SDP for the WebRTCCisco170 West Tasman DriveSan JoseCA95134USAsnandaku@cisco.comCisco170 West Tasman DriveSan JoseCA95134USA+1 408 421-9990fluffy@cisco.com
RAI
The Web Real-Time Communication
working group is charged to provide protocol support for direct interactive
rich communication using audio, video and data between two peers' web browsers.
With in the WebRTC framework, Session Description protocol (SDP)
is used for negotiating session capabilities
between the peers. Such a negotiation happens based on the SDP Offer/Answer exchange
mechanism described in the RFC 3264 .
This document provides an informational reference in describing the role of
SDP and the Offer/Answer exchange mechanism for the most common WebRTC use-cases.
This SDP examples provided in this document is still a work in
progress, but it aims to align closest to the evolving standards work.
Javascript Session Exchange Protocol(JSEP) specifies
a generic protocol needed to generate
Offers and Answers negotiated between the WebRTC peers for setting up, updating
and tearing down a WebRTC session. For this purpose, SDP is used to
construct Offers/Answers for describing
(media and non-media) streams as appropriate for the recipients of the session
description to participate in the session.
The remainder of this document is organized as follows: Section 3 and 4 provides
an overview of SDP and the Offer/Answer exchange mechanism.
Section 5 provides sample SDP generated for the most common WebRTC
use-cases.
The key words "MUST", "MUST NOT", "REQUIRED", "SHOULD", "SHOULD NOT",
"RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be
interpreted as described in .
The purpose of this section is to provide a general overview of SDP and its components.
For a more in-depth understanding, the readers are advised to refer to
.
The Session Description Protocol (SDP) describes
multimedia sessions, which can contain audio, video, whiteboard, fax, modem, and
other streams. SDP provides a general purpose, standard representation to describe
various aspects of multimedia session such as media capabilities,
transport addresses and related metadata in a transport agnostic manner, for
the purposes of session announcement, session invitation and parameter negotiation.
As of today SDP is widely used in the context of Session Initiation Protocol
, Real-time Transport Protocol
and Real-time Streaming Protocol applications .
Below figure introduces high-level breakup of SDP into components that semantically
describe a multimedia session, in our case, a WebRTC session .
It by no means captures everything about SDP and hence, should be used for
informational purposes only.
proposes JavaScript application to fully specify and
control the signaling plane of a multimedia session as described in the JSEP specification
. JSEP provides mechanisms to create session
characterization and media definition information to conduct the session
based on SDP exchanges.
In this context, SDP serves two purposes:
Provide grammatical structure syntactically.Semantically convey partipant's intention and capabilities required to
successfully negotiate a session.
This section introduces SDP Offer/Answer Exchange mechanism mandated by WebRTC
for negotiating session capabilities while setting up, updating and tearing down a
WebRTC session. This section is intentionally brief in nature and interested readers
are recommended to refer for specific details on the
protocol operation.
The Offer/Answer model specifies rule for the
bilateral exchange of Session Description Protocol (SDP) messages for creation of
multimedia streams. It defines protocol with involved participants exchanging
desired session characteristics from each others perspective constructed as SDP to
negotiate the session between them.
In the most basic form,the protocol operation begins by one of the participants
sending an initial SDP Offer describing its intent to start a
multimedia communication session. The participant receiving the offer MAY generate
an SDP Answer accepting the offer or it MAY reject the offer. If the session is
accepted the Offer/Answer model guarantees a common view of the multimedia session
between the participants.
At any time, either participant MAY generate a new SDP offer that updates the
session in progress.
With in the context of WebRTC, the Offer/Answer model defines the state-machinery
for WebRTC peers to negotiate session descriptions between them during the
initial setup stages as well as for eventual session updates.
Javascript Session Establishment Protocol specification
for WebRTC provides the mechanism for generating
SDP Offers and Answers in order for both sides of the session to agree upon
details such as list of media formats to be sent/received, bandwidth information,
crypto parameters, transport parameters, for example.
A typical web based real-time multimedia communication session can be characterized
as below:
It has zero or more Audio only, Video only or Audio/Video RTP Sessions, MAY contain zero or more non-media data sessions, All the sessions are secured with DTLS-SRTP, Supports NAT traversal using ICE mechanism, Provides RTCP based feedback mechanisms, Sessions can be over IPv4-only, IPv6-only, dual-stack based clients.
The examples given in this document follow the conventions listed
below:
In all the examples, Alice and Bob are assumed to be the WebRTC peers.
support for multiplexing
several media streams on a single underlying transport is enabled by default unless
explicitly specified otherwise.
Call flow diagrams that accompany the use-cases capture only the
prominent aspects of the system behavior and intentionally is not detailed
to improve readability.
The SDP examples deviate from actual on-the-wire SDP notation in several ways.
This is done to facilitate readability and to conform to the restrictions
imposed by the RFC formatting rules.
Any SDP line that is indented (compared to the initial line in the
SDP block) is a continuation of the preceding line. The line
break and indent are to be interpreted as a single space
character.
Empty lines in any SDP example are inserted to make functional
divisions in the SDP clearer, and are not actually part of the
SDP syntax.
Excepting the above two conventions, line endings are to be
interpreted as <CR><LF> pairs (that is, an ASCII 13 followed
by an ASCII 10).
Against each SDP line, pointers to the appropriate RFCs are provide
for further information reference. Also an attempt has been made to
provide explanatory notes to enable better understanding of the SDP usage,
wherever appropriate.
Following SDP details are common across all the use-cases defined in
this document unless mentioned otherwise.
DTLS fingerprint for SRTP (a=fingerprint) RTP/RTCP Multiplexing (a=rtcp-mux) RTCP Feedback support (a=rtcp-fb) Host and server-reflexive candidate lines (a=candidate) SRTP Setup framework parameters (a=setup) RTCP attribute (a=rtcp) RTP header extension indicating audio-levels from client to the mixer
For more details, readers are recommended to refer to the
Javascript Session Exchange Protocol(JSEP)
specification.
The term "Session" is used rather loosely in this document to refer to
either a "Communication Session" or a "RTP Session" or a "RTP Stream"
depending on the context.
Payload type 109 is usually used for OPUS, 99 for H.264 and 120 for VP8
in most of the examples to maintain uniformity.
In the actual use that values that represent SSRCs, ICE candidate foundations,
WebRTC Mediastream and MediaStreamTrack Ids can be much larger and random than
the ones shown in the examples.
[OPEN ISSUE-1]: SDP Examples for Data Channel, Simulcast, SVC are still being discussed
and doesn't represent the final solution.
[OPEN ISSUE-2]: API surface for controlling BUNDLE, TRICKLE-ICE are ignored for the
time being.
This common scenario shows SDP for secure Two-way audio session with
Alice offering Opus, PCMU, PCMA and Bob accepting all the audio codecs
offered.
Bob: Offer(Audio:Opus,PCMU,PCMA)
Bob->Alice: Answer(Audio:Opus,PCMU,PCMA)
Alice<->Bob: Two-way Opus Audio (preferred codec)
]]>SDP Contents RFC#/Notesv=0o=- 20518 0 IN IP4 0.0.0.0 - Session Origin Informations=-t=0 0a=msid-semantic:WMSa=group:BUNDLE audiom=audio 54609 UDP/TLS/RTP/SAVPF 109 0 8a=mid:audioa=msid:ma ta Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (ta) c=IN IP4 24.23.204.141a=rtcp:64678 IN IP4 24.23.204.141 - Port for RTCP dataa=rtpmap:109 opus/48000/2 - Opus Codec 48khz, 2 channelsa=ptime:20 - Opus packetization of 20msa=rtpmap:0 PCMU/8000 PCMU Audio Codeca=rtpmap:8 PCMA/8000 PCMA Audio Codeca=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level Alice supports RTP header extension to indicate audio levelsa=sendrecv - Alice can send and recv audioa=setup:actpass - Alice can perform DTLS before Answer arrivesa=rtcp-mux - Alice can perform RTP/RTCP Muxing on port 54609a=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07 - DTLS Fingerprint for SRTPa=ice-ufrag:074c6550 - ICE user fragmenta=ice-pwd:a28a397a4c3f31747d1ee3474af08a068 - ICE passworda=candidate:0 1 UDP 2113667327 192.168.1.4 54609 typ host - RTP Host Candidatea=candidate:1 1 UDP 694302207 24.23.204.141 54609 typ srflx raddr 192.168.1.4 rport 54609 - RTP Server Reflexive ICE Candidatea=candidate:0 2 UDP 2113667326 192.168.1.4 64678 typ host - RTCP Host Candidatea=candidate:1 2 UDP 1694302206 24.23.204.141 64678 typ srflx raddr 192.168.1.4 rport 64678 - RTCP Server Reflexive Candidatea=rtcp-fb:109 nack - Indicates NACK RTCP feedback supporta=ssrc:12345 cname:EocUG1f0fcg/yvY7a=rtcp-rsize - Alice intends to use reduced size RTCP for
this sessiona=ice-options:trickleSDP Contents RFC#/Notesv=0o=- 16833 0 IN IP4 0.0.0.0 - Session Origin Informations=-t=0 0a=msid-semantic:WMSa=group:BUNDLE audiom=audio 49203 UDP/TLS/RTP/SAVPF 109 0 8a=mid:audioa=msid:ma ta Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (ta) c=IN IP4 98.248.92.77a=rtcp:60065 IN IP4 98.248.92.77 - Port for RTCP dataa=rtpmap:109 opus/48000/2 Opus Codeca=ptime:20 Packetization of 20msa=rtpmap:0 PCMU/8000 PCMU Audio Codeca=rtpmap:8 PCMA/8000 PCMA Audio Codeca=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level Bob supports audio level RTP header extension as wella=sendrecv - Bob can send and recv audioa=setup:active - Bob carries out DTLS Handshake in parallela=rtcp-mux - Bob can perform RTP/RTCP Muxing on port 49203a=fingerprint:sha-1 c9:c7:70:9d:1f:66:79:a8:07:99:41:49:83:4a:97:0e:1f:ef:6d:f7 - DTLS Fingerprint for SRTPa=ice-ufrag:05067423 - ICE user fragmenta=ice-pwd:1747d1ee3474a28a397a4c3f3af08a068 - ICE password parametera=candidate:0 1 UDP 2113667327 192.168.1.7 49203 typ host - RTP Host ICE Candidate for Opus Streama=candidate:1 1 UDP 1694302207 98.248.92.77 49203 typ srflx raddr 192.168.1.7 rport 49203 - RTP Server Reflexive ICE Candidatea=candidate:0 2 UDP 2113667326 192.168.1.7 60065 typ host - RTCP Host Candidate a=candidate:1 2 UDP 1694302206 98.248.92.77 60065 typ srflx raddr 192.168.1.7 rport 60065 - RTCP Server Reflexive Candidatea=rtcp-fb:109 nack - Indicates NACK RTCP feedback supporta=ssrc:54321 cname:NWs1ao1HmN4Xa5/yvY7a=rtcp-rsize - Bob intends to use reduced size RTCP
for this sessiona=ice-options:trickle
Alice and Bob establish an audio and video session with Opus as the
audio codec and H.264 as the video codec. This example also illustrates
the negotiation of NACK based RTCP feedback mechanisms - PLI and FIR for
the video session .
Bob: Offer(Audio:Opus,PCMU,PCMA Video:H.264,VP8)
Bob->Alice: Answer(Audio:Opus, Video:H.264)
Alice->Bob: Two-way Opus Audio, H.264 Video
]]>SDP Contents RFC#/Notesv=0o=- 20518 0 IN IP4 0.0.0.0 - Session Origin Informations=-t=0 0a=msid-semantic:WMSa=group:BUNDLE audio videom=audio 54609 UDP/TLS/RTP/SAVPF 109 0 8a=mid:audioa=msid:ma ta Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (ta) c=IN IP4 24.23.204.141a=rtcp:64678 IN IP4 24.23.204.141 - Port for RTCP dataa=rtpmap:109 opus/48000/2 - Opus Codec 48khz, 2 channelsa=ptime:20 - Opus packetization of 20msa=rtpmap:0 PCMU/8000 PCMU Audio Codeca=rtpmap:8 PCMA/8000 PCMA Audio Codeca=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-levela=sendrecv - Alice can send and recv audioa=setup:actpass - Alice can perform DTLS before Answer arrivesa=rtcp-mux - Alice can perform RTP/RTCP Muxing on port 54609a=ice-ufrag:074c6550 - ICE user fragmenta=ice-pwd:a28a397a4c3f31747d1ee3474af08a068 - ICE password parametera=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07 - DTLS Fingerprint for SRTPa=candidate:0 1 UDP 2113667327 192.168.1.4 54609 typ host - RTP ICE Candidatea=candidate:1 1 UDP 694302207 24.23.204.141 54609 typ srflx raddr 192.168.1.4 rport 54609 - RTP Server Reflexive ICE Candidatea=candidate:0 2 UDP 2113667326 192.168.1.4 64678 typ host - RTCP Host Candidate a=candidate:1 2 UDP 1694302206 24.23.204.141 64678 typ srflx raddr 192.168.1.4 rport 64678 - RTCP Server Reflexive Candidate.a=rtcp-fb:109 nack - Indicates NACK RTCP feedback supporta=ssrc:12345 cname:EocUG1f0fcg/yvY7a=rtcp-rsize - Alice intends to use reduced size RTCP
for this sessiona=ice-options:tricklem=video 54609 UDP/TLS/RTP/SAVPF 99 120a=mid:videoa=msid:ma tb Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (tb) c=IN IP4 24.23.204.141a=rtcp:64678 IN IP4 24.23.204.141 - Port for RTCP dataa=rtpmap:99 H264/90000 - H.264 Video Codeca=fmtp:99 profile-level-id=4d0028;packetization-mode=1a=rtpmap:120 VP8/90000 - VP8 video codeca=sendrecv - Alice can send and recv videoa=setup:actpass - Alice can perform DTLS before Answer arrivesa=rtcp-mux - Alice can perform RTP/RTCP Muxing on port 62537a=ice-ufrag:074c6550 - ICE user fragmenta=ice-pwd:a28a397a4c3f31747d1ee3474af08a068 - ICE password parametera=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07 - DTLS Fingerprint for SRTPa=candidate:0 1 UDP 2113667327 192.168.1.4 54609 typ host - RTP Host ICE Candidatea=candidate:1 1 UDP 694302207 24.23.204.141 54609 typ srflx raddr 192.168.1.4 rport 54609 - RTP Server Reflexive ICE Candidatea=candidate:0 2 UDP 2113667326 192.168.1.4 64678 typ host - RTCP Host Candidate a=candidate:1 2 UDP 1694302206 24.23.204.141 64678 typ srflx raddr 192.168.1.4 rport 64678 - RTCP Server Reflexive Candidatea=rtcp-fb:99 nack - Indicates NACK RTCP feedback supporta=rtcp-fb:99 nack pli - Indicates support for Picture loss Indication and NACKa=rtcp-fb:99 ccm fir - Full Intra Frame Request-Codec Control Message supporta=rtcp-fb:120 nack - Indicates NACK RTCP feedback supporta=rtcp-fb:120 nack pli - Indicates support for Picture loss Indication and NACKa=rtcp-fb:120 ccm fir - Full Intra Frame Request-Codec Control Message supporta=ssrc:1366781083 cname:EocUG1f0fcg/yvY7a=rtcp-rsize - Alice intends to use reduced size RTCP
for this sessiona=ice-options:trickleSDP Contents RFC#/Notesv=0o=- 16833 0 IN IP4 0.0.0.0 - Session Origin Informations=-t=0 0a=msid-semantic:WMSa=group:BUNDLE audio videom=audio 49203 UDP/TLS/RTP/SAVPF 109a=mid:audioa=msid:ma ta Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (ta) c=IN IP4 98.248.92.77a=rtcp:60065 IN IP4 98.248.92.77 - Port for RTCP dataa=rtpmap:109 opus/48000/2 - Bob accepts only Opus Codeca=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-levela=ptime:20a=sendrecv - Bob can send and recv audioa=setup:active - Bob carries out DTLS Handshake in parallela=rtcp-mux - Bob can perform RTP/RTCP Muxing on port 49203a=ice-ufrag:c300d85b - ICE username fraga=ice-pwd:de4e99bd291c325921d5d47efbabd9a2 - ICE passworda=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07 - DTLS Fingerprint for SRTPa=candidate:0 1 UDP 2113667327 192.168.1.7 49203 typ host - RTP Host ICE Candidate for Opus Streama=candidate:1 1 UDP 1694302207 98.248.92.77 49203 typ srflx raddr 192.168.1.7 rport 49203 - RTP Server Reflexive ICE Candidatea=candidate:0 2 UDP 2113667326 192.168.1.7 60065 typ host - RTPC Host Candidate a=candidate:1 2 UDP 1694302206 98.248.92.77 60065 typ srflx raddr 192.168.1.7 rport 60065 - RTCP Server Reflexive Candidate.a=ssrc:1366788312 cname:1f0fcgEocUG/yvY7a=rtcp-rsize - Bob intends to use reduced size RTCP
for this sessiona=ice-options:tricklem=video 49203 UDP/TLS/RTP/SAVPF 99a=mid:videoa=msid:ma tb Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (tb) c=IN IP4 98.248.92.77a=rtcp:60065 IN IP4 98.248.92.77 - Port for RTCP dataa=rtpmap:99 H264/90000 - Bob accepts H.264 Video Codec.a=fmtp:99 profile-level-id=4d0028;packetization-mode=1a=sendrecv - Bob can send and recv videoa=setup:active - Bob carries out DTLS Handshake in parallela=rtcp-mux - Bob can perform RTP/RTCP Muxing on port 63130a=ice-ufrag:c300d85b - ICE username fraga=ice-pwd:de4e99bd291c325921d5d47efbabd9a2 - ICE passworda=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07 - DTLS Fingerprint for SRTPa=candidate:0 1 UDP 2113667327 192.168.1.7 49203 typ host - Host ICE Candidate for Opus Streama=candidate:1 1 UDP 1694302207 98.248.92.77 49203 typ srflx raddr 192.168.1.7 rport 49203 - Server Reflexive ICE Candidate for the above host candidatea=candidate:0 2 UDP 2113667326 192.168.1.7 60065 typ host - Second Host Candidate a=candidate:1 2 UDP 1694302206 98.248.92.77 60065 typ srflx raddr 192.168.1.7 rport 60065 - Server Reflexive Candidate for the Second Host Candidatea=rtcp-fb:99 nack - Indicates support for NACK based RTCP feedbacka=rtcp-fb:99 nack pli - Indicates support for Picture loss Indication and NACKa=rtcp-fb:99 ccm fir - Full Intra Frame Request-Codec Control Message supporta=ssrc:3229706345 cname:Q/NWs1ao1HmN4Xa5a=rtcp-rsize - Bob intends to use reduced size RTCP
for this sessiona=ice-options:trickle
This scenario illustrates SDP negotiated to setup a data-only session based
on SCTP Data Channel, thus enabling use-cases such as file-transfer for example.
