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/*
* Copyright (c) 2019 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 "video/encoder_bitrate_adjuster.h"
#include <memory>
#include <vector>
#include "api/units/data_rate.h"
#include "rtc_base/fake_clock.h"
#include "rtc_base/numerics/safe_conversions.h"
#include "test/field_trial.h"
#include "test/gtest.h"
namespace webrtc {
namespace test {
class EncoderBitrateAdjusterTest : public ::testing::Test {
public:
static constexpr int64_t kWindowSizeMs = 3000;
static constexpr int kDefaultBitrateBps = 300000;
static constexpr int kDefaultFrameRateFps = 30;
// For network utilization higher than media utilization, loop over a
// sequence where the first half undershoots and the second half overshoots
// by the same amount.
static constexpr int kSequenceLength = 4;
static_assert(kSequenceLength % 2 == 0, "Sequence length must be even.");
EncoderBitrateAdjusterTest()
: target_bitrate_(DataRate::BitsPerSec(kDefaultBitrateBps)),
target_framerate_fps_(kDefaultFrameRateFps),
tl_pattern_idx_{},
sequence_idx_{} {}
protected:
void SetUpAdjuster(size_t num_spatial_layers,
size_t num_temporal_layers,
bool vp9_svc) {
// Initialize some default VideoCodec instance with the given number of
// layers.
if (vp9_svc) {
codec_.codecType = VideoCodecType::kVideoCodecVP9;
codec_.numberOfSimulcastStreams = 1;
codec_.VP9()->numberOfSpatialLayers = num_spatial_layers;
codec_.VP9()->numberOfTemporalLayers = num_temporal_layers;
for (size_t si = 0; si < num_spatial_layers; ++si) {
codec_.spatialLayers[si].minBitrate = 100 * (1 << si);
codec_.spatialLayers[si].targetBitrate = 200 * (1 << si);
codec_.spatialLayers[si].maxBitrate = 300 * (1 << si);
codec_.spatialLayers[si].active = true;
codec_.spatialLayers[si].numberOfTemporalLayers = num_temporal_layers;
}
} else {
codec_.codecType = VideoCodecType::kVideoCodecVP8;
codec_.numberOfSimulcastStreams = num_spatial_layers;
codec_.VP8()->numberOfTemporalLayers = num_temporal_layers;
for (size_t si = 0; si < num_spatial_layers; ++si) {
codec_.simulcastStream[si].minBitrate = 100 * (1 << si);
codec_.simulcastStream[si].targetBitrate = 200 * (1 << si);
codec_.simulcastStream[si].maxBitrate = 300 * (1 << si);
codec_.simulcastStream[si].active = true;
codec_.simulcastStream[si].numberOfTemporalLayers = num_temporal_layers;
}
}
for (size_t si = 0; si < num_spatial_layers; ++si) {
encoder_info_.fps_allocation[si].resize(num_temporal_layers);
double fraction = 1.0;
for (int ti = num_temporal_layers - 1; ti >= 0; --ti) {
encoder_info_.fps_allocation[si][ti] = static_cast<uint8_t>(
VideoEncoder::EncoderInfo::kMaxFramerateFraction * fraction + 0.5);
fraction /= 2.0;
}
}
adjuster_ = std::make_unique<EncoderBitrateAdjuster>(codec_);
adjuster_->OnEncoderInfo(encoder_info_);
current_adjusted_allocation_ =
adjuster_->AdjustRateAllocation(VideoEncoder::RateControlParameters(
current_input_allocation_, target_framerate_fps_));
}
void InsertFrames(std::vector<std::vector<double>> media_utilization_factors,
int64_t duration_ms) {
InsertFrames(media_utilization_factors, media_utilization_factors,
duration_ms);
}
void InsertFrames(
std::vector<std::vector<double>> media_utilization_factors,
std::vector<std::vector<double>> network_utilization_factors,
int64_t duration_ms) {
RTC_DCHECK_EQ(media_utilization_factors.size(),
network_utilization_factors.size());
const int64_t start_us = rtc::TimeMicros();
while (rtc::TimeMicros() <
start_us + (duration_ms * rtc::kNumMicrosecsPerMillisec)) {
clock_.AdvanceTime(TimeDelta::Seconds(1) / target_framerate_fps_);
for (size_t si = 0; si < NumSpatialLayers(); ++si) {
const std::vector<int>& tl_pattern =
kTlPatterns[NumTemporalLayers(si) - 1];
const size_t ti =
tl_pattern[(tl_pattern_idx_[si]++) % tl_pattern.size()];
uint32_t layer_bitrate_bps =
current_adjusted_allocation_.GetBitrate(si, ti);
double layer_framerate_fps = target_framerate_fps_;
if (encoder_info_.fps_allocation[si].size() > ti) {
uint8_t layer_fps_fraction = encoder_info_.fps_allocation[si][ti];
if (ti > 0) {
// We're interested in the frame rate for this layer only, not
// cumulative frame rate.
