ITU-T J.1291 PDF

This Recommendation specifies the requirements and functions of the audio and video interfaces of cable set-top boxes to ensure full compatibility between cable set-top boxes and TVs/monitors with the same interfaces.

With the rapid growth of ultra-high definition (UHD) video business, digital content via high-definition multimedia interface (HDMI) interfaces has become prevalent. However, there is still demand for analogue connections, such as Radio Corporation of America (RCA) connectors, especially for users with old analogue televisions. The RCA connectors facilitate the transmission of composite video broadcast signal (CVBS) and analogue audio signals from the cable set-top box (STB) to the television via RCA cables. As the trend towards miniaturization of set-top box designs continues, one type of 3.5 mm connect interface is progressively replacing RCA interfaces. To further reduce printed circuit board (PCB) size and optimize the appearance of set-top boxes, it is recommended to utilize the 3.5 mm mini audio and video (AV) interface for transmitting CVBS and analogue audio signals.

The principle of this Recommendation is to ensure sufficient compatibility between the STB and TV, thereby enhancing the user experience.

To provide guidance to manufacturers and encourage the adoption of the universal 3.5 mm mini AV interface, the mechanical dimensions are presented in Appendix I.

This Recommendation specifies electrical requirements for the analogue CVBS and audio using the 3.5 mm mini AV connector in cable STB terminals.

This Recommendation is applicable to cable STB with a physical analogue video and audio output/input interface, other communication devices also refer to this Recommendation.