Research on subtitles

The BBC Academy guide to subtitling.

Good subtitling is an art that requires negotiating conflicting requirements. On the whole, you should aim for subtitles that are faithful to the audio. However, you will need to balance this against considerations such as the action on the screen, speed of speech or editing and visual content.

For example, if you subtitle a scene where a character is speaking rapidly, these are some of the decisions you may have to make:

• Can viewers read the subtitles at the rate of speech?
• Should you edit out some words to allow more time?
• Can subtitles carry over to the next scene so they ‘catch up’ with the speaker?
• Should you use cumulative subtitles to convey the rhythm of speech (for example, if rapping)?
• If there are shot changes within the sequence, should the subtitles be synchronised with those?
• Should you use one, two or three lines of subtitles?
• Should you change the position of the subtitle to avoid obscuring important visual information or to indicate the speaker?

Prefer verbatim

If there is time for verbatim speech, do not edit unnecessarily. Your aim should be to give the viewer as much access to the soundtrack as you possibly can within the constraints of time, space, shot changes, and on-screen visuals, etc. You should never deprive the viewer of words/sounds when there is time to include them and where there is no conflict with the visual information.

However, if you have a very "busy" scene, full of action and disconnected conversations, it might be confusing if you subtitle fragments of speech here and there, rather than allowing the viewer to watch what is going on.

Don't automatically edit out words like "but", "so" or "too". They may be short but they are often essential for expressing meaning.

Similarly, conversational phrases like "you know", "well", "actually" often add flavour to the text.

 Incorrect grammar

You should not correct any incorrect grammar that forms an essential part of dialect, e.g. the Cockney "you was".
A foreign speaker may make grammatical mistakes that do not render the sense incomprehensible but make the subtitle difficult to read in the given time. In this case, you should either give the subtitle more time or change the text as necessary:

I and my wife is being marrying four years since and are having four childs, yes

This could be changed to:

I and my wife have been married four years and have four childs, yes

 Use label

The speech text alone may not always be enough to establish the origin of an overseas/regional speaker. In that case, and if it is necessary for the viewer's understanding of the context of the content, use a label to make the accent clear:

AMERICAN ACCENT:
All the evidence points to a plot.

 Don’t simplify

It is not necessary to simplify or translate for deaf or hard-of-hearing viewers. This is not only condescending, it is also frustrating for lip-readers.

Retain speaker’s first and last words

If the speaker is in shot, try to retain the start and end of his/her speech, as these are most obvious to lip-readers who will feel cheated if these words are removed.

 Edit evenly

Do not take the easy way out by simply removing an entire sentence. Sometimes this will be appropriate, but normally you should aim to edit out a bit of every sentence.

 Keep names

Avoid editing out names when they are used to address people. They are often easy targets, but can be essential for following the plot.

Preserve the style

Your editing should be faithful to the speaker's style of speech, taking into account register, nationality, era, etc. This will affect your choice of vocabulary. For instance:

• register: mother vs mum; deceased vs dead; intercourse vs sex;
• nationality: mom vs mum; trousers vs pants;
• era: wireless vs radio; hackney cab vs taxi.

Similarly, make sure if you edit by using contractions that they are appropriate to the context and register. In a formal context, where a speaker would not use contractions, you should not use them either.

Regional styles must also be considered: e.g. it will not always be appropriate to edit "I've got a cat" to "I've a cat"; and "I used to go there" cannot necessarily be edited to "I'd go there."

 Consider the previous subtitle

Having edited one subtitle, bear your edit in mind when creating the next subtitle. The edit can affect the content as well as the structure of anything that follows.

 Keep the form of the verb

Avoid editing by changing the form of a verb. This sometimes works, but more often than not the change of tense produces a nonsense sentence. Also, if you do edit the tense, you have to make it consistent throughout the rest of the text.

Keep words that can be easily lip-read

Sometimes speakers can be clearly lip-read - particularly in close-ups. Do not edit out words that can be clearly lip-read. This makes the viewer feel cheated. If editing is unavoidable, then try to edit by using words that have similar lip-movements. Also, keep as close as possible to the original word order.

Dates

For displaying the day of the month, use the appropriate numeral followed by lowercase "th", "st" or "nd":

April 2nd.

Subtitle illegible text

If the onscreen graphics are not easily legible because of the streamed image size or quality, the subtitles must include any text contained within those graphics which provide contextual information. This must include the speaker’s identity, what they do and any organisations they represent. Other displayed information affected by legibility problems that must be included in the subtitle includes; phone numbers, email addresses, postal addresses, website URLs, or other contact information.

If the information contained within the graphics is off-topic from what is being spoken, then the information should not be replicated in the subtitle.

