PrefaceStandards development within the Information Technology sector is harmonized with international standards development. Through the CSA Technical Committee on Information Technology (TCIT), Canadians serve as the Canadian Advisory Committee (CAC) on ISO/IEC Joint Technical Committee 1 on Information Technology (ISO/IEC JTC1) for the Standards Council of Canada (SCC), the ISO member body for Canada and sponsor of the Canadian National Committee of the IEC. Also, as a member of the International Telecommunication Union (ITU), Canada participates in the International Telegraph and Telephone Consultative Committee (ITU-T).
ScopeThis International Standard defines a scene description format (Laser) and an aggregation format (SAF) respectively suitable for representing and delivering rich-media services to resource-constrained devices such as mobile phones.
LASER aims at fulfilling all the requirements of rich-media services at the scene description level. LASER supports:
- an optimized set of objects inherited from SVG to describe rich-media scenes;
- a small set of key compatible extensions over SVG;
- the ability to encode and transmit a Laser stream and then reconstruct SVG content;
- dynamic updating of the scene to achieve a reactive, smooth and continuous service;
- simple yet efficient compression to improve delivery and parsing times, as well as storage size, one of the design goals being to allow both for a direct implementation of the SDL as documented, as well as for a decoder compliant with ISO/IEC 23001-1 to decode the Laser bit stream;
- an efficient interface with audio and visual streams with frame-accurate synchronization;
- use of any font format, including the Open Type industry standard; and
- easy conversion from other popular rich-media formats in order to leverage existing content and developer communities.
Technology selection criteria for Laser included compression efficiency, but also code and memory footprint and performance. Other aims included: scalability, adaptability to the user context, extensible of the format, ability to define small profiles, feasibility of a J2ME implementation, error resilience and safety of implementations.
SAF aims at fulfilling all the requirements of rich-media services at the interface between media/scene description and existing transport protocols:
- simple aggregation of any type of stream;
- signaling of MPEG and non-MPEG streams;
- optimized packet headers for bandwidth-limited networks;
- easy mapping to popular streaming formats;
- cache management capability; and
- extensibility.
SAF has been designed to complement Laser for simple, interactive services, bringing:
- efficient and dynamic packaging to cope with high latency networks;
- media interleaving; and
- synchronization support with a very low overhead.
This International Standard defines the usage of SAF for Laser content. However, Laser can be used independently from SAF.
