RTS API Documentation: switch_rtp_engine_s Struct Reference

RTS API Documentation 1.10.11

Collaboration diagram for switch_rtp_engine_s:

Data Fields
switch_secure_settings_t	ssec [CRYPTO_INVALID+1]

switch_rtp_crypto_key_type_t	crypto_type

switch_media_type_t	type

switch_rtp_t *	rtp_session

switch_frame_t	read_frame

switch_codec_t	read_codec

switch_codec_t	write_codec

switch_codec_implementation_t	read_impl

switch_codec_implementation_t	write_impl

switch_size_t	last_ts

switch_size_t	last_seq

uint32_t	check_frames

uint32_t	mismatch_count

uint32_t	last_codec_ms

uint8_t	codec_reinvites

uint32_t	max_missed_packets

uint32_t	max_missed_hold_packets

uint32_t	media_timeout

uint32_t	media_hold_timeout

uint32_t	ssrc

uint32_t	remote_ssrc

switch_port_t	remote_rtcp_port

switch_rtp_bug_flag_t	rtp_bugs

char *	local_sdp_ip

switch_port_t	local_sdp_port

char *	adv_sdp_ip

switch_port_t	adv_sdp_port

char *	proxy_sdp_ip

switch_port_t	proxy_sdp_port

payload_map_t *	cur_payload_map

payload_map_t *	payload_map

payload_map_t *	pmap_tail

uint32_t	timestamp_send

char *	cand_acl [SWITCH_MAX_CAND_ACL]

int	cand_acl_count

ice_t	ice_in

ice_t	ice_out

int8_t	rtcp_mux

dtls_fingerprint_t	local_dtls_fingerprint

dtls_fingerprint_t	remote_dtls_fingerprint

char *	remote_rtp_ice_addr

switch_port_t	remote_rtp_ice_port

char *	remote_rtcp_ice_addr

switch_port_t	remote_rtcp_ice_port

struct media_helper	mh

switch_thread_t *	media_thread

uint8_t	reset_codec

uint8_t	codec_negotiated

uint8_t	fir

uint8_t	pli

uint8_t	nack

uint8_t	tmmbr

uint8_t	no_crypto

uint8_t	dtls_controller

uint8_t	pass_codecs

switch_codec_settings_t	codec_settings

switch_media_flow_t	rmode

switch_media_flow_t	smode

switch_thread_id_t	thread_id

switch_thread_id_t	thread_write_lock

uint8_t	new_ice

uint8_t	new_dtls

uint32_t	sdp_bw

uint32_t	orig_bitrate

float	bw_mult

uint8_t	reject_avp

int	t140_pt

int	red_pt

switch_rtp_text_factory_t *	tf

switch_engine_function_t	engine_function

void *	engine_user_data

int8_t	engine_function_running

switch_frame_buffer_t *	write_fb

Detailed Description

Definition at line 114 of file switch_core_media.c.

Field Documentation

◆ adv_sdp_ip

char* switch_rtp_engine_s::adv_sdp_ip

Definition at line 146 of file switch_core_media.c.

Referenced by switch_core_media_activate_rtp(), switch_core_media_choose_port(), switch_core_media_gen_local_sdp(), switch_core_media_patch_sdp(), switch_core_media_recover_session(), and switch_core_media_set_udptl_image_sdp().

◆ adv_sdp_port

switch_port_t switch_rtp_engine_s::adv_sdp_port

Definition at line 147 of file switch_core_media.c.

Referenced by switch_core_media_choose_port(), switch_core_media_gen_local_sdp(), switch_core_media_patch_sdp(), switch_core_media_recover_session(), and switch_core_media_set_udptl_image_sdp().

◆ bw_mult

float switch_rtp_engine_s::bw_mult

Definition at line 198 of file switch_core_media.c.

Referenced by switch_core_media_get_media_bw_mult(), switch_core_media_set_media_bw_mult(), and switch_core_media_set_outgoing_bitrate().

◆ cand_acl

char* switch_rtp_engine_s::cand_acl[SWITCH_MAX_CAND_ACL]

Definition at line 158 of file switch_core_media.c.

Referenced by check_ice(), and switch_core_media_add_ice_acl().

◆ cand_acl_count

int switch_rtp_engine_s::cand_acl_count

Definition at line 159 of file switch_core_media.c.

