19 Jul 2021

Manual labour: Creating best practice guidelines for captioning DCU Library’s YouTube videos

Post by Eilís O'Neill (@mise_eilis) is a senior library assistant working in DCU Library as a member of the research and teaching team.

DCU Library’s Captioning Best Practices and Subtitle guidelines were born from a request by a DCU student for the transcript of a recorded online training session, hosted on YouTube. When a member of the library’s research and teaching team viewed the automated subtitles and transcript provided by YouTube, they realised how inadequate they were.

The team decided to manually edit the automated subtitles for all our existing YouTube videos but quickly realised that we needed a procedural manual. This would ensure that our captions were standardised and followed best practice guidelines – and who doesn’t love a good procedural manual?  You’ll notice that I refer to both subtitles and captions here; these terms are often used interchangeably. However, captions are generally designed for viewers who can’t hear the audio in a video while subtitles are designed for viewers who can hear but who don’t understand the language in the audio.
The Benefits and Importance of Video Captioning
Making our videos more usable and accessible would have huge benefits for all our viewers, whether they were deaf, hard of hearing or hearing. Many people use subtitles: as much as 20% of the population in the US or UK and 80% of them are hearing, increasing to 35% for some online content (BBC, 2018, para. 2; Datta et al., 2020, p. 195). Studies have found that students given manually captioned instructional videos are more engaged, more responsive to questions, understand and retain the information better and achieve higher grades than students whose videos aren’t captioned (Chazen, 2020; Erler & Automatic Sync Technologies, 2012).

Add to this the fact that the students registered with disability support services in 2018 made up more than 6% of the total student population in higher education in Ireland. (Ahead, 2020, para. 1). Providing accurate captions for our educational video content supports those with different learning needs and styles; viewers can both see and hear the contents of the video simultaneously. Learners have been shown to process information more effectively when it’s presented in more than one sensory mode (Minnesota State captioning committee, 2017).

Accurate captions are essential for viewers who need to access videos in environments where the audio is difficult to hear or is intentionally muted. Online video content is frequently accessed without audio; 85% of Facebook’s videos are watched on mute (Lemonlight, 2020, para. 9). Captions help second language learners understand video content and verbatim captions can also improve reading skills. They help viewers understand complex terminology and decipher unfamiliar accents (Debevc et al., 2014).
Inaccurate captions or subtitles that don’t match the dialogue can negatively affect the viewer’s experience to the point that they stop watching the content (Szarkowska et al., 2020). When captions are less than 97% accurate readers find it difficult to understand the content being presented. At 90% the text can barely be understood at all (Erler & Automatic Sync Technologies, 2012, p. 6). This is significant because the accuracy rates of automatic captioning technologies including YouTube’s have been shown to vary from between 60-90% depending on the speaker’s accent (Minnesota State captioning committee, 2017, p. 13). See in the image below how YouTube’s automated subtitles interpret how easily plagiarism can be spotted by “a trained eye.” YouTube’s automatically generated captions don’t have punctuation or capitalisation; subtitles without punctuation make it harder for viewers to understand grammar, sentence structure and make it harder for them to identify speakers (Datta et al., 2020).

Screenshot from 'Is it easy to spot plagiarism?' 2013 DCU Library
Screenshot from 'Is it easy to spot plagiarism?' 2013 DCU Library

Worthwhile Time and Effort
Manually captioning videos can be time-consuming; it can take anything from 5-10 times the duration of the video to caption it (Enamorado, 2018, para. 2). Editing the automated captions provided by YouTube speeds up the process, as captions don’t have to be created from scratch. It’s worth taking the time to do it, not only because it’s of huge benefit to viewers but also because viewers are 80% more likely to view a video until the end if captions are included (Lemonlight, 2020, para. 9). Manually edited captions also help with search engine optimisation (SEO) because Google indexes captions that you’ve added to videos (Albright, 2018).

