Erik Språng | 7ca375c | 2019-02-06 16:20:17 +0100 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (c) 2019 The WebRTC project authors. All Rights Reserved. |
| 3 | * |
| 4 | * Use of this source code is governed by a BSD-style license |
| 5 | * that can be found in the LICENSE file in the root of the source |
| 6 | * tree. An additional intellectual property rights grant can be found |
| 7 | * in the file PATENTS. All contributing project authors may |
| 8 | * be found in the AUTHORS file in the root of the source tree. |
| 9 | */ |
| 10 | |
| 11 | #include "video/encoder_bitrate_adjuster.h" |
| 12 | |
| 13 | #include <algorithm> |
Mirko Bonadei | 317a1f0 | 2019-09-17 17:06:18 +0200 | [diff] [blame] | 14 | #include <memory> |
Erik Språng | 3d11e2f | 2019-04-15 14:48:30 +0200 | [diff] [blame] | 15 | #include <vector> |
Erik Språng | 7ca375c | 2019-02-06 16:20:17 +0100 | [diff] [blame] | 16 | |
Erik Språng | 3d11e2f | 2019-04-15 14:48:30 +0200 | [diff] [blame] | 17 | #include "rtc_base/experiments/rate_control_settings.h" |
Erik Språng | 7ca375c | 2019-02-06 16:20:17 +0100 | [diff] [blame] | 18 | #include "rtc_base/logging.h" |
| 19 | #include "rtc_base/time_utils.h" |
Erik Språng | 3d11e2f | 2019-04-15 14:48:30 +0200 | [diff] [blame] | 20 | #include "system_wrappers/include/field_trial.h" |
Erik Språng | 7ca375c | 2019-02-06 16:20:17 +0100 | [diff] [blame] | 21 | |
| 22 | namespace webrtc { |
Erik Språng | 3d11e2f | 2019-04-15 14:48:30 +0200 | [diff] [blame] | 23 | namespace { |
| 24 | // Helper struct with metadata for a single spatial layer. |
| 25 | struct LayerRateInfo { |
| 26 | double link_utilization_factor = 0.0; |
| 27 | double media_utilization_factor = 0.0; |
| 28 | DataRate target_rate = DataRate::Zero(); |
Erik Språng | 7ca375c | 2019-02-06 16:20:17 +0100 | [diff] [blame] | 29 | |
Erik Språng | 3d11e2f | 2019-04-15 14:48:30 +0200 | [diff] [blame] | 30 | DataRate WantedOvershoot() const { |
| 31 | // If there is headroom, allow bitrate to go up to media rate limit. |
| 32 | // Still limit media utilization to 1.0, so we don't overshoot over long |
| 33 | // runs even if we have headroom. |
| 34 | const double max_media_utilization = |
| 35 | std::max(1.0, media_utilization_factor); |
| 36 | if (link_utilization_factor > max_media_utilization) { |
| 37 | return (link_utilization_factor - max_media_utilization) * target_rate; |
| 38 | } |
| 39 | return DataRate::Zero(); |
| 40 | } |
| 41 | }; |
| 42 | } // namespace |
Erik Språng | 7ca375c | 2019-02-06 16:20:17 +0100 | [diff] [blame] | 43 | constexpr int64_t EncoderBitrateAdjuster::kWindowSizeMs; |
| 44 | constexpr size_t EncoderBitrateAdjuster::kMinFramesSinceLayoutChange; |
| 45 | constexpr double EncoderBitrateAdjuster::kDefaultUtilizationFactor; |
| 46 | |
| 47 | EncoderBitrateAdjuster::EncoderBitrateAdjuster(const VideoCodec& codec_settings) |
Erik Språng | 3d11e2f | 2019-04-15 14:48:30 +0200 | [diff] [blame] | 48 | : utilize_bandwidth_headroom_(RateControlSettings::ParseFromFieldTrials() |
| 49 | .BitrateAdjusterCanUseNetworkHeadroom()), |
Erik Språng | 7ca375c | 2019-02-06 16:20:17 +0100 | [diff] [blame] | 50 | frames_since_layout_change_(0), |
| 51 | min_bitrates_bps_{} { |
