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/*
* Copyright (c) 2012 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/deprecated/jitter_buffer.h"
#include <algorithm>
#include <limits>
#include <utility>
#include "api/units/timestamp.h"
#include "modules/video_coding/deprecated/frame_buffer.h"
#include "modules/video_coding/deprecated/jitter_buffer_common.h"
#include "modules/video_coding/deprecated/packet.h"
#include "modules/video_coding/timing/inter_frame_delay_variation_calculator.h"
#include "modules/video_coding/timing/jitter_estimator.h"
#include "rtc_base/checks.h"
#include "rtc_base/logging.h"
#include "system_wrappers/include/clock.h"
namespace webrtc {
// Use this rtt if no value has been reported.
static const int64_t kDefaultRtt = 200;
typedef std::pair<uint32_t, VCMFrameBuffer*> FrameListPair;
bool IsKeyFrame(FrameListPair pair) {
return pair.second->FrameType() == VideoFrameType::kVideoFrameKey;
}
bool HasNonEmptyState(FrameListPair pair) {
return pair.second->GetState() != kStateEmpty;
}
void FrameList::InsertFrame(VCMFrameBuffer* frame) {
insert(rbegin().base(), FrameListPair(frame->RtpTimestamp(), frame));
}
VCMFrameBuffer* FrameList::PopFrame(uint32_t timestamp) {
FrameList::iterator it = find(timestamp);
if (it == end())
return NULL;
VCMFrameBuffer* frame = it->second;
erase(it);
return frame;
}
VCMFrameBuffer* FrameList::Front() const {
return begin()->second;
}
VCMFrameBuffer* FrameList::Back() const {
return rbegin()->second;
}
int FrameList::RecycleFramesUntilKeyFrame(FrameList::iterator* key_frame_it,
UnorderedFrameList* free_frames) {
int drop_count = 0;
FrameList::iterator it = begin();
while (!empty()) {
// Throw at least one frame.
it->second->Reset();
free_frames->push_back(it->second);
erase(it++);
++drop_count;
if (it != end() &&
it->second->FrameType() == VideoFrameType::kVideoFrameKey) {
*key_frame_it = it;
return drop_count;
}
}
*key_frame_it = end();
return drop_count;
}
void FrameList::CleanUpOldOrEmptyFrames(VCMDecodingState* decoding_state,
UnorderedFrameList* free_frames) {
while (!empty()) {
VCMFrameBuffer* oldest_frame = Front();
bool remove_frame = false;
if (oldest_frame->GetState() == kStateEmpty && size() > 1) {
// This frame is empty, try to update the last decoded state and drop it
// if successful.
remove_frame = decoding_state->UpdateEmptyFrame(oldest_frame);
} else {
remove_frame = decoding_state->IsOldFrame(oldest_frame);
}
if (!remove_frame) {
break;
}
free_frames->push_back(oldest_frame);
erase(begin());
}
}
void FrameList::Reset(UnorderedFrameList* free_frames) {
while (!empty()) {
begin()->second->Reset();
free_frames->push_back(begin()->second);
erase(begin());
}
}
VCMJitterBuffer::VCMJitterBuffer(Clock* clock,
std::unique_ptr<EventWrapper> event,
const FieldTrialsView& field_trials)
: clock_(clock),
running_(false),
frame_event_(std::move(event)),
max_number_of_frames_(kStartNumberOfFrames),
free_frames_(),
decodable_frames_(),
incomplete_frames_(),
last_decoded_state_(),
first_packet_since_reset_(true),
num_consecutive_old_packets_(0),
num_packets_(0),
num_duplicated_packets_(0),
jitter_estimate_(clock, field_trials),
missing_sequence_numbers_(SequenceNumberLessThan()),
latest_received_sequence_number_(0),
max_nack_list_size_(0),
max_packet_age_to_nack_(0),
max_incomplete_time_ms_(0),
average_packets_per_frame_(0.0f),
frame_counter_(0) {
for (int i = 0; i < kStartNumberOfFrames; i++)
free_frames_.push_back(new VCMFrameBuffer());
}
VCMJitterBuffer::~VCMJitterBuffer() {
Stop();
for (UnorderedFrameList::iterator it = free_frames_.begin();
it != free_frames_.end(); ++it) {
delete *it;
}
for (FrameList::iterator it = incomplete_frames_.begin();
it != incomplete_frames_.end(); ++it) {
delete it->second;
}
for (FrameList::iterator it = decodable_frames_.begin();
it != decodable_frames_.end(); ++it) {
delete it->second;
}
}
void VCMJitterBuffer::Start() {
MutexLock lock(&mutex_);
running_ = true;
num_consecutive_old_packets_ = 0;
num_packets_ = 0;
num_duplicated_packets_ = 0;
// Start in a non-signaled state.
