What are Post-Production Captions?

Post-production captions are added to a video after it is recorded. Adding captions can be a time-consuming process but there are strategies to help make the process easier. It is also possible to pay a service to have videos captioned.

Definitions and Standards

Captions should be:

  • Accurate (~99%)
  • Synchronized to the audio
  • Readable
  • Positioned on the screen so they do not block important information

If captions are being provided as an accommodation this is the legal standard.


CC provides a visual representation of all audio, including words and other sounds (i.e., “dog barking” or “loud explosion”). Captions are designed for viewers who cannot hear the audio. The “closed” part of “closed captions” means that the captions can be turned on or off. Open captions, on the other hand, are integrated into the video itself and cannot be turned off.

The purpose of subtitles is to translate spoken audio into a language understood by the viewer. Subtitles are designed for viewers who can hear but who do not understand the language used in the video.

Transcripts are text representations of audio presented as a separate document or file.

Technology that converts spoken words into text. ASR can be used to create automatically generated captions. ASR cannot yet create captions that consistently meet accessibility standards on its own, though ASR is often used as a first step when creating accessible media.  

  • E.g. Recording a lecture in Zoom can provide ASR transcripts that can be edited for accuracy.

Captions that are created and/or reviewed by a person. At this time, only human-generated captions meet accessibility standards. SAS delivers video with human-generated captions. 

Also called “described video,” AD is an audio track that narrates the relevant visual information that’s contained within a video. AD is an accommodation for blind and low-vision viewers. Standard AD inserts narration into a video without altering the length of the video. Extended AD pauses the video where necessary to include additional information or description. SAS typically delivers videos with standard AD.

Audio Descriptions are not captions but may be part of making audiovisual media fully accessible.

Creating Captions

There are several ways to add captions to pre-recorded video.

A transcript file can be used to create captions for a video. There are two primary ways to accomplish this:

If you do not have a transcript, you can upload your video to a player that will create automatic captions. You can then edit the captions for accuracy.

If you do not have the time or inclination to create your own captions, you can use a third party service to create caption files. There are a number of companies that can perform this service. SAS can assist with this process ONLY for the purposes of student accommodations.

Learn More about Captioning

Anyone who is responsible for creating or reviewing captions can learn more about captioning standards from several sources.

The DCMP provides services designed to support and improve the academic achievement of students who are blind, visually impaired, deaf, hard of hearing, or deaf-blind.

DCMP Captioning Key – The “gold standard” for captioning, the DCMP captioning key outlines specific guidelines for video captioning. DCMP also has a Description Key that provides guidelines for adding audio description to video.

3Play Media provides closed captioning, transcription, and audio description services. In addition, they have an extensive library of resources related to video accessibility.

3Play Media Video Accessibility Course – A free course that anyone can take to learn about creating accessible videos.

The WAI includes strategies, standards, and resources that make the Web accessible to people with disabilities. Part of this effort includes guidance on how to meet WCAG standards for web accessibility.

Standards for Captions and Subtitles

When captions are created for a video, they are accessed from a separate file, called a “sidecar” file. This file is paired with the video and made available within a video player. Caption files include time stamps that tell the player when to show the text and some file formats will also contain formatting information such as caption placement and style. Two common caption file types are SRT (files end with .srt) and WebVTT (files end with .vtt).

3Play Media: Ultimate Guide to Caption and Description Formats for Popular Video Players