CSA - CAN/CSA-ISO/IEC 14496-20-07
Information technology — Coding of audio-visual objects — Part 20: Lightweight Application Scene Representation (LASeR) and Simple Aggregation Format (SAF)
| Organization: | CSA |
| Publication Date: | 1 November 2007 |
| Status: | inactive |
| Page Count: | 230 |
scope:
This 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
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;
⎯ 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.
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