waiting_for_completion_.frame_size = 0;
waiting_for_completion_.timestamp = 0;
waiting_for_completion_.latest_packet_time = -1;
first_packet_since_reset_ = true;
last_decoded_state_.Reset();
decodable_frames_.Reset(&free_frames_);
incomplete_frames_.Reset(&free_frames_);
}
void VCMJitterBuffer::Stop() {
MutexLock lock(&mutex_);
running_ = false;
last_decoded_state_.Reset();
// Make sure we wake up any threads waiting on these events.
frame_event_->Set();
}
bool VCMJitterBuffer::Running() const {
MutexLock lock(&mutex_);
return running_;
}
void VCMJitterBuffer::Flush() {
MutexLock lock(&mutex_);
FlushInternal();
}
void VCMJitterBuffer::FlushInternal() {
decodable_frames_.Reset(&free_frames_);
incomplete_frames_.Reset(&free_frames_);
last_decoded_state_.Reset(); // TODO(mikhal): sync reset.
num_consecutive_old_packets_ = 0;
// Also reset the jitter and delay estimates
jitter_estimate_.Reset();
inter_frame_delay_.Reset();
waiting_for_completion_.frame_size = 0;
waiting_for_completion_.timestamp = 0;
waiting_for_completion_.latest_packet_time = -1;
first_packet_since_reset_ = true;
missing_sequence_numbers_.clear();
}
int VCMJitterBuffer::num_packets() const {
MutexLock lock(&mutex_);
return num_packets_;
}
int VCMJitterBuffer::num_duplicated_packets() const {
MutexLock lock(&mutex_);
return num_duplicated_packets_;
}
// Returns immediately or a `max_wait_time_ms` ms event hang waiting for a
// complete frame, `max_wait_time_ms` decided by caller.
VCMEncodedFrame* VCMJitterBuffer::NextCompleteFrame(uint32_t max_wait_time_ms) {
MutexLock lock(&mutex_);
if (!running_) {
return nullptr;
}
CleanUpOldOrEmptyFrames();
if (decodable_frames_.empty() ||
decodable_frames_.Front()->GetState() != kStateComplete) {
const int64_t end_wait_time_ms =
clock_->TimeInMilliseconds() + max_wait_time_ms;
int64_t wait_time_ms = max_wait_time_ms;
while (wait_time_ms > 0) {
mutex_.Unlock();
const EventTypeWrapper ret =
frame_event_->Wait(static_cast<uint32_t>(wait_time_ms));
mutex_.Lock();
if (ret == kEventSignaled) {
// Are we shutting down the jitter buffer?
if (!running_) {
return nullptr;
}
// Finding oldest frame ready for decoder.
CleanUpOldOrEmptyFrames();
if (decodable_frames_.empty() ||
decodable_frames_.Front()->GetState() != kStateComplete) {
wait_time_ms = end_wait_time_ms - clock_->TimeInMilliseconds();
} else {
break;
}
} else {
break;
}
}
}
if (decodable_frames_.empty() ||
decodable_frames_.Front()->GetState() != kStateComplete) {
return nullptr;
}
return decodable_frames_.Front();
}
VCMEncodedFrame* VCMJitterBuffer::ExtractAndSetDecode(uint32_t timestamp) {
MutexLock lock(&mutex_);
if (!running_) {
return NULL;
}
// Extract the frame with the desired timestamp.