Bob: Offer(DataChannel)
Bob->Alice: Answer(Data-Channel)
Alice->Bob: Two-way SCTP based Data-Channel
]]>SDP Contents RFC#/Notesv=0o=- 20518 0 IN IP4 0.0.0.0 - Session Origin Informations=-t=0 0a=msid-semantic:WMSa=group:BUNDLE dataa=ice-ufrag:074c6550 - Session Level ICE parametera=ice-pwd:a28a397a4c3f31747d1ee3474af08a068 - Session Level ICE parametera=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07 - Session DTLS Fingerprint for SRTPm=application 56966 DTLS/SCTP 5000c=IN IP4 24.23.204.141a=mid:dataa=sctpmap:5000 webrtc-Datachannel 1 - One data stream of type chata=webrtc-Datachannel:5000 stream=1;label="channel 1";subprotocol="chat";a=setup:actpass - Alice can perform DTLS before Answer arrivesa=sendrecv - Alice can send and recv non-media dataa=candidate:0 1 UDP 2113667327 192.168.1.7 56966 typ hosta=candidate:1 1 UDP 1694302207 24.23.204.141 56966 typ srflx raddr 192.168.1.7 rport 56966a=ice-options:trickleSDP Contents RFC#/Notesv=0o=- 16833 0 IN IP4 0.0.0.0 - Session Origin Informations=-t=0 0a=msid-semantic:WMSa=group:BUNDLE datam=application 55700 DTLS/SCTP 5000c=IN IP4 98.248.92.771a=mid:dataa=sctpmap:5000 webrtc-Datachannel 1a=webrtc-Datachannel:5000 stream=1;label="channel 1";subprotocol="chat";a=setup:active - Bob carries out DTLS Handshake in parallela=sendrecv - Bob can send and recv non-media dataa=ice-ufrag:c300d85b - Session Level ICE username fraga=ice-pwd:de4e99bd291c325921d5d47efbabd9a2 - Session Level ICE passworda=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07 - Session DTLS Fingerprint for SRTPa=candidate:0 1 UDP 2113667327 192.168.1.7 55700 typ host - Refer 4.1 SDP Offera=candidate:1 1 UDP 1694302207 98.248.92.77 55700 typ srflx raddr 192.168.1.7 rport 55700 Refer 4.1 SDP Offera=ice-options:trickle
Alice calls Bob, but when Bob answers he places Alice on hold by setting
the SDP direction attribute to a=sendonly in the Answer.
Bob: Offer(Audio:Opus)
Bob->Alice: Answer(Audio:Opus,a=sendonly)
Alice->Bob: One-way Opus Audio (preferred codec)]]>SDP Contents RFC#/Notesv=0o=- 20518 0 IN IP4 0.0.0.0 - Session Origin Informations=-t=0 0a=msid-semantic:WMSa=group:BUNDLE audiom=audio 54609 UDP/TLS/RTP/SAVPF 109a=mid:audioa=msid:ma ta Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (ta) c=IN IP4 24.23.204.141a=rtcp:64678 IN IP4 24.23.204.141 - Port for RTCP dataa=rtpmap:109 opus/48000/2 - Opus Codec 48khz, 2 channelsa=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-levela=ptime:20 - Opus packetization of 20msa=sendrecv - Alice can send and recv audioa=setup:actpass - Alice can perform DTLS before Answer arrivesa=rtcp-mux - Alice can perform RTP/RTCP Muxing on port 54609a=ice-ufrag:074c6550 - ICE user fragment a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068 - ICE passworda=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07 - DTLS Fingerprint for SRTPa=candidate:0 1 UDP 2113667327 192.168.1.4 54609 typ hosta=candidate:1 1 UDP 694302207 24.23.204.141 54609 typ srflx raddr 192.168.1.4 rport 54609a=candidate:0 2 UDP 2113667326 192.168.1.4 64678 typ hosta=candidate:1 2 UDP 1694302206 24.23.204.141 64678 typ srflx raddr 192.168.1.4 rport 64678a=rtcp-fb:109 nack - Indicates NACK RTCP feedback supporta=ssrc:3229706345 cname:Q/NWs1ao1HmN4Xa5a=rtcp-rsizea=ice-options:trickleSDP Contents RFC#/Notesv=0o=- 16833 0 IN IP4 0.0.0.0 - Session Origin Informations=-t=0 0a=msid-semantic:WMSa=group:BUNDLE audiom=audio 49203 UDP/TLS/RTP/SAVPF 109a=mid:audioa=msid:ma ta Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (ta) c=IN IP4 98.248.92.77a=rtcp:60065 IN IP4 98.248.92.77 - Port for RTCP dataa=rtpmap:109 opus/48000/2 - Bob accepts only Opus Codeca=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-levela=ptime:20a=sendonly - Bob puts call On Holda=setup:active - Bob carries out DTLS Handshake in parallela=rtcp-mux - Bob can perform RTP/RTCP Muxing on port 49203a=ice-ufrag:c300d85b - ICE username fraga=ice-pwd:de4e99bd291c325921d5d47efbabd9a2 - ICE passworda=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07 - DTLS Fingerprint for SRTPa=candidate:0 1 UDP 2113667327 192.168.1.7 49203 typ hosta=candidate:1 1 UDP 1694302207 98.248.92.77 49203 typ srflx raddr 192.168.1.7 rport 49203a=candidate:0 2 UDP 2113667326 192.168.1.7 60065 typ hosta=candidate:1 2 UDP 1694302206 98.248.92.77 60065 typ srflx raddr 192.168.1.7 rport 60065a=ssrc:1366781083 cname:EocUG1f0fcg/yvY7a=rtcp-rsizea=ice-options:trickle
In this example, Alice wishes to establish two separate audio streams,
one for normal audio and the other for telephone-events. Alice
offers first audio stream with three codecs and the other
with tones (for DTMF). Bob accepts both
the audio streams by choosing Opus as the audio codec and the telephone-event
for the other stream.
Bob: Offer(Audio:Opus,PCMU,PCMA Audio:telephone-event)
Bob->Alice: Answer(Audio:Opus, Audio:telephone-event)
Alice->Bob: Opus audio stream and telephone-event stream]]>SDP Contents RFC#/Notesv=0o=- 20518 0 IN IP4 0.0.0.0 - Session Origin Informations=-t=0 0a=msid-semantic:WMSa=group:BUNDLE audio dtmfm=audio 54609 UDP/TLS/RTP/SAVPF 109 0 8a=mid:audioa=msid:ma ta Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (ta) c=IN IP4 24.23.204.141a=rtcp:64678 IN IP4 24.23.204.141 - Port for RTCP dataa=rtpmap:109 opus/48000/2 - Opus Codec 48khz, 2 channelsa=ptime:20 - Opus packetization of 20msa=rtpmap:0 PCMU/8000 PCMU Audio Codeca=rtpmap:8 PCMA/8000 PCMA Audio Codeca=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-levela=sendrecv - Alice can send and recv audioa=setup:actpass - Alice can perform DTLS before Answer arrivesa=rtcp-mux - Alice can perform RTP/RTCP Muxing on port 54609a=ice-ufrag:074c6550 - ICE user fragmenta=ice-pwd:a28a397a4c3f31747d1ee3474af08a068 - ICE password parametera=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07 - DTLS Fingerprint for SRTPa=candidate:0 1 UDP 2113667327 192.168.1.4 54609 typ hosta=candidate:1 1 UDP 694302207 24.23.204.141 54609 typ srflx raddr 192.168.1.4 rport 54609a=candidate:0 2 UDP 2113667326 192.168.1.4 64678 typ hosta=candidate:1 2 UDP 1694302206 24.23.204.141 64678 typ srflx raddr 192.168.1.4 rport 64678a=rtcp-fb:109 nack - Indicates NACK RTCP feedback supporta=ssrc:3229706345 cname:Q/NWs1ao1HmN4Xa5a=rtcp-rsizea=ice-options:tricklem=audio 54609 UDP/TLS/RTP/SAVPF 126a=mid:dtmfa=msid:ma tb Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (tb) c=IN IP4 24.23.204.141a=rtcp:64678 IN IP4 24.23.204.141 - Port for RTCP dataa=rtpmap:126 telephone-event/8000a=sendonly - Alice can send DTMF Eventsa=setup:actpass - Alice can perform DTLS before Answer arrivesa=rtcp-muxa=ice-ufrag:074c6550 - ICE user fragmenta=ice-pwd:a28a397a4c3f31747d1ee3474af08a068 - ICE password parametera=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07 - DTLS Fingerprint for SRTPa=candidate:0 1 UDP 2113667327 192.168.1.4 54609 typ hosta=candidate:1 1 UDP 694302207 24.23.204.141 54609 typ srflx raddr 192.168.1.4 rport 54609a=candidate:0 2 UDP 2113667326 192.168.1.4 64678 typ hosta=candidate:1 2 UDP 1694302206 24.23.204.141 64678 typ srflx raddr 192.168.1.4 rport 64678a=rtcp-fb:109 nack - Indicates NACK RTCP feedback supporta=ssrc:9032206345 cname:L/N9lk1ao1HmN4Xa5a=rtcp-rsizea=ice-options:trickleSDP Contents RFC#/Notesv=0o=- 16833 0 IN IP4 0.0.0.0 - Session Origin Informations=-t=0 0a=msid-semantic:WMSa=group:BUNDLE audio dtmfm=audio 49203 UDP/TLS/RTP/SAVPF 109 a=mid:audioa=msid:ma ta Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (ta) c=IN IP4 98.248.92.77a=rtcp:60065 IN IP4 98.248.92.77 - Port for RTCP dataa=rtpmap:109 opus/48000/2 - Bob accepts Opus Codeca=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-levela=ptime:20a=sendrecv - Bob can send and receive Opus audioa=setup:active - Bob carries out DTLS Handshake in parallela=rtcp-mux - Bob can perform RTP/RTCP Muxing on port 49203a=ice-ufrag:c300d85b - ICE username fraga=ice-pwd:de4e99bd291c325921d5d47efbabd9a2 - ICE passworda=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07 - Fingerprint for SRTPa=candidate:0 1 UDP 2113667327 192.168.1.7 49203 typ hosta=candidate:1 1 UDP 1694302207 98.248.92.77 49203 typ srflx raddr 192.168.1.7 rport 49203a=candidate:0 2 UDP 2113667326 192.168.1.7 60065 typ hosta=candidate:1 2 UDP 1694302206 98.248.92.77 60065 typ srflx raddr 192.168.1.7 rport 60065a=ssrc:0634322975 cname:Q/o1HmN4XNWs1aa5a=rtcp-rsize - Alice intends to use reduced size RTCP
for this sessiona=ice-options:tricklem=audio 49203 UDP/TLS/RTP/SAVPF 126a=mid:dtmfa=msid:ma tb Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (tb) c=IN IP4 98.248.92.77a=rtcp:60065 IN IP4 98.248.92.77 - Port for RTCP dataa=rtpmap:126 telephone-event/8000a=recvonly - Alice can receive DTMF eventsa=setup:active - Bob carries out DTLS Handshake in parallela=rtcp-mux - Alice can perform RTP/RTCP Muxing on port 54690a=ice-ufrag:c300d85b - ICE username fraga=ice-pwd:de4e99bd291c325921d5d47efbabd9a2 - ICE passworda=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07 - Fingerprint for SRTPa=candidate:0 1 UDP 2113667327 192.168.1.7 49203 typ hosta=candidate:1 1 UDP 1694302207 98.248.92.77 49203 typ srflx raddr 192.168.1.7 rport 49203a=candidate:0 2 UDP 2113667326 192.168.1.7 60065 typ hosta=candidate:1 2 UDP 1694302206 98.248.92.77 60065 typ srflx raddr 192.168.1.7 rport 60065a=ssrc:6345903220 cname:L/k1aN9lo1HmN4Xa5a=rtcp-rsize - Alice intends to use reduced size RTCP
for this sessiona=ice-options:trickle
In this scenario Alice and Bob engage in 1 way audio and video
session with Bob receiving Alice's audio and her presentation slides as
video stream.
