - kLargeFrameSizeBytes) /
(kIncomingFrameRate - 1);
} else {
delta_frame_size = bitrate_kbps * 1000.0 / (8 * kIncomingFrameRate);
}
const int kNumIterations = 1000;
for (int i = 1; i <= kNumIterations; ++i) {
int j = 0;
if (include_keyframe) {
if (!frame_dropper_.DropFrame()) {
frame_dropper_.Fill(kLargeFrameSizeBytes, false);
total_bytes += kLargeFrameSizeBytes;
}
frame_dropper_.Leak(kIncomingFrameRate);
j++;
}
for (; j < kIncomingFrameRate; ++j) {
if (!frame_dropper_.DropFrame()) {
frame_dropper_.Fill(delta_frame_size, true);
total_bytes += delta_frame_size;
}
frame_dropper_.Leak(kIncomingFrameRate);
}
}
float throughput_kbps = total_bytes * 8.0 / (1000 * kNumIterations);
float deviation_from_target =
(throughput_kbps - kTargetBitRateKbps) * 100.0 / kTargetBitRateKbps;
if (deviation_from_target < 0) {
deviation_from_target = -deviation_from_target;
}
// Variation is < 0.1%
EXPECT_LE(deviation_from_target, 0.1);
}
FrameDropper frame_dropper_;
};
TEST_F(FrameDropperTest, NoDropsWhenDisabled) {
frame_dropper_.Enable(false);
OverflowLeakyBucket();
EXPECT_FALSE(frame_dropper_.DropFrame());
}
TEST_F(FrameDropperTest, DropsByDefaultWhenBucketOverflows) {
OverflowLeakyBucket();
EXPECT_TRUE(frame_dropper_.DropFrame());
}
TEST_F(FrameDropperTest, NoDropsWhenFillRateMatchesLeakRate) {
for (int i = 0; i < 5 * kIncomingFrameRate; ++i) {
frame_dropper_.Fill(kFrameSizeBytes, true);
frame_dropper_.Leak(kIncomingFrameRate);
EXPECT_FALSE(frame_dropper_.DropFrame());
}
}
TEST_F(FrameDropperTest, LargeKeyFrames) {
ValidateNoDropsAtTargetBitrate(kLargeFrameSizeBytes, 1, false);
frame_dropper_.Reset();
ValidateNoDropsAtTargetBitrate(kLargeFrameSizeBytes / 2, 2, false);
frame_dropper_.Reset();
ValidateNoDropsAtTargetBitrate(kLargeFrameSizeBytes / 4, 4, false);
frame_dropper_.Reset();
ValidateNoDropsAtTargetBitrate(kLargeFrameSizeBytes / 8, 8, false);
}
TEST_F(FrameDropperTest, LargeDeltaFrames) {
ValidateNoDropsAtTargetBitrate(kLargeFrameSizeBytes, 1, true);
frame_dropper_.Reset();
ValidateNoDropsAtTargetBitrate(kLargeFrameSizeBytes / 2, 2, true);
frame_dropper_.Reset();
ValidateNoDropsAtTargetBitrate(kLargeFrameSizeBytes / 4, 4, true);
frame_dropper_.Reset();
ValidateNoDropsAtTargetBitrate(kLargeFrameSizeBytes / 8, 8, true);
}
TEST_F(FrameDropperTest, TrafficVolumeAboveAvailableBandwidth) {
ValidateThroughputMatchesTargetBitrate(700, kIncludeKeyFrame);
ValidateThroughputMatchesTargetBitrate(700, kDoNotIncludeKeyFrame);
ValidateThroughputMatchesTargetBitrate(600, kIncludeKeyFrame);
ValidateThroughputMatchesTargetBitrate(600, kDoNotIncludeKeyFrame);
ValidateThroughputMatchesTargetBitrate(500, kIncludeKeyFrame);
ValidateThroughputMatchesTargetBitrate(500, kDoNotIncludeKeyFrame);
}
} // namespace webrtc
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