| /* |
| * Copyright (c) 2015 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 "webrtc/call/bitrate_allocator.h" |
| |
| #include <algorithm> |
| #include <utility> |
| |
| #include "webrtc/modules/bitrate_controller/include/bitrate_controller.h" |
| #include "webrtc/rtc_base/checks.h" |
| #include "webrtc/rtc_base/logging.h" |
| #include "webrtc/system_wrappers/include/clock.h" |
| #include "webrtc/system_wrappers/include/metrics.h" |
| |
| namespace webrtc { |
| |
| // Allow packets to be transmitted in up to 2 times max video bitrate if the |
| // bandwidth estimate allows it. |
| const int kTransmissionMaxBitrateMultiplier = 2; |
| const int kDefaultBitrateBps = 300000; |
| |
| // Require a bitrate increase of max(10%, 20kbps) to resume paused streams. |
| const double kToggleFactor = 0.1; |
| const uint32_t kMinToggleBitrateBps = 20000; |
| |
| const int64_t kBweLogIntervalMs = 5000; |
| |
| namespace { |
| |
| double MediaRatio(uint32_t allocated_bitrate, uint32_t protection_bitrate) { |
| RTC_DCHECK_GT(allocated_bitrate, 0); |
| if (protection_bitrate == 0) |
| return 1.0; |
| |
| uint32_t media_bitrate = allocated_bitrate - protection_bitrate; |
| return media_bitrate / static_cast<double>(allocated_bitrate); |
| } |
| } // namespace |
| |
| BitrateAllocator::BitrateAllocator(LimitObserver* limit_observer) |
| : limit_observer_(limit_observer), |
| bitrate_observer_configs_(), |
| last_bitrate_bps_(0), |
| last_non_zero_bitrate_bps_(kDefaultBitrateBps), |
| last_fraction_loss_(0), |
| last_rtt_(0), |
| num_pause_events_(0), |
| clock_(Clock::GetRealTimeClock()), |
| last_bwe_log_time_(0), |
| total_requested_padding_bitrate_(0), |
| total_requested_min_bitrate_(0) { |
| sequenced_checker_.Detach(); |
| } |
| |
| BitrateAllocator::~BitrateAllocator() { |
| RTC_HISTOGRAM_COUNTS_100("WebRTC.Call.NumberOfPauseEvents", |
| num_pause_events_); |
| } |
| |
| void BitrateAllocator::OnNetworkChanged(uint32_t target_bitrate_bps, |
| uint8_t fraction_loss, |
| int64_t rtt, |
| int64_t bwe_period_ms) { |
| RTC_DCHECK_CALLED_SEQUENTIALLY(&sequenced_checker_); |
| last_bitrate_bps_ = target_bitrate_bps; |
| last_non_zero_bitrate_bps_ = |
| target_bitrate_bps > 0 ? target_bitrate_bps : last_non_zero_bitrate_bps_; |
| last_fraction_loss_ = fraction_loss; |
| last_rtt_ = rtt; |
| last_bwe_period_ms_ = bwe_period_ms; |
| |
| // Periodically log the incoming BWE. |
| int64_t now = clock_->TimeInMilliseconds(); |
| if (now > last_bwe_log_time_ + kBweLogIntervalMs) { |
| LOG(LS_INFO) << "Current BWE " << target_bitrate_bps; |
| last_bwe_log_time_ = now; |
| } |
| |
| ObserverAllocation allocation = AllocateBitrates(target_bitrate_bps); |
| |
| for (auto& config : bitrate_observer_configs_) { |
| uint32_t allocated_bitrate = allocation[config.observer]; |
| uint32_t protection_bitrate = config.observer->OnBitrateUpdated( |
| allocated_bitrate, last_fraction_loss_, last_rtt_, |
| last_bwe_period_ms_); |
| |
| if (allocated_bitrate == 0 && config.allocated_bitrate_bps > 0) { |
| if (target_bitrate_bps > 0) |
| ++num_pause_events_; |
| // The protection bitrate is an estimate based on the ratio between media |
| // and protection used before this observer was muted. |
| uint32_t predicted_protection_bps = |
| (1.0 - config.media_ratio) * config.min_bitrate_bps; |
| LOG(LS_INFO) << "Pausing observer " << config.observer |