layer_fps_fraction -= encoder_info_.fps_allocation[si][ti - 1];
}
layer_framerate_fps =
(target_framerate_fps_ * layer_fps_fraction) /
VideoEncoder::EncoderInfo::kMaxFramerateFraction;
}
double media_utilization_factor = 1.0;
double network_utilization_factor = 1.0;
if (media_utilization_factors.size() > si) {
RTC_DCHECK_EQ(media_utilization_factors[si].size(),
network_utilization_factors[si].size());
if (media_utilization_factors[si].size() > ti) {
media_utilization_factor = media_utilization_factors[si][ti];
network_utilization_factor = network_utilization_factors[si][ti];
}
}
RTC_DCHECK_GE(network_utilization_factor, media_utilization_factor);
// Frame size based on constant (media) overshoot.
const size_t media_frame_size = media_utilization_factor *
(layer_bitrate_bps / 8.0) /
layer_framerate_fps;
constexpr int kFramesWithPenalty = (kSequenceLength / 2) - 1;
RTC_DCHECK_GT(kFramesWithPenalty, 0);
// The positive/negative size diff needed to achieve network rate but
// not media rate penalty is the difference between the utilization
// factors times the media rate frame size, then scaled by the fraction
// between total frames and penalized frames in the sequence.
// Cap to media frame size to avoid negative size undershoot.
const size_t network_frame_size_diff_bytes = std::min(
media_frame_size,
static_cast<size_t>(
(((network_utilization_factor - media_utilization_factor) *
media_frame_size) *
kSequenceLength) /
kFramesWithPenalty +
0.5));
int sequence_idx = sequence_idx_[si][ti];
sequence_idx_[si][ti] = (sequence_idx_[si][ti] + 1) % kSequenceLength;
const DataSize frame_size = DataSize::Bytes(
(sequence_idx < kSequenceLength / 2)
? media_frame_size - network_frame_size_diff_bytes
: media_frame_size + network_frame_size_diff_bytes);
adjuster_->OnEncodedFrame(frame_size, si, ti);
sequence_idx = ++sequence_idx % kSequenceLength;
}
}
}
size_t NumSpatialLayers() const {
if (codec_.codecType == VideoCodecType::kVideoCodecVP9) {
return codec_.VP9().numberOfSpatialLayers;
}
return codec_.numberOfSimulcastStreams;
}
size_t NumTemporalLayers(int spatial_index) {
if (codec_.codecType == VideoCodecType::kVideoCodecVP9) {
return codec_.spatialLayers[spatial_index].numberOfTemporalLayers;
}
return codec_.simulcastStream[spatial_index].numberOfTemporalLayers;
}
void ExpectNear(const VideoBitrateAllocation& expected_allocation,
const VideoBitrateAllocation& actual_allocation,
double allowed_error_fraction) {
for (size_t si = 0; si < kMaxSpatialLayers; ++si) {
for (size_t ti = 0; ti < kMaxTemporalStreams; ++ti) {
if (expected_allocation.HasBitrate(si, ti)) {
EXPECT_TRUE(actual_allocation.HasBitrate(si, ti));
uint32_t expected_layer_bitrate_bps =
expected_allocation.GetBitrate(si, ti);
EXPECT_NEAR(expected_layer_bitrate_bps,
actual_allocation.GetBitrate(si, ti),
static_cast<uint32_t>(expected_layer_bitrate_bps *
allowed_error_fraction));
} else {
EXPECT_FALSE(actual_allocation.HasBitrate(si, ti));
}
}
}
}
VideoBitrateAllocation MultiplyAllocation(
const VideoBitrateAllocation& allocation,
double factor) {
VideoBitrateAllocation multiplied_allocation;
for (size_t si = 0; si < kMaxSpatialLayers; ++si) {
