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/*
* 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/modules/bitrate_controller/include/bitrate_allocator.h"
#include <algorithm>
#include <utility>
#include "webrtc/modules/bitrate_controller/include/bitrate_controller.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;
BitrateAllocator::BitrateAllocator()
: crit_sect_(CriticalSectionWrapper::CreateCriticalSection()),
bitrate_observers_(),
enforce_min_bitrate_(true),
last_bitrate_bps_(kDefaultBitrateBps),
last_fraction_loss_(0),
last_rtt_(0) {
}
void BitrateAllocator::OnNetworkChanged(uint32_t bitrate,
uint8_t fraction_loss,
int64_t rtt) {
CriticalSectionScoped lock(crit_sect_.get());
last_bitrate_bps_ = bitrate;
last_fraction_loss_ = fraction_loss;
last_rtt_ = rtt;
ObserverBitrateMap allocation = AllocateBitrates();
for (const auto& kv : allocation)
kv.first->OnNetworkChanged(kv.second, last_fraction_loss_, last_rtt_);
}
BitrateAllocator::ObserverBitrateMap BitrateAllocator::AllocateBitrates() {
if (bitrate_observers_.empty())
return ObserverBitrateMap();
uint32_t sum_min_bitrates = 0;
for (const auto& observer : bitrate_observers_)
sum_min_bitrates += observer.second.min_bitrate;
if (last_bitrate_bps_ <= sum_min_bitrates)
return LowRateAllocation(last_bitrate_bps_);
else
return NormalRateAllocation(last_bitrate_bps_, sum_min_bitrates);
}
int BitrateAllocator::AddBitrateObserver(BitrateObserver* observer,
uint32_t min_bitrate_bps,
uint32_t max_bitrate_bps) {
CriticalSectionScoped lock(crit_sect_.get());
BitrateObserverConfList::iterator it =
FindObserverConfigurationPair(observer);
// Allow the max bitrate to be exceeded for FEC and retransmissions.
// TODO(holmer): We have to get rid of this hack as it makes it difficult to
// properly allocate bitrate. The allocator should instead distribute any
// extra bitrate after all streams have maxed out.
max_bitrate_bps *= kTransmissionMaxBitrateMultiplier;
if (it != bitrate_observers_.end()) {
// Update current configuration.
it->second.min_bitrate = min_bitrate_bps;
it->second.max_bitrate = max_bitrate_bps;
} else {
// Add new settings.
bitrate_observers_.push_back(BitrateObserverConfiguration(
observer, BitrateConfiguration(min_bitrate_bps, max_bitrate_bps)));
bitrate_observers_modified_ = true;
}
ObserverBitrateMap allocation = AllocateBitrates();
int new_observer_bitrate_bps = 0;
for (auto& kv : allocation) {
kv.first->OnNetworkChanged(kv.second, last_fraction_loss_, last_rtt_);
if (kv.first == observer)
new_observer_bitrate_bps = kv.second;
}
return new_observer_bitrate_bps;
}
void BitrateAllocator::RemoveBitrateObserver(BitrateObserver* observer) {
CriticalSectionScoped lock(crit_sect_.get());
BitrateObserverConfList::iterator it =
FindObserverConfigurationPair(observer);
if (it != bitrate_observers_.end()) {
bitrate_observers_.erase(it);
bitrate_observers_modified_ = true;
}
}
void BitrateAllocator::GetMinMaxBitrateSumBps(int* min_bitrate_sum_bps,
int* max_bitrate_sum_bps) const {
*min_bitrate_sum_bps = 0;
*max_bitrate_sum_bps = 0;
CriticalSectionScoped lock(crit_sect_.get());
for (const auto& observer : bitrate_observers_) {
*min_bitrate_sum_bps += observer.second.min_bitrate;
*max_bitrate_sum_bps += observer.second.max_bitrate;
}
}
BitrateAllocator::BitrateObserverConfList::iterator
BitrateAllocator::FindObserverConfigurationPair(
const BitrateObserver* observer) {
for (auto it = bitrate_observers_.begin(); it != bitrate_observers_.end();
++it) {
if (it->first == observer)
return it;
}
return bitrate_observers_.end();
}
void BitrateAllocator::EnforceMinBitrate(bool enforce_min_bitrate) {
CriticalSectionScoped lock(crit_sect_.get());
enforce_min_bitrate_ = enforce_min_bitrate;
}
BitrateAllocator::ObserverBitrateMap BitrateAllocator::NormalRateAllocation(
uint32_t bitrate,
uint32_t sum_min_bitrates) {
uint32_t number_of_observers = bitrate_observers_.size();
uint32_t bitrate_per_observer =
(bitrate - sum_min_bitrates) / number_of_observers;
// Use map to sort list based on max bitrate.
ObserverSortingMap list_max_bitrates;
for (const auto& observer : bitrate_observers_) {
list_max_bitrates.insert(std::pair<uint32_t, ObserverConfiguration>(
observer.second.max_bitrate,
ObserverConfiguration(observer.first, observer.second.min_bitrate)));
}
ObserverBitrateMap allocation;
ObserverSortingMap::iterator max_it = list_max_bitrates.begin();
while (max_it != list_max_bitrates.end()) {
number_of_observers--;
uint32_t observer_allowance =
max_it->second.min_bitrate + bitrate_per_observer;
if (max_it->first < observer_allowance) {
// We have more than enough for this observer.
// Carry the remainder forward.
uint32_t remainder = observer_allowance - max_it->first;
if (number_of_observers != 0) {
bitrate_per_observer += remainder / number_of_observers;
}
allocation[max_it->second.observer] = max_it->first;
} else {
allocation[max_it->second.observer] = observer_allowance;
}
list_max_bitrates.erase(max_it);
// Prepare next iteration.
max_it = list_max_bitrates.begin();
}
return allocation;
}
BitrateAllocator::ObserverBitrateMap BitrateAllocator::LowRateAllocation(
uint32_t bitrate) {
ObserverBitrateMap allocation;
if (enforce_min_bitrate_) {
// Min bitrate to all observers.
for (const auto& observer : bitrate_observers_)
allocation[observer.first] = observer.second.min_bitrate;
} else {
// Allocate up to |min_bitrate| to one observer at a time, until
// |bitrate| is depleted.
uint32_t remainder = bitrate;
for (const auto& observer : bitrate_observers_) {
uint32_t allocated_bitrate =
std::min(remainder, observer.second.min_bitrate);
allocation[observer.first] = allocated_bitrate;
remainder -= allocated_bitrate;
}
}
return allocation;
}
} // namespace webrtc
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