Bob: Offer(Audio:Opus, Video: VP8)
note left of Bob
Bob accepts Alice's offer
end note
Bob->Alice: Answer(Audio:Opus, Video: VP8)
Alice->Bob: One-way Opus Audio, VP8 Video
note right of Alice
Bob can hear Alice and see her presentation slides.
end note
]]>SDP Contents RFC#/Notesv=0o=- 20519 0 IN IP4 0.0.0.0s=-t=0 0a=msid-semantic:WMSa=group:BUNDLE audio videom=audio 54609 UDP/TLS/RTP/SAVPF 109a=mid:audioa=msid:ma ta Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (ta) c=IN IP4 24.23.204.141a=rtcp:64678 IN IP4 24.23.204.141 - Port for RTCP dataa=rtpmap:109 opus/48000/2a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-levela=ptime:20a=sendonly - Send only audio streama=setup:actpass - Alice can perform DTLS before Answer arrivesa=rtcp-muxa=ice-ufrag:074c6550a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068a=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07a=candidate:0 1 UDP 2113667327 24.23.204.141 54609 typ hosta=candidate:0 2 UDP 2113667326 24.23.204.141 64678 typ hosta=rtcp-fb:109 nacka=ssrc:6345903220 cname:L/k1aN9lo1HmN4Xa5a=rtcp-rsizea=ice-options:tricklem=video 54609 UDP/TLS/RTP/SAVPF 120a=mid:videoa=msid:ma tb Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (tb) c=IN IP4 24.23.204.141a=rtcp:64678 IN IP4 24.23.204.141 - Port for RTCP dataa=rtpmap:120 VP8/90000a=content:slides -Alice's presentation video streama=sendonly - Send only video streama=setup:actpass - Alice can perform DTLS before Answer arrivesa=rtcp-muxa=ice-ufrag:074c6550a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068a=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07a=candidate:0 1 UDP 2113667327 24.23.204.141 54609 typ hosta=candidate:0 2 UDP 2113667326 24.23.204.141 64678 typ hosta=rtcp-fb:120 nacka=rtcp-fb:120 nack plia=rtcp-fb:120 ccm fira=ssrc:3429951804 cname:Q/NWs1ao1HmN4Xa5a=rtcp-rsizea=ice-options:trickleSDP Contents RFC#/Notesv=0o=- 16833 0 IN IP4 0.0.0.0s=-t=0 0a=msid-semantic:WMSa=group:BUNDLE audio videom=audio 49203 UDP/TLS/RTP/SAVPF 109a=mid:audioa=msid:ma ta Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (ta) c=IN IP4 98.248.92.77a=rtcp:60065 IN IP4 98.248.92.77 - Port for RTCP dataa=rtpmap:109 opus/48000/2a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-levela=ptime:20a=recvonly - Receive only audio streama=setup:active - Bob carries out DTLS Handshake in parallela=rtcp-muxa=ice-ufrag:c300d85ba=ice-pwd:de4e99bd291c325921d5d47efbabd9a2a=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07a=candidate:0 1 UDP 2113667327 98.248.92.77 49203 typ hosta=candidate:0 2 UDP 2113667326 98.248.92.77 60065 typ hosta=ssrc:9513429804 cname:Q/o1HmNWs1aN4Xa5a=rtcp-rsizea=ice-options:tricklem=video 49203 UDP/TLS/RTP/SAVPF 120a=mid:videoa=msid:ma tb Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (tb) c=IN IP4 98.248.92.77a=rtcp:60065 IN IP4 98.248.92.77 - Port for RTCP dataa=rtpmap:120 VP8/90000a=content:slidesa=recvonly - Receive Only Alice's presentation streama=setup:active - Bob carries out DTLS Handshake in parallela=rtcp-muxa=ice-ufrag:c300d85ba=ice-pwd:de4e99bd291c325921d5d47efbabd9a2a=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07a=candidate:0 1 UDP 2113667327 98.248.92.77 49203 typ hosta=candidate:0 2 UDP 2113667326 98.248.92.77 60065 typ hosta=ssrc:1366781083 cname:EocUG1f0fcg/yvY7a=rtcp-rsizea=ice-options:trickle
In this example, since Alice is unsure of the Bob's support of the BUNDLE framework,
following 3 step procedures are performed in order to negotiate and setup a
unique BUNDLE Address for the session
An SDP Offer, in which the Alice assigns unique addresses to
each "m=" line in the BUNDLE group, and requests the Answerer to
select the Offerer's BUNDLE address. An SDP Answer, in which the Bob indicates its support for BUNDLE, and
assigns its own BUNDLE address for the BUNDLED m= lines. A subsequent SDP Offer from Alice, which is used to perform a BUNDLE
Address Synchronization (BAS).
Once the Offer/Answer exchange completes, both Alice and Bob each end up using
single RTP Session for both the Media Streams.
Bob: Offer(Audio:Opus Video:VP8)
note right of Alice
Alice offers BUNDLE support with unique address for the audio and video m-line
end note
Bob->Alice: Answer(Audio:Opus Video:VP8) indicating its support for BUNDLE
note left of Bob
Bob uses identical addresses across the m=lines
end note
Alice->Bob: Updated Offer(Audio:Opus Video:VP8) for Bundle Address Synchronzation.
Alice <-> Bob: 2Way Call with Audio and Video Multiplexed
]]>SDP Contents RFC#/Notesv=0o=- 20518 0 IN IP4 0.0.0.0s=-t=0 0a=msid-semantic:WMSa=group:BUNDLE audio video
Alice supports grouping of m=lines under BUNDLE semanticsm=audio 54609 UDP/TLS/RTP/SAVPF 109a=mid:audio Audio m=line part of BUNDLE group with a
unique port numbera=msid:ma ta Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (ta) c=IN IP4 24.23.204.141a=rtcp:64678 IN IP4 24.23.204.141a=rtpmap:109 opus/48000/2a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-levela=ptime:20a=sendrecva=setup:actpass - Alice can perform DTLS before Answer arrivesa=rtcp-muxa=ssrc:11111 cname:EocUG1f0fcg/yvY7a=ice-ufrag:074c6550a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068a=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07a=candidate:0 1 UDP 2113667327 192.168.1.4 54609 typ hosta=candidate:1 1 UDP 694302207 24.23.204.141 54609 typ srflx raddr 192.168.1.4 rport 54609a=candidate:0 2 UDP 2113667326 192.168.1.4 64678 typ hosta=candidate:1 2 UDP 1694302206 24.23.204.141 64678 typ srflx raddr 192.168.1.4 rport 64678a=rtcp-fb:109 nacka=rtcp-rsizea=ice-options:tricklem=video 62537 UDP/TLS/RTP/SAVPF 120a=mid:video Video m=line part of the Bundle group with a unique port numbera=msid:ma tb Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (tb) c=IN IP4 24.23.204.141a=rtcp:54721 IN IP4 24.23.204.141 - Port for RTCP dataa=rtpmap:120 VP8/90000a=sendrecva=setup:actpass - Alice can perform DTLS before Answer arrivesa=rtcp-muxa=ssrc:22222 cname:Q/NWs1ao1HmN4Xa5a=ice-ufrag:6550074ca=ice-pwd:74af08a068a28a397a4c3f31747d1ee34a=fingerprint:sha-1 1f:ef:6d:f7:c9:c7:70:9d:1f:66:99:41:49:83:4a:97:0e79:a8:07a=candidate:0 1 UDP 2113667327 192.168.1.4 62537 typ hosta=candidate:1 1 UDP 1694302207 24.23.204.141 62537 typ srflx raddr 192.168.1.4 rport 62537a=candidate:0 2 2113667326 192.168.1.4 54721 typ hosta=candidate:1 2 UDP 1694302206 24.23.204.141 54721 typ srflx raddr 192.168.1.4 rport 54721a=rtcp-fb:120 nacka=rtcp-fb:120 nack plia=rtcp-fb:120 ccm fira=rtcp-rsizea=ice-options:trickleSDP Contents RFC#/Notesv=0o=- 16833 0 IN IP4 0.0.0.0s=-t=0 0a=msid-semantic:WMSa=group:BUNDLE audio video
Bob supports BUNDLE semantics.m=audio 49203 UDP/TLS/RTP/SAVPF 109a=msid:ma ta Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (ta) a=mid:audio Audio m=line part of the BUNDLE groupc=IN IP4 98.248.92.77a=rtcp:60065 IN IP4 98.248.92.77 - Port for RTCP dataa=rtpmap:109 opus/48000/2a=ptime:20a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-levela=sendrecva=setup:active - Bob carries out DTLS Handshake in parallela=rtcp-fb:109 nacka=rtcp-muxa=ssrc:33333 cname:Q/1HmN4Xa5NWs1aoa=ice-ufrag:c300d85ba=ice-pwd:de4e99bd291c325921d5d47efbabd9a2a=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07a=candidate:0 1 UDP 2113667327 192.168.1.7 49203 typ hosta=candidate:1 1 UDP 1694302207 98.248.92.77 49203 typ srflx raddr 192.168.1.7 rport 49203a=candidate:0 2 UDP 2113667326 192.168.1.7 60065 typ hosta=candidate:1 2 UDP 1694302206 98.248.92.77 60065 typ srflx raddr 192.168.1.7 rport 60065a=rtcp-rsizea=ice-options:tricklem=video 49203 UDP/TLS/RTP/SAVPF 120a=mid:video Video m=line part of the BUNDLE group with
the port from audio line repeated a=msid:ma tb Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (tb) c=IN IP4 98.248.92.77a=rtcp:60065 IN IP4 98.248.92.77 - Port for RTCP dataa=rtpmap:120 VP8/90000a=sendrecva=setup:active - Bob carries out DTLS Handshake in parallela=rtcp-muxa=ssrc:44444 cname:Q/2AqlmN4Xa5NWsa=ice-ufrag:85bc300da=ice-pwd:bd2de4e9991c325921d5d47efbabd9a2a=fingerprint:sha-1 41:49:83:4a:99:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07a=candidate:0 1 UDP 2113667327 192.168.1.7 49203 typ host - Candidate lines identical with the audio m-line.a=candidate:1 1 UDP 1694302207 98.248.92.77 49203 typ srflx raddr 192.168.1.7 rport 49203a=candidate:0 2 UDP 2113667326 192.168.1.7 60065 typ hosta=candidate:1 2 UDP 1694302206 98.248.92.77 60065 typ srflx raddr 192.168.1.7 rport 60065a=rtcp-fb:120 nacka=rtcp-fb:120 nack plia=rtcp-fb:120 ccm fira=rtcp-rsizea=ice-options:trickleSDP Contents RFC#/Notesv=0o=- 20518 0 IN IP4 0.0.0.0s=-t=0 0a=msid-semantic:WMSa=group:BUNDLE audio videom=audio 54609 UDP/TLS/RTP/SAVPF 109a=msid:ma ta Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (ta) a=mid:audio - Port number finalized as Bundle Address.c=IN IP4 24.23.204.141a=rtcp:64678 IN IP4 24.23.204.141a=rtpmap:109 opus/48000/2a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-levela=ptime:20a=sendrecva=setup:actpass - Alice can perform DTLS before Answer arrivesa=rtcp-muxa=ssrc:11111 cname:EocUG1f0fcg/yvY7a=ice-ufrag:074c6550a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068a=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07a=candidate:0 1 UDP 2113667327 192.168.1.4 54609 typ hosta=candidate:1 1 UDP 694302207 24.23.204.141 54609 typ srflx raddr 192.168.1.4 rport 54609a=candidate:0 2 UDP 2113667326 192.168.1.4 64678 typ hosta=candidate:1 2 UDP 1694302206 24.23.204.141 64678 typ srflx raddr 192.168.1.4 rport 64678a=rtcp-fb:109 nacka=rtcp-rsizea=ice-options:tricklem=video 54609 UDP/TLS/RTP/SAVPF 120a=msid:ma tb Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (tb) a=mid:video - Same Bundle address from the audio m=line c=IN IP4 24.23.204.141a=rtcp:64678 IN IP4 24.23.204.141a=rtpmap:120 VP8/90000a=sendrecva=setup:actpass - Alice can perform DTLS before Answer arrivesa=rtcp-muxa=ssrc:22222 cname:Q/NWs1ao1HmN4Xa5a=ice-ufrag:074c6550a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068a=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07a=candidate:0 1 UDP 2113667327 192.168.1.4 54609 typ hosta=candidate:1 1 UDP 694302207 24.23.204.141 54609 typ srflx raddr 192.168.1.4 rport 54609a=candidate:0 2 UDP 2113667326 192.168.1.4 64678 typ hosta=candidate:1 2 UDP 1694302206 24.23.204.141 64678 typ srflx raddr 192.168.1.4 rport 64678a=rtcp-fb:120 nacka=rtcp-fb:120 nack plia=rtcp-fb:120 ccm fira=rtcp-rsizea=ice-options:trickle
This example show-cases SDP for negotiating a session with Audio, Video
and data streams between Alice and Bob with
support known
Bob: Offer(Audio:Opus, Video:VP8, Data)
note right of Alice
Alice indicates BUNDLE support with identical address across all the m=lines.
end note
Bob->Alice: Answer(Audio:Opus Video:VP8, Data)
note left of Bob
Bob does the same
end note
Alice<->Bob: Two way Audio, Video and Data multiplexed
]]>SDP Contents RFC#/Notesv=0o=- 20518 0 IN IP4 0.0.0.0s=-t=0 0a=msid-semantic:WMSa=group:BUNDLE audio video datam=audio 54609 UDP/TLS/RTP/SAVPF 109a=msid:ma ta Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (ta) c=IN IP4 24.23.204.141a=rtcp:64678 IN IP4 24.23.204.141a=mid:audioa=rtpmap:109 opus/48000/2a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-levela=ptime:20a=sendrecva=setup:actpassa=rtcp-muxa=ice-ufrag:074c6550a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068a=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07a=candidate:0 1 UDP 2113667327 192.168.1.4 54609 typ hosta=candidate:1 1 UDP 694302207 24.23.204.141 54609 typ srflx raddr 192.168.1.4 rport 54609a=candidate:0 2 UDP 2113667326 192.168.1.4 64678 typ hosta=candidate:1 2 UDP 1694302206 24.23.204.141 64678 typ srflx raddr 192.168.1.4 rport 64678a=rtcp-fb:109 nacka=ssrc:11111 cname:Q/NWs1ao1HmN4Xa5a=rtcp-rsizea=ice-options:tricklem=video 54609 UDP/TLS/RTP/SAVPF 120a=msid:ma tb Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (tb) c=IN IP4 24.23.204.141a=rtcp:64678 IN IP4 24.23.204.141a=mid:videoa=rtpmap:120 VP8/90000a=sendrecva=setup:actpassa=rtcp-muxa=ice-ufrag:074c6550a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068a=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07a=candidate:0 1 UDP 2113667327 192.168.1.4 54609 typ hosta=candidate:1 1 UDP 694302207 24.23.204.141 54609 typ srflx raddr 192.168.1.4 rport 54609a=candidate:0 2 UDP 2113667326 192.168.1.4 64678 typ hosta=candidate:1 2 UDP 1694302206 24.23.204.141 64678 typ srflx raddr 192.168.1.4 rport 64678a=rtcp-fb:120 nacka=rtcp-fb:120 nack plia=rtcp-fb:120 ccm fira=ssrc:22222 cname:Q/aoNWs11HmN4Xa5a=rtcp-rsizea=ice-options:tricklem=application 54609 DTLS/SCTP 5000c=IN IP4 24.23.204.141a=mid:dataa=sctpmap:5000 webrtc-Datachannel 1a=webrtc-Datachannel:5000 stream=1;label="channel 1";subprotocol="chat";a=sendrecva=setup:actpassa=ice-ufrag:074c6550a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068a=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07a=candidate:0 1 UDP 2113667327 192.168.1.4 54609 typ hosta=candidate:1 1 UDP 694302207 24.23.204.141 54609 typ srflx raddr 192.168.1.4 rport 54609a=ice-options:trickleSDP Contents RFC#/Notesv=0o=- 16833 0 IN IP4 0.0.0.0 - Session Origin Informations=-t=0 0a=msid-semantic:WMSa=group:BUNDLE audio video dataa=ice-options:trickle Bob's trickle support support
is indicated at the session levelm=audio 49203 UDP/TLS/RTP/SAVPF 109a=msid:ma ta Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (ta) c=IN IP4 98.248.92.77a=rtcp:60065 IN IP4 98.248.92.77a=mid:audioa=rtpmap:109 opus/48000/2a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-levela=ptime:20a=sendrecva=setup:activea=rtcp-muxa=rtcp-fb:109 nacka=ice-ufrag:c300d85ba=ice-pwd:de4e99bd291c325921d5d47efbabd9a2a=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07a=candidate:0 1 UDP 2113667327 192.168.1.7 49203 typ hosta=candidate:1 1 UDP 1694302207 98.248.92.77 49203 typ srflx raddr 192.168.1.7 rport 49203a=candidate:0 2 UDP 2113667326 192.168.1.7 60065 typ hosta=candidate:1 2 UDP 1694302206 98.248.92.77 60065 typ srflx raddr 192.168.1.7 rport 60065a=ssrc:33333 cname:L/aoNWs11HmN4Xa5a=rtcp-rsizem=video 49203 UDP/TLS/RTP/SAVPF 120a=msid:ma tb Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (tb) c=IN IP4 98.248.92.77a=rtcp:60065 IN IP4 98.248.92.77a=mid:videoa=rtpmap:120 VP8/90000a=sendrecva=setup:activea=rtcp-muxa=ice-ufrag:c300d85ba=ice-pwd:de4e99bd291c325921d5d47efbabd9a2a=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07a=candidate:0 1 UDP 2113667327 192.168.1.7 49203 typ hosta=candidate:1 1 UDP 1694302207 98.248.92.77 49203 typ srflx raddr 192.168.1.7 rport 49203a=candidate:0 2 UDP 2113667326 192.168.1.7 60065 typ hosta=candidate:1 2 UDP 1694302206 98.248.92.77 60065 typ srflx raddr 192.168.1.7 rport 60065a=rtcp-fb:120 nacka=rtcp-fb:120 nack plia=rtcp-fb:120 ccm fira=ssrc:44444 cname:EocUG1f0fcg/yvY7a=rtcp-rsizem=application 49203 DTLS/SCTP 5000c=IN IP4 98.248.92.771a=mid:dataa=sctpmap:5000 webrtc-Datachannel 1a=webrtc-Datachannel:5000 stream=1;label="channel 1";subprotocol="chat";a=setup:activea=sendrecva=ice-ufrag:c300d85ba=ice-pwd:de4e99bd291c325921d5d47efbabd9a2a=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07a=candidate:0 1 UDP 2113667327 192.168.1.7 49203 typ hosta=candidate:1 1 UDP 1694302207 98.248.92.77 49203 typ srflx raddr 192.168.1.7 rport 49203
This use-case illustrates SDP Offer/Answer exchange when the far-end (Bob)
either doesn't support media bundling or doesn't want to group m=lines over
a single 5-tuple. On successful Offer/Answer exchange, Alice and Bob each end up using unique
5-tuple for audio and video media streams respectively.Bob: Offer(Audio:Opus Video:VP8)
note right of Alice
Alice offers BUNDLE support with unique address for the audio and video m-line
end note
Bob->Alice: Answer(Audio:Opus Video:VP8)
note left of Bob
Bob uses unique addresses as well since he doesn't understand BUNDLE
end note
Alice <-> Bob: 2Way Call with Audio and Video on different addresses.
