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SMN 1.0 Smart Media Network. Auburn University COMP7970 Richard Chapman 19 Sept 2002. Home audio/video. Back side view. And…. How do real users cope?. The problems. Undocumented configuration and interconnection information Difficult to modify or reconfigure: snarl of wire
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SMN 1.0Smart Media Network Auburn University COMP7970 Richard Chapman 19 Sept 2002
The problems • Undocumented configuration and interconnection information • Difficult to modify or reconfigure: snarl of wire • “Secret” knowledge required to operate • Sometimes just cannot be configured
Motivations for a solution • MP3, streaming media, fast Ethernet • Jini, CORBA, OSGi, UPnP • Universal remote controls based on PDA, Mobile phone, web • Utter indifference of consumer electronics manufacturers
Calls for a solution • “A Call for the Home Media Network”, Bell and Gimmell, Communications of the ACM, July 2002, pp. 71-75 • Donald Norman, “The Perils of Home Theater”, IEEE Computer, June 2002.
Requirements • Good audio and video quality • Easy to operate • Easy to configure, udpate, modify • Easy to develop for
Open source Standards based Vendor, OS language neutral Keep orthogonal issues orthogonal Pay attention to the user interface No global state to maintain Capable of redundancy, fault tolerance Support multiple UI’s No preferences or settings Other goals
User stories • “I want to play CD’s, video or listen to the radio” • “I want to record my soaps” • I can listen to music or watch TV or movies”
What can we deduce • Users want to ignore connectivity • Users don’t want to set up the system • Content is what matters
Device categories • Server -- multiple okay, no direct user access • Controller (phone, PDA, web, custom HW) -- multiple controllers okay • Player -- originates content stream (audio, video players, tuner, Internet radio) • Recorders (PVR, MP3 ripper, etc) • Presenters(amp/spkrs, video monitor) • Processors (e.g. EQ, reverb)
What is good • The snarl of wires is gone • The configuration information is no longer secret • Control and data can share one wire
What might be bad? • Audio and video quality? • Use RTP/UDP • Buffering is okay • Compare Gibson Guitar Corp MaGiC, Peak Audio (synchronous protocols for audio over Ethernet, but not TCP/IP) • We’re going to try TCP/IP
The orthogonal issues • Service registration, lookup, discovery • Control messages to devices • Streaming protocol • User interface
Service registration, leasing, lookup, query • Many options exist: OSGi, UPnP, Jini, CORBA, SOAP • We have experience with Jini (smart badges, lego demo, eClassroom) • Want language and OS independence • Want something simple
Problems • CORBA would require “brittle” interface wrappers (IDL) for everything • Jini has more flexibility, but still requires Java on all devices • UPnP -- is Microsoft ready for a university development effort?
SMN 1.0 • Use LDAP for registry • Add a “keepalive daemon” to handle leasing • Use SOAP for control messages • Use XML to store description of device capabilities, control message formats, in the server • Use variety of streaming protocols
Why LDAP? • Solves the registry problem • Simple to implement • Language, vendor, OS independent • Lots of languages have LDAP libraries • OpenLDAP
How much should the controller know about a device? • Nothing: just present the controls to the user in some “nice way” on the interface • Lots: this way you get as much basic functionality as you can • “The universal remote is always missing a few buttons you really need”
User Interface Issues • Make the common tasks simple • One way of doing things • No “set preferences” in the interface • Support multiple interface implementations • No configuration knowledge required • Get away from WIMP and remote controls as interfaces
One knob, one button, one navigator button trackball rotating ring (volume)
What we will do • Define the LDAP schema, SOAP messages, XML format for the server • Implement a basic player, presenter • Implement a couple of controllers • Probably audio only • User study
What else is there to do? • OSGi gateway to the WAN (mobile phone controller, mobile phone presenter, multi-LAN network) • Other controller implementations • Alternative service discovery, registration system