 Line length

In Teletext, which is used to display subtitles on some broadcast platforms, line length is limited to 37 fixed-width (monospaced) characters, since at least 3 of the 40 available bytes are used for control codes. Other platforms use proportional fonts, making it impossible to determine the width of the line based on the number of characters alone. In this case, lines are constrained by the width of the region in which they are displayed. Guidelines for both platforms are summarised in the table below.

If targeting both online and broadcast platforms you must apply both constraints, i.e. ensure that the number of characters within a region does not exceed 37.

Break at natural points

Subtitles and lines should be broken at logical points. The ideal line-break will be at a piece of punctuation like a full stop, comma or dash. If the break has to be elsewhere in the sentence, avoid splitting the following parts of speech:

• article and noun (e.g. the + table; a + book)
• preposition and following phrase (e.g. on + the table; in + a way; about + his life)
• conjunction and following phrase/clause (e.g. and + those books; but + I went there)
• pronoun and verb (e.g. he + is; they + will come; it + comes)
• parts of a complex verb (e.g. have + eaten; will + have + been + doing)

However, since the dictates of space within a subtitle are more severe than between subtitles, line breaks may also take place after a verb. For example:

We are aiming to get
a better television service.

Line endings that break up a closely integrated phrase should be avoided where possible.

We are aiming to get a
better television service.

Line breaks within a word are especially disruptive to the reading process and should be avoided. Ideal formatting should therefore compromise between linguistic and geometric considerations but with priority given to linguistic considerations.

Colours

 Use white on black

Most subtitles are typed in white text on a black background to ensure optimum legibility.
Background colours are no longer used. Use labels to identify non-human speakers:

ROBOT: Hello, sir

Use left-aligned sound labels for alerts:

BUZZER

 Apply speaker colour consistently

Once a speaker has a colour, s/he should keep that colour. Avoid using the same colour for more than one speaker - it can cause a lot of confusion for the viewer.
The exception to this would be content with a lot of shifting main characters like EastEnders, where it is permissible to have two characters per colour, providing they do not appear together. If the amount of placing needed would mean editing very heavily, you can use green as a "floater": that is, it can be used for more than one minor character, again providing they never appear together.

 Multiple speakers in white

White can be used for any number of speakers. If two or more white speakers appear in the same scene, you have to use one of a number of devices to indicate who says what 

9 Typography

9.1 Fonts

Subtitle fonts are determined by the platform, the delivery mechanism and the client as detailed below. Since fonts have different character widths, the final pixel width of a line of subtitles cannot be accurately determined when authoring. 

To minimise the risk of unwanted line wrapping, use a wide font such as Verdana or Tiresias when authoring the subtitles. Presentation processors usually use a narrower font (e.g. Arial) so the rendered line will likely fit within the authored area. Note that platforms may use different reference fonts when resolving the generic font family name specified in the subtitle file. 

Platform	Delivery	Description
BROADCAST	DVB	The subtitle encoder creates bitmap images for each subtitle using the Tiresias Screenfont font
BROADCAST	Teletext	The set top box or television determines the font - this is most commonly used on the Sky platform
ONLINE	IP (XML)	The client determines the font using information from within the subtitle data (e.g. 'SansSerif'). Generally it is better to use system font for readability (e.g. Helvetica for iOS and Roboto for Android). Use of non-platform fonts can adversely impact clarity of presented text

9.2 Size

The final displayed size of closed captions text is determined by multiple factors: the instructions in the subtitle file, the processor and the set of installed fonts available to it, the device screen size and resolution and (on some devices) also user-defined preferences.

While it is not possible (or advisable) to pre-determine the final subtitle size, adhering to the below guidelines will ensure that subtitles are legible at a typical distance from the device and that lines do not reflow or overflow for the vast majority of users. In particular, the final size should never be larger than the authored size so that the subtitler can ensure that important parts of the of the video are not obscured.

9.2.1 Authoring font size

Font size should be set to fit within a line height of 8% of the active video height. Use mixed upper and lower case. This font height is the largest size needed for presentation and is an authoring requirement.

Use a wide font such as Verdana when authoring subtitles (but not in the subtitle file itself; see Fonts and tts:fontFamily). Most processors use a narrower font, so if you author in a wide font you can be reasonably confident that lines will not reflow.

No changes need to be made to other styling attributes to accommodate processors potentially using a smaller font, however care needs to be taken when positioning subtitles in case a smaller font is used, as the following examples show:

The processor displays the larger font size, as authored. The region (not displayed) is indicated with a dotted line.	The region's tts:displayAlign is set to "before" so with a smaller font size the text moves up and the second line obscures the mouth.	To avoid this, set the region'stts:displayAlign property to "center" or "after".

Line break were used to position the subtitles lower within the region.	The line breaks are resized with the rest of the text.	Better to define the region so that it does not cover the face and avoid white space.