VCMFrameBuffer* frame = decodable_frames_.PopFrame(timestamp);
bool continuous = true;
if (!frame) {
frame = incomplete_frames_.PopFrame(timestamp);
if (frame)
continuous = last_decoded_state_.ContinuousFrame(frame);
else
return NULL;
}
// Frame pulled out from jitter buffer, update the jitter estimate.
const bool retransmitted = (frame->GetNackCount() > 0);
if (retransmitted) {
jitter_estimate_.FrameNacked();
} else if (frame->size() > 0) {
// Ignore retransmitted and empty frames.
if (waiting_for_completion_.latest_packet_time >= 0) {
UpdateJitterEstimate(waiting_for_completion_, true);
}
if (frame->GetState() == kStateComplete) {
UpdateJitterEstimate(*frame, false);
} else {
// Wait for this one to get complete.
waiting_for_completion_.frame_size = frame->size();
waiting_for_completion_.latest_packet_time = frame->LatestPacketTimeMs();
waiting_for_completion_.timestamp = frame->RtpTimestamp();
}
}
// The state must be changed to decoding before cleaning up zero sized
// frames to avoid empty frames being cleaned up and then given to the
// decoder. Propagates the missing_frame bit.
frame->PrepareForDecode(continuous);
// We have a frame - update the last decoded state and nack list.
last_decoded_state_.SetState(frame);
DropPacketsFromNackList(last_decoded_state_.sequence_num());
UpdateAveragePacketsPerFrame(frame->NumPackets());
return frame;
}
// Release frame when done with decoding. Should never be used to release
// frames from within the jitter buffer.
void VCMJitterBuffer::ReleaseFrame(VCMEncodedFrame* frame) {
RTC_CHECK(frame != nullptr);
MutexLock lock(&mutex_);
VCMFrameBuffer* frame_buffer = static_cast<VCMFrameBuffer*>(frame);
RecycleFrameBuffer(frame_buffer);
}
// Gets frame to use for this timestamp. If no match, get empty frame.
VCMFrameBufferEnum VCMJitterBuffer::GetFrame(const VCMPacket& packet,
VCMFrameBuffer** frame,
FrameList** frame_list) {
*frame = incomplete_frames_.PopFrame(packet.timestamp);
if (*frame != NULL) {
*frame_list = &incomplete_frames_;
return kNoError;
}
*frame = decodable_frames_.PopFrame(packet.timestamp);
if (*frame != NULL) {
*frame_list = &decodable_frames_;
return kNoError;
}
*frame_list = NULL;
// No match, return empty frame.
*frame = GetEmptyFrame();
if (*frame == NULL) {
// No free frame! Try to reclaim some...
RTC_LOG(LS_WARNING) << "Unable to get empty frame; Recycling.";
bool found_key_frame = RecycleFramesUntilKeyFrame();
*frame = GetEmptyFrame();
RTC_CHECK(*frame);
if (!found_key_frame) {
RecycleFrameBuffer(*frame);
return kFlushIndicator;
}
}
(*frame)->Reset();
return kNoError;
}
int64_t VCMJitterBuffer::LastPacketTime(const VCMEncodedFrame* frame,
bool* retransmitted) const {
RTC_DCHECK(retransmitted);
MutexLock lock(&mutex_);
const VCMFrameBuffer* frame_buffer =
static_cast<const VCMFrameBuffer*>(frame);
*retransmitted = (frame_buffer->GetNackCount() > 0);
return frame_buffer->LatestPacketTimeMs();
}
VCMFrameBufferEnum VCMJitterBuffer::InsertPacket(const VCMPacket& packet,
bool* retransmitted) {
MutexLock lock(&mutex_);
++num_packets_;
// Does this packet belong to an old frame?
if (last_decoded_state_.IsOldPacket(&packet)) {
// Account only for media packets.
if (packet.sizeBytes > 0) {
num_consecutive_old_packets_++;
}
// Update last decoded sequence number if the packet arrived late and
// belongs to a frame with a timestamp equal to the last decoded
// timestamp.
last_decoded_state_.UpdateOldPacket(&packet);
DropPacketsFromNackList(last_decoded_state_.sequence_num());
// Also see if this old packet made more incomplete frames continuous.