for (size_t ti = 0; ti < kMaxTemporalStreams; ++ti) {
if (allocation.HasBitrate(si, ti)) {
multiplied_allocation.SetBitrate(
si, ti,
static_cast<uint32_t>(factor * allocation.GetBitrate(si, ti) +
0.5));
}
}
}
return multiplied_allocation;
}
VideoCodec codec_;
VideoEncoder::EncoderInfo encoder_info_;
std::unique_ptr<EncoderBitrateAdjuster> adjuster_;
VideoBitrateAllocation current_input_allocation_;
VideoBitrateAllocation current_adjusted_allocation_;
rtc::ScopedFakeClock clock_;
DataRate target_bitrate_;
double target_framerate_fps_;
int tl_pattern_idx_[kMaxSpatialLayers];
int sequence_idx_[kMaxSpatialLayers][kMaxTemporalStreams];
const std::vector<int> kTlPatterns[kMaxTemporalStreams] = {
{0},
{0, 1},
{0, 2, 1, 2},
{0, 3, 2, 3, 1, 3, 2, 3}};
};
TEST_F(EncoderBitrateAdjusterTest, SingleLayerOptimal) {
// Single layer, well behaved encoder.
current_input_allocation_.SetBitrate(0, 0, 300000);
target_framerate_fps_ = 30;
SetUpAdjuster(1, 1, false);
InsertFrames({{1.0}}, kWindowSizeMs);
current_adjusted_allocation_ =
adjuster_->AdjustRateAllocation(VideoEncoder::RateControlParameters(
current_input_allocation_, target_framerate_fps_));
// Adjusted allocation near input. Allow 1% error margin due to rounding
// errors etc.
ExpectNear(current_input_allocation_, current_adjusted_allocation_, 0.01);
}
TEST_F(EncoderBitrateAdjusterTest, SingleLayerOveruse) {
// Single layer, well behaved encoder.
current_input_allocation_.SetBitrate(0, 0, 300000);
target_framerate_fps_ = 30;
SetUpAdjuster(1, 1, false);
InsertFrames({{1.2}}, kWindowSizeMs);
current_adjusted_allocation_ =
adjuster_->AdjustRateAllocation(VideoEncoder::RateControlParameters(
current_input_allocation_, target_framerate_fps_));
// Adjusted allocation lowered by 20%.
ExpectNear(MultiplyAllocation(current_input_allocation_, 1 / 1.2),
current_adjusted_allocation_, 0.01);
}
TEST_F(EncoderBitrateAdjusterTest, SingleLayerUnderuse) {
// Single layer, well behaved encoder.
current_input_allocation_.SetBitrate(0, 0, 300000);
target_framerate_fps_ = 30;
SetUpAdjuster(1, 1, false);
InsertFrames({{0.5}}, kWindowSizeMs);
current_adjusted_allocation_ =
adjuster_->AdjustRateAllocation(VideoEncoder::RateControlParameters(
current_input_allocation_, target_framerate_fps_));
// Undershoot, adjusted should exactly match input.
ExpectNear(current_input_allocation_, current_adjusted_allocation_, 0.00);
}
TEST_F(EncoderBitrateAdjusterTest, ThreeTemporalLayersOptimalSize) {
// Three temporal layers, 60%/20%/20% bps distro, well behaved encoder.
current_input_allocation_.SetBitrate(0, 0, 180000);
current_input_allocation_.SetBitrate(0, 1, 60000);
current_input_allocation_.SetBitrate(0, 2, 60000);
target_framerate_fps_ = 30;
SetUpAdjuster(1, 3, false);
InsertFrames({{1.0, 1.0, 1.0}}, kWindowSizeMs);
current_adjusted_allocation_ =
adjuster_->AdjustRateAllocation(VideoEncoder::RateControlParameters(
current_input_allocation_, target_framerate_fps_));
ExpectNear(current_input_allocation_, current_adjusted_allocation_, 0.01);
}
TEST_F(EncoderBitrateAdjusterTest, ThreeTemporalLayersOvershoot) {
// Three temporal layers, 60%/20%/20% bps distro.