Referenced by check_ice(), and switch_core_media_add_ice_acl().

◆ check_frames

uint32_t switch_rtp_engine_s::check_frames

Definition at line 130 of file switch_core_media.c.

Referenced by switch_core_media_proxy_remote_addr(), switch_core_media_read_frame(), and switch_core_media_reset_autofix().

◆ codec_negotiated

uint8_t switch_rtp_engine_s::codec_negotiated

Definition at line 180 of file switch_core_media.c.

Referenced by switch_core_media_gen_local_sdp(), switch_core_media_negotiate_sdp(), switch_core_media_patch_sdp(), switch_core_media_read_frame(), switch_core_media_receive_message(), switch_core_media_recover_session(), and switch_core_media_set_video_codec().

◆ codec_reinvites

uint8_t switch_rtp_engine_s::codec_reinvites

Definition at line 133 of file switch_core_media.c.

◆ codec_settings

switch_codec_settings_t switch_rtp_engine_s::codec_settings

Definition at line 189 of file switch_core_media.c.

Referenced by switch_core_media_set_codec(), switch_core_media_set_video_codec(), switch_core_session_parse_codec_settings(), and switch_media_handle_create().

◆ crypto_type

switch_rtp_crypto_key_type_t switch_rtp_engine_s::crypto_type

Definition at line 116 of file switch_core_media.c.

Referenced by generate_m(), switch_core_media_activate_rtp(), switch_core_media_gen_local_sdp(), switch_core_media_recover_session(), switch_core_session_apply_crypto(), switch_core_session_check_incoming_crypto(), switch_core_session_get_recovery_crypto_key(), switch_core_session_local_crypto_key(), and switch_media_handle_create().

◆ cur_payload_map

◆ dtls_controller

uint8_t switch_rtp_engine_s::dtls_controller

Definition at line 187 of file switch_core_media.c.

Referenced by check_dtls_reinvite(), check_ice(), get_setup(), switch_core_media_activate_rtp(), and switch_ice_direction().

◆ engine_function

switch_engine_function_t switch_rtp_engine_s::engine_function

Definition at line 204 of file switch_core_media.c.

Referenced by switch_core_media_start_engine_function(), text_helper_thread(), and video_helper_thread().

◆ engine_function_running

int8_t switch_rtp_engine_s::engine_function_running

Definition at line 206 of file switch_core_media.c.

Referenced by switch_core_media_check_engine_function(), switch_core_media_end_engine_function(), switch_core_media_start_engine_function(), text_helper_thread(), and video_helper_thread().

◆ engine_user_data

void* switch_rtp_engine_s::engine_user_data

Definition at line 205 of file switch_core_media.c.

Referenced by switch_core_media_start_engine_function(), text_helper_thread(), and video_helper_thread().

◆ fir

uint8_t switch_rtp_engine_s::fir

Definition at line 182 of file switch_core_media.c.

Referenced by switch_core_media_activate_rtp(), switch_core_media_gen_local_sdp(), and switch_core_media_negotiate_sdp().

◆ ice_in

ice_t switch_rtp_engine_s::ice_in

Definition at line 161 of file switch_core_media.c.

Referenced by check_ice(), clear_ice(), switch_core_media_activate_rtp(), and switch_core_session_stop_media().

◆ ice_out

ice_t switch_rtp_engine_s::ice_out

Definition at line 162 of file switch_core_media.c.

Referenced by check_ice(), gen_ice(), generate_m(), switch_core_media_activate_rtp(), switch_core_media_gen_local_sdp(), and switch_core_session_stop_media().

◆ last_codec_ms

uint32_t switch_rtp_engine_s::last_codec_ms

Definition at line 132 of file switch_core_media.c.

Referenced by switch_core_media_read_frame().

◆ last_seq

switch_size_t switch_rtp_engine_s::last_seq

Definition at line 129 of file switch_core_media.c.

Referenced by switch_core_media_read_frame(), switch_core_media_receive_message(), and switch_core_media_reset_autofix().

◆ last_ts

switch_size_t switch_rtp_engine_s::last_ts

Definition at line 128 of file switch_core_media.c.

Referenced by switch_core_media_read_frame(), and switch_core_media_reset_autofix().

◆ local_dtls_fingerprint

dtls_fingerprint_t switch_rtp_engine_s::local_dtls_fingerprint

Definition at line 166 of file switch_core_media.c.

