ISO/IEC TS 20071-25:2017提供了在所有类型视频中使用的字幕/字幕和其他屏幕文本的音频演示建议，无论用于传输和呈现录制或直播视频的语言和技术如何。 ISO/IEC TS 20071-25:2017适用于使字幕/字幕和其他屏幕文本可供有各种需求的用户访问，包括但不限于学习和阅读障碍者、认知障碍者、盲人或低视力者、老年人和非母语人士。它不适用于字幕/副标题或其他屏幕文本，其内容已在配乐中以某种语言和用户可以访问的方式提供。 ISO/IEC TS 20071-25:2017提供了关于作为独立访问服务的语音字幕/字幕的指导，但也提供了关于如何在不同类型的视频中集成语音字幕/字幕、其他语音屏幕文本和音频描述（如果需要）的指导。 注1:ISO/IEC/TS 20071-21中提供了关于音频描述的广泛指南。 ISO/IEC TS 771-25:2017不考虑用于传送和播放视频中文本的内容或音频呈现的设备或传输机制。这些设备包括但不限于电视、计算机、无线设备、投影设备、DVD和家庭影院设备、影院设备和其他形式的用户界面技术。 因此，该文档不考虑代码转换文件以用于各种视频和音频输出。 注2:传输和分发的技术问题由其他文件（如MPEG标准和其他技术标准，如IEC 62731:2013）涵盖。 ISO/IEC TS 20071-25:2017承认用户的各种需求和偏好，以及视频中文本音频呈现的不同方法。 它适用于与原始视频同时播放的音频演示。

ISO/IEC TS 20071-25:2017 provides recommendations on the audio presentation of captions/subtitles and other on-screen text for use in all type of videos regardless of the language and technology being used to transmit and present the recorded or live video. ISO/IEC TS 20071-25:2017 applies to making captions/subtitles and other on-screen text accessible to users with various needs, including but not limited to people with learning and reading disabilities, people with cognitive disabilities, people who are blind or have low vision, older people, and non-native language speakers. It does not apply to captions/subtitles or other on-screen text whose content is already provided in the soundtrack in a language and a way users can access. ISO/IEC TS 20071-25:2017 provides guidance on spoken captions/subtitles as a stand-alone access service but it also provides guidance on how to integrate spoken captions/subtitles, other spoken on-screen text and audio description, if needed, in different types of videos. NOTE 1 Extensive guidance on audio description is provided in ISO/IEC/TS 20071？21. ISO/IEC TS 20071-25:2017 does not consider the devices or transmission mechanisms used to deliver and play the content or the audio presentation of text in videos. These devices include, but are not limited to televisions, computers, wireless devices, projection equipment, DVD and home cinema equipment, cinema equipment and other forms of user interfaces technology. Therefore, this document does not consider transcoding files for the various video and audio outputs. NOTE 2 Technical matters of transmission and distribution are covered by other documents (e.g. MPEG standards and other technical standards such as IEC 62731:2013). ISO/IEC TS 20071-25:2017 acknowledges the various needs and preferences of users, as well as the different approaches to the audio presentation of text in videos. It applies to audio presentations intended to be heard simultaneously along with the original video.