]]>SDP Contents RFC#/Notesv=0o=- 20518 0 IN IP4 0.0.0.0s=-t=0 0a=msid-semantic:WMSa=group:BUNDLE audio video
Alice supports grouping of m=lines under BUNDLE semanticsa=ice-options:tricklem=audio 55232 UDP/TLS/RTP/SAVPF 109a=msid:ma ta Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (ta) a=mid:audio Audio m=line part of BUNDLE group with a
unique port numberc=IN IP4 24.23.204.141a=rtcp:64678 IN IP4 24.23.204.141a=rtpmap:109 opus/48000/2a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-levela=ptime:20a=setup:actpass - Alice can perform DTLS before Answer arrivesa=sendrecva=rtcp-muxa=rtcp-fb:109 nacka=ssrc:11111 cname:EocUG1f0fcg/yvY7a=ice-ufrag:074c6550a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068a=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07a=candidate:0 1 UDP 2113667327 192.168.1.4 55232 typ hosta=candidate:1 1 UDP 694302207 24.23.204.141 55232 typ srflx raddr 192.168.1.4 rport 55232a=candidate:0 2 UDP 2113667326 192.168.1.4 64678 typ hosta=candidate:1 2 UDP 1694302206 24.23.204.141 64678 typ srflx raddr 192.168.1.4 rport 64678a=rtcp-rsizem=video 54332 UDP/TLS/RTP/SAVPF 120a=msid:ma tb Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (tb) a=mid:video Video m=line part of the BUNDLE group with a
unique port numberc=IN IP4 24.23.204.141a=rtcp:54721 IN IP4 24.23.204.141a=rtpmap:120 VP8/90000a=sendrecva=setup:actpass - Alice can perform DTLS before Answer arrivesa=rtcp-muxa=ssrc:22222 cname:yvY7/EocUG1f0fcga=ice-ufrag:7872093a=ice-pwd:ee3474af08a068a28a397a4c3f31747d1a=fingerprint:sha-1 6d:f7:c9:c7:70:9d:1f:66:79:a8:07:99:41:49:83:4a:97:0e:1f:efa=candidate:0 1 UDP 2113667327 192.168.1.4 54332 typ hosta=candidate:1 1 UDP 1694302207 24.23.204.141 54332 typ srflx raddr 192.168.1.4 rport 54332a=candidate:0 2 2113667326 192.168.1.4 54721 typ hosta=candidate:1 2 UDP 1694302206 24.23.204.141 54721 typ srflx raddr 192.168.1.4 rport 54721a=rtcp-fb:120 nacka=rtcp-fb:120 nack plia=rtcp-fb:120 ccm fira=rtcp-rsizeSDP Contents RFC#/Notesv=0o=- 16833 0 IN IP4 0.0.0.0s=-t=0 0a=msid-semantic:WMSa=ice-options:tricklem=audio 53214 UDP/TLS/RTP/SAVPF 109a=msid:ma ta Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (ta) c=IN IP4 98.248.92.77a=rtcp:60065 IN IP4 98.248.92.77a=rtpmap:109 opus/48000/2a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-levela=ptime:20a=setup:active - Bob carries out DTLS Handshake in parallela=sendrecva=rtcp-fb:109 nacka=ice-ufrag:c300d85ba=ice-pwd:de4e99bd291c325921d5d47efbabd9a2a=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07a=candidate:0 1 UDP 2113667327 192.168.1.7 53214 typ hosta=candidate:1 1 UDP 1694302207 98.248.92.77 53214 typ srflx raddr 192.168.1.7 rport 53214a=candidate:0 2 UDP 2113667326 192.168.1.7 60065 typ hosta=candidate:1 2 UDP 1694302206 98.248.92.77 60065 typ srflx raddr 192.168.1.7 rport 60065a=rtcp-rsizem=video 58679 UDP/TLS/RTP/SAVPF 120a=msid:ma tb Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (tb) c=IN IP4 98.248.92.77a=rtcp:56507 IN IP4 98.248.92.77a=rtpmap:120 VP8/90000a=setup:active - Bob carries out DTLS Handshake in parallela=sendrecva=ice-ufrag:85bC300a=ice-pwd:325921d5d47efbabd9a2de4e99bd291ca=fingerprint:sha-1 9d:1f:66:79:a8:07:99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70a=candidate:0 1 UDP 2113667327 192.168.1.7 58679 typ hosta=candidate:1 1 UDP 1694302207 98.248.92.77 58679 typ srflx raddr 192.168.1.7 rport 58679a=candidate:0 2 UDP 2113667326 192.168.1.7 56607 typ hosta=candidate:1 2 UDP 1694302206 98.248.92.77 56607 typ srflx raddr 192.168.1.7 rport 56607a=rtcp-fb:120 nacka=rtcp-fb:120 nack plia=rtcp-fb:120 ccm fira=rtcp-rsize
This example show-cases SDP for negotiating a session with Audio, Video
and data streams between Alice and Bob but with data stream not part of
the BUNDLE group. This is shown by assigning unique port for data media
sections.
Bob: Offer(Audio:Opus, Video:VP8, Data (Not in BUNDLE)
note right of Alice
Alice wants to multiplex audio, video but not data
end note
Bob->Alice: Answer(Audio:Opus Video:VP8, Data)
note left of Bob
Bob does the same
end note
Alice<->Bob: Two way Audio, Video multiplexed except Data
]]>SDP Contents RFC#/Notesv=0o=- 20518 0 IN IP4 0.0.0.0s=-t=0 0a=msid-semantic:WMSa=group:BUNDLE audio video
Alice wants to BUNDLE only audio and video media.a=ice-options:tricklem=audio 54609 UDP/TLS/RTP/SAVPF 109a=msid:ma ta Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (ta) c=IN IP4 24.23.204.141a=rtcp:64678 IN IP4 24.23.204.141a=mid:audioa=rtpmap:109 opus/48000/2a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-levela=ptime:20a=sendrecva=setup:actpassa=rtcp-muxa=ice-ufrag:074c6550a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068a=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07a=candidate:0 1 UDP 2113667327 192.168.1.4 54609 typ hosta=candidate:1 1 UDP 694302207 24.23.204.141 54609 typ srflx raddr 192.168.1.4 rport 54609a=candidate:0 2 UDP 2113667326 192.168.1.4 64678 typ hosta=candidate:1 2 UDP 1694302206 24.23.204.141 64678 typ srflx raddr 192.168.1.4 rport 64678a=rtcp-fb:109 nacka=ssrc:11111 cname:Q/NWs1ao1HmN4Xa5a=rtcp-rsizem=video 54609 UDP/TLS/RTP/SAVPF 120a=msid:ma tb Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (tb) c=IN IP4 24.23.204.141a=rtcp:64678 IN IP4 24.23.204.141a=mid:videoa=rtpmap:120 VP8/90000a=sendrecva=setup:actpassa=rtcp-muxa=ice-ufrag:074c6550a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068a=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07a=candidate:0 1 UDP 2113667327 192.168.1.4 54609 typ hosta=candidate:1 1 UDP 694302207 24.23.204.141 54609 typ srflx raddr 192.168.1.4 rport 54609a=candidate:0 2 UDP 2113667326 192.168.1.4 64678 typ hosta=candidate:1 2 UDP 1694302206 24.23.204.141 64678 typ srflx raddr 192.168.1.4 rport 64678a=rtcp-fb:120 nacka=rtcp-fb:120 nack plia=rtcp-fb:120 ccm fira=ssrc:22222 cname:Q/aoNWs11HmN4Xa5a=rtcp-rsizem=application 10000 DTLS/SCTP 5000c=IN IP4 24.23.204.141a=mid:dataa=sctpmap:5000 webrtc-Datachannel 1a=webrtc-Datachannel:5000 stream=1;label="channel 1";subprotocol="chat";a=sendrecva=setup:actpassa=ice-ufrag:89819013a=ice-pwd:1747d1ee3474af08a068a28a397a4c3f3a=fingerprint:sha-1 0e:1f:ef:6d:f7:c9:c7:70:99:41:49:83:4a:97:9d:1f:66:79:a8:07a=candidate:0 1 UDP 2113667327 192.168.1.4 10000 typ hosta=candidate:1 1 UDP 694302207 24.23.204.141 10000 typ srflx raddr 192.168.1.4 rport 10000SDP Contents RFC#/Notesv=0o=- 16833 0 IN IP4 0.0.0.0 - Session Origin Informations=-t=0 0a=msid-semantic:WMSa=group:BUNDLE audio videoa=ice-options:tricklem=audio 49203 UDP/TLS/RTP/SAVPF 109a=msid:ma ta Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (ta) c=IN IP4 98.248.92.77a=rtcp:60065 IN IP4 98.248.92.77a=mid:audioa=rtpmap:109 opus/48000/2a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-levela=ptime:20a=sendrecva=setup:activea=rtcp-muxa=rtcp-fb:109 nacka=ice-ufrag:c300d85ba=ice-pwd:de4e99bd291c325921d5d47efbabd9a2a=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07a=candidate:0 1 UDP 2113667327 192.168.1.7 49203 typ hosta=candidate:1 1 UDP 1694302207 98.248.92.77 49203 typ srflx raddr 192.168.1.7 rport 49203a=candidate:0 2 UDP 2113667326 192.168.1.7 60065 typ hosta=candidate:1 2 UDP 1694302206 98.248.92.77 60065 typ srflx raddr 192.168.1.7 rport 60065a=ssrc:33333 cname:L/aoNWs11HmN4Xa5a=rtcp-rsizem=video 49203 UDP/TLS/RTP/SAVPF 120a=msid:ma tb Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (tb) c=IN IP4 98.248.92.771a=rtcp:60065 IN IP4 98.248.92.77a=mid:videoa=rtpmap:120 VP8/90000a=sendrecva=setup:activea=rtcp-muxa=ice-ufrag:c300d85ba=ice-pwd:de4e99bd291c325921d5d47efbabd9a2a=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07a=candidate:0 1 UDP 2113667327 192.168.1.7 49203 typ hosta=candidate:1 1 UDP 1694302207 98.248.92.77 49203 typ srflx raddr 192.168.1.7 rport 49203a=candidate:0 2 UDP 2113667326 192.168.1.7 60065 typ hosta=candidate:1 2 UDP 1694302206 98.248.92.77 60065 typ srflx raddr 192.168.1.7 rport 60065a=rtcp-fb:120 nacka=rtcp-fb:120 nack plia=rtcp-fb:120 ccm fira=ssrc:44444 cname:EocUG1f0fcg/yvY7a=rtcp-rsizem=application 20000 DTLS/SCTP 5000c=IN IP4 98.248.92.77a=mid:dataa=sctpmap:5000 webrtc-Datachannel 1a=webrtc-Datachannel:5000 stream=1;label="channel 1";subprotocol="chat";a=setup:activea=sendrecva=ice-ufrag:991Ca2a5ea=ice-pwd:921d5d47efbabd9a2de4e99bd291c325 - Session Level ICE passworda=fingerprint:sha-1 6d:f7:c9:c7:70:9d:1f:66:79:a8:07:99:41:49:83:4a:97:0e:1f:efa=candidate:0 1 UDP 2113667327 192.168.1.7 20000 typ hosta=candidate:1 1 UDP 1694302207 98.248.92.77 20000 typ srflx raddr 192.168.1.7 rport 20000
This example involves 2 Offer/Answer exchanges. First one setting up
Audio-only session followed by an updated Offer/Answer exchange to add
video stream to the ongoing session. Also the newly added video stream
is BUNDLED with the audio stream.