Referenced by check_dtls_reinvite(), generate_local_fingerprint(), generate_m(), switch_core_media_activate_rtp(), switch_core_media_gen_local_sdp(), and switch_core_session_stop_media().

◆ local_sdp_ip

char* switch_rtp_engine_s::local_sdp_ip

Definition at line 144 of file switch_core_media.c.

Referenced by generate_m(), switch_core_media_activate_rtp(), switch_core_media_choose_port(), switch_core_media_gen_local_sdp(), switch_core_media_patch_sdp(), and switch_core_media_recover_session().

◆ local_sdp_port

switch_port_t switch_rtp_engine_s::local_sdp_port

Definition at line 145 of file switch_core_media.c.

Referenced by generate_m(), switch_core_media_activate_rtp(), switch_core_media_choose_port(), switch_core_media_deactivate_rtp(), switch_core_media_gen_local_sdp(), switch_core_media_negotiate_sdp(), switch_core_media_patch_sdp(), and switch_core_media_recover_session().

◆ max_missed_hold_packets

uint32_t switch_rtp_engine_s::max_missed_hold_packets

Definition at line 135 of file switch_core_media.c.

Referenced by check_media_timeout_params(), switch_core_media_activate_rtp(), switch_core_media_negotiate_sdp(), switch_core_media_read_frame(), switch_core_media_receive_message(), and switch_core_media_toggle_hold().

◆ max_missed_packets

uint32_t switch_rtp_engine_s::max_missed_packets

Definition at line 134 of file switch_core_media.c.

Referenced by check_media_timeout_params(), switch_core_media_activate_rtp(), switch_core_media_negotiate_sdp(), switch_core_media_read_frame(), switch_core_media_receive_message(), and switch_core_media_toggle_hold().

◆ media_hold_timeout

uint32_t switch_rtp_engine_s::media_hold_timeout

Definition at line 137 of file switch_core_media.c.

Referenced by check_media_timeout_params(), switch_core_media_negotiate_sdp(), switch_core_media_receive_message(), and switch_core_media_toggle_hold().

◆ media_thread

switch_thread_t* switch_rtp_engine_s::media_thread

Definition at line 176 of file switch_core_media.c.

Referenced by switch_core_media_deactivate_rtp(), switch_core_session_start_audio_write_thread(), switch_core_session_start_text_thread(), switch_core_session_start_video_thread(), and switch_core_session_wake_video_thread().

◆ media_timeout

uint32_t switch_rtp_engine_s::media_timeout

Definition at line 136 of file switch_core_media.c.

Referenced by check_media_timeout_params(), switch_core_media_negotiate_sdp(), switch_core_media_receive_message(), and switch_core_media_toggle_hold().

◆ mh

struct media_helper switch_rtp_engine_s::mh

Definition at line 175 of file switch_core_media.c.

Referenced by switch_core_media_deactivate_rtp(), switch_core_media_get_video_file(), switch_core_media_lock_video_file(), switch_core_media_set_video_file(), switch_core_media_unlock_video_file(), switch_core_session_start_audio_write_thread(), switch_core_session_start_text_thread(), switch_core_session_start_video_thread(), switch_core_session_wake_video_thread(), and video_write_thread().

◆ mismatch_count

uint32_t switch_rtp_engine_s::mismatch_count

Definition at line 131 of file switch_core_media.c.

Referenced by switch_core_media_read_frame().

◆ nack

uint8_t switch_rtp_engine_s::nack

Definition at line 184 of file switch_core_media.c.

Referenced by switch_core_media_activate_rtp(), switch_core_media_gen_local_sdp(), and switch_core_media_negotiate_sdp().

◆ new_dtls

uint8_t switch_rtp_engine_s::new_dtls

Definition at line 195 of file switch_core_media.c.

Referenced by check_dtls_reinvite(), check_ice(), get_setup(), and switch_core_media_negotiate_sdp().

◆ new_ice

uint8_t switch_rtp_engine_s::new_ice

Definition at line 194 of file switch_core_media.c.

Referenced by check_ice(), get_setup(), and switch_core_media_negotiate_sdp().

◆ no_crypto

uint8_t switch_rtp_engine_s::no_crypto

Definition at line 186 of file switch_core_media.c.