| 52 | if (codec_settings.codecType == VideoCodecType::kVideoCodecVP9) { |
| 53 | for (size_t si = 0; si < codec_settings.VP9().numberOfSpatialLayers; ++si) { |
| 54 | if (codec_settings.spatialLayers[si].active) { |
| 55 | min_bitrates_bps_[si] = |
| 56 | std::max(codec_settings.minBitrate * 1000, |
| 57 | codec_settings.spatialLayers[si].minBitrate * 1000); |
| 58 | } |
| 59 | } |
| 60 | } else { |
| 61 | for (size_t si = 0; si < codec_settings.numberOfSimulcastStreams; ++si) { |
| 62 | if (codec_settings.simulcastStream[si].active) { |
| 63 | min_bitrates_bps_[si] = |
| 64 | std::max(codec_settings.minBitrate * 1000, |
| 65 | codec_settings.simulcastStream[si].minBitrate * 1000); |
| 66 | } |
| 67 | } |
| 68 | } |
| 69 | } |
| 70 | |
| 71 | EncoderBitrateAdjuster::~EncoderBitrateAdjuster() = default; |
| 72 | |
| 73 | VideoBitrateAllocation EncoderBitrateAdjuster::AdjustRateAllocation( |
Erik Språng | 3d11e2f | 2019-04-15 14:48:30 +0200 | [diff] [blame] | 74 | const VideoEncoder::RateControlParameters& rates) { |
| 75 | current_rate_control_parameters_ = rates; |
Erik Språng | 7ca375c | 2019-02-06 16:20:17 +0100 | [diff] [blame] | 76 | |
| 77 | // First check that overshoot detectors exist, and store per spatial layer |
| 78 | // how many active temporal layers we have. |
| 79 | size_t active_tls_[kMaxSpatialLayers] = {}; |
| 80 | for (size_t si = 0; si < kMaxSpatialLayers; ++si) { |
| 81 | active_tls_[si] = 0; |
| 82 | for (size_t ti = 0; ti < kMaxTemporalStreams; ++ti) { |
| 83 | // Layer is enabled iff it has both positive bitrate and framerate target. |
Erik Språng | 3d11e2f | 2019-04-15 14:48:30 +0200 | [diff] [blame] | 84 | if (rates.bitrate.GetBitrate(si, ti) > 0 && |
Erik Språng | 7ca375c | 2019-02-06 16:20:17 +0100 | [diff] [blame] | 85 | current_fps_allocation_[si].size() > ti && |
| 86 | current_fps_allocation_[si][ti] > 0) { |
| 87 | ++active_tls_[si]; |
| 88 | if (!overshoot_detectors_[si][ti]) { |
| 89 | overshoot_detectors_[si][ti] = |
Mirko Bonadei | 317a1f0 | 2019-09-17 17:06:18 +0200 | [diff] [blame] | 90 | std::make_unique<EncoderOvershootDetector>(kWindowSizeMs); |
Erik Språng | 7ca375c | 2019-02-06 16:20:17 +0100 | [diff] [blame] | 91 | frames_since_layout_change_ = 0; |
| 92 | } |
| 93 | } else if (overshoot_detectors_[si][ti]) { |
| 94 | // Layer removed, destroy overshoot detector. |
| 95 | overshoot_detectors_[si][ti].reset(); |
| 96 | frames_since_layout_change_ = 0; |
| 97 | } |
| 98 | } |
| 99 | } |
| 100 | |
| 101 | // Next poll the overshoot detectors and populate the adjusted allocation. |
| 102 | const int64_t now_ms = rtc::TimeMillis(); |
| 103 | VideoBitrateAllocation adjusted_allocation; |
Erik Språng | 3d11e2f | 2019-04-15 14:48:30 +0200 | [diff] [blame] | 104 | std::vector<LayerRateInfo> layer_infos; |
| 105 | DataRate wanted_overshoot_sum = DataRate::Zero(); |
| 106 | |
Erik Språng | 7ca375c | 2019-02-06 16:20:17 +0100 | [diff] [blame] | 107 | for (size_t si = 0; si < kMaxSpatialLayers; ++si) { |
Erik Språng | 3d11e2f | 2019-04-15 14:48:30 +0200 | [diff] [blame] | 108 | layer_infos.emplace_back(); |
| 109 | LayerRateInfo& layer_info = layer_infos.back(); |
| 110 | |
| 111 | layer_info.target_rate = |
| 112 | DataRate::bps(rates.bitrate.GetSpatialLayerSum(si)); |
