libdatachannel/include/rtc/rtppacketizationconfig.hpp

/*
 * libdatachannel streamer example
 * Copyright (c) 2020 Filip Klembara (in2core)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; If not, see <http://www.gnu.org/licenses/>.
 */

#ifndef RTPPacketizationConfig_hpp
#define RTPPacketizationConfig_hpp

#if RTC_ENABLE_MEDIA

#include "rtp.hpp"

namespace rtc {

/// RTP configuration used in packetization process
struct RTPPacketizationConfig {
private:
    uint32_t _startTimestamp = 0;
    double _startTime_s = 0;
    RTPPacketizationConfig(const RTPPacketizationConfig&) = delete;
public:
    const SSRC ssrc;
    const std::string cname;
    const uint8_t payloadType;
    const uint32_t clockRate;
    const double & startTime_s = _startTime_s;
    const uint32_t & startTimestamp = _startTimestamp;

    /// current sequence number
    uint16_t sequenceNumber;
    /// current timestamp
    uint32_t timestamp;

    enum class EpochStart: unsigned long long {
        T1970 = 2208988800, // number of seconds between 1970 and 1900
        T1900 = 0
    };

    /// Creates relation between time and timestamp mapping given start time and start timestamp
    /// @param startTime_s Start time of the stream
    /// @param epochStart Type of used epoch
    /// @param startTimestamp Corresponding timestamp for given start time (current timestamp will be used if value is nullopt)
    void setStartTime(double startTime_s, EpochStart epochStart, std::optional<uint32_t> startTimestamp = std::nullopt);


    /// Construct RTP configuration used in packetization process
    /// @param ssrc SSRC of source
    /// @param cname CNAME of source
    /// @param payloadType Payload type of source
    /// @param clockRate Clock rate of source used in timestamps
    /// @param sequenceNumber Initial sequence number of RTP packets (random number is choosed if nullopt)
    /// @param timestamp Initial timastamp of RTP packets (random number is choosed if nullopt)
    RTPPacketizationConfig(SSRC ssrc, std::string cname, uint8_t payloadType, uint32_t clockRate, std::optional<uint16_t> sequenceNumber = std::nullopt, std::optional<uint32_t> timestamp = std::nullopt);

    /// Convert timestamp to seconds
    /// @param timestamp Timestamp
    /// @param clockRate Clock rate for timestamp calculation
    static double getSecondsFromTimestamp(uint32_t timestamp, uint32_t clockRate);

    /// Convert timestamp to seconds
    /// @param timestamp Timestamp
    double timestampToSeconds(uint32_t timestamp);

    /// Convert seconds to timestamp
    /// @param seconds Number of seconds
    /// @param clockRate Clock rate for timestamp calculation
    static uint32_t getTimestampFromSeconds(double seconds, uint32_t clockRate);

    /// Convert seconds to timestamp
    /// @param seconds Number of seconds
    uint32_t secondsToTimestamp(double seconds);
};

} // namespace

#endif /* RTC_ENABLE_MEDIA */

#endif /* RTPPacketizationConfig_hpp */