Referenced by switch_core_media_gen_local_sdp().

◆ orig_bitrate

uint32_t switch_rtp_engine_s::orig_bitrate

Definition at line 197 of file switch_core_media.c.

Referenced by switch_core_media_get_orig_bitrate(), and switch_core_media_set_outgoing_bitrate().

◆ pass_codecs

uint8_t switch_rtp_engine_s::pass_codecs

Definition at line 188 of file switch_core_media.c.

Referenced by switch_core_media_set_rmode(), and switch_core_media_set_smode().

◆ payload_map

payload_map_t* switch_rtp_engine_s::payload_map

Definition at line 153 of file switch_core_media.c.

Referenced by clear_pmaps(), generate_m(), restore_pmaps(), switch_core_media_activate_rtp(), switch_core_media_add_payload_map(), switch_core_media_gen_local_sdp(), switch_core_media_negotiate_sdp(), switch_core_media_read_frame(), switch_core_session_get_payload_code(), and switch_media_handle_create().

◆ pli

uint8_t switch_rtp_engine_s::pli

Definition at line 183 of file switch_core_media.c.

Referenced by switch_core_media_activate_rtp(), switch_core_media_gen_local_sdp(), and switch_core_media_negotiate_sdp().

◆ pmap_tail

payload_map_t* switch_rtp_engine_s::pmap_tail

Definition at line 154 of file switch_core_media.c.

Referenced by switch_core_media_add_payload_map().

◆ proxy_sdp_ip

char* switch_rtp_engine_s::proxy_sdp_ip

Definition at line 148 of file switch_core_media.c.

Referenced by switch_core_media_absorb_sdp(), switch_core_media_gen_local_sdp(), and switch_core_media_set_udptl_image_sdp().

◆ proxy_sdp_port

switch_port_t switch_rtp_engine_s::proxy_sdp_port

Definition at line 149 of file switch_core_media.c.

Referenced by switch_core_media_absorb_sdp(), switch_core_media_gen_local_sdp(), and switch_core_media_set_udptl_image_sdp().

◆ read_codec

switch_codec_t switch_rtp_engine_s::read_codec

Definition at line 122 of file switch_core_media.c.

Referenced by check_jb(), switch_core_media_activate_rtp(), switch_core_media_codec_control(), switch_core_media_gen_local_sdp(), switch_core_media_get_codec(), switch_core_media_negotiate_sdp(), switch_core_media_read_frame(), switch_core_media_read_lock_unlock(), switch_core_media_receive_message(), switch_core_media_set_codec(), switch_core_media_set_video_codec(), switch_core_media_write_frame(), switch_core_session_stop_media(), and switch_media_handle_destroy().

◆ read_frame

switch_frame_t switch_rtp_engine_s::read_frame

Definition at line 121 of file switch_core_media.c.

Referenced by check_engine(), switch_core_media_read_frame(), switch_core_media_set_codec(), switch_core_media_set_video_codec(), and switch_media_handle_create().

◆ read_impl

switch_codec_implementation_t switch_rtp_engine_s::read_impl

Definition at line 125 of file switch_core_media.c.

Referenced by check_jb(), check_media_timeout_params(), switch_core_media_activate_rtp(), switch_core_media_bug_read(), switch_core_media_negotiate_sdp(), switch_core_media_read_frame(), switch_core_media_set_codec(), and switch_core_media_write_frame().

◆ red_pt

int switch_rtp_engine_s::red_pt

Definition at line 201 of file switch_core_media.c.

Referenced by build_red_packet(), switch_core_media_gen_local_sdp(), switch_core_media_read_frame(), and switch_core_session_write_text_frame().

◆ reject_avp

uint8_t switch_rtp_engine_s::reject_avp

Definition at line 199 of file switch_core_media.c.

Referenced by switch_core_media_gen_local_sdp(), and switch_core_media_negotiate_sdp().

◆ remote_dtls_fingerprint

dtls_fingerprint_t switch_rtp_engine_s::remote_dtls_fingerprint

Definition at line 167 of file switch_core_media.c.

Referenced by check_dtls_reinvite(), check_ice(), generate_local_fingerprint(), and switch_core_media_activate_rtp().

◆ remote_rtcp_ice_addr

char* switch_rtp_engine_s::remote_rtcp_ice_addr

Definition at line 172 of file switch_core_media.c.

