CEA-608 and CEA-708 captions are the two closed caption standards for broadcast television. CEA-608 captions are the old standard used in analog television while CEA-708 captions are the new standard format used in current digital television broadcasts. (CEA – Consumer Electronics Association)
In the US, with the signing of DTV Delay Act in 2009, analog television was officially replaced by digital television. This required the captioning providers to switch from CEA-608 captions to CEA-708 captions. Although CEA-608 captions are still supported by digital television, CEA-708 captions are considered to be the preferred choice as CEA-708 caption standard complies with the FCC closed caption regulations.
With the DTV Delay Act, analog television slowly moved out from modern use; CEA-608 captions will also wean away from use.
CEA-608 Closed Captions (Line 21 Captions)
Analog broadcast television used to use 608-captions as their standard; however, 608-standard can also be embedded in digital television. These closed captions are displayed in conventional uppercase with black-box background. 608 captions can be viewed only if you have a decoder as they are concealed in the Line 21 data area of the analog television signal. This is the reason why 608 captions are also known as Line-21 Captions. There are two fields in Line-21; first field is normally used to transmit English captions while the second field is used for Spanish, French, Portuguese, Italian, German and Dutch closed captions. The main problem with 608-caption standard is that it does not adhere to many of the FCC closed caption regulations.
CEA-708 Closed Captions
708 captions are low bandwidth textual, and it is the standard used by all digital television broadcasts. 708-caption standard is much more advanced than CEA-608 captions. This captions standard is used in both standard-definition and high-definition digital broadcasts; it is a misconception that 708-captions are only used in high-definition channels. With 708 caption standard, viewers can control appearance of the captions. This standard allows viewers to select font options, text sizes, text colors and background colors. In CEA-708 captions there are 8 options for font, 3 for text sizes, 64 for text colors and 64 for background colors. CEA-708 caption does not work in analog television broadcasts. 708 captions support almost all languages used across the world. This standard also supports any special character or symbol. 708 captions have multilingual competence, which allows the broadcasters to reach out to a wider audience across the world.