An interesting David and Goliath story with potential international repercussions took place in 2020. The National Association of the Deaf in the U.S. A. won a law suit brought against Harvard University and MIT for violating US accessibility laws. The suit focused on their failure to provide high-quality captions for their online programming to people who are deaf and hard of hearing. The auto-captions provided on platforms like YouTube were deemed inaccurate and of poor quality. A precedent has now been set which holds universities in the U.S.A. accountable for providing high-quality captioning for their online video content (Leduc, 2020). It’s worth noting that Ireland’s Disability Act 2005 mandates that public services, including those provided by publicly-funded Irish Universities, be made accessible and inclusive for all people regardless of disability (Lewis, 2017). Compiling this manual and committing to the creation of high-quality captions for our video content is a proactive rather than a reactive step that anticipates the needs of our users and supports their learning.
Re-Use, Re-Purpose
We’ve made the manual available as an Open Educational Resource on the Zenodo platform under a Creative Commons Attribution 4.0 licence. It draws on current best practices recommended by deaf and hard of hearing advocacy organisations, broadcasting guidelines, academic journal articles, principles of universal design and World Wide Web Consortium (W3C) standards. It shows users how to improve the readability of captions through the application of punctuation, capitalisation, line breaks and sentence layout, numbering and date and time. It also goes through the pros and cons of using YouTube’s subtitles and gives instructions on how to edit these to produce high-quality captions. We hope that these guidelines will be used and adapted by other organisations who wish to make their educational online content more accessible to their users.


Ahead. (2020, July 24). Launch of Students with Disabilities Engaged with Support Services in Higher Education in Ireland 2018/19 Report. Ahead.ie; AHEAD. https://ahead.ie/Launch-of-New-Report-on-Numbers-of-Students-with-Disabilites-in-Higher-Education

Albright, D. (2018, March 7). 7 Reasons Your Videos Need Subtitles [Infographic]. Uscreen. https://www.uscreen.tv/blog/7-reasons-videos-need-subtitles-infographic/

BBC. (2018). BBC Subtitle Guidelines. BBC. https://bbc.github.io/subtitle-guidelines/

Chazen, D. (2020, June 22). Closed Captioning Best Practices & Subtitle Guidelines. Verbit. https://verbit.ai/closed-captioning-best-practices-subtitle-guidelines/

Datta, P., Jakubowicz, P., Vogler, C., & Kushalnagar, R. (2020). Readability of Punctuation in Automatic Subtitles. In K. Miesenberger, R. Manduchi, M. Covarrubias Rodriguez, & P. Peňáz (Eds.), Computers Helping People with Special Needs (pp. 195–201). Springer International Publishing. https://doi.org/10.1007/978-3-030-58805-2_23

Debevc, M., Stjepanovič, Z., & Holzinger, A. (2014). Development and evaluation of an e-learning course for deaf and hard of hearing based on the advanced Adapted Pedagogical Index method. Interactive Learning Environments, 22(1), 35–50. Academic Search Complete.

Enamorado, S. (2018, December 20). How Long Does It Take To Manually Caption YouTube Videos? 3Play Media. https://www.3playmedia.com/blog/long-take-manually-caption-videos/

Erler, K., & Automatic Sync Technologies. (2012). The essential Higher Ed closed captioning guide. https://secfac.wisc.edu/wp-content/uploads/sites/50/2017/09/The-Essential-Higher-Ed-Closed-Captioning-Guide.pdf

Leduc, J. (2020, March 25). Overview of NAD v. Harvard and NAD v. MIT Lawsuits. 3Play Media. https://www.3playmedia.com/blog/harvard-mit-sued-captioning-violation-ada-rehabilitation-act/

Lemonlight. (2020, February 12). How Video Captions Help Attract and Engage More Users. Lemonlight – High-Quality, Affordable Video Production. https://www.lemonlight.com/blog/how-video-captions-help-attract-and-engage-more-users/

Lewis, E. (2017, March 14). Accessibility Laws in the Emerald Isle. 3Play Media. https://www.3playmedia.com/blog/accessibility-laws-emerald-isle/

Minnesota State captioning committee. (2017). A campus toolkit for course captioning. https://ccaps.umn.edu/documents/CPE-Conferences/MnLC/MNStateCaptioningToolkit.pdf

Szarkowska, A., Díaz Cintas, J., & Gerber-Morón, O. (2020). Quality is in the eye of the stakeholders: What do professional subtitlers and viewers think about subtitling? Universal Access in the Information Society. https://doi.org/10.1007/s10209-020-00739-2


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