| << " with configured min bitrate " << config.min_bitrate_bps |
| << " and current estimate of " << target_bitrate_bps |
| << " and protection bitrate " << predicted_protection_bps; |
| } else if (allocated_bitrate > 0 && config.allocated_bitrate_bps == 0) { |
| if (target_bitrate_bps > 0) |
| ++num_pause_events_; |
| LOG(LS_INFO) << "Resuming observer " << config.observer |
| << ", configured min bitrate " << config.min_bitrate_bps |
| << ", current allocation " << allocated_bitrate |
| << " and protection bitrate " << protection_bitrate; |
| } |
| |
| // Only update the media ratio if the observer got an allocation. |
| if (allocated_bitrate > 0) |
| config.media_ratio = MediaRatio(allocated_bitrate, protection_bitrate); |
| config.allocated_bitrate_bps = allocated_bitrate; |
| } |
| UpdateAllocationLimits(); |
| } |
| |
| void BitrateAllocator::AddObserver(BitrateAllocatorObserver* observer, |
| uint32_t min_bitrate_bps, |
| uint32_t max_bitrate_bps, |
| uint32_t pad_up_bitrate_bps, |
| bool enforce_min_bitrate) { |
| RTC_DCHECK_CALLED_SEQUENTIALLY(&sequenced_checker_); |
| auto it = FindObserverConfig(observer); |
| |
| // Update settings if the observer already exists, create a new one otherwise. |
| if (it != bitrate_observer_configs_.end()) { |
| it->min_bitrate_bps = min_bitrate_bps; |
| it->max_bitrate_bps = max_bitrate_bps; |
| it->pad_up_bitrate_bps = pad_up_bitrate_bps; |
| it->enforce_min_bitrate = enforce_min_bitrate; |
| } else { |
| bitrate_observer_configs_.push_back( |
| ObserverConfig(observer, min_bitrate_bps, max_bitrate_bps, |
| pad_up_bitrate_bps, enforce_min_bitrate)); |
| } |
| |
| ObserverAllocation allocation; |
| if (last_bitrate_bps_ > 0) { |
| // Calculate a new allocation and update all observers. |
| allocation = AllocateBitrates(last_bitrate_bps_); |
| for (auto& config : bitrate_observer_configs_) { |
| uint32_t allocated_bitrate = allocation[config.observer]; |
| uint32_t protection_bitrate = config.observer->OnBitrateUpdated( |
| allocated_bitrate, last_fraction_loss_, last_rtt_, |
| last_bwe_period_ms_); |
| config.allocated_bitrate_bps = allocated_bitrate; |
| if (allocated_bitrate > 0) |
| config.media_ratio = MediaRatio(allocated_bitrate, protection_bitrate); |
| } |
| } else { |
| // Currently, an encoder is not allowed to produce frames. |
| // But we still have to return the initial config bitrate + let the |
| // observer know that it can not produce frames. |
| allocation = AllocateBitrates(last_non_zero_bitrate_bps_); |
| observer->OnBitrateUpdated(0, last_fraction_loss_, last_rtt_, |
| last_bwe_period_ms_); |
| } |
| UpdateAllocationLimits(); |
| } |
| |
| void BitrateAllocator::UpdateAllocationLimits() { |
| RTC_DCHECK_CALLED_SEQUENTIALLY(&sequenced_checker_); |
| uint32_t total_requested_padding_bitrate = 0; |
| uint32_t total_requested_min_bitrate = 0; |
| |
| for (const auto& config : bitrate_observer_configs_) { |
| uint32_t stream_padding = config.pad_up_bitrate_bps; |
| if (config.enforce_min_bitrate) { |
| total_requested_min_bitrate += config.min_bitrate_bps; |
| } else if (config.allocated_bitrate_bps == 0) { |
| stream_padding = |
| std::max(MinBitrateWithHysteresis(config), stream_padding); |
| } |
| total_requested_padding_bitrate += stream_padding; |
| } |
| |
