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Diffstat (limited to 'pjmedia/src/pjmedia/rtp.h')
| -rw-r--r-- | pjmedia/src/pjmedia/rtp.h | 240 |
1 files changed, 240 insertions, 0 deletions
diff --git a/pjmedia/src/pjmedia/rtp.h b/pjmedia/src/pjmedia/rtp.h new file mode 100644 index 00000000..e10b561c --- /dev/null +++ b/pjmedia/src/pjmedia/rtp.h @@ -0,0 +1,240 @@ +/* $Header: /pjproject/pjmedia/src/pjmedia/rtp.h 6 8/24/05 10:30a Bennylp $ */
+
+#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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