Erik Språng | 7ca375c | 2019-02-06 16:20:17 +0100 | [diff] [blame] | 113 | |
| 114 | // Adjustment is done per spatial layer only (not per temporal layer). |
Erik Språng | 7ca375c | 2019-02-06 16:20:17 +0100 | [diff] [blame] | 115 | if (frames_since_layout_change_ < kMinFramesSinceLayoutChange) { |
Erik Språng | 3d11e2f | 2019-04-15 14:48:30 +0200 | [diff] [blame] | 116 | layer_info.link_utilization_factor = kDefaultUtilizationFactor; |
| 117 | layer_info.media_utilization_factor = kDefaultUtilizationFactor; |
| 118 | } else if (active_tls_[si] == 0 || |
| 119 | layer_info.target_rate == DataRate::Zero()) { |
Erik Språng | 7ca375c | 2019-02-06 16:20:17 +0100 | [diff] [blame] | 120 | // No signaled temporal layers, or no bitrate set. Could either be unused |
| 121 | // spatial layer or bitrate dynamic mode; pass bitrate through without any |
| 122 | // change. |
Erik Språng | 3d11e2f | 2019-04-15 14:48:30 +0200 | [diff] [blame] | 123 | layer_info.link_utilization_factor = 1.0; |
| 124 | layer_info.media_utilization_factor = 1.0; |
Erik Språng | 7ca375c | 2019-02-06 16:20:17 +0100 | [diff] [blame] | 125 | } else if (active_tls_[si] == 1) { |
| 126 | // A single active temporal layer, this might mean single layer or that |
| 127 | // encoder does not support temporal layers. Merge target bitrates for |
| 128 | // this spatial layer. |
| 129 | RTC_DCHECK(overshoot_detectors_[si][0]); |
Erik Språng | 3d11e2f | 2019-04-15 14:48:30 +0200 | [diff] [blame] | 130 | layer_info.link_utilization_factor = |
| 131 | overshoot_detectors_[si][0] |
| 132 | ->GetNetworkRateUtilizationFactor(now_ms) |
| 133 | .value_or(kDefaultUtilizationFactor); |
| 134 | layer_info.media_utilization_factor = |
| 135 | overshoot_detectors_[si][0] |
| 136 | ->GetMediaRateUtilizationFactor(now_ms) |
| 137 | .value_or(kDefaultUtilizationFactor); |
| 138 | } else if (layer_info.target_rate > DataRate::Zero()) { |
Erik Språng | 7ca375c | 2019-02-06 16:20:17 +0100 | [diff] [blame] | 139 | // Multiple temporal layers enabled for this spatial layer. Update rate |
| 140 | // for each of them and make a weighted average of utilization factors, |
| 141 | // with bitrate fraction used as weight. |
| 142 | // If any layer is missing a utilization factor, fall back to default. |
Erik Språng | 3d11e2f | 2019-04-15 14:48:30 +0200 | [diff] [blame] | 143 | layer_info.link_utilization_factor = 0.0; |
| 144 | layer_info.media_utilization_factor = 0.0; |
Erik Språng | 7ca375c | 2019-02-06 16:20:17 +0100 | [diff] [blame] | 145 | for (size_t ti = 0; ti < active_tls_[si]; ++ti) { |
| 146 | RTC_DCHECK(overshoot_detectors_[si][ti]); |
Erik Språng | 3d11e2f | 2019-04-15 14:48:30 +0200 | [diff] [blame] | 147 | const absl::optional<double> ti_link_utilization_factor = |
Erik Språng | 6c072ef | 2019-04-01 12:57:28 +0200 | [diff] [blame] | 148 | overshoot_detectors_[si][ti]->GetNetworkRateUtilizationFactor( |
| 149 | now_ms); |
Erik Språng | 3d11e2f | 2019-04-15 14:48:30 +0200 | [diff] [blame] | 150 | const absl::optional<double> ti_media_utilization_factor = |
| 151 | overshoot_detectors_[si][ti]->GetMediaRateUtilizationFactor(now_ms); |
| 152 | if (!ti_link_utilization_factor || !ti_media_utilization_factor) { |
