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/* $Id$ */
/*
* Copyright (C) 2003-2006 Benny Prijono <benny@prijono.org>
*
* 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, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#ifndef __PJMEDIA_RTP_H__
#define __PJMEDIA_RTP_H__
#include <pj/types.h>
/**
* @file rtp.h
* @brief RTP implementation.
*/
PJ_BEGIN_DECL
/**
* @defgroup PJMED_RTP RTP
* @ingroup PJMEDIA
* @{
*
* The RTP module is designed to be dependent only to PJLIB, it does not depend
* on any other parts of PJMEDIA library. The RTP module does not even depend
* on any transports (sockets), to promote even more use.
*
* An RTCP implementation is also separated from this module.
*
* The functions that are provided by this module:
* - creating RTP header for each outgoing packet.
* - decoding RTP packet into RTP header and payload.
* - provide simple RTP session management (sequence number, etc.)
*
* The RTP module does not use any dynamic memory at all.
*
* \section P1 How to Use the RTP Module
*
* First application must call #pj_rtp_session_init to initialize the RTP
* session.
*
* When application wants to send RTP packet, it needs to call
* #pj_rtp_encode_rtp to build the RTP header. Note that this WILL NOT build
* the complete RTP packet, but instead only the header. Application can
* then either concatenate the header with the payload, or send the two
* fragments (the header and the payload) using scatter-gather transport API
* (e.g. \a sendv()).
*
* When application receives an RTP packet, first it should call
* #pj_rtp_decode_rtp to decode RTP header and payload, then it should call
* #pj_rtp_session_update to check whether we can process the RTP payload,
* and to let the RTP session updates its internal status. The decode function
* is guaranteed to point the payload to the correct position regardless of
* any options present in the RTP packet.
*
*/
#ifdef _MSC_VER
# pragma warning ( disable : 4214 )
#endif
/**
* Error codes.
*/
enum pj_rtp_error_t
{
PJ_RTP_ERR_RTP_PACKING, /**< Invalid RTP packet. */
PJ_RTP_ERR_INVALID_VERSION, /**< Invalid RTP version. */
PJ_RTP_ERR_INVALID_SSRC, /**< Invalid SSRC. */
PJ_RTP_ERR_INVALID_PT, /**< Invalid payload type. */
PJ_RTP_ERR_INVALID_PACKET, /**< Invalid packet. */
PJ_RTP_ERR_SESSION_RESTARTED, /**< Session has just been restarted. */
PJ_RTP_ERR_SESSION_PROBATION, /**< Session in probation. */
PJ_RTP_ERR_BAD_SEQUENCE, /**< Bad RTP sequence number. */
};
#pragma pack(1)
/**
* RTP packet header.
*/
struct pj_rtp_hdr
{
#if defined(PJ_IS_BIG_ENDIAN) && (PJ_IS_BIG_ENDIAN!=0)
pj_uint16_t v:2; /**< packet type/version */
pj_uint16_t p:1; /**< padding flag */
pj_uint16_t x:1; /**< extension flag */
pj_uint16_t cc:4; /**< CSRC count */
pj_uint16_t m:1; /**< marker bit */
pj_uint16_t pt:7; /**< payload type */
#else
pj_uint16_t cc:4; /**< CSRC count */
pj_uint16_t x:1; /**< header extension flag */
pj_uint16_t p:1; /**< padding flag */
pj_uint16_t v:2; /**< packet type/version */
pj_uint16_t pt:7; /**< payload type */
pj_uint16_t m:1; /**< marker bit */
#endif
pj_uint16_t seq; /**< sequence number */
pj_uint32_t ts; /**< timestamp */
pj_uint32_t ssrc; /**< synchronization source */
};
#pragma pack()
typedef struct pj_rtp_hdr pj_rtp_hdr;
/**
* RTP extendsion header.
*/
struct pj_rtp_ext_hdr
{
pj_uint16_t profile_data;
pj_uint16_t length;
};
typedef struct pj_rtp_ext_hdr pj_rtp_ext_hdr;
/**
* A generic sequence number management, used by both RTP and RTCP.
