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

#include "c_rtp.h"
#include "c_udp.h"
#include "rohc_traces_internal.h"
#include "rohc_packets.h"
#include "rohc_utils.h"
#include "sdvl.h"
#include "crc.h"
#include <stdlib.h>
#include <string.h>
#include <assert.h>

Include dependency graph for c_rtp.c:

Functions
static bool	c_rtp_create (struct rohc_comp_ctxt const context, const struct rohc_pkt_hdrs const uncomp_pkt_hdrs)
	Create a new RTP context and initialize it thanks to the given IP/UDP/RTP packet. More...

static void	c_rtp_destroy (struct rohc_comp_ctxt *const context)
	Destroy the RTP context. More...

static int	c_rtp_encode (struct rohc_comp_ctxt const context, const struct rohc_pkt_hdrs const uncomp_pkt_hdrs, uint8_t const rohc_pkt, const size_t rohc_pkt_max_len, rohc_packet_t const packet_type)
	Encode an IP/UDP/RTP packet according to a pattern decided by several different factors. More...

static rohc_packet_t	c_rtp_decide_FO_packet (const struct rohc_comp_ctxt *const context)
	Decide which packet to send when in First Order (FO) state. More...

static rohc_packet_t	c_rtp_decide_SO_packet (const struct rohc_comp_ctxt *const context)
	Decide which packet to send when in Second Order (SO) state. More...

static rohc_packet_t	c_rtp_decide_UOR2_pkt (const struct rohc_comp_ctxt *const ctxt, const size_t nr_ipv4_non_rnd, const size_t nr_ipv4_non_rnd_with_bits)
	Decide which UOR2* packet to send. More...

static rohc_ext_t	c_rtp_decide_extension (const struct rohc_comp_ctxt *const context, const rohc_packet_t packet_type)
	Decide what extension shall be used in the UO-1-ID/UOR-2 packet. More...

static uint32_t	c_rtp_get_next_sn (const struct rohc_comp_ctxt const context, const struct rohc_pkt_hdrs const uncomp_pkt_hdrs)
	Determine the SN value for the next packet. More...

static bool	rtp_encode_uncomp_fields (struct rohc_comp_ctxt const context, const struct rohc_pkt_hdrs const uncomp_pkt_hdrs)
	Encode uncompressed RTP fields. More...

static size_t	rtp_code_static_rtp_part (const struct rohc_comp_ctxt const context, const uint8_t const next_header, uint8_t *const dest, const size_t counter)
	Build the static part of the UDP/RTP headers. More...

static size_t	rtp_code_dynamic_rtp_part (const struct rohc_comp_ctxt const context, const uint8_t const next_header, uint8_t *const dest, const size_t counter)
	Build the dynamic part of the UDP/RTP headers. More...

static void	rtp_changed_rtp_dynamic (const struct rohc_comp_ctxt const context, const struct udphdr const udp, const struct rtphdr *const rtp)
	Check if the dynamic part of the UDP/RTP headers changed. More...

Variables
const struct rohc_comp_profile	c_rtp_profile
	Define the compression part of the RTP profile as described in the RFC 3095. More...

Detailed Description

ROHC compression context for the RTP profile.

Author: David Moreau from TAS; Didier Barvaux didie.nosp@m.r.ba.nosp@m.rvaux.nosp@m.@tou.nosp@m.louse.nosp@m..viv.nosp@m.eris..nosp@m.com; Didier Barvaux didie.nosp@m.r@ba.nosp@m.rvaux.nosp@m..org

Function Documentation

◆ c_rtp_create()

static bool c_rtp_create	(	struct rohc_comp_ctxt *const	context,
		const struct rohc_pkt_hdrs *const	uncomp_pkt_hdrs
	)

static

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
uncomp_pkt_hdrs	The uncompressed headers to initialize the new context

Returns: true if successful, false otherwise

◆ c_rtp_decide_extension()

static rohc_ext_t c_rtp_decide_extension	(	const struct rohc_comp_ctxt *const	context,
		const rohc_packet_t	packet_type
	)

static

Decide what extension shall be used in the UO-1-ID/UOR-2 packet.

Extensions 0, 1 & 2 are IPv4 only because of the IP-ID.

