What is the problem we are solving?

1
What is the problem we are solving?

• How a conference aware participant manipulates
  media streams at the mixer
• The client is a UA (in sip)
• The server is the focus (which directly controls
  the mixer)
• Ultimately, we have to render a UI that controls
  the media flow

2
Whats wrong with draft-mahy-xcon-media-policy-con
trol?

• Its way too complicated
• It doesnt address the problem, except indirectly
• It will be very hard to create interoperable
  implementations

3
Not addressing the problem

• Its a language to describe media flow graphs
• Real devices have fixed flows, with specific
  controls
• Real interfaces twist knobs, push buttons and
  make selections on specific controls

4
Not facilitating interoperable implementations

• Either the client must impose its concept of
  flow graphs on the server, or the server must
  impose its concept of flow graphs on the client
• But the client doesnt know, and the proposal
  doesnt say, how it discovers the capabilities of
  the server
• And the server doesnt know, and the proposal
  doesnt say, how it discovers the UI capabilities
  of the client
• And the language allows arbitrary manipulation of
  arbitrary flows, so this is a very hard problem
• Infinite number of graphs create the same mixed
  media

5
What to do

• Essentially, drop the lower levels (streams.
  Groups, operators,)
• Leaves you with collections
• AKA Templates

6
What is a template?

• A predefined function block with a predefined set
  of parameters, a predefined set of controls, and
  a set of roles
• Parameters let you keep the number of templates
  small
• Controls lets you build UIs that reasonably match
  the other sides view of the world
• Roles define what controls in the template that a
  given user sees

7
Example of a template simple mix-minus audio
mixer

• Inputs - n input audio streams
• Outputs - m output audio streams
• Parameters
• n/m
• Controls
• MixVolume(n,m)
• Mute(n,m), t/f, permitted
• MasterVolume(m)

8
What do you do with a template

• Server declares availability of a (set of)
  templates, with parameter values
• Client specifies which role it is taking and
  values for the controls available to that role
• Templates could have events
• Templates could interact (video follows audio)

9
Non-problems

• How the focus manipulates the mixer
• How one describes what a mixer is capable of
  doing

10
Other Problems

• Who does media policy eg. who is allowed to mute.
  Is that CPCP or MPCP?
• No crisp boundary between CP and MP