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2.2.4 Subtitling

Subtitling is helpful for people who cannot hear or who have restricted hearing. Subtitling gives a written presentation of the speech in the video and appears towards the bottom of the screen. Subtitles also help people who are watching the video in a noisy setting, or if they have a poor Internet connection or their first language is not the one used by the teacher in the video. Subtitles should be as close as possible to the original text, provided this does not interfere with understanding. It is okay to edit sentences if this is necessary to make them easier to understand. Subtitles are in the teaching language. Other languages may also be integrated. It should be possible to switch subtitling on and off (closed captions). This is normally shown using the CC symbol. Closed captions offer far more flexibility and present fewer barriers, because some users are absolutely reliant on subtitles, but they can be distracting to others. If the player does not allow CC to be switched on and off, subtitles may be permanently integrated (hardcoded) in one version of the video. In this case, a second version of the video without subtitles should ideally also be provided. The most common file formats for subtitles are .srt and .vtt. You should find out which formats the available player supports.

There are various methods available for producing subtitles:

  • Automatically-generated subtitles, where the speech is converted into text using linguistic data processing; this can save time and effort. If your institution does not have its own software solution for automated subtitles, one common, free, automated method is to have subtitles generated using YouTube. A service that has to be paid for is offered by e.g. Amberscript. Subtitles produced on the platforms can be edited and downloaded as files. This function allows you to incorporate them later in the chosen player and/or to hardcode them in to the video. There are various detailed instructions on the Internet on how to do this with YouTube, e.g. these in German by TJFBG. Even if the videos are not published on YouTube, you should consider or discuss whether uploading the video involves any data protection issues. The GDPR, national and federal state laws and the rules of the organisation all apply. Consult the data protection officer in charge and your in-house information/IT security officer. Although the quality of speech-to-text programs have improved markedly in recent years, automatically-generated subtitles must always be checked to see that they are correct (e.g. specialist terms, names, theories) and where necessary amended. It is advisable to use a process of multiple checks.
  • Producing subtitles manually is very time-consuming compared to the automated systems. Without a script, the audio track must be completely transcribed and timestamps have to be added. The actual speaker’s script for the video can help to save on time and effort here. After comparing the script with the audio track of the video, the individual sentences can be copied into the subtitle editor using copy/paste and the timestamps can also be placed in the video using the editor. One particularly good browser-based editor tool is Subtitle Horse, and as a desktop editor there is Subtitle Workshop. The TU Dortmund’s guide on producing subtitles for university teaching courses is a very practical German-language guide with numerous handy tips. It also includes information on standards for subtitling, file formats and another editor program.
  • The scope of video subtitling can vary. Besides subtitles in the teaching language, e.g. German speech, subtitles can also be translated into other languages.
  • When subtitling you must follow the subtitling standards concerning design, insertion, content, etc. The websites of broadcaster NDR and of the BIK-für-Alle project give a comprehensive overview of applicable standards.

The DaLele4All team decided to commission automatically-produced subtitles in German externally. This job was also commissioned from the SUB video team. These subtitles were then edited by student assistants and hardcoded into a copy of the spoken video by the team.

Example of a screen with subtitles: A lecture slide is shown on the left of the image and the lecturer is placed on the right, displayed up to the waist. Below the slide in the center, a two-line subtitle is shown in white font, backed by a dark bar.
Diagram 9: Example of subtitling

To do this you must make the following decisions and checks:
  1. Choose a method (automatic or manual production of subtitles)
  2. Choose what is included (subtitling in teaching language and poss. others)
  3. Produce the subtitles
  4. Check the subtitles and where necessary revise (e.g. stylistic highlighting or hardcoding)

Practical tips

  • Remember to keep sentences short and simple when you write the script. This makes them far easier to read as subtitles. Complicated sentences with numerous clauses make subtitles hard to understand. For instance, we divided the following original sentence into three for the subtitles:
    Old version: “Similar to how the increasing use of steam-powered machinery in the 19th century and then the motorisation of our society powered by oil in the 20th century shaped daily life in our society, growing use of data today will lead to an equally profound change in our lives.”
    Revised: “In the 19th century, increasing use of steam-powered machinery led to radical changes in the working lives of broad segments of society. Then, in the 20th century, the motorisation of our society powered by oil shaped business and private life significantly. And in this century we can already see how much growing use of data will lead to equally profound changes in our lives.”
  • When recording the video, you should also take care to speak more slowly and allow pauses so that the subtitles can be seen for long enough; this improves accessibility.
  • If you are subtitling a video with several speakers, choose a subtitling editor (e.g. Subtitle Workshop) that offers a variety of font colours. This way you can allocate a font colour to each speaker. Take care when selecting the colours to ensure that they are legible against the black background that is often used for subtitling, as this can affect accessibility. The font colour should be clearly distinguished from the background (see also information from the Bundesarbeitsgemeinschaft der Taubblinden e.V.). Alternatively, when the speaker changes, mark this in the subtitles by giving the name followed by a colon or hyphen.
  • Besides the necessary correction of typos, it is a good idea to edit subtitles slightly. Expressions that are natural in the flow of speech, such as “er” or “um”, as well as fillers (e.g. so, like) or repetitions can be deleted from the subtitles in teaching videos. In other formats such as interview sequences or school classroom interactions that are being analysed, it may on the other hand be advisable not to edit the subtitles at all.
  • If you have made minor slips in your spoken text, they should simply be corrected in the subtitles. In order to make people who watch the video without subtitles aware of a linguistic slip, you should highlight the mistake or correction. You can add a note e.g. with an overlay and/or audible addition at the relevant point in the video, or else at the end of the video. Make sure that the correction is clearly noted in all versions.