CAN/CSA-ISO/IEC 14496-20-09

This National Standard of Canada is equivalent to International Standard ISO/IEC 14496-20:2008. 1 Scope This part of ISO/IEC 14496 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 bitstream, - an efficient interface with audio and visual streams with frame-accurate synchronization, - use of any font format, including the OpenType 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, extensibility 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, - signalling 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 part of ISO/IEC 14496 defines the usage of SAF for LASeR content; however, LASeR can be used independently from SAF.