FindAndInsertContinuousFramesWithState(last_decoded_state_);
if (num_consecutive_old_packets_ > kMaxConsecutiveOldPackets) {
RTC_LOG(LS_WARNING)
<< num_consecutive_old_packets_
<< " consecutive old packets received. Flushing the jitter buffer.";
FlushInternal();
return kFlushIndicator;
}
return kOldPacket;
}
num_consecutive_old_packets_ = 0;
VCMFrameBuffer* frame;
FrameList* frame_list;
const VCMFrameBufferEnum error = GetFrame(packet, &frame, &frame_list);
if (error != kNoError)
return error;
Timestamp now = clock_->CurrentTime();
// We are keeping track of the first and latest seq numbers, and
// the number of wraps to be able to calculate how many packets we expect.
if (first_packet_since_reset_) {
// Now it's time to start estimating jitter
// reset the delay estimate.
inter_frame_delay_.Reset();
}
// Empty packets may bias the jitter estimate (lacking size component),
// therefore don't let empty packet trigger the following updates:
if (packet.video_header.frame_type != VideoFrameType::kEmptyFrame) {
if (waiting_for_completion_.timestamp == packet.timestamp) {
// This can get bad if we have a lot of duplicate packets,
// we will then count some packet multiple times.
waiting_for_completion_.frame_size += packet.sizeBytes;
waiting_for_completion_.latest_packet_time = now.ms();
} else if (waiting_for_completion_.latest_packet_time >= 0 &&
waiting_for_completion_.latest_packet_time + 2000 <= now.ms()) {
// A packet should never be more than two seconds late
UpdateJitterEstimate(waiting_for_completion_, true);
waiting_for_completion_.latest_packet_time = -1;
waiting_for_completion_.frame_size = 0;
waiting_for_completion_.timestamp = 0;
}
}
VCMFrameBufferStateEnum previous_state = frame->GetState();
// Insert packet.
FrameData frame_data;
frame_data.rtt_ms = kDefaultRtt;
frame_data.rolling_average_packets_per_frame = average_packets_per_frame_;
VCMFrameBufferEnum buffer_state =
frame->InsertPacket(packet, now.ms(), frame_data);
if (buffer_state > 0) {
if (first_packet_since_reset_) {
latest_received_sequence_number_ = packet.seqNum;
first_packet_since_reset_ = false;
} else {
if (IsPacketRetransmitted(packet)) {
frame->IncrementNackCount();
}
if (!UpdateNackList(packet.seqNum) &&
packet.video_header.frame_type != VideoFrameType::kVideoFrameKey) {
buffer_state = kFlushIndicator;
}
latest_received_sequence_number_ =
LatestSequenceNumber(latest_received_sequence_number_, packet.seqNum);
}
}
// Is the frame already in the decodable list?
bool continuous = IsContinuous(*frame);
switch (buffer_state) {
case kGeneralError:
case kTimeStampError:
case kSizeError: {
RecycleFrameBuffer(frame);
break;
}
case kCompleteSession: {
if (previous_state != kStateComplete) {
if (continuous) {
// Signal that we have a complete session.