Bob: Offer(Audio:Opus)
note right of Alice
Alice indicates support for BUNDLE
end note
Bob->Alice: Answer(Audio:Opus)
note left of Bob
Bob also indicates support for BUNDLE
end note
Alice<->Bob: Two way Audio only session
Alice->Bob: Updated Offer(Audio:Opus, Video:VP8)
note right of Alice
Alice adds video stream to BUNDLE with audio
end note
Bob->Alice: Updated Answer(Audio:Opus, Video:VP8)
note left of Bob
Bob also does the same
end note
Alice<->Bob: Two way Opus Audio and VP8 Video session
]]>SDP Contents RFC#/Notesv=0o=- 20518 0 IN IP4 0.0.0.0s=-t=0 0a=msid-semantic:WMSa=group:BUNDLE audio
Alice wants to BUNDLE only audio and video media.a=ice-options:tricklem=audio 54609 UDP/TLS/RTP/SAVPF 109a=msid:ma ta Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (ta) c=IN IP4 24.23.204.141a=rtcp:64678 IN IP4 24.23.204.141a=mid:audioa=rtpmap:109 opus/48000/2a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-levela=ptime:20a=sendrecva=setup:actpassa=rtcp-muxa=ice-ufrag:074c6550a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068a=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07a=candidate:0 1 UDP 2113667327 192.168.1.4 54609 typ hosta=candidate:1 1 UDP 694302207 24.23.204.141 54609 typ srflx raddr 192.168.1.4 rport 54609a=candidate:0 2 UDP 2113667326 192.168.1.4 64678 typ hosta=candidate:1 2 UDP 1694302206 24.23.204.141 64678 typ srflx raddr 192.168.1.4 rport 64678a=rtcp-fb:109 nacka=ssrc:11111 cname:Q/NWs1ao1HmN4Xa5a=rtcp-rsizeSDP Contents RFC#/Notesv=0o=- 16833 0 IN IP4 0.0.0.0 - Session Origin Informations=-t=0 0a=msid-semantic:WMSa=group:BUNDLE audioa=ice-options:tricklem=audio 49203 UDP/TLS/RTP/SAVPF 109a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-levela=msid:ma ta Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (ta) c=IN IP4 98.248.92.77a=rtcp:60065 IN IP4 98.248.92.77a=mid:audioa=rtpmap:109 opus/48000/2a=ptime:20a=sendrecva=setup:activea=rtcp-muxa=rtcp-fb:109 nacka=ice-ufrag:c300d85ba=ice-pwd:de4e99bd291c325921d5d47efbabd9a2a=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07a=candidate:0 1 UDP 2113667327 192.168.1.7 49203 typ hosta=candidate:1 1 UDP 1694302207 98.248.92.77 49203 typ srflx raddr 192.168.1.7 rport 49203a=candidate:0 2 UDP 2113667326 192.168.1.7 60065 typ hosta=candidate:1 2 UDP 1694302206 98.248.92.77 60065 typ srflx raddr 192.168.1.7 rport 60065a=ssrc:33333 cname:L/aoNWs11HmN4Xa5a=rtcp-rsizeSDP Contents RFC#/Notesv=1 Version number incrementedo=- 20518 0 IN IP4 0.0.0.0s=-t=0 0a=msid-semantic:WMSa=group:BUNDLE audio video
Alice wants to BUNDLE only audio and video media.a=ice-options:tricklem=audio 54609 UDP/TLS/RTP/SAVPF 109a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-levela=msid:ma ta Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (ta) c=IN IP4 24.23.204.141a=rtcp:64678 IN IP4 24.23.204.141a=mid:audioa=rtpmap:109 opus/48000/2a=ptime:20a=sendrecva=setup:actpassa=rtcp-muxa=ice-ufrag:074c6550a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068a=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07a=candidate:0 1 UDP 2113667327 192.168.1.4 54609 typ hosta=candidate:1 1 UDP 694302207 24.23.204.141 54609 typ srflx raddr 192.168.1.4 rport 54609a=candidate:0 2 UDP 2113667326 192.168.1.4 64678 typ hosta=candidate:1 2 UDP 1694302206 24.23.204.141 64678 typ srflx raddr 192.168.1.4 rport 64678a=rtcp-fb:109 nacka=ssrc:11111 cname:Q/NWs1ao1HmN4Xa5a=rtcp-rsizem=video 54609 UDP/TLS/RTP/SAVPF 120a=msid:ma tb Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (tb) c=IN IP4 24.23.204.141a=rtcp:64678 IN IP4 24.23.204.141a=mid:videoa=rtpmap:120 VP8/90000a=sendrecva=setup:actpassa=rtcp-muxa=ice-ufrag:074c6550a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068a=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07a=candidate:0 1 UDP 2113667327 192.168.1.4 54609 typ hosta=candidate:1 1 UDP 694302207 24.23.204.141 54609 typ srflx raddr 192.168.1.4 rport 54609a=candidate:0 2 UDP 2113667326 192.168.1.4 64678 typ hosta=candidate:1 2 UDP 1694302206 24.23.204.141 64678 typ srflx raddr 192.168.1.4 rport 64678a=rtcp-fb:120 nacka=rtcp-fb:120 nack plia=rtcp-fb:120 ccm fira=ssrc:22222 cname:Q/aoNWs11HmN4Xa5a=rtcp-rsizeSDP Contents RFC#/Notesv=1 Version number incrementedo=- 16833 0 IN IP4 0.0.0.0 - Session Origin Informations=-t=0 0a=msid-semantic:WMSa=group:BUNDLE audio videoa=ice-options:tricklem=audio 49203 UDP/TLS/RTP/SAVPF 109a=msid:ma ta Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (ta) c=IN IP4 98.248.92.77a=rtcp:60065 IN IP4 98.248.92.77a=mid:audioa=rtpmap:109 opus/48000/2a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-levela=ptime:20a=sendrecva=setup:activea=rtcp-muxa=rtcp-fb:109 nacka=ice-ufrag:c300d85ba=ice-pwd:de4e99bd291c325921d5d47efbabd9a2a=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07a=candidate:0 1 UDP 2113667327 192.168.1.7 49203 typ hosta=candidate:1 1 UDP 1694302207 98.248.92.77 49203 typ srflx raddr 192.168.1.7 rport 49203a=candidate:0 2 UDP 2113667326 192.168.1.7 60065 typ hosta=candidate:1 2 UDP 1694302206 98.248.92.77 60065 typ srflx raddr 192.168.1.7 rport 60065a=ssrc:33333 cname:L/aoNWs11HmN4Xa5a=rtcp-rsizem=video 49203 UDP/TLS/RTP/SAVPF 120a=msid:ma tb Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (tb) c=IN IP4 98.248.92.77a=rtcp:60065 IN IP4 98.248.92.77a=mid:videoa=rtpmap:120 VP8/90000a=sendrecva=setup:activea=rtcp-muxa=ice-ufrag:c300d85ba=ice-pwd:de4e99bd291c325921d5d47efbabd9a2a=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07a=candidate:0 1 UDP 2113667327 192.168.1.7 49203 typ hosta=candidate:1 1 UDP 1694302207 98.248.92.77 49203 typ srflx raddr 192.168.1.7 rport 49203a=candidate:0 2 UDP 2113667326 192.168.1.7 60065 typ hosta=candidate:1 2 UDP 1694302206 98.248.92.77 60065 typ srflx raddr 192.168.1.7 rport 60065a=rtcp-fb:120 nacka=rtcp-fb:120 nack plia=rtcp-fb:120 ccm fira=ssrc:44444 cname:EocUG1f0fcg/yvY7a=rtcp-rsize
This section deals with scenarios related to multiresolution negotiation
such as layered coding, simulcast, along with techniques that deal with
providing robustness against transmission errors such as FEC and RTX.
Also to note, meachnisms such as FEC and RTX could be envisioned in the
above basic scenarios as well.
This SDP below shows Offer/Answer exchange with an audio and two video streams
each of which can be sent at two different resolutions. One video stream supports VP8, while the other supports H.264. bundle-only framework is used along with BUNDLE grouping framework
to enable multiplexing of all the 5 streams (1 audio stream + 4 video streams)
over a single RTP Session.
Bob: Offer(Audio:Opus,Video1:VP8,Video2:H.264) with bundle-only for video
note left of Bob
Bob accepts Alice's offer and 2 encodings per stream
end note
Alice->Bob: One-Way 1 Opus, 2 H.264 and 2 VP8 video streams, all mulitplexed
]]>SDP Contents RFC#/Notesv=0o=- 20519 0 IN IP4 0.0.0.0s=-t=0 0a=msid-semantic:WMSa=group:BUNDLE m0 m1 m2
Alice supports grouping of m=lines under BUNDLE semanticsa=ice-options:tricklem=audio 54609 UDP/TLS/RTP/SAVPF 109a=msid:ma ta Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (ta) c=IN IP4 24.23.204.141a=rtcp:64678 IN IP4 24.23.204.141a=mid:m0 Audio m=line part of BUNDLE group
with a unique port numbera=rtpmap:109 opus/48000/2a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-levela=ptime:20a=sendonlya=setup:actpass - Alice can perform DTLS before Answer arrivesa=rtcp-muxa=rtcp-fb:109 nacka=ssrc:11111 EocUG1f0fcga=ice-ufrag:074c6550a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068a=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07a=candidate:0 1 UDP 2113667327 192.168.1.4 54609 typ hosta=candidate:1 1 UDP 694302207 24.23.204.141 54609 typ srflx raddr 192.168.1.4 rport 54609a=candidate:0 2 UDP 2113667326 192.168.1.4 64678 typ hosta=candidate:1 2 UDP 1694302206 24.23.204.141 64678 typ srflx raddr 192.168.1.4 rport 64678a=rtcp-rsizem=video 0 UDP/TLS/RTP/SAVPF 98 100 bundle-only video line with port number set to zeroa=msid:ma tb Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (tb) c=IN IP4 24.23.204.141a=rtcp:64678 IN IP4 24.23.204.141a=mid:m1 Video m=line part of BUNDLE groupa=rtpmap:98 VP8/90000a=rtpmap:100 VP8/90000a=imageattr:98 [x=1280,y=720]Camera-1,Encoding-1 Resolutiona=fmtp:98 max-fr=30a=imageattr:100 [x=640,y=480] Camera-1,Encoding-2 Resolutiona=fmtp:100 max-fr=15a=ssrc-group:SIMULCAST 12345 45678a=ssrc:12345 cname:axzo1278npDlAzM73
Camera-1,Encoding-1 SSRC with Session CNAMEa=ssrc:45678 cname:axzo1278npDlAzM73
Camera-1,Encoding-2 SSRC with Session CNAMEa=sendonly - Send only video streama=rtcp-muxa=bundle-onlya=rtcp-fb:98 nacka=rtcp-fb:98 nack plia=rtcp-fb:98 ccm fira=rtcp-fb:100 nacka=rtcp-fb:100 nack plia=rtcp-fb:100 ccm fira=rtcp-rsizem=video 0 UDP/TLS/RTP/SAVPF 101 102 bundle-only video line with port number set to zero a=msid:ma tc Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (tc) c=IN IP4 24.23.204.141a=rtcp:64678 IN IP4 24.23.204.141a=mid:m2 Video m=line part of BUNDLE groupa=rtpmap:101 H264/90000a=rtpmap:102 H264/90000a=fmtp:101 profile-level-id=4d0028;packetization-mode=1;max-fr=30 Camera-2,Encoding-1 Resolutiona=fmtp:102 profile-level-id=4d0028;packetization-mode=1;max-fr=15Camera-1,Encoding-2 Resolutiona=ssrc-group:SIMULCAST 67890 56789a=ssrc:67890 cname:axzo1278npDlAzM73
Camera-1,Encoding-1 SSRC with Session CNAMEa=ssrc:56789 cname:axzo1278npDlAzM73
Camera-1,Encoding-2 SSRC with Session CNAMEa=sendonly - Send only video streama=rtcp-muxa=bundle-onlya=rtcp-fb:101 nacka=rtcp-fb:101 nack plia=rtcp-fb:101 ccm fira=rtcp-fb:102 nacka=rtcp-fb:102 nack plia=rtcp-fb:102 ccm fira=rtcp-rsizeSDP Contents RFC#/Notesv=0o=- 20519 0 IN IP4 0.0.0.0s=-t=0 0a=msid-semantic:WMSa=group:BUNDLE m0 m1 m2
Alice supports grouping of m=lines under BUNDLE semanticsa=ice-options:tricklem=audio 49203 UDP/TLS/RTP/SAVPF 109c=IN IP4 98.248.92.77a=rtcp:60065 IN IP4 98.248.92.77a=mid:m0 Audio m=line part of BUNDLE group
with a unique port numbera=msid:ma ta Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (ta) a=rtpmap:109 opus/48000/2a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-levela=rtcp-fb:109 nacka=ptime:20a=sendonlya=setup:active - Bob carries out DTLS Handshake in parallela=rtcp-muxa=ssrc:22222 cname:y8/C90alEocUG1f0fcga=ice-ufrag:c300d85ba=ice-pwd:de4e99bd291c325921d5d47efbabd9a2a=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07a=candidate:0 1 UDP 2113667327 192.168.1.7 49203 typ hosta=candidate:1 1 UDP 694302207 98.248.92.77 49203 typ srflx raddr 192.168.1.4 rport 49203a=candidate:0 2 UDP 2113667326 192.168.1.7 64678 typ hosta=candidate:1 2 UDP 1694302206 98.248.92.77 60065 typ srflx raddr 192.168.1.4 rport 60065a=rtcp-rsizem=video 49203 UDP/TLS/RTP/SAVPF 98 100 BUNDLE accepted with port repeated from the audio port a=msid:ma tb Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (tb) c=IN IP4 98.248.92.77a=rtcp:60065 IN IP4 98.248.92.77a=mid:m1 Video m=line part of BUNDLE groupa=rtpmap:98 VP8/90000a=rtpmap:100 VP8/90000a=imageattr:98 [x=1280,y=720]Camera-1,Encoding-1 Resolutiona=fmtp:98 max-fr=30a=imageattr:100 [x=640,y=480] Camera-1,Encoding-2 Resolutiona=fmtp:100 max-fr=15a=recvonly - receive only video streama=ssrc:54321 cname:axzo1278npDlAzM73a=ice-ufrag:c300d85ba=ice-pwd:de4e99bd291c325921d5d47efbabd9a2a=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07a=candidate:0 1 UDP 2113667327 192.168.1.7 49203 typ hosta=candidate:1 1 UDP 694302207 98.248.92.77 49203 typ srflx raddr 192.168.1.4 rport 49203a=candidate:0 2 UDP 2113667326 192.168.1.7 60065 typ hosta=candidate:1 2 UDP 1694302206 98.248.92.77 60065 typ srflx raddr 192.168.1.4 rport 60065a=setup:active - Bob carries out DTLS Handshake in parallela=rtcp-mux a=bundle-onlya=rtcp-rsizem=video 54609 UDP/TLS/RTP/SAVPF 101 102 BUNDLE accepted with port repeated from the audio port c=IN IP4 98.248.92.77a=rtcp:56503 IN IP4 98.248.92.77a=msid:ma tc Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (tc) a=mid:m2 Video m=line part of BUNDLE groupa=rtpmap:101 H264/90000a=rtpmap:102 H264/90000a=recvonly - Send only video streama=fmtp:101 profile-level-id=4d0028;packetization-mode=1;max-fr=30 Camera-2,Encoding-1 Resolutiona=fmtp:102 profile-level-id=4d0028;packetization-mode=1;max-fr=15Camera-1,Encoding-2 Resolutiona=ssrc:90876 cname:axzo1278npDlAzM73a=ice-ufrag:ufrag:c300d85ba=ice-pwd:de4e99bd291c325921d5d47efbabd9a2a=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07a=candidate:0 1 UDP 2113667327 192.168.1.7 49203 typ hosta=candidate:1 1 UDP 694302207 98.248.92.77 49203 typ srflx raddr 192.168.1.7 rport 49203a=candidate:0 2 UDP 2113667326 192.168.1.7 60065 typ hosta=candidate:1 2 UDP 1694302206 98.248.92.77 60065 typ srflx raddr 192.168.1.7 rport 60065a=setup:active - Bob carries out DTLS Handshake in parallela=rtcp-mux a=bundle-onlya=rtcp-rsize This section shows an SDP Offer/Answer for a session with an audio and a single video
stream. The video stream is layered coding at 3 different
resolutions based on . The video m=line shows 3 streams
with last stream (payload 100) dependent on streams with payload 96
and 97 for decoding.
Bob: Offer(Audio:Opus Video: H.264 SVC) bundle-only
note left of Bob
Bob accepts Alice's Offered Codec operation points
end note
Bob->Alice: Answer(Video: H.264) bundle-only
Alice->Bob: One-Way H.264 Video with codec points as indicated by Bob.
