; zero or more media descriptions
; "m=" media name and transport address
; "i=" media title (OPTIONAL)
; "c=" connection information (OPTIONAL)
; "b=" zero or more bandwidth information lines (OPTIONAL)
; "k=" encryption key (OPTIONAL)
; "a=" zero or more media attribute lines (OPTIONAL)

SDP example

v=0
o=alice 2890844526 2890844526 IN IP4 host.atlanta.example.com
s=
c=IN IP4 host.atlanta.example.com
t=0 0
m=audio 49170 RTP/AVP 0 8 97
a=rtpmap:0 PCMU/8000
a=rtpmap:8 PCMA/8000
a=rtpmap:97 iLBC/8000
m=video 51372 RTP/AVP 31 32
a=rtpmap:31 H261/90000
a=rtpmap:32 MPV/90000

SDP — Protocol Version (v=)

RFC 4566 – Section 5.1

proto-version =

%x76 "=" 1*DIGIT CRLF

SDP — Origin (o=)

RFC 4566 – Section 5.2

origin-field =

%x6f "=" username SP sess‑id SP sess‑version SP nettype SP addrtype SP unicast‑address CRLF

username =

non‑ws‑string

sess-id =

1*DIGIT

sess-version =

1*DIGIT

nettype =

token

; Network Type
; → IANA
; IN
; → RFC 4566 – Section 8.2.6
; TN
; → RFC 2848 – Section 3.4.1
; ATM
; → RFC 3108 – Section 9
; PSTN
; → RFC 7195 – Section 8.2

addrtype =

token

; Address Type
; → IANA
; IP4, IP6
; → RFC 4566 – Section 8.2.7
; NSAP, GWID, E164
; → RFC 3108 – Section 9
; E164
; → RFC 7195 – Section 8.3

SDP — Session Name (s=)

RFC 4566 – Section 5.3

session-name-field =

%x73 "=" text CRLF

SDP — Session Information (i=)

RFC 4566 – Section 5.4

information-field =

[ %x69 "=" text CRLF ]

SDP — URI (u=)

RFC 4566 – Section 5.5

uri-field =

[ %x75 "=" uri CRLF]

uri =

URI‑reference

SDP — Email Address (e=)

RFC 4566 – Section 5.6

email-fields =

*( %x65 "=" email‑address CRLF )

email-address =

address‑and‑comment / dispname‑and‑address / addr‑spec

address-and-comment =

addr‑spec 1*SP "(" 1*email‑safe ")"

dispname-and-address =

1*email‑safe 1*SP "<" addr‑spec ">"

SDP — Phone Number (p=)

RFC 4566 – Section 5.6

phone-fields =

*( %x70 "=" phone‑number CRLF )

phone-number =

phone *SP "(" 1*email‑safe ")" / 1*email‑safe "<" phone ">" / phone

phone =

[ "+" ] DIGIT 1*( SP / "-" / DIGIT )

SDP — Connection Data (c=)

RFC 4566 – Section 5.7

connection-field =

[ %x63 "=" nettype SP addrtype SP connection‑address CRLF ]

connection-address =

multicast-address /
unicast-address /
; → RFC 4566 – Section 5.7
global-number-digits / ;
"-"
; → RFC 7195 – Section 5.7

SDP — Bandwidth (b=)

RFC 4566 – Section 5.8

bandwidth-fields =

*( %x62 "=" bwtype ":" bandwidth CRLF )

bwtype =

token

; Bandwidth Type
; → IANA
; "CT" Conference Total
; "AS" Application Specific
; → RFC 4566 – Section 5.8
; "RS" RTCP for Senders
; "RR" RTCP for Receivers
; → RFC 3556 – Section 2
; "TIAS" Transport Independent Application Specific
; → RFC 3890 – Section 6.2.2

bandwidth =

1*DIGIT

SDP — Timing (t= r= z=)

