Captioning and Subtitling Services

Posts tagged ‘Line 21 caption’

608 and 708 Captions

CEA-608 captions, also known as Line 21 captions, were the standard for analog television broadcasts.  CEA-608 captions are embedded in the television signal and hidden in line 21 of the vertical blanking interval (VBI).  CEA-608 captions become visible when the consumer activates a decoder, either built into the television or existing separately as a set-top box. CEA-608 captions appear in white font on a black, boxed background.  Many languages may be excluded from CEA-608 captioning entirely as not all alphabetical characters are supported.

CEA-708 captions are the standard for digital television broadcasts, whether in standard definition or high definition.  As digital television does not have VBI, CEA-708 captions are placed into MPEG-2 video streams in the picture user data.  A consumer with a digital television featuring a built-in decoder may choose to view the closed captions in any of eight different fonts, three different font sizes, and 64 different colors of font and background, thus customizing the caption display.  CEA-708 captions also have the advantage of supporting Unicode characters, allowing the captioning of most all of the world’s languages.  CEA-708 captioning allows for more flexible placement of captions.  CEA-608 captions may also be transported through CEA-708.

PLEASE NOTE:  Up-converted 608 captions are not “True 708 Captions” and cannot take advantage of any of the new 708 caption features, such as multiple fonts and styles, multiple windows, or Unicode character support. CompuScripts Captioning delivers true 708 captions.