frame_event_->Set();
}
}
*retransmitted = (frame->GetNackCount() > 0);
if (continuous) {
decodable_frames_.InsertFrame(frame);
FindAndInsertContinuousFrames(*frame);
} else {
incomplete_frames_.InsertFrame(frame);
}
break;
}
case kIncomplete: {
if (frame->GetState() == kStateEmpty &&
last_decoded_state_.UpdateEmptyFrame(frame)) {
RecycleFrameBuffer(frame);
return kNoError;
} else {
incomplete_frames_.InsertFrame(frame);
}
break;
}
case kNoError:
case kOutOfBoundsPacket:
case kDuplicatePacket: {
// Put back the frame where it came from.
if (frame_list != NULL) {
frame_list->InsertFrame(frame);
} else {
RecycleFrameBuffer(frame);
}
++num_duplicated_packets_;
break;
}
case kFlushIndicator:
RecycleFrameBuffer(frame);
return kFlushIndicator;
default:
RTC_DCHECK_NOTREACHED();
}
return buffer_state;
}
bool VCMJitterBuffer::IsContinuousInState(
const VCMFrameBuffer& frame,
const VCMDecodingState& decoding_state) const {
// Is this frame complete and continuous?
return (frame.GetState() == kStateComplete) &&
decoding_state.ContinuousFrame(&frame);
}
bool VCMJitterBuffer::IsContinuous(const VCMFrameBuffer& frame) const {
if (IsContinuousInState(frame, last_decoded_state_)) {
return true;
}
VCMDecodingState decoding_state;
decoding_state.CopyFrom(last_decoded_state_);
for (FrameList::const_iterator it = decodable_frames_.begin();
it != decodable_frames_.end(); ++it) {
VCMFrameBuffer* decodable_frame = it->second;
if (IsNewerTimestamp(decodable_frame->RtpTimestamp(),
frame.RtpTimestamp())) {
break;
}
decoding_state.SetState(decodable_frame);
if (IsContinuousInState(frame, decoding_state)) {
return true;
}
}
return false;
}
void VCMJitterBuffer::FindAndInsertContinuousFrames(
const VCMFrameBuffer& new_frame) {
VCMDecodingState decoding_state;
decoding_state.CopyFrom(last_decoded_state_);
decoding_state.SetState(&new_frame);
FindAndInsertContinuousFramesWithState(decoding_state);
}
void VCMJitterBuffer::FindAndInsertContinuousFramesWithState(
const VCMDecodingState& original_decoded_state) {
// Copy original_decoded_state so we can move the state forward with each
// decodable frame we find.
VCMDecodingState decoding_state;
decoding_state.CopyFrom(original_decoded_state);
// When temporal layers are available, we search for a complete or decodable
// frame until we hit one of the following:
// 1. Continuous base or sync layer.
// 2. The end of the list was reached.
for (FrameList::iterator it = incomplete_frames_.begin();
it != incomplete_frames_.end();) {
VCMFrameBuffer* frame = it->second;
if (IsNewerTimestamp(original_decoded_state.time_stamp(),
frame->RtpTimestamp())) {
++it;
continue;
}
if (IsContinuousInState(*frame, decoding_state)) {
decodable_frames_.InsertFrame(frame);
incomplete_frames_.erase(it++);
decoding_state.SetState(frame);
} else if (frame->TemporalId() <= 0) {
break;
} else {
++it;
}
}
}
uint32_t VCMJitterBuffer::EstimatedJitterMs() {
MutexLock lock(&mutex_);
const double rtt_mult = 1.0f;
return jitter_estimate_.GetJitterEstimate(rtt_mult, std::nullopt).ms();
}
void VCMJitterBuffer::SetNackSettings(size_t max_nack_list_size,
int max_packet_age_to_nack,
int max_incomplete_time_ms) {
MutexLock lock(&mutex_);
RTC_DCHECK_GE(max_packet_age_to_nack, 0);
RTC_DCHECK_GE(max_incomplete_time_ms_, 0);
max_nack_list_size_ = max_nack_list_size;
max_packet_age_to_nack_ = max_packet_age_to_nack;
max_incomplete_time_ms_ = max_incomplete_time_ms;
}
int VCMJitterBuffer::NonContinuousOrIncompleteDuration() {
if (incomplete_frames_.empty()) {
return 0;
}
uint32_t start_timestamp = incomplete_frames_.Front()->RtpTimestamp();
if (!decodable_frames_.empty()) {
start_timestamp = decodable_frames_.Back()->RtpTimestamp();
}
return incomplete_frames_.Back()->RtpTimestamp() - start_timestamp;
}
uint16_t VCMJitterBuffer::EstimatedLowSequenceNumber(
const VCMFrameBuffer& frame) const {
RTC_DCHECK_GE(frame.GetLowSeqNum(), 0);
if (frame.HaveFirstPacket())
return frame.GetLowSeqNum();
// This estimate is not accurate if more than one packet with lower sequence
// number is lost.