// 10% overshoot on all layers.
current_input_allocation_.SetBitrate(0, 0, 180000);
current_input_allocation_.SetBitrate(0, 1, 60000);
current_input_allocation_.SetBitrate(0, 2, 60000);
target_framerate_fps_ = 30;
SetUpAdjuster(1, 3, false);
InsertFrames({{1.1, 1.1, 1.1}}, kWindowSizeMs);
current_adjusted_allocation_ =
adjuster_->AdjustRateAllocation(VideoEncoder::RateControlParameters(
current_input_allocation_, target_framerate_fps_));
// Adjusted allocation lowered by 10%.
ExpectNear(MultiplyAllocation(current_input_allocation_, 1 / 1.1),
current_adjusted_allocation_, 0.01);
}
TEST_F(EncoderBitrateAdjusterTest, ThreeTemporalLayersUndershoot) {
// Three temporal layers, 60%/20%/20% bps distro, undershoot all layers.
current_input_allocation_.SetBitrate(0, 0, 180000);
current_input_allocation_.SetBitrate(0, 1, 60000);
current_input_allocation_.SetBitrate(0, 2, 60000);
target_framerate_fps_ = 30;
SetUpAdjuster(1, 3, false);
InsertFrames({{0.8, 0.8, 0.8}}, kWindowSizeMs);
current_adjusted_allocation_ =
adjuster_->AdjustRateAllocation(VideoEncoder::RateControlParameters(
current_input_allocation_, target_framerate_fps_));
// Adjusted allocation identical since we don't boost bitrates.
ExpectNear(current_input_allocation_, current_adjusted_allocation_, 0.0);
}
TEST_F(EncoderBitrateAdjusterTest, ThreeTemporalLayersSkewedOvershoot) {
// Three temporal layers, 60%/20%/20% bps distro.
// 10% overshoot on base layer, 20% on higher layers.
current_input_allocation_.SetBitrate(0, 0, 180000);
current_input_allocation_.SetBitrate(0, 1, 60000);
current_input_allocation_.SetBitrate(0, 2, 60000);
target_framerate_fps_ = 30;
SetUpAdjuster(1, 3, false);
InsertFrames({{1.1, 1.2, 1.2}}, kWindowSizeMs);
current_adjusted_allocation_ =
adjuster_->AdjustRateAllocation(VideoEncoder::RateControlParameters(
current_input_allocation_, target_framerate_fps_));
// Expected overshoot is weighted by bitrate:
// (0.6 * 1.1 + 0.2 * 1.2 + 0.2 * 1.2) = 1.14
ExpectNear(MultiplyAllocation(current_input_allocation_, 1 / 1.14),
current_adjusted_allocation_, 0.01);
}
TEST_F(EncoderBitrateAdjusterTest, FourTemporalLayersSkewedOvershoot) {
// Three temporal layers, 40%/30%/15%/15% bps distro.
// 10% overshoot on base layer, 20% on higher layers.
current_input_allocation_.SetBitrate(0, 0, 120000);
current_input_allocation_.SetBitrate(0, 1, 90000);
current_input_allocation_.SetBitrate(0, 2, 45000);
current_input_allocation_.SetBitrate(0, 3, 45000);
target_framerate_fps_ = 30;
SetUpAdjuster(1, 4, false);
InsertFrames({{1.1, 1.2, 1.2, 1.2}}, kWindowSizeMs);
current_adjusted_allocation_ =
adjuster_->AdjustRateAllocation(VideoEncoder::RateControlParameters(
current_input_allocation_, target_framerate_fps_));
// Expected overshoot is weighted by bitrate:
// (0.4 * 1.1 + 0.3 * 1.2 + 0.15 * 1.2 + 0.15 * 1.2) = 1.16
ExpectNear(MultiplyAllocation(current_input_allocation_, 1 / 1.16),
current_adjusted_allocation_, 0.01);
}
TEST_F(EncoderBitrateAdjusterTest, ThreeTemporalLayersNonLayeredEncoder) {
// Three temporal layers, 60%/20%/20% bps allocation, 10% overshoot,
// encoder does not actually support temporal layers.
