Recommendations for video subtitles
Videos with audio content need to have subtitles. This is the only way to ensure that people with hearing impairments can also access all essential information.
The legal situation requires all videos with audio content to have subtitles (Swiss accessibility standard eCH0059, based on the WCAG). ETH Zurich pursues the pragmatic strategy of focusing primarily on videos with high external impact and reach.
We have put together some tips and recommendations to help you create high-quality subtitles. Unless otherwise indicated, these are recommendations and not guidelines.
Recommendations on character count and readability
- Character count: Use a maximum of 45 characters per line
- Reading speed:
- For TV subtitles, it is assumed that people can read around 20 characters per second for news programmes.
- In all other contexts, the assumption is 15 characters per second. These figures give the audience a chance to read the content at a comfortable speed.
- If the subtitle consists of just a single word, a display duration of one second is sufficient. From two words on, the subtitles should be displayed for a minimum of two seconds.
- For TV subtitles, it is assumed that people can read around 20 characters per second for news programmes.
- Editing: Subtitles can usually be edited to remove peculiarities of speech such as filler words (um, uh, etc.) and redundant content.
- Number of lines: It’s best to have the subtitles on one line.
- Placement (depends on the tool): Subtitles are usually displayed at the bottom of the frame. In some situations, this can cover up too much of the image. In these cases, you can also place subtitles at the top of the frame if it makes sense. Not all tools for subtitle creation give users the option of choosing the placement.
Recommendations for use of colour
- Text and background colour: Users can customise the settings for subtitles on YouTube and Vimeo as they see fit. The ETH video player (Matterhorn) does not offer this option.
- Showing a change of speaker: Generally, a change of speaker only needs to be indicated within the same subtitle; normally the viewer recognises that the speaker has changed by how the video is cut. A change of speaker can be shown by putting the person’s name in brackets or by using a dash.
- Using different colours per speaker:
- It is not necessary to visually indicate different speakers through the use of colour. It is an option but not mandatory.
- If you’re working with colour, you can indicate a change of speaker by changing the colour (make sure that each speaker has the same colour throughout the video).
- It is not necessary to visually indicate different speakers through the use of colour. It is an option but not mandatory.
Recommendations on writing style, abbreviations and non-textual elements
- Abbreviations: Common abbreviations can be used in subtitles (such as e.g., etc.).
- Numbers: Numbers up to and including 12 should be written out.
- Commas: If the sentence requires a comma, the line should end after this comma. This is more pleasant for the reader than trying to insert words after the comma, even if they fit.
- Title: Titles of films, magazines, books, etc. should be set apart using quotation marks: “ETH life”, “History of Switzerland”, etc.
- Music: Music and certain musical pieces are set apart using square brackets, e.g. [Beethoven’s Fifth Symphony], [guitar music], [Carmina Burana].
- Setting: Descriptive details that give more information about the setting are set apart using asterisks, e.g. * loud music* or *gentle rustling*.
- Speaking volume: When describing how something is said, this information is put in brackets, e.g. (quietly), (whispering), (shouting).
- Emphasis: If you would like to emphasise a word, you can write it by spacing out the letters: I would like to e m p h a s i s e a word Note: if you write a word in this way, you need to add three spaces before and after the word so that it is clearly set apart from the rest of the text.
- Unfinished sentences: You can indicate unfinished or interrupted sentences with the use of an ellipsis: ...