Closed captioning consists of onscreen text which includes dialogue and sound descriptions necessary for deaf and hard of hearing viewers. Offline and online closed captioning differ in both their output style and creation processes.
Online Closed Captioning
Also referred to as live closed captioning, professional subtitlers create online closed captions on-the-spot for live programmes. Typically, there are two methods to working with online closed captions. Live stenographers may work to type in real-time, or captioners may rely on recognition software. Live closed captioning takes a significant amount of skill and costs can be very high.
For many live broadcast programmes, speakers may use autocues, where a screen displays a script which they will read from. Working from pre-supplied scripts can be beneficial to video service providers and broadcasters as a means of saving time and money, whilst also improving the quality of finished captions. Live closed captions are broadcast immediately, with the ultimate goal of syncing as much as possible with the live video feed. Therefore, there is little to no time left for error corrections or proofreading. Where possible, producers may supply scripts ahead of time to assist with the video transcription aspect of subtitling. However, where unpredictable names, places or jargon arise, there is always a relative risk of error.
Where broadcasters require live closed caption translation, the process will be almost identical. However, a skilled linguist will need to be on-hand to provide a direct translation service and even more expertise will be needed to ensure high quality foreign captions.
Online closed captions often display in a roll-up or paint on style. This helps to avoid distracting viewers too much as the text is often not entirely in sync.
Offline Closed Captioning
In contrast to online closed captions, offline captions are created from pre-supplied video footage which is not being broadcast live. Offline closed captions should always be the preferred option in terms of saving money and massively improving quality. Working on closed captioning offline makes it easier for subtitlers to identify speakers and accurately describe important sound effects, as well as research spellings and correct errors.
In cases where a production script is not available, video transcription services may also be required. In some cases, one captioning company may be able to take on both transcription and subtitling as a full package. Though offline closed captions will not feed directly into live broadcasts, urgent closed captioning services are sometimes available. Capital Captions offer turnarounds as low as six hours.
In terms of styles for offline closed captioning, pop-on, roll-up and paint-on are all available. Some of the most common formats include CEA-608, CEA708, DFXP, XML, TTML, EBU-TT, EBU-STL, WebVTT and SCC.
If you would like to know more about closed captioning and how it works, or how offline and online closed captioning differ, feel free to browse through our summaries on closed captioning formats and guidelines. Alternatively, if you need any advice around captioning your own videos, don’t hesitate to contact us via email, or give us a call on 01634 867131.