Group PJMEDIA_SDP¶

group PJMEDIA_SDP

SDP data structure representation and parsing.

The basic SDP session descriptor and elements are described in header file <pjmedia/sdp.h>. This file contains declaration for SDP session descriptor and SDP media descriptor, along with their attributes. This file also declares functions to parse SDP message.

Defines

PJMEDIA_MAX_SDP_FMT¶: The PJMEDIA_MAX_SDP_FMT macro defines maximum format in a media line.

PJMEDIA_MAX_SDP_BANDW¶: The PJMEDIA_MAX_SDP_BANDW macro defines maximum bandwidth information lines in a media line.

PJMEDIA_MAX_SDP_ATTR¶: The PJMEDIA_MAX_SDP_ATTR macro defines maximum SDP attributes in media and session descriptor.

PJMEDIA_MAX_SDP_MEDIA¶: The PJMEDIA_MAX_SDP_MEDIA macro defines maximum SDP media lines in a SDP session descriptor.

Functions

pjmedia_sdp_attr *pjmedia_sdp_attr_create(pj_pool_t *pool, const char *name, const pj_str_t *value)¶

Create SDP attribute.

Parameters

pool – Pool to create the attribute.
name – Attribute name.
value – Optional attribute value.

Returns

The new SDP attribute.

pjmedia_sdp_attr *pjmedia_sdp_attr_clone(pj_pool_t *pool, const pjmedia_sdp_attr *attr)¶

Clone attribute

Parameters

pool – Pool to be used.
attr – The attribute to clone.

Returns

New attribute as cloned from the attribute.

pjmedia_sdp_attr *pjmedia_sdp_attr_find(unsigned count, pjmedia_sdp_attr *const attr_array[], const pj_str_t *name, const pj_str_t *fmt)¶

Find the first attribute with the specified type.

See: pjmedia_sdp_attr_find2, pjmedia_sdp_media_find_attr, pjmedia_sdp_media_find_attr2

Parameters

count – Number of attributes in the array.
attr_array – Array of attributes.
name – Attribute name to find.
fmt – Optional string to indicate which payload format to find for rtpmap and fmt attributes. For other types of attributes, the value should be NULL.

Returns

The specified attribute, or NULL if it can’t be found.

pjmedia_sdp_attr *pjmedia_sdp_attr_find2(unsigned count, pjmedia_sdp_attr *const attr_array[], const char *name, const pj_str_t *fmt)¶

Find the first attribute with the specified type.

See: pjmedia_sdp_attr_find, pjmedia_sdp_media_find_attr, pjmedia_sdp_media_find_attr2

Parameters

count – Number of attributes in the array.
attr_array – Array of attributes.
name – Attribute name to find.
fmt – Optional string to indicate which payload format to find for rtpmap and fmt attributes. For other types of attributes, the value should be NULL.

Returns

The specified attribute, or NULL if it can’t be found.

pj_status_t pjmedia_sdp_attr_add(unsigned *count, pjmedia_sdp_attr *attr_array[], pjmedia_sdp_attr *attr)¶

Add a new attribute to array of attributes.

See: pjmedia_sdp_media_add_attr

Parameters

count – Number of attributes in the array.
attr_array – Array of attributes.
attr – The attribute to add.

Returns

PJ_SUCCESS or the error code.

unsigned pjmedia_sdp_attr_remove_all(unsigned *count, pjmedia_sdp_attr *attr_array[], const char *name)¶

Remove all attributes with the specified name in array of attributes.

See: pjmedia_sdp_media_remove_all_attr

Parameters

count – Number of attributes in the array.
attr_array – Array of attributes.
name – Attribute name to find.

Returns

Number of attributes removed.

pj_status_t pjmedia_sdp_attr_remove(unsigned *count, pjmedia_sdp_attr *attr_array[], pjmedia_sdp_attr *attr)¶

Remove the specified attribute from the attribute array.

See: pjmedia_sdp_media_remove_attr

Parameters

count – Number of attributes in the array.
attr_array – Array of attributes.
attr – The attribute instance to remove.

Returns

PJ_SUCCESS when attribute has been removed, or PJ_ENOTFOUND when the attribute can not be found.

pj_status_t pjmedia_sdp_attr_to_rtpmap(pj_pool_t *pool, const pjmedia_sdp_attr *attr, pjmedia_sdp_rtpmap **p_rtpmap)¶

Convert generic attribute to SDP rtpmap. This function allocates a new attribute and call pjmedia_sdp_attr_get_rtpmap().

See: pjmedia_sdp_attr_get_rtpmap

Parameters

pool – Pool used to create the rtpmap attribute.
attr – Generic attribute to be converted to rtpmap, which name must be “rtpmap”.
p_rtpmap – Pointer to receive SDP rtpmap attribute.

Returns

PJ_SUCCESS if the attribute can be successfully converted to rtpmap type.

pj_status_t pjmedia_sdp_attr_get_rtpmap(const pjmedia_sdp_attr *attr, pjmedia_sdp_rtpmap *rtpmap)¶

Get the rtpmap representation of the same SDP attribute.

