ISO/IEC 23002-4:20 18基于ISO/IEC 23001-4中规定的解码器描述来定义MPEG视频工具库(VTL)的描述。该工具库定义了FU的规范，这些FU足以根据以下编码标准构建完整的解码解决方案: -ISO/IEC 14496-2(MPEG-4简单简档)， -ISO/IEC 14496-10(MPEG-4 AVC约束基线简档和渐进高简档)， -ISO/IEC 14496-16(MPEG-4 SC3DMC)，以及 -ISO/IEC 23008-2(HEVC主配置文件)。 ISO/IEC 23001-4的目标是定义通用框架原则，并且该文档定义了MPEG VTL，其包括来自现有MPEG编码标准的相关工具（或FU）。每个FU都以文本描述的形式定义，可以在4.1中找到。输入和输出行为遵循第5条、第6条和第7条中描述的约定。可以使用任何软件或硬件语言和组件来设计符合ISO/IEC 23002-4:20 18的实现。FUs文本规范的参考软件是用RVC-CAL语言编写的，其正式语法在ISO/IEC 23001-4中提供。

ISO/IEC 23002-4:2018 defines the description of the MPEG video tool library (VTL) based on the decoder description specified in ISO/IEC 23001-4. This tool library defines the specification of FUs, which are sufficient to build complete decoding solutions according to the following coding standards:
- ISO/IEC 14496-2 (MPEG-4 Simple Profile),
- ISO/IEC 14496-10 (MPEG-4 AVC Constrained Baseline Profile and Progressive High Profile),
- ISO/IEC 14496-16 (MPEG-4 SC3DMC), and
- ISO/IEC 23008-2 (HEVC Main Profile).
The objective of ISO/IEC 23001-4 is to define the general framework principles, and this document defines the MPEG VTL that includes relevant tools (or FUs) from the existing MPEG coding standards. Each FU is defined in the form of a textual description, which can be found in 4.1. The input and output behaviour follows the conventions described in Clause 5, Clause 6, and Clause 7.
ISO/IEC 23002-4:2018 compliant implementations can be designed using any software or hardware language and components. The reference software for the textual specification of FUs is written in RVC-CAL language of which a formal syntax is provided in ISO/IEC 23001-4.