Referenced by check_ice().

◆ remote_rtcp_ice_port

switch_port_t switch_rtp_engine_s::remote_rtcp_ice_port

Definition at line 173 of file switch_core_media.c.

Referenced by check_ice().

◆ remote_rtcp_port

switch_port_t switch_rtp_engine_s::remote_rtcp_port

Definition at line 140 of file switch_core_media.c.

Referenced by check_ice(), clear_ice(), switch_core_media_activate_rtp(), switch_core_media_negotiate_sdp(), and switch_core_media_proxy_remote_addr().

◆ remote_rtp_ice_addr

char* switch_rtp_engine_s::remote_rtp_ice_addr

Definition at line 169 of file switch_core_media.c.

Referenced by check_ice().

◆ remote_rtp_ice_port

switch_port_t switch_rtp_engine_s::remote_rtp_ice_port

Definition at line 170 of file switch_core_media.c.

Referenced by check_ice().

◆ remote_ssrc

uint32_t switch_rtp_engine_s::remote_ssrc

Definition at line 139 of file switch_core_media.c.

Referenced by check_ice(), switch_core_media_activate_rtp(), and switch_core_session_stop_media().

◆ reset_codec

uint8_t switch_rtp_engine_s::reset_codec

Definition at line 179 of file switch_core_media.c.

Referenced by switch_core_media_negotiate_sdp(), and switch_core_media_read_frame().

◆ rmode

switch_media_flow_t switch_rtp_engine_s::rmode

Definition at line 190 of file switch_core_media.c.

Referenced by switch_core_media_check_dtls(), switch_core_media_gen_local_sdp(), switch_core_media_negotiate_sdp(), switch_core_media_set_rmode(), and switch_core_session_remote_media_flow().

◆ rtcp_mux

int8_t switch_rtp_engine_s::rtcp_mux

Definition at line 164 of file switch_core_media.c.

Referenced by check_dtls_reinvite(), check_ice(), generate_m(), switch_core_media_activate_rtp(), switch_core_media_gen_local_sdp(), and switch_core_media_negotiate_sdp().

◆ rtp_bugs

switch_rtp_bug_flag_t switch_rtp_engine_s::rtp_bugs

Definition at line 141 of file switch_core_media.c.

Referenced by switch_core_media_activate_rtp(), and switch_core_media_negotiate_sdp().

◆ rtp_session

switch_rtp_t* switch_rtp_engine_s::rtp_session

Definition at line 120 of file switch_core_media.c.

Referenced by check_dtls_reinvite(), check_engine(), check_ice(), check_jb(), check_jb_sync(), check_media_timeout_params(), clear_ice(), switch_core_media_activate_rtp(), switch_core_media_break(), switch_core_media_check_autoadj(), switch_core_media_check_dtls(), switch_core_media_check_udptl_mode(), switch_core_media_choose_port(), switch_core_media_clear_rtp_flag(), switch_core_media_deactivate_rtp(), switch_core_media_get_jb(), switch_core_media_get_rtp_session(), switch_core_media_get_stats(), switch_core_media_get_timer(), switch_core_media_kill_socket(), switch_core_media_negotiate_sdp(), switch_core_media_patch_sdp(), switch_core_media_pause(), switch_core_media_process_t38_passthru(), switch_core_media_proxy_remote_addr(), switch_core_media_queue_rfc2833(), switch_core_media_queue_rfc2833_in(), switch_core_media_read_frame(), switch_core_media_read_lock_unlock(), switch_core_media_ready(), switch_core_media_receive_message(), switch_core_media_recover_session(), switch_core_media_reset_jb(), switch_core_media_resume(), switch_core_media_set_codec(), switch_core_media_set_rtp_flag(), switch_core_media_set_rtp_session(), switch_core_media_set_telephony_event(), switch_core_media_set_telephony_recv_event(), switch_core_media_set_video_codec(), switch_core_media_start_udptl(), switch_core_media_sync_stats(), switch_core_media_toggle_hold(), switch_core_media_udptl_mode(), switch_core_media_write_frame(), switch_core_session_apply_crypto(), switch_core_session_check_incoming_crypto(), switch_core_session_get_rtp_session(), switch_core_session_passthru(), switch_core_session_start_text_thread(), switch_core_session_start_video_thread(), switch_core_session_stop_media(), and switch_core_session_wake_video_thread().

