SAF, the aggregation of LASeR and audiovisual material

SAF (Simple Aggregation Format) is part of the LASeR standard defining tools to fulfill all the requirements of rich-media service design at the interface between scene representation and transport mechanisms. SAF features the following functionality:
- simple aggregation of any type of media streams (MPEG or non-MPEG streams), resulting in a SAF stream with a low overhead multiplexing schema for low bandwidth networks,
- and possibility to cache SAF streams.

The result of the multiplexing of media streams is a SAF stream which can be delivered over any delivery mechanism: download-and-play, progressive download, streaming or broadcasting.
The purpose of the LASeR Systems decoder model is to provide an abstract view of the behaviour of the terminal. It may be used by the sender to predict how the receiving terminal will behave in terms of buffer management and synchronization when decoding data received in the form of elementary streams. The LASeR systems decoder model includes a timing model and a buffer model. The LASeR systems decoder model specifies:
- the conceptual interface for accessing data streams (Delivery Layer),
- decoding buffers for coded data for each elementary stream,
- the behavior of elementary stream decoders,
- composition memory for decoded data from each decoder, and
- the output behavior of composition memory towards the compositor.

Each elementary stream is attached to one single decoding buffer.
A multimedia presentation is a collection of a scene description and media (zero, one or more). A media is an individual audiovisual content of the following type: image (still picture), video (moving pictures), audio and by extension, font data. A scene description is constituted of text, graphics, animation, interactivity and spatial, audio and temporal layout. The sequence of a scene description and its timed modifications is called a scene description stream. A scene description stream is called a LASeR Stream.
Modifications to the scenes are called LASeR Commands. A command is used to act on elements or attributes of the scene at a given instant in time. LASeR Commands that need to be executed at the same time are grouped into one LASeR Access Unit (AU)

A scene description specifies four aspects of a presentation:
- how the scene elements (media or graphics) are organised spatially, e.g. the - spatial layout of the visual elements;
- how the scene elements (media or graphics) are organised temporally, i.e. if and how they are synchronised, when they start or end;
- how to interact with the elements in the scene (media or graphics), e.g. when a user clicks on an image;
- and if the scene is changing, how the scene changes happen.

Mattia Donna Bianco

A roadmap to converging video services

Despite the rosy pictures we are often shown of encroachment of new media in the TV turf and the support of statistical evidence suggesting that more people spend more time with non-TV video, TV is as healthy as ever. In a recent Nielsen report Americans are said to have watched more TV in 2010 than ever before: total viewing of broadcast networks and basic cable channels is up ~1 percent, i.e. ~34 hours per person per week.

“Conservative” extensions of TV to the web like Hulu, Netflix or Apple TV are reported to fare rather well. On the other hand “innovative” attempts at integrating the television and “web video” experiences, like Google TV, receive mixed reports and see their deployment delayed.

The issue is further complicated by the underground battle around the enabling technologies to be adopted for streaming video to the end user via the internet. In the “analogue TV” age Consumer Electronics (CE) has thrived by adhering to established standards. In the now consolidated “digital TV” age CE has kept on thriving based on established standards. Should the “TV on the web” age be dominated by a handful of behemoths brandishing their technologies as a weapon to preserve and extend their walled gardens?

Judging from the number of initiatives addressing the need for standards in this space, one would say that the relevant industries do think that proprietary technologies should not be the only game in town. Unfortunately most initiatives have issued or are in the process of issuing specifications that appear to be driven by the desire of industries to protect their existing businesses by adding new features while keeping out potential new competitors. Whether this is what consumers are interested in is another story that may very well not be in their priority list.

ISO/IEC JTC 1/SC 29/ WG 11 (MPEG) has been working for the last few years – and keeps on doing so – to develop the key technologies that will enable, as done for digital TV, the creation of a level play field on which the third generation of CE can flourish. Some of these technologies target:

• New video and audio compression for more rewarding user experiences while keeping down the bitrate
• Media composition and presentation
• More attractive ways for the user to interact with services
• More effective ways to deliver content to end users when network is unreliable
• Multichannel distribution of content
• New ways to do business with content

This collection of basic technologies is very important for a smooth transition from “digital TV” to “TV on the web” based on standards. To make this happen, however, industry needs comprehensive specifications that integrate the technologies so that they can be seamlessly integrated in products and deployed to provide interoperable services.

In 2008 the Digital Media Project (DMP), an industry association based in Geneva, is in the process of launching a new project on “Digital media platform for the 2^nd decade of the 21^st century” (P21-2). The goal of this project is to integrate all technologies that are required to provide a solution that is attractive for consumers, profitable for content creators, secure for service providers and rewarding for device manufacturers.

A precursor of P21-2 is wim.tv, a service on the web that lets different types of entrepreneurs do business with video and advertisement content. wim.tv is enabled by CEDEO’s Platform for Digital Asset Trading (PDAT), designed to offer users all services required to do business with video content on the web effectively and profitably, e.g.

• Describe content
• Negotiate terms
• Request/generate/process events
• Issue licences
• Associate content/ads
• Stream video securely
• Interact with content
• Pay/cash

PDAT is an early implementation of the emerging MPEG-M standard (ISO/IEC 23006 Multimedia Service Platform Technologies). Its modular architecture allows for the easy replacement and introduction of existing and new modules to extend the range of services offered to its users.

Currently PDAT supports the following browsers: IE, Firefox, Chrome and Safari, running on Android, Linux, Mac OS (10.5 onward) and Windows (XP onward). The wim.tv player is a PDAT plugin.
Wim.tv is an ideal platform for the convergence of television services. It is based on international standards, has a growing community and its player is easily portable in such environments as Web, IP and mobile TV.

Initiatives such as wim.tv can provide the video ecosystem the means to move to the next level because of the existence of standard API to access services.

Leonardo Chiariglione