See: pjmedia_sdp_attr_to_rtpmap

Parameters

attr – Generic attribute to be converted to rtpmap, which name must be “rtpmap”.
rtpmap – SDP rtpmap attribute to be initialized.

Returns

PJ_SUCCESS if the attribute can be successfully converted to rtpmap attribute.

pj_status_t pjmedia_sdp_rtpmap_to_attr(pj_pool_t *pool, const pjmedia_sdp_rtpmap *rtpmap, pjmedia_sdp_attr **p_attr)¶

Convert rtpmap attribute to generic attribute.

Parameters

pool – Pool to be used.
rtpmap – The rtpmap attribute.
p_attr – Pointer to receive the generic SDP attribute.

Returns

PJ_SUCCESS on success.

pj_status_t pjmedia_sdp_attr_get_fmtp(const pjmedia_sdp_attr *attr, pjmedia_sdp_fmtp *fmtp)¶

Get the fmtp representation of the same SDP attribute.

Parameters

attr – Generic attribute to be converted to fmtp, which name must be “fmtp”.
fmtp – SDP fmtp attribute to be initialized.

Returns

PJ_SUCCESS on success.

pj_status_t pjmedia_sdp_attr_get_rtcp(const pjmedia_sdp_attr *attr, pjmedia_sdp_rtcp_attr *rtcp)¶

Parse a generic SDP attribute to get SDP rtcp attribute values.

Parameters

attr – Generic attribute to be converted to rtcp, which name must be “rtcp”.
rtcp – SDP rtcp attribute to be initialized.

Returns

PJ_SUCCESS on success.

pjmedia_sdp_attr *pjmedia_sdp_attr_create_rtcp(pj_pool_t *pool, const pj_sockaddr *a)¶

Create a=rtcp attribute.

Parameters

pool – Pool to create the attribute.
a – Socket address.

Returns

SDP RTCP attribute.

pjmedia_sdp_conn *pjmedia_sdp_conn_clone(pj_pool_t *pool, const pjmedia_sdp_conn *rhs)¶

Clone connection info.

Parameters

pool – Pool to allocate memory for the new connection info.
rhs – The connection into to clone.

Returns

The new connection info.

pjmedia_sdp_bandw *pjmedia_sdp_bandw_clone(pj_pool_t *pool, const pjmedia_sdp_bandw *rhs)¶

Clone bandwidth info.

Parameters

pool – Pool to allocate memory for the new bandwidth info.
rhs – The bandwidth into to clone.

Returns

The new bandwidth info.

pjmedia_sdp_media *pjmedia_sdp_media_clone(pj_pool_t *pool, const pjmedia_sdp_media *rhs)¶

Clone SDP media description.

Parameters

pool – Pool to allocate memory for the new media description.
rhs – The media descriptin to clone.

Returns

New media description.

pjmedia_sdp_attr *pjmedia_sdp_media_find_attr(const pjmedia_sdp_media *m, const pj_str_t *name, const pj_str_t *fmt)¶

Find the first occurence of the specified attribute name in the media descriptor. Optionally the format may be specified.

Parameters

m – The SDP media description.
name – Attribute name to find.
fmt – Optional payload type to match in the attribute list, when the attribute is rtpmap or fmtp. For other types of SDP attributes, this value should be NULL.

Returns

The first instance of the specified attribute or NULL.

pjmedia_sdp_attr *pjmedia_sdp_media_find_attr2(const pjmedia_sdp_media *m, const char *name, const pj_str_t *fmt)¶

Find the first occurence of the specified attribute name in the SDP media descriptor. Optionally the format may be specified.

Parameters

m – The SDP media description.
name – Attribute name to find.
fmt – Optional payload type to match in the attribute list, when the attribute is rtpmap or fmtp. For other types of SDP attributes, this value should be NULL.

Returns

The first instance of the specified attribute or NULL.

pj_status_t pjmedia_sdp_media_add_attr(pjmedia_sdp_media *m, pjmedia_sdp_attr *attr)¶

Add new attribute to the media descriptor.

Parameters

m – The SDP media description.
attr – Attribute to add.

Returns

PJ_SUCCESS or the appropriate error code.

unsigned pjmedia_sdp_media_remove_all_attr(pjmedia_sdp_media *m, const char *name)¶

Remove all attributes with the specified name from the SDP media descriptor.

Parameters

m – The SDP media description.
name – Attribute name to remove.

Returns

The number of attributes removed.

pj_status_t pjmedia_sdp_media_remove_attr(pjmedia_sdp_media *m, pjmedia_sdp_attr *attr)¶

Remove the occurence of the specified attribute from the SDP media descriptor.

Parameters

m – The SDP media descriptor.
attr – The attribute to find and remove.

Returns

PJ_SUCCESS if the attribute can be found and has been removed from the array.

pj_status_t pjmedia_sdp_media_cmp(const pjmedia_sdp_media *sd1, const pjmedia_sdp_media *sd2, unsigned option)¶

Compare two SDP media for equality.