◆ sdp_bw

uint32_t switch_rtp_engine_s::sdp_bw

Definition at line 196 of file switch_core_media.c.

Referenced by switch_core_media_negotiate_sdp(), and switch_core_session_parse_codec_settings().

◆ smode

switch_media_flow_t switch_rtp_engine_s::smode

Definition at line 191 of file switch_core_media.c.

Referenced by switch_core_media_gen_local_sdp(), switch_core_media_negotiate_sdp(), switch_core_media_set_smode(), switch_core_session_media_flow(), switch_core_session_wait_for_video_input_params(), and switch_media_handle_create().

◆ ssec

switch_secure_settings_t switch_rtp_engine_s::ssec[CRYPTO_INVALID+1]

Definition at line 115 of file switch_core_media.c.

Referenced by generate_m(), switch_core_media_build_crypto(), switch_core_media_gen_local_sdp(), switch_core_media_recover_session(), switch_core_session_apply_crypto(), switch_core_session_check_incoming_crypto(), switch_core_session_clear_crypto(), switch_core_session_get_recovery_crypto_key(), switch_core_session_local_crypto_key(), and switch_media_handle_create().

◆ ssrc

uint32_t switch_rtp_engine_s::ssrc

Definition at line 138 of file switch_core_media.c.

Referenced by generate_m(), switch_core_media_activate_rtp(), switch_core_media_gen_local_sdp(), and switch_media_handle_create().

◆ t140_pt

int switch_rtp_engine_s::t140_pt

Definition at line 200 of file switch_core_media.c.

Referenced by build_red_packet(), switch_core_media_gen_local_sdp(), and switch_core_session_write_text_frame().

◆ tf

switch_rtp_text_factory_t* switch_rtp_engine_s::tf

Definition at line 202 of file switch_core_media.c.

Referenced by build_red_packet(), switch_core_media_activate_rtp(), switch_core_media_deactivate_rtp(), switch_core_media_read_frame(), and switch_core_session_write_text_frame().

◆ thread_id

switch_thread_id_t switch_rtp_engine_s::thread_id

Definition at line 192 of file switch_core_media.c.

Referenced by audio_write_thread(), switch_core_session_in_video_thread(), text_helper_thread(), and video_helper_thread().

◆ thread_write_lock

switch_thread_id_t switch_rtp_engine_s::thread_write_lock

Definition at line 193 of file switch_core_media.c.

Referenced by switch_core_media_write_frame(), switch_core_session_write_video_frame(), and video_write_thread().

◆ timestamp_send

uint32_t switch_rtp_engine_s::timestamp_send

Definition at line 156 of file switch_core_media.c.

Referenced by switch_core_media_write_frame().

◆ tmmbr

uint8_t switch_rtp_engine_s::tmmbr

Definition at line 185 of file switch_core_media.c.

Referenced by switch_core_media_activate_rtp(), switch_core_media_gen_local_sdp(), and switch_core_media_negotiate_sdp().

◆ type

switch_media_type_t switch_rtp_engine_s::type

Definition at line 118 of file switch_core_media.c.

Referenced by check_dtls_reinvite(), check_ice(), check_media_timeout_params(), switch_core_media_set_rtp_session(), switch_core_session_check_incoming_crypto(), and switch_media_handle_create().

◆ write_codec

switch_codec_t switch_rtp_engine_s::write_codec

Definition at line 123 of file switch_core_media.c.

Referenced by switch_core_media_codec_control(), switch_core_media_codec_get_cap(), switch_core_media_receive_message(), switch_core_media_set_codec(), switch_core_media_set_outgoing_bitrate(), switch_core_media_set_video_codec(), switch_core_session_stop_media(), and switch_media_handle_destroy().

◆ write_fb

switch_frame_buffer_t* switch_rtp_engine_s::write_fb

Definition at line 207 of file switch_core_media.c.

Referenced by audio_write_thread(), perform_write(), switch_core_media_deactivate_rtp(), and switch_media_handle_destroy().

◆ write_impl

switch_codec_implementation_t switch_rtp_engine_s::write_impl

Definition at line 126 of file switch_core_media.c.

Referenced by switch_core_media_set_codec().

The documentation for this struct was generated from the following file:

switch_core_media.c