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/*
* Copyright (c) 2013 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/remote_bitrate_estimator/inter_arrival.h"
#include "modules/include/module_common_types_public.h"
#include "rtc_base/logging.h"
namespace webrtc {
static const int kBurstDeltaThresholdMs = 5;
static const int kMaxBurstDurationMs = 100;
InterArrival::InterArrival(uint32_t timestamp_group_length_ticks,
double timestamp_to_ms_coeff)
: kTimestampGroupLengthTicks(timestamp_group_length_ticks),
current_timestamp_group_(),
prev_timestamp_group_(),
timestamp_to_ms_coeff_(timestamp_to_ms_coeff),
num_consecutive_reordered_packets_(0) {}
bool InterArrival::ComputeDeltas(uint32_t timestamp,
int64_t arrival_time_ms,
int64_t system_time_ms,
size_t packet_size,
uint32_t* timestamp_delta,
int64_t* arrival_time_delta_ms,
int* packet_size_delta) {
RTC_DCHECK(timestamp_delta);
RTC_DCHECK(arrival_time_delta_ms);
RTC_DCHECK(packet_size_delta);
bool calculated_deltas = false;
if (current_timestamp_group_.IsFirstPacket()) {
// We don't have enough data to update the filter, so we store it until we
// have two frames of data to process.
current_timestamp_group_.timestamp = timestamp;
current_timestamp_group_.first_timestamp = timestamp;
current_timestamp_group_.first_arrival_ms = arrival_time_ms;
} else if (!PacketInOrder(timestamp)) {
return false;
} else if (NewTimestampGroup(arrival_time_ms, timestamp)) {
// First packet of a later frame, the previous frame sample is ready.
if (prev_timestamp_group_.complete_time_ms >= 0) {
*timestamp_delta =
current_timestamp_group_.timestamp - prev_timestamp_group_.timestamp;
*arrival_time_delta_ms = current_timestamp_group_.complete_time_ms -
prev_timestamp_group_.complete_time_ms;
// Check system time differences to see if we have an unproportional jump
// in arrival time. In that case reset the inter-arrival computations.
int64_t system_time_delta_ms =
current_timestamp_group_.last_system_time_ms -
prev_timestamp_group_.last_system_time_ms;
if (*arrival_time_delta_ms - system_time_delta_ms >=
kArrivalTimeOffsetThresholdMs) {
RTC_LOG(LS_WARNING)
<< "The arrival time clock offset has changed (diff = "
<< *arrival_time_delta_ms - system_time_delta_ms
<< " ms), resetting.";
Reset();
return false;
}
if (*arrival_time_delta_ms < 0) {
// The group of packets has been reordered since receiving its local
// arrival timestamp.
++num_consecutive_reordered_packets_;
if (num_consecutive_reordered_packets_ >= kReorderedResetThreshold) {
RTC_LOG(LS_WARNING)
<< "Packets are being reordered on the path from the "
"socket to the bandwidth estimator. Ignoring this "
"packet for bandwidth estimation, resetting.";
Reset();
}
return false;
} else {
num_consecutive_reordered_packets_ = 0;
}
RTC_DCHECK_GE(*arrival_time_delta_ms, 0);
*packet_size_delta = static_cast<int>(current_timestamp_group_.size) -
static_cast<int>(prev_timestamp_group_.size);
calculated_deltas = true;
}
prev_timestamp_group_ = current_timestamp_group_;
// The new timestamp is now the current frame.
current_timestamp_group_.first_timestamp = timestamp;
current_timestamp_group_.timestamp = timestamp;
current_timestamp_group_.first_arrival_ms = arrival_time_ms;
current_timestamp_group_.size = 0;
} else {
current_timestamp_group_.timestamp =
LatestTimestamp(current_timestamp_group_.timestamp, timestamp);
}
// Accumulate the frame size.
current_timestamp_group_.size += packet_size;
current_timestamp_group_.complete_time_ms = arrival_time_ms;
current_timestamp_group_.last_system_time_ms = system_time_ms;
return calculated_deltas;
}
bool InterArrival::PacketInOrder(uint32_t timestamp) {
if (current_timestamp_group_.IsFirstPacket()) {
return true;
} else {
// Assume that a diff which is bigger than half the timestamp interval
// (32 bits) must be due to reordering. This code is almost identical to
// that in IsNewerTimestamp() in module_common_types.h.
uint32_t timestamp_diff =
timestamp - current_timestamp_group_.first_timestamp;
return timestamp_diff < 0x80000000;
}
}
// Assumes that `timestamp` is not reordered compared to
// `current_timestamp_group_`.
bool InterArrival::NewTimestampGroup(int64_t arrival_time_ms,
uint32_t timestamp) const {
if (current_timestamp_group_.IsFirstPacket()) {
return false;
} else if (BelongsToBurst(arrival_time_ms, timestamp)) {
return false;
} else {
uint32_t timestamp_diff =
timestamp - current_timestamp_group_.first_timestamp;
return timestamp_diff > kTimestampGroupLengthTicks;
}
}
bool InterArrival::BelongsToBurst(int64_t arrival_time_ms,
uint32_t timestamp) const {
RTC_DCHECK_GE(current_timestamp_group_.complete_time_ms, 0);
int64_t arrival_time_delta_ms =
arrival_time_ms - current_timestamp_group_.complete_time_ms;
uint32_t timestamp_diff = timestamp - current_timestamp_group_.timestamp;
int64_t ts_delta_ms = timestamp_to_ms_coeff_ * timestamp_diff + 0.5;
if (ts_delta_ms == 0)
return true;
int propagation_delta_ms = arrival_time_delta_ms - ts_delta_ms;
if (propagation_delta_ms < 0 &&
arrival_time_delta_ms <= kBurstDeltaThresholdMs &&
arrival_time_ms - current_timestamp_group_.first_arrival_ms <
kMaxBurstDurationMs)
return true;
return false;
}
void InterArrival::Reset() {
num_consecutive_reordered_packets_ = 0;
current_timestamp_group_ = TimestampGroup();
prev_timestamp_group_ = TimestampGroup();
}
} // namespace webrtc
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