*/
struct pj_rtp_seq_session
{
pj_uint16_t max_seq; /**< highest sequence number heard */
pj_uint32_t cycles; /**< shifted count of seq. number cycles */
pj_uint32_t base_seq; /**< base seq number */
pj_uint32_t bad_seq; /**< last 'bad' seq number + 1 */
pj_uint32_t probation; /**< sequ. packets till source is valid */
};
typedef struct pj_rtp_seq_session pj_rtp_seq_session;
/**
* RTP session descriptor.
*/
struct pj_rtp_session
{
pj_rtp_hdr out_hdr; /**< Saved header for outgoing packets. */
pj_rtp_seq_session seq_ctrl; /**< Sequence number management. */
pj_uint16_t out_pt; /**< Default outgoing payload type. */
pj_uint32_t out_extseq; /**< Outgoing extended sequence number. */
pj_uint32_t peer_ssrc; /**< Peer SSRC. */
pj_uint32_t received; /**< Number of received packets. */
};
typedef struct pj_rtp_session pj_rtp_session;
/**
* \brief Initialize RTP session.
* This function will initialize the RTP session according to given parameters.
*
* @param ses The session.
* @param default_pt Default payload type.
* @param sender_ssrc SSRC used for outgoing packets.
*
* @return zero if successfull.
*/
PJ_DECL(pj_status_t) pj_rtp_session_init( pj_rtp_session *ses,
int default_pt, pj_uint32_t sender_ssrc );
/**
* \brief Encode outgoing RTP packet header.
* Create the RTP header based on arguments and current state of the RTP
* session.
*
* @param ses The session.
* @param pt Payload type.
* @param m Marker flag.
* @param payload_len Payload length in bytes.
* @param ts_len Timestamp length.
* @param rtphdr Upon return will point to RTP packet header.
* @param hdrlen Upon return will indicate the size of RTP packet header
*
* @return zero if successfull.
*/
PJ_DECL(pj_status_t) pj_rtp_encode_rtp( pj_rtp_session *ses, int pt, int m,
int payload_len, int ts_len,
const void **rtphdr, int *hdrlen );
/**
* \brief Decode an incoming RTP packet.
* This function will decode incoming packet into RTP header and payload.
* The decode function is guaranteed to point the payload to the correct
* position regardless of any options present in the RTP packet.
*
* @param ses The session.
* @param pkt The received RTP packet.
* @param pkt_len The length of the packet.
* @param hdr Upon return will point to the location of the RTP header
* inside the packet.
* @param payload Upon return will point to the location of the
* payload inside the packet.
* @param payloadlen Upon return will indicate the size of the payload.
*
* @return zero if successfull.
*/
PJ_DECL(pj_status_t) pj_rtp_decode_rtp( pj_rtp_session *ses,
const void *pkt, int pkt_len,
const pj_rtp_hdr **hdr,
const void **payload,
unsigned *payloadlen);
/**
* \brief Update RTP session with an incoming RTP packet.
* Call this function everytime
* an RTP packet is received to check whether the packet can be received and to
* let the RTP session performs its internal calculations.
*
* @param ses The session.
* @param hdr The RTP header of the incoming packet.
*
* @return zero if the packet is valid and can be processed, otherwise will
* return one of the error in #pj_rtp_error_t.
*/
PJ_DECL(pj_status_t) pj_rtp_session_update( pj_rtp_session *ses,
const pj_rtp_hdr *hdr);
/**
* \brief Internal.
* Internal function for sequence control, shared by RTCP implementation.
*/
void pj_rtp_seq_init(pj_rtp_seq_session *seq_ctrl, pj_uint16_t seq);
/**
* \brief Internal.
* Internal function for sequence control, shared by RTCP implementation.
*/
void pj_rtp_seq_restart(pj_rtp_seq_session *seq_ctrl, pj_uint16_t seq);
/**
* \brief Internal.
* Internal function for sequence control, shared by RTCP implementation.
*/
int pj_rtp_seq_update(pj_rtp_seq_session *seq_ctrl, pj_uint16_t seq);
/**
* @}
*/
PJ_END_DECL
#endif /* __PJMEDIA_RTP_H__ */
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