current_input_allocation_.SetBitrate(0, 0, 180000);
current_input_allocation_.SetBitrate(0, 1, 60000);
current_input_allocation_.SetBitrate(0, 2, 60000);
target_framerate_fps_ = 30;
SetUpAdjuster(1, 1, false);
InsertFrames({{1.1}}, kWindowSizeMs);
current_adjusted_allocation_ =
adjuster_->AdjustRateAllocation(VideoEncoder::RateControlParameters(
current_input_allocation_, target_framerate_fps_));
// Expect the actual 10% overuse to be detected and the allocation to
// only contain the one entry.
VideoBitrateAllocation expected_allocation;
expected_allocation.SetBitrate(
0, 0,
static_cast<uint32_t>(current_input_allocation_.get_sum_bps() / 1.10));
ExpectNear(expected_allocation, current_adjusted_allocation_, 0.01);
}
TEST_F(EncoderBitrateAdjusterTest, IgnoredStream) {
// Encoder with three temporal layers, but in a mode that does not support
// deterministic frame rate. Those are ignored, even if bitrate overshoots.
current_input_allocation_.SetBitrate(0, 0, 180000);
current_input_allocation_.SetBitrate(0, 1, 60000);
target_framerate_fps_ = 30;
SetUpAdjuster(1, 1, false);
encoder_info_.fps_allocation[0].clear();
adjuster_->OnEncoderInfo(encoder_info_);
InsertFrames({{1.1}}, kWindowSizeMs);
current_adjusted_allocation_ =
adjuster_->AdjustRateAllocation(VideoEncoder::RateControlParameters(
current_input_allocation_, target_framerate_fps_));
// Values passed through.
ExpectNear(current_input_allocation_, current_adjusted_allocation_, 0.00);
}
TEST_F(EncoderBitrateAdjusterTest, DifferentSpatialOvershoots) {
// Two streams, both with three temporal layers.
// S0 has 5% overshoot, S1 has 25% overshoot.
current_input_allocation_.SetBitrate(0, 0, 180000);
current_input_allocation_.SetBitrate(0, 1, 60000);
current_input_allocation_.SetBitrate(0, 2, 60000);
current_input_allocation_.SetBitrate(1, 0, 400000);
current_input_allocation_.SetBitrate(1, 1, 150000);
current_input_allocation_.SetBitrate(1, 2, 150000);
target_framerate_fps_ = 30;
// Run twice, once configured as simulcast and once as VP9 SVC.
for (int i = 0; i < 2; ++i) {
SetUpAdjuster(2, 3, i == 0);
InsertFrames({{1.05, 1.05, 1.05}, {1.25, 1.25, 1.25}}, kWindowSizeMs);
current_adjusted_allocation_ =
adjuster_->AdjustRateAllocation(VideoEncoder::RateControlParameters(
current_input_allocation_, target_framerate_fps_));
VideoBitrateAllocation expected_allocation;
for (size_t ti = 0; ti < 3; ++ti) {
expected_allocation.SetBitrate(
0, ti,
static_cast<uint32_t>(current_input_allocation_.GetBitrate(0, ti) /
1.05));
expected_allocation.SetBitrate(
1, ti,
static_cast<uint32_t>(current_input_allocation_.GetBitrate(1, ti) /
1.25));
}
ExpectNear(expected_allocation, current_adjusted_allocation_, 0.01);
}
}
TEST_F(EncoderBitrateAdjusterTest, HeadroomAllowsOvershootToMediaRate) {
// Two streams, both with three temporal layers.
// Media rate is 1.0, but network rate is higher.