| if (total_requested_padding_bitrate == total_requested_padding_bitrate_ && |
| total_requested_min_bitrate == total_requested_min_bitrate_) { |
| return; |
| } |
| |
| total_requested_min_bitrate_ = total_requested_min_bitrate; |
| total_requested_padding_bitrate_ = total_requested_padding_bitrate; |
| |
| LOG(LS_INFO) << "UpdateAllocationLimits : total_requested_min_bitrate: " |
| << total_requested_min_bitrate |
| << "bps, total_requested_padding_bitrate: " |
| << total_requested_padding_bitrate << "bps"; |
| limit_observer_->OnAllocationLimitsChanged(total_requested_min_bitrate, |
| total_requested_padding_bitrate); |
| } |
| |
| void BitrateAllocator::RemoveObserver(BitrateAllocatorObserver* observer) { |
| RTC_DCHECK_CALLED_SEQUENTIALLY(&sequenced_checker_); |
| auto it = FindObserverConfig(observer); |
| if (it != bitrate_observer_configs_.end()) { |
| bitrate_observer_configs_.erase(it); |
| } |
| |
| UpdateAllocationLimits(); |
| } |
| |
| int BitrateAllocator::GetStartBitrate(BitrateAllocatorObserver* observer) { |
| RTC_DCHECK_CALLED_SEQUENTIALLY(&sequenced_checker_); |
| const auto& it = FindObserverConfig(observer); |
| if (it == bitrate_observer_configs_.end()) { |
| // This observer hasn't been added yet, just give it its fair share. |
| return last_non_zero_bitrate_bps_ / |
| static_cast<int>((bitrate_observer_configs_.size() + 1)); |
| } else if (it->allocated_bitrate_bps == -1) { |
| // This observer hasn't received an allocation yet, so do the same. |
| return last_non_zero_bitrate_bps_ / |
| static_cast<int>(bitrate_observer_configs_.size()); |
| } else { |
| // This observer already has an allocation. |
| return it->allocated_bitrate_bps; |
| } |
| } |
| |
| BitrateAllocator::ObserverConfigs::iterator |
| BitrateAllocator::FindObserverConfig(const BitrateAllocatorObserver* observer) { |
| RTC_DCHECK_CALLED_SEQUENTIALLY(&sequenced_checker_); |
| for (auto it = bitrate_observer_configs_.begin(); |
| it != bitrate_observer_configs_.end(); ++it) { |
| if (it->observer == observer) |
| return it; |
| } |
| return bitrate_observer_configs_.end(); |
| } |
| |
| BitrateAllocator::ObserverAllocation BitrateAllocator::AllocateBitrates( |
| uint32_t bitrate) { |
| RTC_DCHECK_CALLED_SEQUENTIALLY(&sequenced_checker_); |
| if (bitrate_observer_configs_.empty()) |
| return ObserverAllocation(); |
| |
| if (bitrate == 0) |
| return ZeroRateAllocation(); |
| |
| uint32_t sum_min_bitrates = 0; |
| uint32_t sum_max_bitrates = 0; |
| for (const auto& observer_config : bitrate_observer_configs_) { |
| sum_min_bitrates += observer_config.min_bitrate_bps; |
| sum_max_bitrates += observer_config.max_bitrate_bps; |
| } |
| |
| // Not enough for all observers to get an allocation, allocate according to: |
| // enforced min bitrate -> allocated bitrate previous round -> restart paused |
| // streams. |
| if (!EnoughBitrateForAllObservers(bitrate, sum_min_bitrates)) |
| return LowRateAllocation(bitrate); |
| |
| // All observers will get their min bitrate plus an even share of the rest. |
| if (bitrate <= sum_max_bitrates) |
| return NormalRateAllocation(bitrate, sum_min_bitrates); |
| |
| // All observers will get up to kTransmissionMaxBitrateMultiplier x max. |
| return MaxRateAllocation(bitrate, sum_max_bitrates); |
| } |
| |
| BitrateAllocator::ObserverAllocation BitrateAllocator::ZeroRateAllocation() { |