Parameters

context	The compression context
packet_type	The type of ROHC packet that is created

Returns: The extension code among ROHC_EXT_NO, ROHC_EXT_0, ROHC_EXT_1 and ROHC_EXT_3 if successful, ROHC_EXT_UNKNOWN otherwise

◆ c_rtp_decide_FO_packet()

static rohc_packet_t c_rtp_decide_FO_packet ( const struct rohc_comp_ctxt *const context )

static

Decide which packet to send when in First Order (FO) state.

Packets that can be used are the IR-DYN and UO-2 packets.

See also: decide_packet

Parameters

context The compression context

Returns

The packet type among:

ROHC_PACKET_UOR_2_RTP
ROHC_PACKET_UOR_2_TS
ROHC_PACKET_UOR_2_ID
ROHC_PACKET_IR_DYN

◆ c_rtp_decide_SO_packet()

static rohc_packet_t c_rtp_decide_SO_packet ( const struct rohc_comp_ctxt *const context )

static

Decide which packet to send when in Second Order (SO) state.

Packets that can be used are the UO-0, UO-1 and UO-2 (with or without extensions) packets.

See also: decide_packet

Parameters

context The compression context

Returns

The packet type among:

ROHC_PACKET_UO_0
ROHC_PACKET_UO_1_RTP
ROHC_PACKET_UO_1_TS
ROHC_PACKET_UO_1_ID
ROHC_PACKET_UOR_2_RTP
ROHC_PACKET_UOR_2_TS
ROHC_PACKET_UOR_2_ID
ROHC_PACKET_IR_DYN

◆ c_rtp_decide_UOR2_pkt()

static rohc_packet_t c_rtp_decide_UOR2_pkt	(	const struct rohc_comp_ctxt *const	ctxt,
		const size_t	nr_ipv4_non_rnd,
		const size_t	nr_ipv4_non_rnd_with_bits
	)

static

Decide which UOR2* packet to send.

See also: decide_packet

Parameters

ctxt	The compression context
nr_ipv4_non_rnd	The nr of IPv4 headers with non-random IP-ID
nr_ipv4_non_rnd_with_bits	The nr of IPv4 headers with non-random IP-ID and some IP-ID bits to transmit

Returns

The packet type among:

ROHC_PACKET_UOR_2_RTP
ROHC_PACKET_UOR_2_TS
ROHC_PACKET_UOR_2_ID

◆ c_rtp_destroy()

static void c_rtp_destroy ( struct rohc_comp_ctxt *const context )

static

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

◆ c_rtp_encode()

static int c_rtp_encode	(	struct rohc_comp_ctxt *const	context,
		const struct rohc_pkt_hdrs *const	uncomp_pkt_hdrs,
		uint8_t *const	rohc_pkt,
		const size_t	rohc_pkt_max_len,
		rohc_packet_t *const	packet_type
	)

static

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

Parameters

context	The compression context
uncomp_pkt_hdrs	The uncompressed headers to encode
rohc_pkt	OUT: The ROHC packet
rohc_pkt_max_len	The maximum length of the ROHC packet
packet_type	OUT: The type of ROHC packet that is created

Returns: The length of the ROHC packet if successful, -1 otherwise

◆ c_rtp_get_next_sn()

static uint32_t c_rtp_get_next_sn	(	const struct rohc_comp_ctxt *const	context,
		const struct rohc_pkt_hdrs *const	uncomp_pkt_hdrs
	)

static

Determine the SN value for the next packet.

Profile SN is the 16-bit RTP SN.

Parameters

context	The compression context
uncomp_pkt_hdrs	The uncompressed headers to encode

Returns: The SN

◆ rtp_changed_rtp_dynamic()

static void rtp_changed_rtp_dynamic	(	const struct rohc_comp_ctxt *const	context,
		const struct udphdr *const	udp,
		const struct rtphdr *const	rtp
	)

static

Check if the dynamic part of the UDP/RTP headers changed.

Parameters

context	The compression context
udp	The UDP header
rtp	The RTP header

◆ rtp_code_dynamic_rtp_part()

static size_t rtp_code_dynamic_rtp_part	(	const struct rohc_comp_ctxt *const	context,
		const uint8_t *const	next_header,
		uint8_t *const	dest,
		const size_t	counter
	)

static

Build the dynamic part of the UDP/RTP headers.