ScopedFieldTrials field_trial(
"WebRTC-VideoRateControl/adjuster_use_headroom:true/");
const uint32_t kS0Bitrate = 300000;
const uint32_t kS1Bitrate = 900000;
current_input_allocation_.SetBitrate(0, 0, kS0Bitrate / 3);
current_input_allocation_.SetBitrate(0, 1, kS0Bitrate / 3);
current_input_allocation_.SetBitrate(0, 2, kS0Bitrate / 3);
current_input_allocation_.SetBitrate(1, 0, kS1Bitrate / 3);
current_input_allocation_.SetBitrate(1, 1, kS1Bitrate / 3);
current_input_allocation_.SetBitrate(1, 2, kS1Bitrate / 3);
target_framerate_fps_ = 30;
// Run twice, once configured as simulcast and once as VP9 SVC.
for (int i = 0; i < 2; ++i) {
SetUpAdjuster(2, 3, i == 0);
// Network rate has 10% overshoot, but media rate is correct at 1.0.
InsertFrames({{1.0, 1.0, 1.0}, {1.0, 1.0, 1.0}},
{{1.1, 1.1, 1.1}, {1.1, 1.1, 1.1}},
kWindowSizeMs * kSequenceLength);
// Push back by 10%.
current_adjusted_allocation_ =
adjuster_->AdjustRateAllocation(VideoEncoder::RateControlParameters(
current_input_allocation_, target_framerate_fps_));
ExpectNear(MultiplyAllocation(current_input_allocation_, 1 / 1.1),
current_adjusted_allocation_, 0.01);
// Add 10% link headroom, overshoot is now allowed.
current_adjusted_allocation_ =
adjuster_->AdjustRateAllocation(VideoEncoder::RateControlParameters(
current_input_allocation_, target_framerate_fps_,
DataRate::BitsPerSec(current_input_allocation_.get_sum_bps() *
1.1)));
ExpectNear(current_input_allocation_, current_adjusted_allocation_, 0.01);
}
}
TEST_F(EncoderBitrateAdjusterTest, DontExceedMediaRateEvenWithHeadroom) {
// Two streams, both with three temporal layers.
// Media rate is 1.1, but network rate is higher.
ScopedFieldTrials field_trial(
"WebRTC-VideoRateControl/adjuster_use_headroom:true/");
const uint32_t kS0Bitrate = 300000;
const uint32_t kS1Bitrate = 900000;
current_input_allocation_.SetBitrate(0, 0, kS0Bitrate / 3);
current_input_allocation_.SetBitrate(0, 1, kS0Bitrate / 3);
current_input_allocation_.SetBitrate(0, 2, kS0Bitrate / 3);
current_input_allocation_.SetBitrate(1, 0, kS1Bitrate / 3);
current_input_allocation_.SetBitrate(1, 1, kS1Bitrate / 3);
current_input_allocation_.SetBitrate(1, 2, kS1Bitrate / 3);
target_framerate_fps_ = 30;
// Run twice, once configured as simulcast and once as VP9 SVC.
for (int i = 0; i < 2; ++i) {
SetUpAdjuster(2, 3, i == 0);
// Network rate has 30% overshoot, media rate has 10% overshoot.
InsertFrames({{1.1, 1.1, 1.1}, {1.1, 1.1, 1.1}},
{{1.3, 1.3, 1.3}, {1.3, 1.3, 1.3}},
kWindowSizeMs * kSequenceLength);
// Push back by 30%.
current_adjusted_allocation_ =
adjuster_->AdjustRateAllocation(VideoEncoder::RateControlParameters(
current_input_allocation_, target_framerate_fps_));
// The up-down causes a bit more noise, allow slightly more error margin.
ExpectNear(MultiplyAllocation(current_input_allocation_, 1 / 1.3),
current_adjusted_allocation_, 0.015);
// Add 100% link headroom, overshoot from network to media rate is allowed.
current_adjusted_allocation_ =
adjuster_->AdjustRateAllocation(VideoEncoder::RateControlParameters(
current_input_allocation_, target_framerate_fps_,
DataRate::BitsPerSec(current_input_allocation_.get_sum_bps() * 2)));
ExpectNear(MultiplyAllocation(current_input_allocation_, 1 / 1.1),
current_adjusted_allocation_, 0.015);
}
}
} // namespace test
} // namespace webrtc