srs/trunk/3rdparty/srt-1-fit/srtcore/buffer_tools.h

/*
 * SRT - Secure, Reliable, Transport
 * Copyright (c) 2018 Haivision Systems Inc.
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 *
 */

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  following disclaimer.

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  and/or other materials provided with the distribution.

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/*****************************************************************************
written by
   Yunhong Gu, last updated 05/05/2009
modified by
   Haivision Systems Inc.
*****************************************************************************/

#ifndef INC_SRT_BUFFER_TOOLS_H
#define INC_SRT_BUFFER_TOOLS_H

#include "common.h"

namespace srt
{

/// The AvgBufSize class is used to calculate moving average of the buffer (RCV or SND)
class AvgBufSize
{
    typedef sync::steady_clock::time_point time_point;

public:
    AvgBufSize()
        : m_dBytesCountMAvg(0.0)
        , m_dCountMAvg(0.0)
        , m_dTimespanMAvg(0.0)
    {
    }

public:
    bool isTimeToUpdate(const time_point& now) const;
    void update(const time_point& now, int pkts, int bytes, int timespan_ms);

public:
    inline double pkts() const { return m_dCountMAvg; }
    inline double timespan_ms() const { return m_dTimespanMAvg; }
    inline double bytes() const { return m_dBytesCountMAvg; }

private:
    time_point m_tsLastSamplingTime;
    double     m_dBytesCountMAvg;
    double     m_dCountMAvg;
    double     m_dTimespanMAvg;
};

/// The class to estimate source bitrate based on samples submitted to the buffer.
/// Is currently only used by the CSndBuffer.
class CRateEstimator
{
    typedef sync::steady_clock::time_point time_point;
    typedef sync::steady_clock::duration   duration;
public:
    CRateEstimator();

public:
    uint64_t getInRatePeriod() const { return m_InRatePeriod; }

    /// Retrieve input bitrate in bytes per second
    int getInputRate() const { return m_iInRateBps; }

    void setInputRateSmpPeriod(int period);

    /// Update input rate calculation.
    /// @param [in] time   current time
    /// @param [in] pkts   number of packets newly added to the buffer
    /// @param [in] bytes  number of payload bytes in those newly added packets
    void updateInputRate(const time_point& time, int pkts = 0, int bytes = 0);

    void resetInputRateSmpPeriod(bool disable = false) { setInputRateSmpPeriod(disable ? 0 : INPUTRATE_FAST_START_US); }

private:                                                       // Constants
    static const uint64_t INPUTRATE_FAST_START_US   = 500000;  //  500 ms
    static const uint64_t INPUTRATE_RUNNING_US      = 1000000; // 1000 ms
    static const int64_t  INPUTRATE_MAX_PACKETS     = 2000;    // ~ 21 Mbps of 1316 bytes payload
    static const int      INPUTRATE_INITIAL_BYTESPS = BW_INFINITE;

private:
    int        m_iInRatePktsCount;  // number of payload packets added since InRateStartTime.
    int        m_iInRateBytesCount; // number of payload bytes added since InRateStartTime.
    time_point m_tsInRateStartTime;
    uint64_t   m_InRatePeriod; // usec
    int        m_iInRateBps;   // Input Rate in Bytes/sec
};


class CSndRateEstimator
{
    typedef sync::steady_clock::time_point time_point;

public:
    CSndRateEstimator(const time_point& tsNow);

    /// Add sample.
    /// @param [in] time   sample (sending) time.
    /// @param [in] pkts   number of packets in the sample.
    /// @param [in] bytes  number of payload bytes in the sample.
    void addSample(const time_point& time, int pkts = 0, size_t bytes = 0);

    /// Retrieve estimated bitrate in bytes per second
    int getRate() const { return m_iRateBps; }

    /// Retrieve estimated bitrate in bytes per second inluding the current sampling interval.
    int getCurrentRate() const;

private:
    static const int NUM_PERIODS        = 10;
    static const int SAMPLE_DURATION_MS = 100; // 100 ms
    struct Sample
    {
        int m_iPktsCount;  // number of payload packets
        int m_iBytesCount; // number of payload bytes

        void reset()
        {
            m_iPktsCount  = 0;
            m_iBytesCount = 0;
        }

        Sample()
            : m_iPktsCount(0)
            , m_iBytesCount(0)
        {
        }

        Sample(int iPkts, int iBytes)
            : m_iPktsCount(iPkts)
            , m_iBytesCount(iBytes)
        {
        }

        Sample operator+(const Sample& other)
        {
            return Sample(m_iPktsCount + other.m_iPktsCount, m_iBytesCount + other.m_iBytesCount);
        }

        Sample& operator+=(const Sample& other)
        {
            *this = *this + other;
            return *this;
        }

        bool empty() const { return m_iPktsCount == 0; }
    };

    int incSampleIdx(int val, int inc = 1) const;

    Sample m_Samples[NUM_PERIODS];

    time_point m_tsFirstSampleTime; //< Start time of the first sameple.
    int        m_iFirstSampleIdx;   //< Index of the first sample.
    int        m_iCurSampleIdx;     //< Index of the current sample being collected.
    int        m_iRateBps;          // Input Rate in Bytes/sec
};

} // namespace srt

#endif