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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.
*/
#ifndef SYSTEM_WRAPPERS_INCLUDE_RTP_TO_NTP_ESTIMATOR_H_
#define SYSTEM_WRAPPERS_INCLUDE_RTP_TO_NTP_ESTIMATOR_H_
#include <list>
#include "api/optional.h"
#include "modules/include/module_common_types_public.h"
#include "rtc_base/numerics/moving_median_filter.h"
#include "system_wrappers/include/ntp_time.h"
#include "typedefs.h" // NOLINT(build/include)
namespace webrtc {
// Class for converting an RTP timestamp to the NTP domain in milliseconds.
// The class needs to be trained with (at least 2) RTP/NTP timestamp pairs from
// RTCP sender reports before the convertion can be done.
class RtpToNtpEstimator {
public:
RtpToNtpEstimator();
~RtpToNtpEstimator();
// RTP and NTP timestamp pair from a RTCP SR report.
struct RtcpMeasurement {
RtcpMeasurement(uint32_t ntp_secs,
uint32_t ntp_frac,
int64_t unwrapped_timestamp);
bool IsEqual(const RtcpMeasurement& other) const;
NtpTime ntp_time;
int64_t unwrapped_rtp_timestamp;
};
// Estimated parameters from RTP and NTP timestamp pairs in |measurements_|.
struct Parameters {
// Implicit conversion from int because MovingMedianFilter returns 0
// internally if no samples are present. However, it should never happen as
// we don't ask smoothing_filter_ to return anything if there were no
// samples.
Parameters(const int& value) { // NOLINT
RTC_NOTREACHED();
}
Parameters() : frequency_khz(0.0), offset_ms(0.0) {}
double frequency_khz;
double offset_ms;
// Needed to make it work inside MovingMedianFilter
bool operator<(const Parameters& other) const;
bool operator==(const Parameters& other) const;
bool operator<=(const Parameters& other) const;
bool operator!=(const Parameters& other) const;
};
// Updates measurements with RTP/NTP timestamp pair from a RTCP sender report.
// |new_rtcp_sr| is set to true if a new report is added.
bool UpdateMeasurements(uint32_t ntp_secs,
uint32_t ntp_frac,
uint32_t rtp_timestamp,
bool* new_rtcp_sr);
// Converts an RTP timestamp to the NTP domain in milliseconds.
// Returns true on success, false otherwise.
bool Estimate(int64_t rtp_timestamp, int64_t* rtp_timestamp_ms) const;
// Returns estimated rtp to ntp linear transform parameters.
const rtc::Optional<Parameters> params() const;
static const int kMaxInvalidSamples = 3;
private:
void UpdateParameters();
int consecutive_invalid_samples_;
std::list<RtcpMeasurement> measurements_;
Parameters params_;
MovingMedianFilter<Parameters> smoothing_filter_;
bool params_calculated_;
mutable TimestampUnwrapper unwrapper_;
const bool is_experiment_enabled_;
};
} // namespace webrtc
#endif // SYSTEM_WRAPPERS_INCLUDE_RTP_TO_NTP_ESTIMATOR_H_
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