return frame.GetLowSeqNum() - 1;
}
std::vector<uint16_t> VCMJitterBuffer::GetNackList(bool* request_key_frame) {
MutexLock lock(&mutex_);
*request_key_frame = false;
if (last_decoded_state_.in_initial_state()) {
VCMFrameBuffer* next_frame = NextFrame();
const bool first_frame_is_key =
next_frame &&
next_frame->FrameType() == VideoFrameType::kVideoFrameKey &&
next_frame->HaveFirstPacket();
if (!first_frame_is_key) {
bool have_non_empty_frame =
decodable_frames_.end() != find_if(decodable_frames_.begin(),
decodable_frames_.end(),
HasNonEmptyState);
if (!have_non_empty_frame) {
have_non_empty_frame =
incomplete_frames_.end() != find_if(incomplete_frames_.begin(),
incomplete_frames_.end(),
HasNonEmptyState);
}
bool found_key_frame = RecycleFramesUntilKeyFrame();
if (!found_key_frame) {
*request_key_frame = have_non_empty_frame;
return std::vector<uint16_t>();
}
}
}
if (TooLargeNackList()) {
*request_key_frame = !HandleTooLargeNackList();
}
if (max_incomplete_time_ms_ > 0) {
int non_continuous_incomplete_duration =
NonContinuousOrIncompleteDuration();
if (non_continuous_incomplete_duration > 90 * max_incomplete_time_ms_) {
RTC_LOG_F(LS_WARNING) << "Too long non-decodable duration: "
<< non_continuous_incomplete_duration << " > "
<< 90 * max_incomplete_time_ms_;
FrameList::reverse_iterator rit = find_if(
incomplete_frames_.rbegin(), incomplete_frames_.rend(), IsKeyFrame);
if (rit == incomplete_frames_.rend()) {
// Request a key frame if we don't have one already.
*request_key_frame = true;
return std::vector<uint16_t>();
} else {
// Skip to the last key frame. If it's incomplete we will start
// NACKing it.
// Note that the estimated low sequence number is correct for VP8
// streams because only the first packet of a key frame is marked.
last_decoded_state_.Reset();
DropPacketsFromNackList(EstimatedLowSequenceNumber(*rit->second));
}
}
}
std::vector<uint16_t> nack_list(missing_sequence_numbers_.begin(),
missing_sequence_numbers_.end());
return nack_list;
}
VCMFrameBuffer* VCMJitterBuffer::NextFrame() const {
if (!decodable_frames_.empty())
return decodable_frames_.Front();
if (!incomplete_frames_.empty())
return incomplete_frames_.Front();
return NULL;
}
bool VCMJitterBuffer::UpdateNackList(uint16_t sequence_number) {
// Make sure we don't add packets which are already too old to be decoded.
if (!last_decoded_state_.in_initial_state()) {
latest_received_sequence_number_ = LatestSequenceNumber(
latest_received_sequence_number_, last_decoded_state_.sequence_num());
}
if (IsNewerSequenceNumber(sequence_number,
latest_received_sequence_number_)) {
// Push any missing sequence numbers to the NACK list.
