1. SIP/RTSP convergence draft-whitehead-mmusic-sip-for-streaming-media-05
Authors:
Jan Lindquist
Marie-Jose Montpetit
Xavier Marjou
Sam Ganesan

2. Presentation Outline Use Cases + possible solutions
Server Control of Streaming Session
Remote Access to Private/Firewalled Video Content
VOD services that requires resource or QOS-guarantees
Intelligent selectionof media encoding
Voice/video mailbox
Motion Detection
Considerations for session control protocol

3. Use-Case 1: Server Control of Streaming Session (1/2)
Need: The server must be able to indicate the end of session to the client (e.g. if the server needs to be stopped for administrative purpose).
Possible solutions:
Use a SIP BYE message,
or, add a new RTSP message (eg draft-stiemerling-rtsp-announce-01)

4. Use-Case 1: Server Control of Streaming Session (2/2)
SIP
Proxy/Reg(B)
Media
Relay
Agent A
NAT(B)
Agent B
Public side
Private side
SIP BYE
SIP BYE
SIP 200 OK
SIP 200 OK

5. Use-Case 2: Remote Access to Private/Firewalled Video Content (1/3)
Need: to reach the RTSP server located behind a residential NAT
Possible solutions:
A SIP/RTSP-like solution helps, as shown on next slide,
or, Add an RTSP REGISTER message, and extends RTSP proxy.

6. Use-Case 2: Remote Access to Private/Firewalled Video Content (2/3)
SIP
Proxy/Reg(B)
Media
Relay
Agent A
NAT(B)
Agent B
Public side
Private side
SIP REGISTER (with outbound)
SIP INVITE
m=application 9 TCP/RTSP-like
c=IN IP4 IP-agent-a a=setup:active
SIP INVITE
m=application TCP/RTSP-like
c=IN IP4 IP-media-relay a=setup:passive
TCP SYN
TCP SYN
RTSP-like PLAY
RTP Media
RTP Media

7. Use-Case 2: Remote Access to Private/Firewalled Video Content (3/3)
Note: In the previous slide, an SBC is used for shorter call-flows, but similar call-flows can be established with ICE instead of SBC so that media flows go through NATs.
A SIP/RTSP solution both allows NAT traversal and authentication of user A.

8. Use-Case 3: Intelligent selection of media encoding (1/1)
Need: perform a negotiation between clients and server on media formats, media codecs and bandwidth available.
Possible Solutions
The SDP offer/answer can be re-used
Offer/answer enable a media formats negotiation (add/remove streams for example for SVC)
Offer/answer enables the "client" to indicate its media preferences
Add offer/answer mechanism to RTSP

9. Use-Case 4: VOD services that requires resource or QOS-guarantees (1/2)
Need: establish an end to end session setup and management in order to control the network resources and QoS
Possible Solutions
Use SIP to setup session and use IMS architecture to ensure available resources and QoS.

10. Use-Case 4: VOD services that requires resource or QOS-guarantees (2/2)
SIP
Proxy/Reg(B)
Media
Relay
Agent A
Agent B
Public side
SIP INVITE (SDP offer)
SIP INVITE (SDP offer)
SIP 200 OK (SDP answer)
SIP 200 OK (SDP answer)
RTSP-like PLAY
RTP Media
RTP Media

11. Use-Case 5: Voice/video mailbox (1/1)
Need: establish a session to a mailbox server and perform playback control of the voice/video messages with the possibility to save or delete messages. The mailbox can be in the home or in the network.
Possible Solutions
Reuse SIP registration to be able to access mailbox in the home and add some extensions to be able to control individual voice/video messages.

12. Use-Case 6: Motion Detection (1/4)
Need: after being informed of motion detection connect to a home monitoring equipment and see live video feed plus be able to rewind the video feed.
Possible Solutions
Reuse the SIP registration and get notified of motion detected using SIP message. Then perform SIP invite to establish a connection to the video feed.
A SMTP or SIP message with an RTSP link
does not always work, as shown on next slide.
or, a SIP with offer/answer solution

13. Use-Case 6 : Motion Detection (2/4)
A MESSAGE with link does not suffice because of NATs
SIP
Proxy/Reg(B)
Media
Relay
Agent A
NAT(B)
Agent B
Public side
Private side
Waiting For Motion events
SMTP or SIP MESSAGE
rtsp://IP-Agent-B/stream
SMTP or SIP MESSAGE
rtsp://IP-Agent-B/stream, or
rtsp://IP-Agent-B-corrected/stream
Event arises
TCP SYN for RTSP

14. Use-Case 6 : Motion Detection (3/4)
SIP
Proxy/Reg(B)
Media
Relay
Agent A
NAT(B)
Agent B
Public side
Private side
Waiting Motion events
SIP INVITE
m=application TCP/RTSP-like
c=IN IP4 IP-media-relay a=setup:active
SIP INVITE
m=application 9 TCP/RTSP-like
c=IN IP4 IP-agent-a a=setup:passive
Event arises
TCP SYN
TCP SYN
RTSP-like PLAY
RTP Media
RTP Media

15. Use-Case 6 : Motion Detection (4/4)
Note: Again an SBC is used for shorter call-flows, but similar call-flows can be drawn with ICE instead of SBC in order to that media flows go through NATs.

16. Considerations for session control protocol
The session protocol shall allow server initiated control of streaming sessions such as server-initiated session terminations. RTSP TEARDOWNs are from client to server only.
RTSP protocol assumes a media server is located in the network and not in the home. The session protocol shall be possible to establish a relationship that allows for control of media resoruces in both the home and network.
The session protocol shall be able to handle NAT and not affect the call flows being defined.
If assuming SIP for session protocol there is a well accepted architecture defined called IMS, IP Multimedia Solution, which is accepted by a number of standard organizations like 3GPP, ETSI TISPAN, ATIS, etc. There is a number of services have been defined using the architecture like telephony, push to talk, presence, messaging, chat and IPTV.
In conjunction with IMS there is a resource and admition control architecture called RACS defined in ETSI TISPAN which helps ensure QoS for services defined over IMS and addresses reuse of network resources. What is of special interest is bandwidth reservation is addressed for unicast and multicast media streams as well as handling of multicast addresses used for IPTV.
IMS also provides additional authentication mechanisms which allow alternatives for HTTP Digest like the Authentication and Key Agreement mechanism (AKA).

17. Requirements
REQ-1 The media control protocol must support commands such as play, pause, rewind, forward, fast rewind, fast forward, slow rewind, and slow forward.
REQ-2 It must be possible to negotiate the media control protocol of a media stream.
REQ-3 If the media control protocol does not apply to all media streams of a given session, it must be possible to indicate the specific media streams that are under the scope of the trick-play control protocol.
REQ-4 The media control protocol must allow for asynchronous media event notifications (e.g.: end-of-stream)".
REQ-5 The protocol SHOULD work over TCP.
REQ-6 The media stream, or media control server, to be controlled by the client may be located in the network or in the home network.
REQ-7 The media control protocol shall consider additional commands not available in RTSP to control the media in the server. Examples of such commands are deletion or saving of voice messages.