blob: 9d6da051d5027bd8f3a8a0d2a71818d0ac226547 [file] [log] [blame]
* 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 <list>
#include "webrtc/system_wrappers/include/ntp_time.h"
#include "webrtc/typedefs.h"
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 {
// RTP and NTP timestamp pair from a RTCP SR report.
struct RtcpMeasurement {
RtcpMeasurement(uint32_t ntp_secs, uint32_t ntp_frac, uint32_t timestamp);
bool IsEqual(const RtcpMeasurement& other) const;
NtpTime ntp_time;
uint32_t rtp_timestamp;
// Estimated parameters from RTP and NTP timestamp pairs in |measurements_|.
struct Parameters {
double frequency_khz = 0.0;
double offset_ms = 0.0;
bool calculated = false;
// 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;
const Parameters& params() const { return params_; }
static const int kMaxInvalidSamples = 3;
void UpdateParameters();
int consecutive_invalid_samples_;
std::list<RtcpMeasurement> measurements_;
Parameters params_;
// Returns:
// 1: forward wrap around.
// 0: no wrap around.
// -1: backwards wrap around (i.e. reordering).
int CheckForWrapArounds(uint32_t new_timestamp, uint32_t old_timestamp);
} // namespace webrtc