 Dynamic part of UDP header (5.7.7.5):

    +---+---+---+---+---+---+---+---+
 1  /           Checksum            /   2 octets
    +---+---+---+---+---+---+---+---+

 Dynamic part of RTP header (5.7.7.6):

    +---+---+---+---+---+---+---+---+
 2  |  V=2  | P | RX|      CC       |  (RX is NOT the RTP X bit)
    +---+---+---+---+---+---+---+---+
 3  | M |            PT             |
    +---+---+---+---+---+---+---+---+
 4  /      RTP Sequence Number      /  2 octets
    +---+---+---+---+---+---+---+---+
 5  /   RTP Timestamp (absolute)    /  4 octets
    +---+---+---+---+---+---+---+---+
 6  /      Generic CSRC list        /  variable length
    +---+---+---+---+---+---+---+---+
 7  : Reserved  | X |  Mode |TIS|TSS:  if RX = 1
    +---+---+---+---+---+---+---+---+
 8  :         TS_Stride             :  1-4 octets, if TSS = 1
    +---+---+---+---+---+---+---+---+
 9  :         Time_Stride           :  1-4 octets, if TIS = 1
    +---+---+---+---+---+---+---+---+

Parts 6 & 9 are not supported yet. The TIS flag in part 7 is not supported.

Parameters

context	The compression context
next_header	The UDP/RTP headers
dest	The rohc-packet-under-build buffer
counter	The current position in the rohc-packet-under-build buffer

Returns: The new position in the rohc-packet-under-build buffer

◆ rtp_code_static_rtp_part()

static size_t rtp_code_static_rtp_part	(	const struct rohc_comp_ctxt *const	context,
		const uint8_t *const	next_header,
		uint8_t *const	dest,
		const size_t	counter
	)

static

Build the static part of the UDP/RTP headers.

 Static part of UDP header (5.7.7.5):

    +---+---+---+---+---+---+---+---+
 1  /          Source Port          /   2 octets
    +---+---+---+---+---+---+---+---+
 2  /       Destination Port        /   2 octets
    +---+---+---+---+---+---+---+---+

 Static part of RTP header (5.7.7.6):

    +---+---+---+---+---+---+---+---+
 3  /             SSRC              /   4 octets
    +---+---+---+---+---+---+---+---+

Parts 1 & 2 are done by the udp_code_static_udp_part() function. Part 3 is done by this function.

Parameters

context	The compression context
next_header	The UDP/RTP headers
dest	The rohc-packet-under-build buffer
counter	The current position in the rohc-packet-under-build buffer

Returns: The new position in the rohc-packet-under-build buffer

See also: udp_code_static_udp_part

◆ rtp_encode_uncomp_fields()

static bool rtp_encode_uncomp_fields	(	struct rohc_comp_ctxt *const	context,
		const struct rohc_pkt_hdrs *const	uncomp_pkt_hdrs
	)

static

Encode uncompressed RTP fields.

Handle the RTP TS field.

Parameters

context	The compression context
uncomp_pkt_hdrs	The uncompressed headers to encode

Returns: true in case of success, false otherwise

Variable Documentation

◆ c_rtp_profile

const struct rohc_comp_profile c_rtp_profile

Initial value:

=
{
        .id             = ROHC_PROFILE_RTP, 
        .create         = c_rtp_create,     
        .destroy        = c_rtp_destroy,
        .encode         = c_rtp_encode,
        .feedback       = rohc_comp_rfc3095_feedback,
}

Define the compression part of the RTP profile as described in the RFC 3095.

Functions

Variables

Detailed Description

Function Documentation

◆ c_rtp_create()

◆ c_rtp_decide_extension()

◆ c_rtp_decide_FO_packet()

◆ c_rtp_decide_SO_packet()

◆ c_rtp_decide_UOR2_pkt()

◆ c_rtp_destroy()

◆ c_rtp_encode()

◆ c_rtp_get_next_sn()

◆ rtp_changed_rtp_dynamic()

◆ rtp_code_dynamic_rtp_part()

◆ rtp_code_static_rtp_part()

◆ rtp_encode_uncomp_fields()

Variable Documentation

◆ c_rtp_profile