owntone-server/src/outputs/rtp_common.h

#ifndef __RTP_COMMON_H__
#define __RTP_COMMON_H__

#include <stdint.h>
#include <inttypes.h>
#include <stdbool.h>

struct rtcp_timestamp
{
  uint32_t pos;
  struct timespec ts;
};

struct rtp_packet
{
  uint16_t seqnum;     // Sequence number
  int samples;         // Number of samples in the packet

  uint8_t *header;     // Pointer to the RTP header

  uint8_t *payload;    // Pointer to the RTP payload
  size_t payload_size; // Size of allocated memory for RTP payload
  size_t payload_len;  // Length of payload (must of course not exceed size)

  uint8_t *data;       // Pointer to the complete packet data
  size_t data_size;    // Size of packet data
  size_t data_len;     // Length of actual packet data
};

// An RTP session is characterised by all the receivers belonging to the session
// getting the same RTP and RTCP packets. So if you have clients that require
// different sample rates or where only some can accept encrypted payloads then
// you need multiple sessions.
struct rtp_session
{
  uint32_t ssrc_id;
  uint32_t pos;
  uint16_t seqnum;

  // True if we haven't started streaming yet
  bool is_virgin;

  struct media_quality quality;

  // Packet buffer (ring buffer), used for retransmission
  struct rtp_packet *pktbuf;
  size_t pktbuf_next;
  size_t pktbuf_size;
  size_t pktbuf_len;

  // Time of playback start (given by player)
  struct timespec start_time;

  // Number of seconds that we tell the client to buffer (this will mean that
  // the position that we send in the sync packages are offset by this amount
  // compared to the rtptimes of the corresponding RTP packages we are sending)
  int buffer_duration;

  // Number of samples to elapse before sync'ing. If 0 we set it to the s/r, so
  // we sync once a second. If negative we won't sync.
  int sync_each_nsamples;
  int sync_counter;
  struct rtp_packet sync_packet_next;

  struct rtcp_timestamp sync_last_check;
};


struct rtp_session *
rtp_session_new(struct media_quality *quality, int pktbuf_size, int sync_each_nsamples, int buffer_duration);

void
rtp_session_free(struct rtp_session *session);

void
rtp_session_restart(struct rtp_session *session, struct timespec *ts);

struct rtp_packet *
rtp_packet_next(struct rtp_session *session, size_t payload_len, int samples);

void
rtp_packet_commit(struct rtp_session *session, struct rtp_packet *pkt);

struct rtp_packet *
rtp_packet_get(struct rtp_session *session, uint16_t seqnum);

bool
rtp_sync_check(struct rtp_session *session, struct rtp_packet *pkt);

struct rtp_packet *
rtp_sync_packet_next(struct rtp_session *session);

#endif  /* !__RTP_COMMON_H__ */