]]>SDP Contents RFC#/Notesv=0o=- 20519 0 IN IP4 0.0.0.0s=-t=0 0a=msid-semantic:WMSa=group:BUNDLE m0 m1
Alice supports grouping of m=lines under BUNDLE semanticsa=ice-options:tricklem=audio 54609 UDP/TLS/RTP/SAVPF 109 a=msid:ma ta Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (ta) c=IN IP4 24.23.204.141a=rtcp:64678 IN IP4 24.23.204.141a=mid:m0 Audio m=line part of BUNDLE group
with a unique port numbera=rtpmap:109 opus/48000/2a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-levela=ptime:20a=sendonlya=rtcp-fb:109 nacka=setup:actpass - Alice can perform DTLS before Answer arrivesa=rtcp-muxa=ice-ufrag:074c6550a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068a=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07a=candidate:0 1 UDP 2113667327 192.168.1.4 54609 typ hosta=candidate:1 1 UDP 694302207 24.23.204.141 54609 typ srflx raddr 192.168.1.4 rport 54609a=candidate:0 2 UDP 2113667326 192.168.1.4 64678 typ hosta=candidate:1 2 UDP 1694302206 24.23.204.141 64678 typ srflx raddr 192.168.1.4 rport 64678a=ssrc:67890 cname:axzo1278npDlAzM73a=rtcp-rsizem=video 0 UDP/TLS/RTP/SAVPF 96 97 100bundle-only video line with port number set to zeroa=msid:ma tb Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (tc) c=IN IP4 24.23.204.141a=rtcp:64678 IN IP4 24.23.204.141a=mid:m1 Audio m=line part of BUNDLE groupa=msid:ma tba=rtpmap:96 H264/90000a=fmtp:96 profile-level-id=4d0028;packetization-mode=1;max-fr=30;max-fs=8040H.264 Layer 1a=rtpmap:97 H264/90000a=fmtp:97 profile-level-id=4d0028;packetization-mode=1;max-fr=15;max-fs=1200 H.264 Layer 2a=rtpmap:100 H264-SVC/90000a=fmtp:100 profile-level-id=4d0028;packetization-mode=1;max-fr=30;max-fs=8040a=depend:100 lay m1:96,97;Layer 3 dependent on layers 1 and 2a=sendonly - Send only video streama=rtcp-muxa=bundle-onlya=ssrc:1732846380 cname:axzo1278npDlAzM73a=ssrc:1732846381 cname:axzo1278npDlAzM73a=ssrc:1732846382 cname:axzo1278npDlAzM73a=rtcp-fb:* nacka=rtcp-fb:* nack plia=rtcp-fb:* ccm fira=rtcp-rsizeSDP Contents RFC#/Notesv=0o=- 20519 0 IN IP4 0.0.0.0s=-t=0 0a=msid-semantic:WMSa=group:BUNDLE m0 m1
Alice supports grouping of m=lines under BUNDLE semanticsa=ice-options:tricklem=audio 49203 UDP/TLS/RTP/SAVPF 109 a=msid:ma ta Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (ta) c=IN IP4 98.248.92.77a=rtcp:60065 IN IP4 98.248.92.77a=mid:m0 Audio m=line part of BUNDLE group
with a unique port numbera=rtpmap:109 opus/48000/2a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-levela=ptime:20a=rtcp-fb:109 nacka=recvonlya=setup:active - Bob carries out DTLS Handshake in parallela=rtcp-muxa=ice-ufrag:074c6550a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068a=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07a=candidate:0 1 UDP 2113667327 192.168.1.7 54609 typ hosta=candidate:1 1 UDP 694302207 98.248.92.77 49203 typ srflx raddr 192.168.1.5 rport 49203a=candidate:0 2 UDP 2113667326 192.168.1.7 60065 typ hosta=candidate:1 2 UDP 1694302206 98.248.92.77 60065 typ srflx raddr 192.168.1.5 rport 60065a=rtcp-rsizem=video 54609 UDP/TLS/RTP/SAVPF 96 100 BUNDLE accepted Bundle address same as audio m=line.a=msid:ma tb Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (tb) c=IN IP4 98.248.92.77a=rtcp:56503 IN IP4 98.248.92.77a=mid:m1 Video m=line part of BUNDLE groupa=rtpmap:96 H264/90000a=fmtp:96 profile-level-id=4d0028;packetization-mode=1;max-fr=30;max-fs=8040H.264 Layer 1a=rtpmap:100 H264-SVC/90000a=fmtp:100 profile-level-id=4d0028;packetization-mode=1;max-fr=30;max-fs=8040a=depend:100 lay m1:96; Bob chooses 2 Codec Operation pointsa=ice-ufrag:074c6550a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068a=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07a=candidate:0 1 UDP 2113667327 192.168.1.5 54609 typ hosta=candidate:1 1 UDP 694302207 24.23.204.142 54609 typ srflx raddr 192.168.1.5 rport 54609a=candidate:0 2 UDP 2113667326 192.168.1.5 64678 typ hosta=candidate:1 2 UDP 1694302206 24.23.204.142 64678 typ srflx raddr 192.168.1.5 rport 64678a=recvonly - Receive only video streama=setup:active - Bob carries out DTLS Handshake in parallela=rtcp-muxa=bundle-onlya=ssrc:4638117328 cname:axzo1278npDlAzM73a=rtcp-rsize
This section shows an SDP Offer/Answer exchange for a simulcast scenario
with 2 two resolutions and has
style re-transmission flows.
Bob: Offer(Audio:Opus Video:VP8 with 2 resolutions and RTX Stream) bundle-only
note left of Bob
Bob accepts all the streams offered by Alice
end note
Bob->Alice: Answer(Audio:Opus Video:VP8 with 2 resolutions and RTX Stream) bundle-only
Alice<->Bob: 2 Way Audio and Simulcast Video with RTX Streams
]]>SDP Contents RFC#/Notesv=0o=- 20519 0 IN IP4 0.0.0.0s=-t=0 0a=msid-semantic:WMSa=group:BUNDLE m0 m1
Alice supports grouping of m=lines under BUNDLE semanticsa=ice-options:tricklem=audio 54609 UDP/TLS/RTP/SAVPF 109 a=msid:ma ta Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (ta) c=IN IP4 24.23.204.141a=rtcp:64678 IN IP4 24.23.204.141a=mid:m0 Audio m=line part of BUNDLE group
with a unique port numbera=rtpmap:109 opus/48000/2a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-levela=ptime:20a=rtcp-fb:109 nacka=sendrecva=setup:actpass - Alice can perform DTLS before Answer arrivesa=rtcp-muxa=ssrc:11111 cname:EocUG1f0fcg/yvY7a=ice-ufrag:074c6550a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068a=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07a=candidate:0 1 UDP 2113667327 192.168.1.4 54609 typ hosta=candidate:1 1 UDP 694302207 24.23.204.141 54609 typ srflx raddr 192.168.1.4 rport 54609a=candidate:0 2 UDP 2113667326 192.168.1.4 64678 typ hosta=candidate:1 2 UDP 1694302206 24.23.204.141 64678 typ srflx raddr 192.168.1.4 rport 64678a=rtcp-rsizem=video 0 UDP/TLS/RTP/SAVPF 98 100 101 103bundle-only video line with port number set to zeroa=msid:ma tb Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (tb) c=IN IP4 24.23.204.141a=rtcp:64678 IN IP4 24.23.204.141a=mid:m1 Audio m=line part of BUNDLE groupa=rtpmap:98 VP8/90000a=rtpmap:100 VP8/90000a=rtpmap:101 VP8/90000a=rtpmap:103 VP8/90000a=fmtp:98 max-fr=30;max-fs=8040a=fmtp:100 max-fr=15;max-fs=1200a=fmtp:101 apt=98;rtx-time=3000a=fmtp:103 apt=100;rtx-time=3000a=ssrc-group:SIMULCAST 12345 78990 Simulcast group a=ssrc-group:FID 12345 34567 a=ssrc-group:FID 78990 90887 a=ssrc:12345 cname:Q/NWs1ao1HmN4Xa5a=ssrc:78990 cname:Q/NWs1ao1HmN4Xa5a=ssrc:34567 cname:Q/NWs1ao1HmN4Xa5a=ssrc:90887 cname:Q/NWs1ao1HmN4Xa5a=sendrecva=rtcp-muxa=bundle-onlya=rtcp-fb:* nacka=rtcp-fb:* nack plia=rtcp-fb:* ccm fira=rtcp-rsizeSDP Contents RFC#/Notesv=0o=- 20519 0 IN IP4 0.0.0.0s=-t=0 0a=msid-semantic:WMSa=group:BUNDLE m0 m1
Alice supports grouping of m=lines under BUNDLE semanticsa=ice-options:tricklem=audio 49203 UDP/TLS/RTP/SAVPF 109 a=msid:ma ta Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (ta) c=IN IP4 98.248.92.77a=rtcp:60065 IN IP4 98.248.92.77a=mid:m0 Audio m=line part of BUNDLE group
with a unique port numbera=rtpmap:109 opus/48000/2a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-levela=ptime:20a=rtcp-fb:109 nacka=sendrecva=setup:activea=rtcp-muxa=ssrc:33333 cname:L/HmN4Xa5NWs1ao1a=ice-ufrag:074c6550a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068a=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07a=candidate:0 1 UDP 2113667327 192.168.1.7 54609 typ hosta=candidate:1 1 UDP 694302207 98.248.92.77 54609 typ srflx raddr 192.168.1.7 rport 49203a=candidate:0 2 UDP 2113667326 192.168.1.7 64678 typ hosta=candidate:1 2 UDP 1694302206 98.248.92.77 64678 typ srflx raddr 192.168.1.7 rport 60065a=rtcp-rsizem=video 49203 UDP/TLS/RTP/SAVPF 98 100 101 103BUNDLE accepted with Bundle address identical to audio m-linea=msid:ma tb Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (tb) c=IN IP4 98.248.92.77a=rtcp:60065 IN IP4 98.248.92.77a=mid:m1 Video m=line part of BUNDLE groupa=rtpmap:98 VP8/90000a=rtpmap:100 VP8/90000a=rtpmap:101 VP8/90000a=rtpmap:103 VP8/90000a=fmtp:98 max-fr=30;max-fs=8040a=fmtp:100 max-fr=15;max-fs=1200a=fmtp:101 apt=98;rtx-time=3000a=fmtp:103 apt=100;rtx-time=3000a=ice-ufrag:074c6550a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068a=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07a=candidate:0 1 UDP 2113667327 192.168.1.7 49203 typ hosta=candidate:1 1 UDP 694302207 98.248.92.77 49203 typ srflx raddr 192.168.1.7 rport 49203a=candidate:0 2 UDP 2113667326 192.168.1.7 60065 typ hosta=candidate:1 2 UDP 1694302206 98.248.92.772 60065 typ srflx raddr 192.168.1.7 rport 60065a=ssrc-group:SIMULCAST 54321 77656 Simulcast group a=ssrc-group:FID 54321 88776 a=ssrc-group:FID 77656 12908 a=ssrc:54321 cname:LP/NWs1ao1HmN4Xa5a=ssrc:77656 cname:LP/NWs1ao1HmN4Xa5a=ssrc:88776 cname:LP/NWs1ao1HmN4Xa5a=ssrc:12908 cname:LP/NWs1ao1HmN4Xa5a=sendrecva=setup:active - Bob carries out DTLS Handshake in parallela=rtcp-muxa=bundle-onlya=rtcp-fb:* nacka=rtcp-fb:* nack plia=rtcp-fb:* ccm fira=rtcp-rsize
This section shows an SDP Offer/Answer exchange for a simulcast scenario
with 2 two resolutions and has
style re-transmission flows.
It also showcases when Bob rejects one of the Simulcast Video Stream which
results in the rejection of the associated repair stream implicitly
Bob: Offer(Audio:Opus Video:VP8 with 2 resolutions and RTX Streams) bundle-only
note left of Bob
Bob accepts one simulcast,rtx and rejects the other
end note
Bob->Alice: Answer(Audio:Opus Video:VP8 with 1 resolution and the RTX Stream) bundle-only
Alice->Bob: 1 Way Audio, Video Session
note right of Alice
Only 1 Video stream and its associated RTX stream
is sent to Bob
end note
]]>SDP Contents RFC#/Notesv=0o=- 20519 0 IN IP4 0.0.0.0s=-t=0 0a=msid-semantic:WMSa=group:BUNDLE m0 m1
Alice supports grouping of m=lines under BUNDLE semanticsa=ice-options:tricklem=audio 54609 UDP/TLS/RTP/SAVPF 109 a=msid:ma ta Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (ta) c=IN IP4 24.23.204.141a=rtcp:64678 IN IP4 24.23.204.141a=mid:m0 Audio m=line part of BUNDLE group
with a unique port numbera=rtpmap:109 opus/48000/2a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-levela=ptime:20a=rtcp-fb:109 nacka=sendonlya=setup:actpass - Alice can perform DTLS before Answer arrivesa=rtcp-muxa=ssrc:11111 cname:LP/NWs1ao1HmN4Xa5a=ice-ufrag:074c6550a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068a=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07a=candidate:0 1 UDP 2113667327 192.168.1.4 54609 typ hosta=candidate:1 1 UDP 694302207 24.23.204.141 54609 typ srflx raddr 192.168.1.4 rport 54609a=candidate:0 2 UDP 2113667326 192.168.1.4 64678 typ hosta=candidate:1 2 UDP 1694302206 24.23.204.141 64678 typ srflx raddr 192.168.1.4 rport 64678a=rtcp-rsizem=video 0 UDP/TLS/RTP/SAVPF 98 100 101 103bundle-only video line with port number set to zeroa=msid:ma tb Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (tb) c=IN IP4 24.23.204.141a=rtcp:64678 IN IP4 24.23.204.141a=mid:m1 Audio m=line part of BUNDLE groupa=rtpmap:98 VP8/90000a=rtpmap:100 VP8/90000a=rtpmap:101 VP8/90000a=rtpmap:103 VP8/90000a=fmtp:98 max-fr=30;max-fs=8040a=fmtp:100 max-fr=15;max-fs=1200a=fmtp:101 apt=98;rtx-time=3000a=fmtp:103 apt=100;rtx-time=3000a=ssrc-group:SIMULCAST 12345 78990 Simulcast group a=ssrc-group:FID 12345 34567 a=ssrc-group:FID 78990 90887 a=ssrc:12345 cname:Q/NWs1ao1HmN4Xa5a=ssrc:78990 cname:Q/NWs1ao1HmN4Xa5a=ssrc:34567 cname:Q/NWs1ao1HmN4Xa5a=ssrc:90887 cname:Q/NWs1ao1HmN4Xa5a=sendonlya=rtcp-muxa=bundle-onlya=rtcp-fb:* nacka=rtcp-fb:* nack plia=rtcp-fb:* ccm fira=rtcp-rsizeSDP Contents RFC#/Notesv=0o=- 20519 0 IN IP4 0.0.0.0s=-t=0 0a=msid-semantic:WMSa=group:BUNDLE m0 m1
Alice supports grouping of m=lines under BUNDLE semanticsa=ice-options:tricklem=audio 49203 UDP/TLS/RTP/SAVPF 109 a=msid:ma ta Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (ta) c=IN IP4 98.248.92.77a=rtcp:49203 IN IP4 98.248.92.77a=mid:m0 Audio m=line part of BUNDLE group
with a unique port numbera=rtpmap:109 opus/48000/2a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-levela=ptime:20a=recvonlya=setup:active - Bob carries out DTLS Handshake in parallela=rtcp-muxa=ice-ufrag:074c6550a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068a=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07a=candidate:0 1 UDP 2113667327 192.168.1.7 49203 typ hosta=candidate:1 1 UDP 694302207 98.248.92.77 49203 typ srflx raddr 192.168.1.7 rport 49203a=candidate:0 2 UDP 2113667326 192.168.1.7 60065 typ hosta=candidate:1 2 UDP 1694302206 98.248.92.77 60065 typ srflx raddr 192.168.1.7 rport 60065a=rtcp-rsizem=video 49203 UDP/TLS/RTP/SAVPF 98 101 BUNDLE accepted with Bundle address identical to audio m-linea=msid:ma tb Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (tb) c=IN IP4 98.248.92.77a=rtcp:60065 IN IP4 98.248.92.77a=mid:m1 Video m=line part of BUNDLE groupa=rtpmap:98 VP8/90000a=rtpmap:101 VP8/90000a=fmtp:98 max-fr=30;max-fs=8040a=fmtp:101 apt=98;rtx-time=3000a=ice-ufrag:074c6550a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068a=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07a=candidate:0 1 UDP 2113667327 192.168.1.7 49203 typ hosta=candidate:1 1 UDP 694302207 98.248.92.77 49203 typ srflx raddr 192.168.1.5 rport 49203a=candidate:0 2 UDP 2113667326 192.168.1.7 60065 typ hosta=candidate:1 2 UDP 1694302206 98.248.92.77 60065 typ srflx raddr 192.168.1.5 rport 60065a=ssrc:54321 cname:NWs1ao1HmN4Xa5a=recvonlya=setup:active - Bob carries out DTLS Handshake in parallela=rtcp-muxa=bundle-onlya=rtcp-rsize
This section shows an SDP Offer/Answer exchange for Simulcast
video stream at two resolutions and and has
style FEC flows.
On completion of Offer/Answer exchange we end up one audio stream, 2 simulcast video
streams and 2 associated FEC streams are sent over a single 5-tuple.
