ISO/IEC 14496-20:20 08定义了场景描述格式(LASeR)和聚合格式(SAF)，它们分别适用于表示富媒体服务并将富媒体服务递送到诸如移动电话的资源受限设备。 LASeR旨在满足富媒体服务在场景描述层面的所有需求。激光支架: 从SVG继承的用于描述富媒体场景的优化对象集， SVG上的一小部分关键兼容扩展， 编码和传输激光流然后重建SVG内容的能力， 场景的动态更新以实现响应式、流畅连续的服务， 简单而高效的压缩，以改善交付和解析时间以及存储大小，设计目标之一是允许直接实现所记录的SDL，以及符合ISO/IEC 23001标准的解码器-为了解码激光比特流， 与具有帧精确同步的音频和视频流的高效接口， 使用任何字体格式，包括OpenType行业标准，以及 从其他流行的富媒体格式轻松转换，以便利用现有的内容和开发人员社区。 激光的技术选择标准包括压缩效率，但也包括代码和内存占用以及性能。其他目标包括:可伸缩性、对用户环境的适应性、格式的可扩展性、定义小概要的能力、J2ME实现的可行性、错误恢复和实现的安全性。 SAF旨在在媒体/场景描述和现有传输协议之间的接口上满足富媒体服务的所有要求:任何类型的流的简单聚合， MPEG和非MPEG流的信令， 针对带宽受限的网络优化的数据包报头， 轻松映射到流行的流媒体格式， 高速缓存管理能力，以及 可扩展性。 SAF旨在补充激光，提供简单的交互式服务，带来: 高效动态打包应对高时延网络， 媒体交织，以及 开销非常低的同步支持。 ISO/IEC 14496-20:20 08定义了SAF用于激光内容；然而，激光可以独立于SAF使用。

ISO/IEC 14496-20:2008 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,
• 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.

ISO/IEC 14496-20:2008 defines the usage of SAF for LASeR content; however, LASeR can be used independently from SAF.