608 Captions vs. 708 Captions: What’s the Difference?

By: Verbit Editorial
old school tv on the floor

In a recent survey, 50% of respondents said that they watch television with subtitles most of the time. Individuals of all backgrounds and abilities use captions and subtitles. However, the Federal Communications Commission (FCC) sets critical guidelines for TV captions to ensure that they provide sufficient support for viewers who are Deaf or hard of hearing. These guidelines undergo regular updates to ensure that they evolve with the needs of audience members. 

One major update to captioning standards occurred because of the transition from analog to digital television in the US. This transition coincided with the passage of the DTV Delay Act in 2009. In order to adapt to this shift, the methods for closed captioning encryption and decoding needed to change as well. As a result, producers introduced a new standard form of captioning. This new captioning format, CTA-708, replaced the previous format, CEA-608.

Table of Contents:

Understanding the Basics of Closed Captioning

Captioning refers to the process of converting the audio track of a video to on-screen text. Closed captioning is a specific style of captioning that allows audience members to enable or disable captions at will. They often appear as white text encased in a black box. Users can typically control these captions either through an on-screen button/menu option (as with smart TVs or streaming services). Alternatively, viewers can enable their captions via the [CC] button on a remote control.

What are 608 Captions?

During the days of analog television, CEA-608 captions were standard in the industry. These captions (sometimes referred to as EIA-608 captions) transmit to a user’s television set via Line 21 captioning data. Line 21 is a data transmission stream that viewers can’t see, but that transmits critical data that runs in the background. 608 caption data relies on Line 21 and needs to be decoded to display captions on the screen.

608 captions typically appear as white text within a black box. The customization options for this type of captioning are somewhat limited. 608 captions also have a limited number of available text characters. As a result, it’s not necessarily possible to display captions in languages with certain special characters. Additionally, Line 21 is only capable of transmitting two fields of data at once. Because of this limitation, 608 captions can generally only support two language options at a time.

What are 708 Captions?

CTA-708 captions (formerly CEA-708 captions) are compatible with digital television. MPEG-2 video streams transmit 708 captions instead of Line 21. MPEG-2 is the standard format for digital TV signals and is capable of transmitting more complex data compared to analog signals. Due to this heightened processing power, 708 captions offer more customizable formatting options. With 708 captions, it’s possible to display captions in a wider variety of languages.

608 vs. 708 Captions

The expectation is that all closed captions will transition to the 708 caption format at some point in the future. However, exactly when this will occur remains unclear. Even after the transition to digital television, CEA-608 captions are popular, and some TV providers even require this format. One issue is that 608 captions can accommodate customers with older television sets.  While 608 captions are compatible with digital television, analog television can’t support 708 captions. As a result, only 608 captions are capable of accommodating all TVs.

On the other hand, 708 captions are capable of offering a wider variety of formatting and language options. For instance, users are able to adjust the size, color, and font style of 708 captions according to their personal preferences. This functionality may be particularly valuable to viewers with certain sensory sensitivities or those who experience some degree of vision loss or colorblindness.

Also, while 608 captions can only appear in two languages simultaneously, users can view 708 captions in a wide variety of languages. Because 708 captions are capable of transmitting special characters, it’s possible to use them for captions in non-Western languages.  

Find the Right Fit with Verbit

Media professionals around the world rely on Verbit for their closed captioning needs. Verbit uses a dual approach to transcription that allows them to produce a high volume of captions that achieve targeted accuracy rates as high as 99%. This level of accuracy helps to support critical accessibility guidelines like those set by the FCC and the ADA.  

Verbit’s closed captioning services support media companies, content creators and business professionals looking to improve accessibility and expand their reach. With Verbit’s combination of artificial intelligence and professional human transcribers, users can create accurate captions in web-compatible file formats like SRT and VTT. Additionally, Verbit’s closed captions work for broadcast television purposes. Verbit’s dedicated customer support team has the industry know-how and experience necessary to help you find the right captioning style. Reach out today to learn more about how Verbit’s platform can help to support more inclusive media for all.