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
class RTC_CPP_EXPORT RTPPacketizationConfig {
	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 rtc

#endif /* RTC_ENABLE_MEDIA */

#endif /* RTPPacketizationConfig_hpp */