| 153 | layer_info.link_utilization_factor = kDefaultUtilizationFactor; |
| 154 | layer_info.media_utilization_factor = kDefaultUtilizationFactor; |
Erik Språng | 7ca375c | 2019-02-06 16:20:17 +0100 | [diff] [blame] | 155 | break; |
| 156 | } |
| 157 | const double weight = |
Erik Språng | 3d11e2f | 2019-04-15 14:48:30 +0200 | [diff] [blame] | 158 | static_cast<double>(rates.bitrate.GetBitrate(si, ti)) / |
| 159 | layer_info.target_rate.bps(); |
| 160 | layer_info.link_utilization_factor += |
| 161 | weight * ti_link_utilization_factor.value(); |
| 162 | layer_info.media_utilization_factor += |
| 163 | weight * ti_media_utilization_factor.value(); |
Erik Språng | 7ca375c | 2019-02-06 16:20:17 +0100 | [diff] [blame] | 164 | } |
| 165 | } else { |
| 166 | RTC_NOTREACHED(); |
| 167 | } |
| 168 | |
Erik Språng | 3d11e2f | 2019-04-15 14:48:30 +0200 | [diff] [blame] | 169 | if (layer_info.link_utilization_factor < 1.0) { |
| 170 | // TODO(sprang): Consider checking underuse and allowing it to cancel some |
| 171 | // potential overuse by other streams. |
Erik Språng | 7ca375c | 2019-02-06 16:20:17 +0100 | [diff] [blame] | 172 | |
Erik Språng | 3d11e2f | 2019-04-15 14:48:30 +0200 | [diff] [blame] | 173 | // Don't boost target bitrate if encoder is under-using. |
| 174 | layer_info.link_utilization_factor = 1.0; |
| 175 | } else { |
| 176 | // Don't reduce encoder target below 50%, in which case the frame dropper |
| 177 | // should kick in instead. |
| 178 | layer_info.link_utilization_factor = |
| 179 | std::min(layer_info.link_utilization_factor, 2.0); |
Erik Språng | 7ca375c | 2019-02-06 16:20:17 +0100 | [diff] [blame] | 180 | |
Erik Språng | 3d11e2f | 2019-04-15 14:48:30 +0200 | [diff] [blame] | 181 | // Keep track of sum of desired overshoot bitrate. |
| 182 | wanted_overshoot_sum += layer_info.WantedOvershoot(); |
| 183 | } |
| 184 | } |
| 185 | |
| 186 | // Available link headroom that can be used to fill wanted overshoot. |
| 187 | DataRate available_headroom = DataRate::Zero(); |
| 188 | if (utilize_bandwidth_headroom_) { |
| 189 | available_headroom = |
| 190 | rates.bandwidth_allocation - DataRate::bps(rates.bitrate.get_sum_bps()); |
| 191 | } |
| 192 | |
| 193 | // All wanted overshoots are satisfied in the same proportion based on |
| 194 | // available headroom. |
| 195 | const double granted_overshoot_ratio = |
| 196 | wanted_overshoot_sum == DataRate::Zero() |
| 197 | ? 0.0 |
| 198 | : std::min(1.0, available_headroom.bps<double>() / |
| 199 | wanted_overshoot_sum.bps()); |
| 200 | |
| 201 | for (size_t si = 0; si < kMaxSpatialLayers; ++si) { |
| 202 | LayerRateInfo& layer_info = layer_infos[si]; |
| 203 | double utilization_factor = layer_info.link_utilization_factor; |
| 204 | DataRate allowed_overshoot = |
| 205 | granted_overshoot_ratio * layer_info.WantedOvershoot(); |
| 206 | if (allowed_overshoot > DataRate::Zero()) { |
| 207 | // Pretend the target bitrate is higher by the allowed overshoot. |
| 208 | // Since utilization_factor = actual_bitrate / target_bitrate, it can be |
| 209 | // done by multiplying by old_target_bitrate / new_target_bitrate. |
| 210 | utilization_factor *= layer_info.target_rate.bps<double>() / |
| 211 | (allowed_overshoot.bps<double>() + |