Bob: Offer(Audio:Opus Video:VP8 with 2 resolutions with FEC Streams) bundle-only
note left of Bob
Bob accepts simulcast stream as well as FEC streams
end note
Bob->Alice: Answer(Audio:Opus Video:VP8 with 2 resolutions with FEC Streams) bundle-only
Alice->Bob: 1 Way Audio, Video Session
note right of Alice
Successful Session with 4 video streams (Simulcast + FEC) and 1 Audio Stream
]]>SDP Contents RFC#/Notesv=0o=- 20519 0 IN IP4 0.0.0.0s=-t=0 0a=msid-semantic:WMSa=group:BUNDLE m0 m1
Alice supports grouping of m=lines under BUNDLE semanticsa=ice-options:tricklem=audio 54609 UDP/TLS/RTP/SAVPF 109 a=msid:ma ta Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (ta) c=IN IP4 24.23.204.141a=rtcp:64678 IN IP4 24.23.204.141a=mid:m0 Audio m=line part of BUNDLE group
with a unique port numbera=rtpmap:109 opus/48000/2a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-levela=ptime:20a=rtcp-fb:109 nacka=sendrecva=setup:actpass - Alice can perform DTLS before Answer arrivesa=rtcp-muxa=ssrc:11111 cname:Q/NWs1ao1HmN4Xa5a=ice-ufrag:074c6550a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068a=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07a=candidate:0 1 UDP 2113667327 192.168.1.4 54609 typ hosta=candidate:1 1 UDP 694302207 24.23.204.141 54609 typ srflx raddr 192.168.1.4 rport 54609a=candidate:0 2 UDP 2113667326 192.168.1.4 64678 typ hosta=candidate:1 2 UDP 1694302206 24.23.204.141 64678 typ srflx raddr 192.168.1.4 rport 64678a=rtcp-rsizem=video 0 UDP/TLS/RTP/SAVPF 98 100 101 103bundle-only video line with port number set to zeroa=msid:ma tb Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (tb) c=IN IP4 24.23.204.141a=rtcp:64678 IN IP4 24.23.204.141a=mid:m1 Video m=line part of BUNDLE groupa=rtpmap:98 VP8/90000a=rtpmap:100 VP8/90000a=rtpmap:101 1d-interleaved-parityfec/90000a=rtpmap:103 1d-interleaved-parityfec/90000a=fmtp:98 max-fr=30;max-fs=8040a=fmtp:100 max-fr=15;max-fs=1200a=fmtp:101 L=5; D=10; repair-window=200000a=fmtp:103 L=5; D=10; repair-window=200000a=ssrc-group:SIMULCAST 12345 78990 Simulcast group a=ssrc-group:FEC-FR 12345 34567 a=ssrc-group:FEC-FR 78990 90887 a=ssrc:12345 cname:Q/NWs1ao1HmN4Xa5a=ssrc:78990 cname:Q/NWs1ao1HmN4Xa5a=ssrc:34567 cname:Q/NWs1ao1HmN4Xa5a=ssrc:90887 cname:Q/NWs1ao1HmN4Xa5a=sendrecva=rtcp-muxa=bundle-onlya=rtcp-fb:* nacka=rtcp-fb:* nack plia=rtcp-fb:* ccm fira=rtcp-rsizeSDP Contents RFC#/Notesv=0o=- 20519 0 IN IP4 0.0.0.0s=-t=0 0a=msid-semantic:WMSa=group:BUNDLE m0 m1
Alice supports grouping of m=lines under BUNDLE semanticsa=ice-options:tricklem=audio 49203 UDP/TLS/RTP/SAVPF 109 a=msid:ma ta Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (ta) c=IN IP4 98.248.92.77a=rtcp:60065 IN IP4 98.248.92.77a=mid:m0 Audio m=line part of BUNDLE group
with a unique port numbera=rtpmap:109 opus/48000/2a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-levela=ptime:20a=rtcp-fb:109 nacka=sendrecv a=setup:active - Bob carries out DTLS Handshake in parallela=rtcp-muxa=ssrc:33333 cname:Y9/cZke09JAtpl98a=ice-ufrag:074c6550a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068a=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07a=candidate:0 1 UDP 2113667327 192.168.1.7 49203 typ hosta=candidate:1 1 UDP 694302207 98.248.92.77 49203 typ srflx raddr 192.168.1.7 rport 49203a=candidate:0 2 UDP 2113667326 192.168.1.7 60065 typ hosta=candidate:1 2 UDP 1694302206 98.248.92.77 60065 typ srflx raddr 192.168.1.7 rport 60065a=rtcp-rsizem=video 49203 UDP/TLS/RTP/SAVPF 98 100 101 103BUNDLE accepted with Bundle Address identical to audio m=line.a=msid:ma tb Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (tb) c=IN IP4 98.248.92.77a=rtcp:60065 IN IP4 98.248.92.77a=mid:m1 Video m=line part of BUNDLE groupa=rtpmap:98 VP8/90000a=rtpmap:100 VP8/90000a=rtpmap:101 1d-interleaved-parityfec/90000a=rtpmap:103 1d-interleaved-parityfec/90000a=fmtp:98 max-fr=30;max-fs=8040a=fmtp:100 max-fr=15;max-fs=1200a=fmtp:101 L=5; D=10; repair-window=200000a=fmtp:103 L=5; D=10; repair-window=200000a=ssrc-group:SIMULCAST 54321 77656 Simulcast group a=ssrc-group:FEC-FR 54321 88776 a=ssrc-group:FEC-FR 77656 12908 a=ssrc:54321 cname:Q/1HmN4Xa5CClapaa=ssrc:77656 cname:Q/1HmN4Xa5CClapaa=ssrc:88776 cname:Q/1HmN4Xa5CClapaa=ssrc:12908 cname:Q/1HmN4Xa5CClapaa=sendrecva=setup:active - Bob carries out DTLS Handshake in parallela=rtcp-muxa=bundle-onlya=ice-ufrag:074c6550a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068a=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07a=candidate:0 1 UDP 2113667327 192.168.1.7 49203 typ hosta=candidate:1 1 UDP 694302207 98.248.92.77 49203 typ srflx raddr 192.168.1.7 rport 49203a=candidate:0 2 UDP 2113667326 192.168.1.7 60065 typ hosta=candidate:1 2 UDP 1694302206 98.248.92.77 60065 typ srflx raddr 192.168.1.7 rport 60065a=rtcp-fb:* nacka=rtcp-fb:* nack plia=rtcp-fb:* ccm fira=rtcp-rsize
The examples in the section provide SDP for a variety of scenarios
related to RTP Header extension, Legacy Interop scenarios and more.
This example shows Alice indicating the support of the RTP header extension
to include the audio-level of the audio sample carried in the RTP packet.
Bob: Offer(Audio:Opus,PCMU,PCMA)
note right of Alice
Alice indicates support for including audio-level
end note
Bob->Alice: Answer(Audio:Opus,PCMU,PCMA)
note left of Bob
Bob accepts and indicates his support as well
end note
Alice<->Bob: Two-way Opus Audio
note right of Alice
Per packet audio-level is included in the RTP header.
end note]]>SDP Contents RFC#/Notesv=0o=- 20518 0 IN IP4 0.0.0.0s=-t=0 0a=msid-semantic:WMSa=group:BUNDLE audioa=ice-options:tricklem=audio 54609 UDP/TLS/RTP/SAVPF 109 0 8a=mid:audioa=msid:ma ta Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (ta) c=IN IP4 24.23.204.141a=rtcp:64678 IN IP4 24.23.204.141a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-levela=rtpmap:109 opus/48000/2a=ptime:20a=rtpmap:0 PCMU/8000a=rtpmap:0 PCMA/8000a=sendrecva=setup:actpassa=rtcp-muxa=ice-ufrag:074c6550a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068a=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07a=candidate:0 1 UDP 2113667327 192.168.1.4 54609 typ hosta=candidate:1 1 UDP 694302207 24.23.204.141 54609 typ srflx raddr 192.168.1.4 rport 54609a=candidate:0 2 UDP 2113667326 192.168.1.4 64678 typ hosta=candidate:1 2 UDP 1694302206 24.23.204.141 64678 typ srflx raddr 192.168.1.4 rport 64678a=rtcp-fb:* nacka=ssrc:11111 cname:QCL/1HmN4Xa5CClapaa=rtcp-rsizeSDP Contents RFC#/Notesv=0o=- 16833 0 IN IP4 0.0.0.0 - Session Origin Informations=-t=0 0a=msid-semantic:WMSa=group:BUNDLE audioa=ice-options:tricklem=audio 49203 UDP/TLS/RTP/SAVPF 109 0 98a=mid:audioa=msid:ma ta Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (ta) c=IN IP4 98.248.92.77a=rtcp:60065 IN IP4 98.248.92.77a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-levela=rtpmap:109 opus/48000/2 - Bob accepts only Opus Codeca=ptime:20a=rtpmap:0 PCMU/8000 PCMU Audio Codeca=rtpmap:0 PCMA/8000 PCMA Audio Codeca=rtcp-fb:* nacka=sendrecv - Bob can send and recv audioa=setup:active - Bob carries out DTLS Handshake in parallela=rtcp-mux - Bob can perform RTP/RTCP Muxing on port 49203a=ice-ufrag:c300d85ba=ice-pwd:de4e99bd291c325921d5d47efbabd9a2a=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07a=candidate:0 1 UDP 2113667327 192.168.1.7 49203 typ hosta=candidate:1 1 UDP 1694302207 98.248.92.77 49203 typ srflx raddr 192.168.1.7 rport 49203a=candidate:0 2 UDP 2113667326 192.168.1.7 60065 typ hosta=candidate:1 2 UDP 1694302206 98.248.92.77 60065 typ srflx raddr 192.168.1.7 rport 60065a=ssrc:1732846380 cname:EocUG1f0fcg/yvY7a=rtcp-rsize
This example shows SDP for RTP header extension that allows RTP-level
mixers in audio conferences to deliver information about the audio level
of individual participants.
Mixer: Offer(Audio:Opus,PCMU,PCMA)
note right of Alice
Alice indicates its interest to audio levels for the contributing sources
end note
Mixer->Alice: Answer(Audio:Opus,PCMU,PCMA)
note left of Bob
Mixer indicates it can provide audio-levels per CSRC
end note
Alice<->Mixer: Two-way Opus Audio
note right of Alice
Audio levels per CSRC is included in the RTP Header
end note]]>SDP Contents RFC#/Notesv=0o=- 20518 0 IN IP4 0.0.0.0 - Session Origin Informations=-t=0 0a=msid-semantic:WMSa=group:BUNDLE audioa=ice-options:tricklem=audio 54609 UDP/TLS/RTP/SAVPF 109 0 8a=mid:audioa=msid:ma ta Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (ta) c=IN IP4 24.23.204.141a=rtcp:64678 IN IP4 24.23.204.141a=extmap:1/recvonly urn:ietf:params:rtp-hdrext:csrc-audio-levela=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-levela=rtpmap:109 opus/48000/2 - Opus Codec 48khz, 2 channelsa=ptime:20 - Opus packetization of 20msa=rtpmap:0 PCMU/8000 PCMU Audio Codeca=rtpmap:0 PCMA/8000 PCMA Audio Codeca=rtcp-fb:* nacka=sendrecv - Alice can send and recv audioa=setup:actpass - Alice can perform DTLS before Answer arrivesa=rtcp-mux - Alice can perform RTP/RTCP Muxing on port 54609a=ice-ufrag:074c6550a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068a=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07a=candidate:0 1 UDP 2113667327 192.168.1.4 54609 typ hosta=candidate:1 1 UDP 694302207 24.23.204.141 54609 typ srflx raddr 192.168.1.4 rport 54609a=candidate:0 2 UDP 2113667326 192.168.1.4 64678 typ hosta=candidate:1 2 UDP 1694302206 24.23.204.141 64678 typ srflx raddr 192.168.1.4 rport 64678a=ssrc:11111 cname:QCL/1HmN4Xa5CClapaa=rtcp-rsizeSDP Contents RFC#/Notesv=0o=- 16833 0 IN IP4 0.0.0.0 - Session Origin Informations=-t=0 0a=msid-semantic:WMSa=group:BUNDLE audioa=ice-options:tricklem=audio 49203 UDP/TLS/RTP/SAVPF 109 0 98a=mid:audioa=msid:ma ta Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (ta) c=IN IP4 98.248.92.77a=rtcp:60065 IN IP4 98.248.92.77a=extmap:1/sendonly urn:ietf:params:rtp-hdrext:csrc-audio-levela=rtpmap:109 opus/48000/2 - Bob accepts only Opus Codeca=ptime:20a=rtpmap:0 PCMU/8000 PCMU Audio Codeca=rtpmap:0 PCMA/8000 PCMA Audio Codeca=rtcp-fb:* nacka=sendrecv - Bob can send and recv audioa=setup:active - Bob carries out DTLS Handshake in parallela=rtcp-mux - Bob can perform RTP/RTCP Muxing on port 49203a=ice-ufrag:c300d85ba=ice-pwd:de4e99bd291c325921d5d47efbabd9a2a=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07a=candidate:0 1 UDP 2113667327 192.168.1.7 49203 typ hosta=candidate:1 1 UDP 1694302207 98.248.92.77 49203 typ srflx raddr 192.168.1.7 rport 49203a=candidate:0 2 UDP 2113667326 192.168.1.7 60065 typ hosta=candidate:1 2 UDP 1694302206 98.248.92.77 60065 typ srflx raddr 192.168.1.7 rport 60065a=ssrc:2222 cname:HmN4Xa5CC/lapaa=rtcp-rsize
In the scenario described below, Alice is a multi-stream capable WebRTC endpoint
while Bob is a legacy VOIP end-point. The SDP Offer/Answer exchange demonstrates
successful session setup with fallback to audio only stream negotiated
via bundle-only framework between the end-points. Specifically,
Offer from Alice describes 2 cameras via 2 video m=lines with both marked
as bundle-only.
Since Bob doesnot recognize either BUNDLE mechanism or
bundle-only attribute, he accepts only the audio stream from Alice.
