Media Stream Selection

1
Media Stream Selection

• draft-westerlund-dispatch-stream-selection-00
• draft-westerlund-avtext-rtp-stream-pause-00
• Bo Burman ltbo.burman_at_ericsson.comgt

2
IPR Disclosure

• For referred drafts
• http//datatracker.ietf.org/ipr/1641/
• http//datatracker.ietf.org/ipr/1644/

3
Discussion Goals

• Solution for RTP Media Stream Selection can be
  based on one or more of three signaling types
• Signaling plane only
• Media control overlay
• Media plane only
• Ideally decide targeted solution and WG(s) during
  IETF 83

4
Main Topologies

• Centralized (Star) Conference
• Point-to-Point Call

A
C
Conf
B
D
A
B
Video conferencing is main targeted application
5
Wanted Functionality

• Choose What Content to Receive
• A media receiver wants to dynamically choose
  which media stream to receive, out of many
  possible, from a certain media sender, out of
  many possible
• Request to Pause Sending of a Content
• A media receiver wants to ask the media sender to
  temporarily stop sending a specific media stream,
  and to resume it with short notice

6
Relation to SDP

• SDP handles semi-static properties of RTP
  transport flows
• Opening
• Closing
• Directionality
• Activating
• Inactivating

7
Choose What Content to Receive
Sender 1
Sender 2

• Whenever there are more media streams from all
  senders than what can be presented simultaneously
  by a single receiver, some subset has to be
  selected
• The receiver has commonly not been in charge of
  that selection
• Multi-stream capable receivers making local
  composition will not burden central composition
  by multiple different choices

1
1
3
3
2
2
CentralConferenceNode
I want Sender 1 2 here
Always give me Sender 2 3
Never send Sender 1 1
Receiver
8
Request to Pause Sending of a Content
Sender
I dont need your stream 1 right now

• Whenever there are more media senders than
  presentation resources, some media may not be
  presented by any receiver, wasting uplink
  bandwidth
• Applicable also in other multi-party or
  multi-stream situations
• Need for a stream can be based on central
  forwarding decisions or end-user UI interactions
  and thus be highly dynamic
• Pausing has fairly relaxed timing, but resuming
  can be time critical

1
3
2

Resume stream 3 now
CentralConferenceNode
I dont need this stream right now
Receiver
Receiver
9
Assumed Signaling System

• Different Topology than the media plane
• Has Application Server (AS) to handle application
  session signaling, especially for multi-party
• Any solution must work with service established
  by SIP/SDP signaling

AS
SIPProxy
SIPProxy
MediaServer
Alice
Bob
10
Three Possible Solutions 1

• Media Control Overlay
• Pros
• Protocol tailored for need
• Bandwidth efficient
• Need only be processed in nodes that are actually
  involved in functionality
• Possible re-use of permission handling (for BFCP)
• Cons
• Need control as an extra media stream and (at
  least semi-reliable) transport for it

AS
SIPProxy
SIPProxy
MediaServer
Alice
Bob
11
Three Possible Solutions 2

• Media Plane
• Pros
• Bandwidth efficient
• Implementation well localized to media stream
  handling
• Cons
• Need to traverse every node in the media path
  until reaching targeted node
• May not have sufficient identification
  information without being complemented by other
  signaling

AS
SIPProxy
SIPProxy
MediaServer
Alice
Bob
12
Three Possible Solutions 3

• Signaling Plane
• Pros
• Likely connected to overall resource reservation
• Has access to conference meta information, like
  identification
• Cons
• Risk being too slow for sufficiently good user
  experience
• Every message potentially has to be processed by
  policy control nodes etc
• Likely rather large amount of data needed per
  message

AS
SIPProxy
SIPProxy
MediaServer
Alice
Bob
13
Which Method(s) to Choose?

• Media Control Overlay
• Media Plane
• Signaling Plane
• Combination
• NOTE Choice will impact in which WG work is done

14
Possible Destination WGs

• May require re-charter
• Media Control Overlay
• BFCPBIS
• MEDIACTRL
• Media Plane
• AVTCORE
• AVTEXT
• Signaling Plane
• MMUSIC
• New WG