CEA708

CEA-708, also known as Digital Closed Captioning or DTVCC, is a standard for encoding and presenting closed captions in digital television streams. Developed by the Consumer Electronics Association, it is widely implemented in ATSC digital television environments in the United States and Canada. CEA-708 supersedes the older CEA-608 standard used for analog captioning and is designed to carry caption data within MPEG-2 transport streams as DTVCC data packets. The data are decoded by capable receivers, enabling on-screen captions with advanced styling and placement.

The standard provides multiple caption services, support for several languages, and a comprehensive set of presentation features. It offers flexible windowing and positioning, allowing captions to appear in specific areas of the screen or in dedicated caption windows. Styling options include font selection, size, color, and opacity, along with various display modes such as scroll, pop-on, and roll-up. CEA-708 also supports extended character sets and enhanced control over caption timing and transitions. For compatibility, it includes mechanisms to render CEA-608 captions when needed, ensuring backward compatibility with legacy material.

Implementation is through DTVCC data carried in the video stream, typically within the MPEG-2 transport stream as packets interpreted by the TV or receiver. Modern devices commonly decode both 608 and 708 streams, providing access to digital captions while preserving access to older content. CEA-708 captions are standard for ATSC broadcasts and are supported by a wide range of digital television receivers, set-top boxes, and media players, contributing to accessibility for viewers who are deaf or hard of hearing and for users requiring language subtitles.