| RTC_DCHECK_CALLED_SEQUENTIALLY(&sequenced_checker_); |
| ObserverAllocation allocation; |
| for (const auto& observer_config : bitrate_observer_configs_) |
| allocation[observer_config.observer] = 0; |
| return allocation; |
| } |
| |
| BitrateAllocator::ObserverAllocation BitrateAllocator::LowRateAllocation( |
| uint32_t bitrate) { |
| RTC_DCHECK_CALLED_SEQUENTIALLY(&sequenced_checker_); |
| ObserverAllocation allocation; |
| // Start by allocating bitrate to observers enforcing a min bitrate, hence |
| // remaining_bitrate might turn negative. |
| int64_t remaining_bitrate = bitrate; |
| for (const auto& observer_config : bitrate_observer_configs_) { |
| int32_t allocated_bitrate = 0; |
| if (observer_config.enforce_min_bitrate) |
| allocated_bitrate = observer_config.min_bitrate_bps; |
| |
| allocation[observer_config.observer] = allocated_bitrate; |
| remaining_bitrate -= allocated_bitrate; |
| } |
| |
| // Allocate bitrate to all previously active streams. |
| if (remaining_bitrate > 0) { |
| for (const auto& observer_config : bitrate_observer_configs_) { |
| if (observer_config.enforce_min_bitrate || |
| LastAllocatedBitrate(observer_config) == 0) |
| continue; |
| |
| uint32_t required_bitrate = MinBitrateWithHysteresis(observer_config); |
| if (remaining_bitrate >= required_bitrate) { |
| allocation[observer_config.observer] = required_bitrate; |
| remaining_bitrate -= required_bitrate; |
| } |
| } |
| } |
| |
| // Allocate bitrate to previously paused streams. |
| if (remaining_bitrate > 0) { |
| for (const auto& observer_config : bitrate_observer_configs_) { |
| if (LastAllocatedBitrate(observer_config) != 0) |
| continue; |
| |
| // Add a hysteresis to avoid toggling. |
| uint32_t required_bitrate = MinBitrateWithHysteresis(observer_config); |
| if (remaining_bitrate >= required_bitrate) { |
| allocation[observer_config.observer] = required_bitrate; |
| remaining_bitrate -= required_bitrate; |
| } |
| } |
| } |
| |
| // Split a possible remainder evenly on all streams with an allocation. |
| if (remaining_bitrate > 0) |
| DistributeBitrateEvenly(remaining_bitrate, false, 1, &allocation); |
| |
| RTC_DCHECK_EQ(allocation.size(), bitrate_observer_configs_.size()); |
| return allocation; |
| } |
| |
| BitrateAllocator::ObserverAllocation BitrateAllocator::NormalRateAllocation( |
| uint32_t bitrate, |
| uint32_t sum_min_bitrates) { |
| RTC_DCHECK_CALLED_SEQUENTIALLY(&sequenced_checker_); |
| ObserverAllocation allocation; |
| for (const auto& observer_config : bitrate_observer_configs_) |
| allocation[observer_config.observer] = observer_config.min_bitrate_bps; |
| |
| bitrate -= sum_min_bitrates; |
| if (bitrate > 0) |
| DistributeBitrateEvenly(bitrate, true, 1, &allocation); |
| |
| return allocation; |
| } |
| |
| BitrateAllocator::ObserverAllocation BitrateAllocator::MaxRateAllocation( |
| uint32_t bitrate, |
| uint32_t sum_max_bitrates) { |
| RTC_DCHECK_CALLED_SEQUENTIALLY(&sequenced_checker_); |
| ObserverAllocation allocation; |
| |
| for (const auto& observer_config : bitrate_observer_configs_) { |
| allocation[observer_config.observer] = observer_config.max_bitrate_bps; |
| bitrate -= observer_config.max_bitrate_bps; |
| } |
| DistributeBitrateEvenly(bitrate, true, kTransmissionMaxBitrateMultiplier, |
| &allocation); |
| return allocation; |
| } |
| |
