Boost User Experience: How to Meet Netflix Captioning and Subtitle Requirements
Closed Captioning and Asset Quality
Netflix has increasingly high standards when it comes to subtitles (language translations) and closed captions (timed text). Localization has become imperative to ensure that viewers are not only able to understand the content but are able to read the text naturally in their own language. A considerable amount of research has also gone into the timing of the text to ensure readability.
Netflix fact: subscribers watch ~1 billion hours of programming per week.
In 2012, Netflix and the National Association of the Deaf (NAD) teamed up to guarantee closed captions in 100% of Netflix streaming content by 2014. This is one example of how the company is working to provide the best viewing experience to hard-of-hearing individuals as well as those who just want to enjoy content in a livelier environment. According to Netflix, “We need to change the way we think about subtitles and closed captions. They are no longer secondary assets in a world where content knows no physical borders.”
General Netflix Video Hosting and Caption Requirements
Getting your content hosted on Netflix is no easy feat. Netflix has a database of content that’s being considered for the platform, but Netflix is also deciding which pieces are added to that database. To put your film in the running, it’s best to go through a distributor who can then leverage connections within the company.
If your piece is selected for the Netflix database, the next step is marketing. The more popular a movie is, the more likely it is to be chosen. Higher demand will also drive higher licensing fees, which works in your favor. If you’re successful, you’ll need to follow the Netflix Timed Text Style Guide for any timed text. This will provide you with information such as file format, frame gap requirements and more.
Free or paid?
Paid. Netflix “strongly encourages” content to go through Netflix Preferred Vendors (NPVs) for assets such as subtitles and closed captioning.
Netflix fact: The biggest streaming day of the year is January 1st.
Type of content
TV shows, original series, movies, documentaries, feature films (all without commercials or ads)
Caption file format
Subtitle and SDH files for all languages must be delivered in TTML1 format (.xml or .ttml), except for Japanese, which must be delivered in IMSC1.1 format (.xml).
Captions need a “duration” in order to be shown at the correct time. For Netflix, the minimum duration is 5/6 (five-sixths) of a second per subtitle event (e.g. 20 frames for 24fps). The maximum duration is 7 seconds per subtitle event.
Only text & characters included in the NETFLIX Glyph List can be used.
Line Breaks & Treatment
Text should usually be kept to one line, unless it exceeds the character limitation. Netflix wants captioners to follow these basic principles when the text has to be broken into 2 lines:
The line should be broken:
- after punctuation marks
- before conjunctions
- before prepositions
The line break should not separate:
- a noun from an article
- a noun from an adjective
- a first name from a last name
- a verb from a subject pronoun
- a prepositional verb from its preposition
- a verb from an auxiliary, reflexive pronoun or negation
Captions should be center justified and placed at the top or bottom of the screen.
Netflix requires KNPs & formality tables to be created and used for translation to ensure consistency across episodes and seasons. You can find a template on Netflix’s website here.
TTML files created for Netflix subtitles should have the following technical specifications:
- Only use percentage values. Do not use pixel values.
- Use tts:textAlign and tts:displayAlign for positioning along with static values for tts:extent and tts:origin.
- tts:fontSize shall be defined as 100%. Pixel values should not be used.
- Sample TTML snippet for Subtitle and SDH can be found here.
Netflix is constantly making updates to their captioning and subtitling requirements, so it’s always important to stay up-to-date with the latest captioning and subtitling requirements here. The detailed and up-to-date English caption requirements can be found here. Netflix has extremely high standards for their captions & subtitles compared to other streaming companies, so it’s important to stay informed.