VOIP Interop
note right of Alice
Alice is a multistream capable WebRTC end-point & Bob is behind a legacy VOIP system
end note
Alice->Bob: Offer(Audio:Opus Video: 2 VP8, 2 H2.64 Streams) with bundle-only offer
note right of Alice
Alice marks both the video streams as bundle-only
end note
Bob->Alice: Answer(Audio:Opus)
note left of Bob
Bob accepts only Audio stream since he doesn't recognize
bundle-only streams
end note
Alice<->Bob: Two-way Opus Audio
]]>SDP Contents RFC#/Notesv=0o=- 20519 0 IN IP4 0.0.0.0s=-t=0 0a=msid-semantic:WMSa=group:BUNDLE m0 m1 m2
Alice supports grouping of m=lines under BUNDLE semanticsa=ice-options:tricklem=audio 54609 UDP/TLS/RTP/SAVPF 109c=IN IP4 24.23.204.141a=rtcp:64678 IN IP4 24.23.204.141a=mid:m0 Audio m=line part of BUNDLE group
with a unique port numbera=msid:ma ta Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (ta) a=rtpmap:109 opus/48000/2a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-levela=ptime:20a=rtcp-fb:109 nacka=sendrecva=setup:actpass - Alice can perform DTLS before Answer arrivesa=rtcp-muxa=ice-ufrag:074c6550a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068a=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07a=candidate:0 1 UDP 2113667327 192.168.1.4 54609 typ hosta=candidate:1 1 UDP 694302207 24.23.204.141 54609 typ srflx raddr 192.168.1.4 rport 54609a=candidate:0 2 UDP 2113667326 192.168.1.4 64678 typ hosta=candidate:1 2 UDP 1694302206 24.23.204.141 64678 typ srflx raddr 192.168.1.4 rport 64678a=ssrc:11111 cname:axzo1278npDlAzM73Ea=rtcp-rsizem=video 0 UDP/TLS/RTP/SAVPF 98 100 bundle-only video line with port number set to zero c=IN IP4 24.23.204.141a=rtcp:64678 IN IP4 24.23.204.141a=mid:m1 Video m=line part of BUNDLE groupa=msid:ma tb Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (tb) a=rtpmap:98 VP8/90000a=rtpmap:100 VP8/90000a=imageattr:98 [x=1280,y=720]Camera-1,Encoding-1 Resolutiona=fmtp:98 max-fr=30a=imageattr:100 [x=640,y=480] Camera-1,Encoding-2 Resolutiona=fmtp:100 max-fr=15a=ssrc-group:SIMULCAST 12345 45678a=ssrc:12345 cname:axzo1278npDlAzM73Ea=ssrc:45678 cname:axzo1278npDlAzM73a=bundle-onlya=rtcp-rsizem=video 0 UDP/TLS/RTP/SAVPF 101 103 bundle-only video line with port number set to zero c=IN IP4 24.23.204.141a=rtcp:64678 IN IP4 24.23.204.141a=mid:m2 Video m=line part of BUNDLE groupa=msid:ma tc Identifies RTCMediaStream ID (ma) and RTCMediaStreamTrack ID (tc) a=rtpmap:101 H264/90000a=rtpmap:103 H264/90000a=fmtp:101 profile-level-id=4d0028;packetization-mode=1;max-fr=30 Camera-2,Encoding-1 Resolutiona=fmtp:100 profile-level-id=4d0028;packetization-mode=1;max-fr=15Camera-1,Encoding-2 Resolutiona=ssrc-group:SIMULCAST 67890 56789a=ssrc:67890 cname:axzo1278npDlAzM73a=ssrc:56789 cname:axzo1278npDlAzM73a=bundle-onlya=rtcp-rsizeSDP Contents RFC#/Notesv=0o=- 20519 0 IN IP4 0.0.0.0s=-t=0 0a=msid-semantic:WMSm=audio 49203 UDP/TLS/RTP/SAVPF 109c=IN IP4 24.23.204.141a=rtcp:60065 IN IP4 24.23.204.141a=rtpmap:109 opus/48000/2a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-levela=ptime:20a=rtcp-fb:109 nacka=sendrecva=setup:active - Bob carries out DTLS Handshake in parallela=ice-ufrag:ufrag:c300d85ba=ice-pwd:de4e99bd291c325921d5d47efbabd9a2a=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07a=candidate:0 1 UDP 2113667327 192.168.1.7 49203 typ hosta=candidate:1 1 UDP 694302207 98.248.92.77 49203 typ srflx raddr 192.168.1.7 rport 49203a=candidate:0 2 UDP 2113667326 192.168.1.7 60065 typ hosta=candidate:1 2 UDP 1694302206 98.248.92.77 60065 typ srflx raddr 192.168.1.7 rport 60065a=rtcp-rsizem=video 0 UDP/TLS/RTP/SAVPF 98 100 Bob doesn't recognize bundle-only and hence rejects the video stream c=IN IP4 98.248.92.77a=rtpmap:98 VP8/90000a=rtpmap:100 VP8/90000a=imageattr:98 [x=1280,y=720]Camera-1,Encoding-1 Resolutiona=fmtp:98 max-fr=30a=imageattr:100 [x=640,y=480] Camera-1,Encoding-2 Resolutiona=fmtp:100 max-fr=15m=video 0 UDP/TLS/RTP/SAVPF 98 100 Bob doesn't recognize bundle-only and hence rejects the video streamc=IN IP4 98.248.92.77a=rtpmap:101 H264/90000a=rtpmap:103 H264/90000a=fmtp:101 profile-level-id=4d0028;packetization-mode=1;max-fr=30 Camera-2,Encoding-1 Resolutiona=fmtp:100 profile-level-id=4d0028;packetization-mode=1;max-fr=15Camera-1,Encoding-2 Resolution
In this section, we attempt to provide session descriptions showcasing inter-operability
between a WebRTC end-point and a Legacy VOIP end-point. The ideas included in here
are not fully baked into the standards and might be controversial in nature. The hope here is
to demonstrate a plausible SDP composition to enchance seamless inter-operability between the
aforementioned communication systems.
In the scenario desribed below, Alice sends Offer with two
sets of media descriptions per media type.
One set that correponds to compliant
UDP/TLS/RTP/SAVPF based audio and video descriptions.
Another set with RTP/AVP based audio and video descriptions for the
legacy Interop purposes.
Also to note, Alice includes session level DTLS information and media level
RTCP feedback information as applicable to both the sets of
media descriptions
On the other hand, Bob being a Legacy VOIP end-point, recognizes only the
media descriptions with RTP/AVP as the application protocol.
The security and fedback requirements for the session are either handled by a
intermediate gateway or with some
combination of Bob's capabilities and the intermediate gateway.
VOIP Interop
note right of Alice
Alice is on a WebRTC end-point & Bob is behind a legacy VOIP system
end note
Alice->Bob: Offer(Audio:Opus Video:VP8)
note right of Alice
Alice includes 2 copies of media descriptions
1. WebRTC compliant media description (UDP/TLS/RTP/SAVPF)
2. Legacy compliant media description (RTP/AVP)
end note
Bob->Alice: Answer(Audio:Opus Video:VP8)
note right of Bob
Bob recognizes"legacy compliant" media description from Alice.
and accepts the same.
end note
Alice->Bob: Two-way Opus Audio, VP8 Video
note right of Alice
Session also suports RTP/RTCP Mux, RTCP feedback (nack,pli)
end note
]]>SDP Contents RFC#/Notesv=0o=- 20518 0 IN IP4 0.0.0.0s=-t=0 0a=ice-ufrag:074c6550a=ice-pwd:a28a397a4c3f31747d1ee3474af08a068a=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07a=rtcp-rsizem=audio 54609 UDP/TLS/RTP/SAVPF 109c=IN IP4 24.23.204.141a=rtpmap:109 opus/48000a=ptime:20a=sendrecva=rtcp-muxa=candidate:0 1 UDP 2113667327 192.168.1.4 54609 typ hosta=candidate:1 1 UDP 694302207 24.23.204.141 54609 typ srflx raddr 192.168.1.4 rport 54609a=candidate:0 2 UDP 2113667326 192.168.1.4 64678 typ hosta=candidate:1 2 UDP 1694302206 24.23.204.141 64678 typ srflx raddr 192.168.1.4 rport 64678a=rtcp-fb:109 nackm=video 62537 UDP/TLS/RTP/SAVPF 120c=IN IP4 24.23.204.141a=rtpmap:120 VP8/90000a=sendrecva=rtcp-muxa=candidate:0 1 UDP 2113667327 192.168.1.4 62537 typ hosta=candidate:1 1 UDP 1694302207 24.23.204.141 62537 typ srflx raddr 192.168.1.4 rport 62537a=candidate:0 2 2113667326 192.168.1.4 54721 typ hosta=candidate:1 2 UDP 1694302206 24.23.204.141 54721 typ srflx raddr 192.168.1.4 rport 54721a=rtcp-fb:120 nack plia=rtcp-fb:120 ccm fir---------------These set of media descriptions are for Legacy Inter-op purposesm=audio 54732 RTP/AVP 109Alice includes RTP/AVP audio stream descriptionc=IN IP4 24.23.204.141a=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:7f:7d:f9:c9:c7:70:9d:1f:66:79:a8:07a=rtpmap:109 opus/48000a=ptime:20a=sendrecva=rtcp-muxAlice still includes RTP/RTCP Mux supporta=candidate:0 1 UDP 2113667327 192.168.1.4 54732 typ hosta=candidate:1 1 UDP 694302207 24.23.204.141 54732 typ srflx raddr 192.168.1.4 rport 54732a=candidate:0 2 UDP 2113667326 192.168.1.4 64678 typ hosta=candidate:1 2 UDP 1694302206 24.23.204.141 64678 typ srflx raddr 192.168.1.4 rport 64678a=rtcp-fb:109 nackShe adds her intent for NACK RTCP feedback supportm=video 62445 RTP/AVP 120Alice includes RTP/AVP video stream description c=IN IP4 24.23.204.141a=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:7d:f7:c9:c7:70:9d:1f:66:79:a8:07a=rtpmap:120 VP8/90000a=sendrecva=rtcp-muxAlice intends to perform RTP/RTCP Muxa=candidate:0 1 UDP 2113667327 192.168.1.4 62445 typ hosta=candidate:1 1 UDP 1694302207 24.23.204.141 62537 typ srflx raddr 192.168.1.4 rport 62445a=candidate:0 2 2113667326 192.168.1.4 54721 typ hosta=candidate:1 2 UDP 1694302206 24.23.204.141 54721 typ srflx raddr 192.168.1.4 rport 54721a=rtcp-fb:120 nack pli Alice indicates support for Picture loss Indication and NACK RTCP feedbacka=rtcp-fb:120 ccm firSDP Contents RFC#/Notesv=0o=- 16833 0 IN IP4 0.0.0.0s=-t=0 0a=ice-ufrag:c300d85ba=ice-pwd:de4e99bd291c325921d5d47efbabd9a2a=fingerprint:sha-1 99:41:49:83:4a:97:0e:1f:ef:6d:f7:c9:c7:70:9d:1f:66:79:a8:07m=audio 49203 RTP/AVP 109 Bob accepts RTP/AVP based audio streamc=IN IP4 98.248.92.77a=rtpmap:109 opus/48000a=ptime:20a=sendrecva=candidate:0 1 UDP 2113667327 192.168.1.7 49203 typ hosta=candidate:1 1 UDP 1694302207 98.248.92.77 49203 typ srflx raddr 192.168.1.7 rport 49203a=candidate:0 2 UDP 2113667326 192.168.1.7 60065 typ hosta=candidate:1 2 UDP 1694302206 98.248.92.77 60065 typ srflx raddr 192.168.1.7 rport 60065m=video 63130 RTP/SAVP 120 Bob accepts RTP/AVP based video stram c=IN IP4 98.248.92.771a=rtpmap:120 VP8/90000a=sendrecva=candidate:0 1 UDP 2113667327 192.168.1.7 63130 typ hosta=candidate:1 1 UDP 1694302207 98.248.92.77 63130 typ srflx raddr 192.168.1.7 rport 63130a=candidate:0 2 UDP 2113667326 192.168.1.7 56607 typ hosta=candidate:1 2 UDP 1694302206 98.248.92.77 56607 typ srflx raddr 192.168.1.7 rport 56607This document requires no actions from IANA.
We would like to thanks Justin Uberti for his detailed review and inputs.
[RFC EDITOR NOTE: Please remove this section when publishing]Changes from draft-nandakumar-rtcweb-sdp-03
Aligned more closely with JSEP version -05 Added Conventions to help readability Add more examples to clarify BUNDLE use-cases Changes from draft-nandakumar-rtcweb-sdp-02
Major refactoring was done to group the examples in to categories SDP was updated through out to reflect JSEP-04 style of defining
attributes per m=line than at the session level. Added 8 new examples. Updated references for Trickle, Unified Plan Add section to explain the syntax conventions followed in the
examples. Changes from draft-nandakumar-rtcweb-sdp-01
Updated references to OPUS RTP Payload Specification.Updated BUNDLE examples based on the latest
draft-ietf-mmusic-sdp-bundle-negotiation.Added examples for multiple audio and video flows based on
Unified Plan.Added new examples for RTX and FEC streams Updated Simulcast and SVC examplesChanges from draft-nandakumar-rtcweb-sdp-00
Fixed editorial comments on the mailing list.Updated Data-channel SDP information based on draft-ietf-mmusic-sctp-sdp.Updated BUNDLE examples based on draft-ietf-mmusic-sdp-bundle-negotiation.Added examples for few more BUNDLE variantsAdded new examples for Simulcast and SVCAn Offer/Answer Model with Session Description Protocol
(SDP)SDP: Session Description ProtocolKey words for use in RFCs to Indicate
Requirement LevelsHarvard University1350 Mass. Ave.CambridgeMA 02138- +1 617 495 3864sob@harvard.edu
General
keywordInteractive Connectivity Establishment (ICE):
A Protocol for Network Address Translator (NAT) Traversal for
Offer/Answer Protocols
WebRTC 1.0: Real-time Communication Between Browsers
W3C
Javascript Session Establishment Protocol
Google
Cisco Systems
Cross Session Stream Identification in the Session Description Protocol
Google
Support for Reduced-Size Real-Time Transport Control Protocol (RTCP):
Opportunities and ConsequencesRTP Profile for Audio and Video Conferences
with Minimal ControlReal-time Transport Protocol (RTP) Payload Format
for internet Low Bit Rate Codec (iLBC) SpeechThe Session Description Protocol (SDP) Content AttributeMultiplexing RTP Data and Control Packets on a Single PortSession Description Protocol (SDP) Bandwidth Modifiers
for RTP Control Protocol (RTCP) BandwidthCodec Control Messages in the
RTP Audio-Visual Profile with Feedback (AVPF)RTP Retransmission Payload FormatForward Error Correction Grouping Semantics
in the Session Description ProtocolRTP Payload Format for H.264 VideoNegotiation of Generic Image Attributes in
the Session Description Protocol (SDP)RTP Payload Format for Opus Speech and Audio CodecRTP Payload Format for VP8 VideoRTP Payload Format for H.264 VideoSignaling Media Decoding Dependency in the Session Description Protocol (SDP)This memo defines semantics that allow for signaling the decoding dependency of different media descriptions with the same media type in the Session Description Protocol (SDP). This is required, for example, if media data is separated and transported in different network streams as a result of the use of a layered or multiple descriptive media coding process.</t><t> A new grouping type "DDP" -- decoding dependency -- is defined, to be used in conjunction with RFC 3388 entitled "Grouping of Media Lines in the Session Description Protocol". In addition, an attribute is specified describing the relationship of the media streams in a "DDP" group indicated by media identification attribute(s) and media format description(s). [STANDARDS-TRACK]Source-Specific Media Attributes in the Session Description Protocol (SDP)The Session Description Protocol (SDP) provides mechanisms to describe attributes of multimedia sessions and of individual media streams (e.g., Real-time Transport Protocol (RTP) sessions) within a multimedia session, but does not provide any mechanism to describe individual media sources within a media stream. This document defines a mechanism to describe RTP media sources, which are identified by their synchronization source (SSRC) identifiers, in SDP, to associate attributes with these sources, and to express relationships among sources. It also defines several source-level attributes that can be used to describe properties of media sources. [STANDARDS-TRACK]RTCWeb Datagram ConnectionStream Control Transmission Protocol (SCTP)-Based Media Transport in the
Session Description Protocol (SDP) Multiplexing Negotiation Using Session Description Protocol (SDP) Port
Numbers A Unified Plan for Using SDP with Large Numbers of Media Flows A Unified Plan for Using SDP with Large Numbers of Media Flows Multiplexing Negotiation Using Session Description Protocol (SDP) Port
Numbers Guidelines for Choosing RTP Control Protocol (RTCP)
Canonical Names (CNAMEs) RTP: A Transport Protocol for Real-Time Applications SIP: Session Initiation Protocol Real Time Streaming Protocol (RTSP)Real Time Control Protocol (RTCP) attribute in
Session Description Protocol (SDP)Framework for Establishing a Secure Real-time Transport Protocol (SRTP)
Security Context Using Datagram Transport Layer Security (DTLS)RTP Payload for DTMF Digits, Telephony Tones and Telephony SignalsA Real-time Transport Protocol (RTP) Header Extension for Client-to-Mixer Audio Level IndicationThis document defines a mechanism by which packets of Real-time Transport Protocol (RTP) audio streams can indicate, in an RTP header extension, the audio level of the audio sample carried in the RTP packet. In large conferences, this can reduce the load on an audio mixer or other middlebox that wants to forward only a few of the loudest audio streams, without requiring it to decode and measure every stream that is received. [STANDARDS-TRACK]A Real-time Transport Protocol (RTP) Header Extension for Mixer-to-Client Audio Level IndicationThis document describes a mechanism for RTP-level mixers in audio conferences to deliver information about the audio level of individual participants. Such audio level indicators are transported in the same RTP packets as the audio data they pertain to. [STANDARDS-TRACK]