| 212 | layer_info.target_rate.bps<double>()); |
Erik Språng | 7ca375c | 2019-02-06 16:20:17 +0100 | [diff] [blame] | 213 | } |
| 214 | |
Erik Språng | 3d11e2f | 2019-04-15 14:48:30 +0200 | [diff] [blame] | 215 | if (min_bitrates_bps_[si] > 0 && |
| 216 | layer_info.target_rate > DataRate::Zero() && |
| 217 | DataRate::bps(min_bitrates_bps_[si]) < layer_info.target_rate) { |
| 218 | // Make sure rate adjuster doesn't push target bitrate below minimum. |
| 219 | utilization_factor = |
| 220 | std::min(utilization_factor, layer_info.target_rate.bps<double>() / |
| 221 | min_bitrates_bps_[si]); |
| 222 | } |
| 223 | |
| 224 | if (layer_info.target_rate > DataRate::Zero()) { |
| 225 | RTC_LOG(LS_VERBOSE) << "Utilization factors for spatial index " << si |
| 226 | << ": link = " << layer_info.link_utilization_factor |
| 227 | << ", media = " << layer_info.media_utilization_factor |
| 228 | << ", wanted overshoot = " |
| 229 | << layer_info.WantedOvershoot().bps() |
| 230 | << " bps, available headroom = " |
| 231 | << available_headroom.bps() |
| 232 | << " bps, total utilization factor = " |
| 233 | << utilization_factor; |
Erik Språng | 0e1a1f9 | 2019-02-18 18:45:13 +0100 | [diff] [blame] | 234 | } |
| 235 | |
Erik Språng | 7ca375c | 2019-02-06 16:20:17 +0100 | [diff] [blame] | 236 | // Populate the adjusted allocation with determined utilization factor. |
| 237 | if (active_tls_[si] == 1 && |
Erik Språng | 3d11e2f | 2019-04-15 14:48:30 +0200 | [diff] [blame] | 238 | layer_info.target_rate > |
| 239 | DataRate::bps(rates.bitrate.GetBitrate(si, 0))) { |
Erik Språng | 7ca375c | 2019-02-06 16:20:17 +0100 | [diff] [blame] | 240 | // Bitrate allocation indicates temporal layer usage, but encoder |
| 241 | // does not seem to support it. Pipe all bitrate into a single |
| 242 | // overshoot detector. |
Erik Språng | 3d11e2f | 2019-04-15 14:48:30 +0200 | [diff] [blame] | 243 | uint32_t adjusted_layer_bitrate_bps = |
| 244 | std::min(static_cast<uint32_t>( |
| 245 | layer_info.target_rate.bps() / utilization_factor + 0.5), |
| 246 | layer_info.target_rate.bps<uint32_t>()); |
Erik Språng | 7ca375c | 2019-02-06 16:20:17 +0100 | [diff] [blame] | 247 | adjusted_allocation.SetBitrate(si, 0, adjusted_layer_bitrate_bps); |
| 248 | } else { |
| 249 | for (size_t ti = 0; ti < kMaxTemporalStreams; ++ti) { |
Erik Språng | 3d11e2f | 2019-04-15 14:48:30 +0200 | [diff] [blame] | 250 | if (rates.bitrate.HasBitrate(si, ti)) { |
| 251 | uint32_t adjusted_layer_bitrate_bps = std::min( |
| 252 | static_cast<uint32_t>( |
| 253 | rates.bitrate.GetBitrate(si, ti) / utilization_factor + 0.5), |
| 254 | rates.bitrate.GetBitrate(si, ti)); |
Erik Språng | 7ca375c | 2019-02-06 16:20:17 +0100 | [diff] [blame] | 255 | adjusted_allocation.SetBitrate(si, ti, adjusted_layer_bitrate_bps); |
| 256 | } |
| 257 | } |
| 258 | } |
| 259 | |
| 260 | // In case of rounding errors, add bitrate to TL0 until min bitrate |
| 261 | // constraint has been met. |
| 262 | const uint32_t adjusted_spatial_layer_sum = |
| 263 | adjusted_allocation.GetSpatialLayerSum(si); |
Erik Språng | 3d11e2f | 2019-04-15 14:48:30 +0200 | [diff] [blame] | 264 | if (layer_info.target_rate > DataRate::Zero() && |
