mirror of
https://github.com/mollyim/webrtc.git
synced 2025-05-13 05:40:42 +01:00
e4c49e379a
Bug: webrtc:13982 Change-Id: Ib32b374237e19d10b3d36fe981939289c34dd6e8 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/288965 Commit-Queue: Evan Shrubsole <eshr@webrtc.org> Auto-Submit: Evan Shrubsole <eshr@webrtc.org> Commit-Queue: Harald Alvestrand <hta@webrtc.org> Reviewed-by: Harald Alvestrand <hta@webrtc.org> Cr-Commit-Position: refs/heads/main@{#39075}
72 lines
2.4 KiB
C++
72 lines
2.4 KiB
C++
/*
|
|
* 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 <stdint.h>
|
|
|
|
#include <list>
|
|
|
|
#include "absl/types/optional.h"
|
|
#include "rtc_base/checks.h"
|
|
#include "rtc_base/numerics/sequence_number_unwrapper.h"
|
|
#include "system_wrappers/include/ntp_time.h"
|
|
|
|
namespace webrtc {
|
|
|
|
// Converts an RTP timestamp to the NTP domain.
|
|
// 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:
|
|
static constexpr int kMaxInvalidSamples = 3;
|
|
|
|
RtpToNtpEstimator() = default;
|
|
RtpToNtpEstimator(const RtpToNtpEstimator&) = delete;
|
|
RtpToNtpEstimator& operator=(const RtpToNtpEstimator&) = delete;
|
|
~RtpToNtpEstimator() = default;
|
|
|
|
enum UpdateResult { kInvalidMeasurement, kSameMeasurement, kNewMeasurement };
|
|
// Updates measurements with RTP/NTP timestamp pair from a RTCP sender report.
|
|
UpdateResult UpdateMeasurements(NtpTime ntp, uint32_t rtp_timestamp);
|
|
|
|
// Converts an RTP timestamp to the NTP domain.
|
|
// Returns invalid NtpTime (i.e. NtpTime(0)) on failure.
|
|
NtpTime Estimate(uint32_t rtp_timestamp) const;
|
|
|
|
// Returns estimated rtp_timestamp frequency, or 0 on failure.
|
|
double EstimatedFrequencyKhz() const;
|
|
|
|
private:
|
|
// Estimated parameters from RTP and NTP timestamp pairs in `measurements_`.
|
|
// Defines linear estimation: NtpTime (in units of 1s/2^32) =
|
|
// `Parameters::slope` * rtp_timestamp + `Parameters::offset`.
|
|
struct Parameters {
|
|
double slope;
|
|
double offset;
|
|
};
|
|
|
|
// RTP and NTP timestamp pair from a RTCP SR report.
|
|
struct RtcpMeasurement {
|
|
NtpTime ntp_time;
|
|
int64_t unwrapped_rtp_timestamp;
|
|
};
|
|
|
|
void UpdateParameters();
|
|
|
|
int consecutive_invalid_samples_ = 0;
|
|
std::list<RtcpMeasurement> measurements_;
|
|
absl::optional<Parameters> params_;
|
|
mutable RtpTimestampUnwrapper unwrapper_;
|
|
};
|
|
} // namespace webrtc
|
|
|
|
#endif // SYSTEM_WRAPPERS_INCLUDE_RTP_TO_NTP_ESTIMATOR_H_
|