blob: 5b9580c1275c9d9f5e7dff05b73a958a8379e848 [file] [log] [blame]
/*
* Copyright (c) 2021 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/audio_coding/neteq/relative_arrival_delay_tracker.h"
#include <algorithm>
namespace webrtc {
absl::optional<int> RelativeArrivalDelayTracker::Update(uint32_t timestamp,
int sample_rate_hz) {
if (sample_rate_hz <= 0) {
return absl::nullopt;
}
if (!last_timestamp_) {
// Restart relative delay esimation from this packet.
delay_history_.clear();
packet_iat_stopwatch_ = tick_timer_->GetNewStopwatch();
last_timestamp_ = timestamp;
return absl::nullopt;
}
const int expected_iat_ms =
1000ll * static_cast<int32_t>(timestamp - *last_timestamp_) /
sample_rate_hz;
const int iat_ms = packet_iat_stopwatch_->ElapsedMs();
const int iat_delay_ms = iat_ms - expected_iat_ms;
UpdateDelayHistory(iat_delay_ms, timestamp, sample_rate_hz);
int relative_delay = CalculateRelativePacketArrivalDelay();
packet_iat_stopwatch_ = tick_timer_->GetNewStopwatch();
last_timestamp_ = timestamp;
return relative_delay;
}
void RelativeArrivalDelayTracker::Reset() {
delay_history_.clear();
packet_iat_stopwatch_ = tick_timer_->GetNewStopwatch();
last_timestamp_ = absl::nullopt;
}
void RelativeArrivalDelayTracker::UpdateDelayHistory(int iat_delay_ms,
uint32_t timestamp,
int sample_rate_hz) {
PacketDelay delay;
delay.iat_delay_ms = iat_delay_ms;
delay.timestamp = timestamp;
delay_history_.push_back(delay);
while (static_cast<int32_t>(timestamp - delay_history_.front().timestamp) >
max_history_ms_ * sample_rate_hz / 1000) {
delay_history_.pop_front();
}
}
int RelativeArrivalDelayTracker::CalculateRelativePacketArrivalDelay() const {
// This effectively calculates arrival delay of a packet relative to the
// packet preceding the history window. If the arrival delay ever becomes
// smaller than zero, it means the reference packet is invalid, and we
// move the reference.
int relative_delay = 0;
for (const PacketDelay& delay : delay_history_) {
relative_delay += delay.iat_delay_ms;
relative_delay = std::max(relative_delay, 0);
}
return relative_delay;
}
} // namespace webrtc