Erik Språng | 7ca375c | 2019-02-06 16:20:17 +0100 | [diff] [blame] | 265 | adjusted_spatial_layer_sum < min_bitrates_bps_[si]) { |
| 266 | adjusted_allocation.SetBitrate(si, 0, |
| 267 | adjusted_allocation.GetBitrate(si, 0) + |
| 268 | min_bitrates_bps_[si] - |
| 269 | adjusted_spatial_layer_sum); |
| 270 | } |
| 271 | |
| 272 | // Update all detectors with the new adjusted bitrate targets. |
| 273 | for (size_t ti = 0; ti < kMaxTemporalStreams; ++ti) { |
| 274 | const uint32_t layer_bitrate_bps = adjusted_allocation.GetBitrate(si, ti); |
| 275 | // Overshoot detector may not exist, eg for ScreenshareLayers case. |
| 276 | if (layer_bitrate_bps > 0 && overshoot_detectors_[si][ti]) { |
| 277 | // Number of frames in this layer alone is not cumulative, so |
| 278 | // subtract fps from any low temporal layer. |
| 279 | const double fps_fraction = |
| 280 | static_cast<double>( |
| 281 | current_fps_allocation_[si][ti] - |
| 282 | (ti == 0 ? 0 : current_fps_allocation_[si][ti - 1])) / |
| 283 | VideoEncoder::EncoderInfo::kMaxFramerateFraction; |
| 284 | |
| 285 | overshoot_detectors_[si][ti]->SetTargetRate( |
| 286 | DataRate::bps(layer_bitrate_bps), |
Erik Språng | 3d11e2f | 2019-04-15 14:48:30 +0200 | [diff] [blame] | 287 | fps_fraction * rates.framerate_fps, now_ms); |
Erik Språng | 7ca375c | 2019-02-06 16:20:17 +0100 | [diff] [blame] | 288 | } |
| 289 | } |
| 290 | } |
| 291 | |
| 292 | return adjusted_allocation; |
| 293 | } |
| 294 | |
| 295 | void EncoderBitrateAdjuster::OnEncoderInfo( |
| 296 | const VideoEncoder::EncoderInfo& encoder_info) { |
| 297 | // Copy allocation into current state and re-allocate. |
| 298 | for (size_t si = 0; si < kMaxSpatialLayers; ++si) { |
| 299 | current_fps_allocation_[si] = encoder_info.fps_allocation[si]; |
| 300 | } |
| 301 | |
| 302 | // Trigger re-allocation so that overshoot detectors have correct targets. |
Erik Språng | 3d11e2f | 2019-04-15 14:48:30 +0200 | [diff] [blame] | 303 | AdjustRateAllocation(current_rate_control_parameters_); |
Erik Språng | 7ca375c | 2019-02-06 16:20:17 +0100 | [diff] [blame] | 304 | } |
| 305 | |
| 306 | void EncoderBitrateAdjuster::OnEncodedFrame(const EncodedImage& encoded_image, |
| 307 | int temporal_index) { |
| 308 | ++frames_since_layout_change_; |
| 309 | // Detectors may not exist, for instance if ScreenshareLayers is used. |
| 310 | auto& detector = |
| 311 | overshoot_detectors_[encoded_image.SpatialIndex().value_or(0)] |
| 312 | [temporal_index]; |
| 313 | if (detector) { |
| 314 | detector->OnEncodedFrame(encoded_image.size(), rtc::TimeMillis()); |
| 315 | } |
| 316 | } |
| 317 | |
| 318 | void EncoderBitrateAdjuster::Reset() { |
| 319 | for (size_t si = 0; si < kMaxSpatialLayers; ++si) { |
| 320 | for (size_t ti = 0; ti < kMaxTemporalStreams; ++ti) { |
| 321 | overshoot_detectors_[si][ti].reset(); |
| 322 | } |
| 323 | } |
| 324 | // Call AdjustRateAllocation() with the last know bitrate allocation, so that |
| 325 | // the appropriate overuse detectors are immediately re-created. |
Erik Språng | 3d11e2f | 2019-04-15 14:48:30 +0200 | [diff] [blame] | 326 | AdjustRateAllocation(current_rate_control_parameters_); |
Erik Språng | 7ca375c | 2019-02-06 16:20:17 +0100 | [diff] [blame] | 327 | } |
| 328 | |
| 329 | } // namespace webrtc |