for (uint16_t i = latest_received_sequence_number_ + 1;
IsNewerSequenceNumber(sequence_number, i); ++i) {
missing_sequence_numbers_.insert(missing_sequence_numbers_.end(), i);
}
if (TooLargeNackList() && !HandleTooLargeNackList()) {
RTC_LOG(LS_WARNING) << "Requesting key frame due to too large NACK list.";
return false;
}
if (MissingTooOldPacket(sequence_number) &&
!HandleTooOldPackets(sequence_number)) {
RTC_LOG(LS_WARNING)
<< "Requesting key frame due to missing too old packets";
return false;
}
} else {
missing_sequence_numbers_.erase(sequence_number);
}
return true;
}
bool VCMJitterBuffer::TooLargeNackList() const {
return missing_sequence_numbers_.size() > max_nack_list_size_;
}
bool VCMJitterBuffer::HandleTooLargeNackList() {
// Recycle frames until the NACK list is small enough. It is likely cheaper to
// request a key frame than to retransmit this many missing packets.
RTC_LOG_F(LS_WARNING) << "NACK list has grown too large: "
<< missing_sequence_numbers_.size() << " > "
<< max_nack_list_size_;
bool key_frame_found = false;
while (TooLargeNackList()) {
key_frame_found = RecycleFramesUntilKeyFrame();
}
return key_frame_found;
}
bool VCMJitterBuffer::MissingTooOldPacket(
uint16_t latest_sequence_number) const {
if (missing_sequence_numbers_.empty()) {
return false;
}
const uint16_t age_of_oldest_missing_packet =
latest_sequence_number - *missing_sequence_numbers_.begin();
// Recycle frames if the NACK list contains too old sequence numbers as
// the packets may have already been dropped by the sender.
return age_of_oldest_missing_packet > max_packet_age_to_nack_;
}
bool VCMJitterBuffer::HandleTooOldPackets(uint16_t latest_sequence_number) {
bool key_frame_found = false;
const uint16_t age_of_oldest_missing_packet =
latest_sequence_number - *missing_sequence_numbers_.begin();
RTC_LOG_F(LS_WARNING) << "NACK list contains too old sequence numbers: "
<< age_of_oldest_missing_packet << " > "
<< max_packet_age_to_nack_;
while (MissingTooOldPacket(latest_sequence_number)) {
key_frame_found = RecycleFramesUntilKeyFrame();
}
return key_frame_found;
}
void VCMJitterBuffer::DropPacketsFromNackList(
uint16_t last_decoded_sequence_number) {
// Erase all sequence numbers from the NACK list which we won't need any
// longer.
missing_sequence_numbers_.erase(
missing_sequence_numbers_.begin(),
missing_sequence_numbers_.upper_bound(last_decoded_sequence_number));
}
VCMFrameBuffer* VCMJitterBuffer::GetEmptyFrame() {
if (free_frames_.empty()) {
if (!TryToIncreaseJitterBufferSize()) {
return NULL;
}
}
VCMFrameBuffer* frame = free_frames_.front();
free_frames_.pop_front();
return frame;
}
bool VCMJitterBuffer::TryToIncreaseJitterBufferSize() {
if (max_number_of_frames_ >= kMaxNumberOfFrames)
return false;
free_frames_.push_back(new VCMFrameBuffer());
++max_number_of_frames_;
return true;
}
// Recycle oldest frames up to a key frame, used if jitter buffer is completely
// full.
bool VCMJitterBuffer::RecycleFramesUntilKeyFrame() {
// First release incomplete frames, and only release decodable frames if there
// are no incomplete ones.
