Wednesday, March 17, 2010

O Universal Multimedia Access, Where Art Thou? (Part IV)

-by Christian Timmerer, Klagenfurt University, Austria

Preface: First I thought about writing this article for a journal or something equivalent but then I concluded to make this article available through my blog. The aim is to perform an experiment in order to determine whether it is possible (a) to get direct feedback through comments and (b) to be referenced from elsewhere. As it is a quite comprehensive article, it’s split up in separate parts. If someone (i.e., a journal editor) is interested in publishing this article, yes, I can still do that! :-)

Part I was about giving an introduction to the topic and an overview on multimedia content adaptation techniques. Part II was about the adaptation by transformation approach that utilizes scalable coding formats such as JPEG2000, MPEG-4 BSAC, and MPEG-4 SVC. Part III comprises adaptation decision-taking also known as the brain of multimedia content adaptation and this part is about standardization support for UMA.

Part IV - Standardization support for UMA

The nice thing about standards is that there are so many to choose from. Furthermore, if you do not like any of them, you can just wait for next year’s model.
--Andrew S. Tanenbaum

A couple of standardization organizations (SDOs) provide support for UMA:

Word Wide Web Consortium (W3C):
Internet Engineering Task Force (IETF):
  • Audio/Video Transport (AVT)
  • Media Server Control (MEDIACTRL)
  • Multiparty Multimedia Session Control (MMUSIC)
  • Session Description Protocol (SDP) and Session Initiation Protocol (SIP)
  • Next Steps in Signaling (NSIS)
Moving Picture Experts Group (MPEG):
A comprehensive description format with respect to UMA is Part 7 of MPEG-21 entitled Digital Item Adaptation [2]. This part of MPEG-21 defines - among others - the Usage Environment Description (UED) providing means for describing the context in which Digital Items may be consumed. The UED is clustered into the following categories with some examples given:
  • User Characteristics: e.g., usage history, display presentation preferences, audio/visual impairments, mobility, etc.
  • Terminal Capabilities: e.g., coding capabilities, display capabilities, audio output capabilities, etc.
  • Network Characteristics: e.g., network capabilities (e.g., max capacity, min guaranteed) and conditions (e.g., available bandwidth)
  • Natural Environment Characteristics: e.g., noise level, illumination characteristics, location, time, etc.
The UED is defined as an XML Schema which is publicly available here.

This is the end of Part IV and I'm currently not sure whether a Part V will follow...

[1] Ian Burnett, Fernando Pereira, Rik Van de Walle, and Rob Koenen (eds.), The MPEG-21 Book, John Wiley and Sons Ltd, 2006.
[2] Anthony Vetro and Christian Timmerer, Digital Item Adaptation: Overview of Standardization and Research Activities, IEEE Transactions on Multimedia, vol. 7, no. 3, pp. 418-426, June 2005.

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