SMPTE ST 334-1:2015

This standard defines a method of mapping closed captioning and certain other related data services into the 10-bit vertical ancillary (“VANC”) data space. It specifies the structure of packets carrying CEA-708, as well as CEA-608 closed captioning data, time code data, and ATSC A/65 closed caption descriptor information, which may be carried in vertical ancillary data space, via serial data communications interfaces, or via other means.

The related data services include data broadcast services intended for the public as well as broadcaster internal control and communications.