FrameList::iterator key_frame_it;
bool key_frame_found = false;
int dropped_frames = 0;
dropped_frames += incomplete_frames_.RecycleFramesUntilKeyFrame(
&key_frame_it, &free_frames_);
key_frame_found = key_frame_it != incomplete_frames_.end();
if (dropped_frames == 0) {
dropped_frames += decodable_frames_.RecycleFramesUntilKeyFrame(
&key_frame_it, &free_frames_);
key_frame_found = key_frame_it != decodable_frames_.end();
}
if (key_frame_found) {
RTC_LOG(LS_INFO) << "Found key frame while dropping frames.";
// Reset last decoded state to make sure the next frame decoded is a key
// frame, and start NACKing from here.
last_decoded_state_.Reset();
DropPacketsFromNackList(EstimatedLowSequenceNumber(*key_frame_it->second));
} else if (decodable_frames_.empty()) {
// All frames dropped. Reset the decoding state and clear missing sequence
// numbers as we're starting fresh.
last_decoded_state_.Reset();
missing_sequence_numbers_.clear();
}
return key_frame_found;
}
void VCMJitterBuffer::UpdateAveragePacketsPerFrame(int current_number_packets) {
if (frame_counter_ > kFastConvergeThreshold) {
average_packets_per_frame_ =
average_packets_per_frame_ * (1 - kNormalConvergeMultiplier) +
current_number_packets * kNormalConvergeMultiplier;
} else if (frame_counter_ > 0) {
average_packets_per_frame_ =
average_packets_per_frame_ * (1 - kFastConvergeMultiplier) +
current_number_packets * kFastConvergeMultiplier;
frame_counter_++;
} else {
average_packets_per_frame_ = current_number_packets;
frame_counter_++;
}
}
// Must be called under the critical section `mutex_`.
void VCMJitterBuffer::CleanUpOldOrEmptyFrames() {
decodable_frames_.CleanUpOldOrEmptyFrames(&last_decoded_state_,
&free_frames_);
incomplete_frames_.CleanUpOldOrEmptyFrames(&last_decoded_state_,
&free_frames_);
if (!last_decoded_state_.in_initial_state()) {
DropPacketsFromNackList(last_decoded_state_.sequence_num());
}
}
// Must be called from within `mutex_`.
bool VCMJitterBuffer::IsPacketRetransmitted(const VCMPacket& packet) const {
return missing_sequence_numbers_.find(packet.seqNum) !=
missing_sequence_numbers_.end();
}
// Must be called under the critical section `mutex_`. Should never be
// called with retransmitted frames, they must be filtered out before this
// function is called.
void VCMJitterBuffer::UpdateJitterEstimate(const VCMJitterSample& sample,
bool incomplete_frame) {
if (sample.latest_packet_time == -1) {
return;
}
UpdateJitterEstimate(sample.latest_packet_time, sample.timestamp,
sample.frame_size, incomplete_frame);
}
// Must be called under the critical section mutex_. Should never be
// called with retransmitted frames, they must be filtered out before this
// function is called.
void VCMJitterBuffer::UpdateJitterEstimate(const VCMFrameBuffer& frame,
bool incomplete_frame) {
if (frame.LatestPacketTimeMs() == -1) {
return;
}
// No retransmitted frames should be a part of the jitter
// estimate.
UpdateJitterEstimate(frame.LatestPacketTimeMs(), frame.RtpTimestamp(),
frame.size(), incomplete_frame);
}
// Must be called under the critical section `mutex_`. Should never be
// called with retransmitted frames, they must be filtered out before this
// function is called.
void VCMJitterBuffer::UpdateJitterEstimate(int64_t latest_packet_time_ms,
uint32_t timestamp,
unsigned int frame_size,
bool /*incomplete_frame*/) {
if (latest_packet_time_ms == -1) {
return;
}
auto frame_delay = inter_frame_delay_.Calculate(
timestamp, Timestamp::Millis(latest_packet_time_ms));
bool not_reordered = frame_delay.has_value();
// Filter out frames which have been reordered in time by the network
if (not_reordered) {
// Update the jitter estimate with the new samples
jitter_estimate_.UpdateEstimate(*frame_delay, DataSize::Bytes(frame_size));
}
}
void VCMJitterBuffer::RecycleFrameBuffer(VCMFrameBuffer* frame) {
frame->Reset();
free_frames_.push_back(frame);
}
} // namespace webrtc