ROHC compression context for the RTP profile. More...

#include "c_generic.h"
#include "ts_sc_comp.h"
#include "protocols/udp.h"
#include "protocols/rtp.h"

Include dependency graph for c_rtp.h:

This graph shows which files directly or indirectly include this file:

Data Structures
struct	rtp_tmp_vars
	Define the RTP and UDP specific temporary variables in the profile compression context. More...
struct	sc_rtp_context
	Define the RTP part of the profile decompression context. More...
Functions
int	c_rtp_create (struct c_context const context, const struct ip_packet ip)
	Create a new RTP context and initialize it thanks to the given IP/UDP/RTP packet.
void	c_rtp_destroy (struct c_context *const context)
	Destroy the RTP context.
int	c_rtp_check_context (const struct c_context context, const struct ip_packet ip)
	Check if the IP/UDP/RTP packet belongs to the context.
int	c_rtp_encode (struct c_context const context, const struct ip_packet ip, const int packet_size, unsigned char const dest, const int dest_size, rohc_packet_t const packet_type, int *const payload_offset)
	Encode an IP/UDP/RTP packet according to a pattern decided by several different factors.
void	rtp_decide_state (struct c_context *const context)
	Decide the state that should be used for the next packet compressed with the ROHC RTP profile.
int	rtp_code_uo_remainder (struct c_context context, const unsigned char next_header, unsigned char *dest, int counter)

Detailed Description

ROHC compression context for the RTP profile.

Author:: David Moreau from TAS; Didier Barvaux <didier.barvaux@toulouse.viveris.com>

Function Documentation

int c_rtp_check_context	(	const struct c_context *	context,
		const struct ip_packet *	ip
	)

Check if the IP/UDP/RTP packet belongs to the context.

Conditions are:

the number of IP headers must be the same as in context
IP version of the two IP headers must be the same as in context
IP packets must not be fragmented
the source and destination addresses of the two IP headers must match the ones in the context
the transport protocol must be UDP
the source and destination ports of the UDP header must match the ones in the context
IPv6 only: the Flow Label of the two IP headers must match the ones the context
the SSRC field of the RTP header must match the one in the context

All the context but the last one are done by the c_udp_check_context() function.

This function is one of the functions that must exist in one profile for the framework to work.

Parameters:

context	The compression context
ip	The IP/UDP/RTP packet to check

Returns:: 1 if the IP/UDP/RTP packet belongs to the context, 0 if it does not belong to the context and -1 if an error occurs

See also:: c_udp_check_context

References c_udp_check_context(), ip_get_inner_packet(), ip_get_next_layer(), ip_get_protocol(), sc_rtp_context::old_rtp, rohc_debugf, ROHC_IPPROTO_IPIP, ROHC_IPPROTO_IPV6, c_context::specific, c_generic_context::specific, and rtphdr::ssrc.

int c_rtp_create	(	struct c_context *const	context,
		const struct ip_packet *	ip
	)

Create a new RTP context and initialize it thanks to the given IP/UDP/RTP packet.

This function is one of the functions that must exist in one profile for the framework to work.

Parameters:

context	The compression context
ip	The IP/UDP/RTP packet given to initialize the new context

Returns:: 1 if successful, 0 otherwise

void c_rtp_destroy ( struct c_context *const context )

Destroy the RTP context.

This function is one of the functions that must exist in one profile for the framework to work.

Parameters:

context The RTP compression context to destroy

References c_destroy_sc(), c_generic_destroy(), c_context::specific, c_generic_context::specific, and sc_rtp_context::ts_sc.

int c_rtp_encode	(	struct c_context *const	context,
		const struct ip_packet *	ip,
		const int	packet_size,
		unsigned char *const	dest,
		const int	dest_size,
		rohc_packet_t *const	packet_type,
		int *const	payload_offset
	)

Encode an IP/UDP/RTP packet according to a pattern decided by several different factors.

Parameters:

context	The compression context
ip	The IP packet to encode
packet_size	The length of the IP packet to encode
dest	The rohc-packet-under-build buffer
dest_size	The length of the rohc-packet-under-build buffer
packet_type	OUT: The type of ROHC packet that is created
payload_offset	The offset for the payload in the IP packet

Returns:: The length of the created ROHC packet

References c_generic_encode(), ip_get_inner_packet(), ip_get_next_layer(), ip_get_protocol(), sc_rtp_context::old_rtp, sc_rtp_context::old_udp, PACKET_IR, PACKET_IR_DYN, generic_tmp_vars::packet_type, rohc_debugf, ROHC_IPPROTO_IPIP, ROHC_IPPROTO_IPV6, ROHC_IPPROTO_UDP, rtp_changed_rtp_dynamic(), rtp_tmp_vars::send_rtp_dynamic, c_context::specific, c_generic_context::specific, sc_rtp_context::tmp, and c_generic_context::tmp.

int rtp_code_uo_remainder	(	struct c_context *	context,
		const unsigned char *	next_header,
		unsigned char *	dest,
		int	counter
	)

void rtp_decide_state ( struct c_context *const context )

Decide the state that should be used for the next packet compressed with the ROHC RTP profile.

The three states are:

Initialization and Refresh (IR),
First Order (FO),
Second Order (SO).

Parameters:

context The compression context

References change_state(), decide_state(), FO, INIT_TS, IR, MAX_IR_COUNT, rohc_debugf, rtp_tmp_vars::send_rtp_dynamic, c_context::specific, c_generic_context::specific, ts_sc_comp::state, c_context::state, sc_rtp_context::tmp, sc_rtp_context::ts_sc, and sc_rtp_context::udp_checksum_change_count.

Referenced by c_rtp_create().

Data Structures

Functions

Detailed Description

Function Documentation