| uint32_t BitrateAllocator::LastAllocatedBitrate( |
| const ObserverConfig& observer_config) { |
| // Return the configured minimum bitrate for newly added observers, to avoid |
| // requiring an extra high bitrate for the observer to get an allocated |
| // bitrate. |
| return observer_config.allocated_bitrate_bps == -1 |
| ? observer_config.min_bitrate_bps |
| : observer_config.allocated_bitrate_bps; |
| } |
| |
| uint32_t BitrateAllocator::MinBitrateWithHysteresis( |
| const ObserverConfig& observer_config) { |
| uint32_t min_bitrate = observer_config.min_bitrate_bps; |
| if (LastAllocatedBitrate(observer_config) == 0) { |
| min_bitrate += std::max(static_cast<uint32_t>(kToggleFactor * min_bitrate), |
| kMinToggleBitrateBps); |
| } |
| // Account for protection bitrate used by this observer in the previous |
| // allocation. |
| // Note: the ratio will only be updated when the stream is active, meaning a |
| // paused stream won't get any ratio updates. This might lead to waiting a bit |
| // longer than necessary if the network condition improves, but this is to |
| // avoid too much toggling. |
| if (observer_config.media_ratio > 0.0 && observer_config.media_ratio < 1.0) |
| min_bitrate += min_bitrate * (1.0 - observer_config.media_ratio); |
| |
| return min_bitrate; |
| } |
| |
| void BitrateAllocator::DistributeBitrateEvenly(uint32_t bitrate, |
| bool include_zero_allocations, |
| int max_multiplier, |
| ObserverAllocation* allocation) { |
| RTC_DCHECK_CALLED_SEQUENTIALLY(&sequenced_checker_); |
| RTC_DCHECK_EQ(allocation->size(), bitrate_observer_configs_.size()); |
| |
| ObserverSortingMap list_max_bitrates; |
| for (const auto& observer_config : bitrate_observer_configs_) { |
| if (include_zero_allocations || |
| allocation->at(observer_config.observer) != 0) { |
| list_max_bitrates.insert(std::pair<uint32_t, const ObserverConfig*>( |
| observer_config.max_bitrate_bps, &observer_config)); |
| } |
| } |
| auto it = list_max_bitrates.begin(); |
| while (it != list_max_bitrates.end()) { |
| RTC_DCHECK_GT(bitrate, 0); |
| uint32_t extra_allocation = |
| bitrate / static_cast<uint32_t>(list_max_bitrates.size()); |
| uint32_t total_allocation = |
| extra_allocation + allocation->at(it->second->observer); |
| bitrate -= extra_allocation; |
| if (total_allocation > max_multiplier * it->first) { |
| // There is more than we can fit for this observer, carry over to the |
| // remaining observers. |
| bitrate += total_allocation - max_multiplier * it->first; |
| total_allocation = max_multiplier * it->first; |
| } |
| // Finally, update the allocation for this observer. |
| allocation->at(it->second->observer) = total_allocation; |
| it = list_max_bitrates.erase(it); |
| } |
| } |
| |
| bool BitrateAllocator::EnoughBitrateForAllObservers(uint32_t bitrate, |
| uint32_t sum_min_bitrates) { |
| RTC_DCHECK_CALLED_SEQUENTIALLY(&sequenced_checker_); |
| if (bitrate < sum_min_bitrates) |
| return false; |
| |
| uint32_t extra_bitrate_per_observer = |
| (bitrate - sum_min_bitrates) / |
| static_cast<uint32_t>(bitrate_observer_configs_.size()); |
| for (const auto& observer_config : bitrate_observer_configs_) { |
| if (observer_config.min_bitrate_bps + extra_bitrate_per_observer < |
| MinBitrateWithHysteresis(observer_config)) { |
| return false; |
| } |
| } |
| return true; |
| } |
| } // namespace webrtc |