Parameters

sd1 – The first SDP media to compare.
sd2 – The second SDP media to compare.
option – Comparison option, which should be zero for now.

Returns

PJ_SUCCESS when both SDP medias are equal, or the appropriate status code describing which part of the descriptors that are not equal.

pj_status_t pjmedia_sdp_transport_cmp(const pj_str_t *t1, const pj_str_t *t2)¶

Compare two media transports for compatibility.

Parameters

t1 – The first media transport to compare.
t2 – The second media transport to compare.

Returns

PJ_SUCCESS when both media transports are compatible, otherwise returns PJMEDIA_SDP_ETPORTNOTEQUAL.

pj_status_t pjmedia_sdp_media_deactivate(pj_pool_t *pool, pjmedia_sdp_media *m)¶

Deactivate SDP media.

Parameters

pool – Memory pool to allocate memory from.
m – The SDP media to deactivate.

Returns

PJ_SUCCESS when SDP media successfully deactivated, otherwise appropriate status code returned.

pjmedia_sdp_media *pjmedia_sdp_media_clone_deactivate(pj_pool_t *pool, const pjmedia_sdp_media *rhs)¶

Clone SDP media description and deactivate the new SDP media.

Parameters

pool – Memory pool to allocate memory for the clone.
rhs – The SDP media to clone.

Returns

New media descrption with deactivated indication.

pj_status_t pjmedia_sdp_parse(pj_pool_t *pool, char *buf, pj_size_t len, pjmedia_sdp_session **p_sdp)¶

Parse SDP message.

Parameters

pool – The pool to allocate SDP session description.
buf – The message buffer.
len – The length of the message.
p_sdp – Pointer to receive the SDP session descriptor.

Returns

PJ_SUCCESS if message was successfully parsed into SDP session descriptor.

int pjmedia_sdp_print(const pjmedia_sdp_session *sdp, char *buf, pj_size_t size)¶

Print SDP description to a buffer.

Parameters

sdp – The SDP session description.
buf – The buffer.
size – The buffer length.

Returns

the length printed, or -1 if the buffer is too short.

pj_status_t pjmedia_sdp_validate(const pjmedia_sdp_session *sdp)¶

Perform semantic validation for the specified SDP session descriptor. This function perform validation beyond just syntactic verification, such as to verify the value of network type and address type, check the connection line, and verify that rtpmap attribute is present when dynamic payload type is used.

Parameters: sdp – The SDP session descriptor to validate.
Returns: PJ_SUCCESS on success.

pjmedia_sdp_session *pjmedia_sdp_session_clone(pj_pool_t *pool, const pjmedia_sdp_session *sdp)¶

Clone SDP session descriptor.

Parameters

pool – The pool used to clone the session.
sdp – The SDP session to clone.

Returns

New SDP session.

pj_status_t pjmedia_sdp_session_cmp(const pjmedia_sdp_session *sd1, const pjmedia_sdp_session *sd2, unsigned option)¶

Compare two SDP session for equality.

Parameters

sd1 – The first SDP session to compare.
sd2 – The second SDP session to compare.
option – Must be zero for now.

Returns

PJ_SUCCESS when both SDPs are equal, or otherwise the status code indicates which part of the session descriptors are not equal.

pj_status_t pjmedia_sdp_session_add_attr(pjmedia_sdp_session *s, pjmedia_sdp_attr *attr)¶

Add new attribute to the session descriptor.

Parameters

s – The SDP session description.
attr – Attribute to add.

Returns

PJ_SUCCESS or the appropriate error code.

struct pjmedia_sdp_attr¶

#include <sdp.h>

Generic representation of attribute.

See: pjmedia_sdp_attr

struct pjmedia_sdp_rtpmap¶

#include <sdp.h>

This structure declares SDP rtpmap attribute.

See: pjmedia_sdp_rtpmap

struct pjmedia_sdp_fmtp¶

#include <sdp.h>

This structure describes SDP fmtp attribute.

See: pjmedia_sdp_fmtp

struct pjmedia_sdp_rtcp_attr¶: #include <sdp.h>
This structure describes SDP rtcp attribute.

struct pjmedia_sdp_conn¶

#include <sdp.h>

This structure describes SDP connection info (“c=” line).

See: pjmedia_sdp_conn

struct pjmedia_sdp_bandw¶: #include <sdp.h>
This structure describes SDP bandwidth info (“b=” line).

struct pjmedia_sdp_media¶

#include <sdp.h>

This structure describes SDP media descriptor. A SDP media descriptor starts with “m=” line and contains the media attributes and optional connection line.

See: pjmedia_sdp_media

struct pjmedia_sdp_session¶

#include <sdp.h>

This structure describes SDP session description. A SDP session descriptor contains complete information about a session, and normally is exchanged with remote media peer using signaling protocol such as SIP.

See: pjmedia_sdp_session