信息技术.MPEG系统技术.第5部分:字符串语法描述语言(BSDL)

[中文适用范围]： ISO/IEC 23001的这一部分规定了BSDL（比特流语法描述语言），这是一种基于W3C XML Schema的语言，用名为BS Description的XML文档来描述比特流的结构。 BSDL 提供了一种规范语法，用于在 XML 中描述比特流的高级语法；生成的 XML 文档称为比特流语法描述（BS 描述，BSD）。 此描述并不是要取代原始的二进制格式，而是充当附加层，类似于元数据。 在大多数情况下，它不会逐位描述比特流，而是解决其高级结构，例如，比特流如何组织在数据层或数据包中。 此外，BS描述本身是可扩展的，这意味着它可以在不同的语法层描述比特流，例如，根据应用，更精细或更粗糙的细节级别。 该语言最初是在数字项目适应 (ISO/IEC 21000-7) 的背景下开发的，作为适应可扩展多媒体内容的通用工具。 然而，它的用途不限于适应，并且可能与解析比特流的任何应用程序相关。 这就是 ISO/IEC 23001 的这一部分从 ISO/IEC 21000-7 中提取 BSDL 规范以使其可供其他上下文使用的原因。 [外文原描述]： ISO/IEC 23001-5:2008 specifies BSDL (Bitstream Syntax Description Language), a language based on W3C XML Schema to describe the structure of a bitstream with an XML document named BS Description. BSDL provides a normative grammar to describe in XML the high-level syntax of a bitstream; the resulting XML document is called a Bitstream Syntax Description (BS Description, BSD). This description is not meant to replace the original binary format, but acts as an additional layer, similar to metadata. In most cases, it will not describe the bitstream on a bit-per-bit basis, but rather address its high-level structure, e.g., how the bitstream is organized in layers or packets of data. Furthermore, the BS Description is itself scalable, which means it may describe the bitstream at different syntactic layers, e.g., finer or coarser levels of detail, depending on the application. This language was initially developed in the context of Digital Item Adaptation (ISO/IEC 21000-7) as a generic tool for adapting scalable multimedia content. However, its use is not restricted to adaptation and may be relevant for any application parsing a bitstream. This is why ISO/IEC 23001-5:2008 extracts the BSDL specification from ISO/IEC 21000-7 to make it available to other contexts.