RFC 4566 – Section 5.9 – Section 5.10 – Section 5.11

time-fields =

1*( %x74 "=" start‑time SP stop‑time *( CRLF repeat‑fields ) CRLF) [ zone‑adjustments CRLF ]

start-time =

time / "0"

stop-time =

time / "0"

time =

POS‑DIGIT 9*DIGIT

repeat-fields =

%x72 "=" repeat‑interval SP typed‑time 1*( SP typed‑time )

repeat-interval =

POS‑DIGIT *DIGIT [ fixed‑len‑time‑unit ]

typed-time =

1*DIGIT [ fixed‑len‑time‑unit ]

fixed-len-time-unit =

"d" / "h" / "m" / "s"

zone-adjustments =

%x7a "=" time SP [ "-" ] typed‑time *( SP time SP [ "-" ] typed‑time )

SDP — Encryption Key (k=)

RFC 4566 – Section 5.12

key-field =

[ %x6b "=" key‑type CRLF ]

key-type =

"prompt" / "clear:" text / "base64:" base64 / "uri:" uri

base64 =

*base64‑unit [ base64‑pad ]

base64-unit =

4base64‑char

base64-pad =

2base64‑char "==" / 3base64‑pad "="

base64-char =

ALPHA / DIGIT / "+" / "/"

SDP — Attributes (a=)

RFC 4566 – Section 5.13

attribute-fields =

*( %x61 "=" attribute CRLF )

attribute =

( att‑field ":" att‑value ) / att‑field

att-field =

token

att-value =

byte‑string

SDP — Media Descriptions (m=)

RFC 4566 – Section 5.14

media-descriptions =

media‑field
information‑field
*connection‑field
bandwidth‑fields
key‑field
attribute‑fields

)

media-field =

%x6d "=" media SP port [ "/" integer ] SP proto 1*( SP fmt ) CRLF

media =

token

; Media Type
; → IANA
; audio, video, text, application, message
; → RFC 4566 – Section 8.2.1
; image
; → RFC 6466 – Section 1

port =

1*DIGIT

proto =

token *( "/" token )

; Transport Protocol, see: IANA
; RTP/AVP
; RTP/SAVP
; udp
; → RFC 4566 – Section 8.2.2
; TCP
; → RFC 4145 – Section 3
; TCP/RTP/AVP
; → RFC 4571 – Section 4
; TCP/TLS
; → RFC 8122 – Section 4
; TCP/BFCP
; TCP/TLS/BFCP
; → RFC 4583 – Section 3
; RTP/AVPF
; → RFC 4585 – Section 9
; TCP/MSRP
; TCP/TLS/MSRP
; → RFC 4975 – Section 8.1
; RTP/SAVPF
; → RFC 5124 – Section 3.1
; DCCP
; DCCP/RTP/AVP
; DCCP/RTP/SAVP
; DCCP/RTP/AVPF
; DCCP/RTP/SAVPF
; → RFC 5762 – Section 5.1
; UDP/TLS/RTP/SAVP
; DCCP/TLS/RTP/SAVP
; UDP/TLS/RTP/SAVPF
; DCCP/TLS/RTP/SAVPF
; → RFC 5764 – Section 9
; UDP/MBMS-FEC/RTP/AVP
; UDP/MBMS-FEC/RTP/SAVP
; UDP/MBMS-REPAIR
; → RFC 6064 – Section 8.1
; FEC/UDP
; UDP/FEC
; → RFC 6364 – Section 8.1
; TCP/MRCPv2
; TCP/TLS/MRCPv2
; → RFC 6787 – Section 13.7.1
; PSTN
; → RFC 7195 – Section 8.4
; UDP/TLS/UDPTL
; → RFC 7345 – Section 7
; TCP/RTP/AVPF
; TCP/RTP/SAVP
; TCP/RTP/SAVPF
; TCP/DTLS/RTP/SAVP
; TCP/DTLS/RTP/SAVPF
; TCP/TLS/RTP/AVP
; TCP/TLS/RTP/AVPF
; → RFC 7850 – Section 5

fmt =

token