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These are the textual representation of a video’s soundtrack; they are critical for viewers who have a hearing impairment, Captions are not only used by the deaf or hard-of-hearing, they’re useful to students who need a multi-modal experience in video learning programs, and by those who use English as a second language and still need assistance recognizing expressions and speech patterns. Regardless, captions work toward a more inclusive society.

General guidelines and common best practices to help with readability:

It is important that the captions be (1) synchronized and appear at approximately the same time as the audio is available; (2) verbatim when time allows, or as close as possible; (3) equivalent and equal in content; and (4) accessible and readily available to those who need or want them.

The most important thing about captions and subtitles is that, when they appear on the screen, they are in an easy-to-read format. Currently available methods of captioning Web content vary in their capabilities, but good captions adhere to the following guidelines when possible:

  • Each caption frame should hold 1 to 3 lines of text onscreen at a time, viewable for a duration of 3 to 7 seconds. Preferably, limit on-screen captions to no more than two lines.
  • Each line should not exceed 32 characters.
  • The font should be sans-serif, such as Helvetica medium.
  • Each caption frame should be replaced by another caption.
  • All caption frames should be precisely time-synched to the audio.
  • A caption frame should be repositioned if it obscures onscreen text or other essential visual elements.
  • Descriptions inside square brackets like [music] or [laughter] can help people with hearing disabilities to understand what is happening in your video.
  • Speakers should be identified when more than one person is on-screen or when the speaker is not visible. Where the captioning tool allows for it, captions located in different parts of the screen can aid such understanding.
  • Add tags like >> at the beginning of a new line to identify speakers or change of speaker.
  • Punctuation should be used to clarify meaning.
  • Spelling should be 99%+ correct throughout the production.
  • Non-speech sounds like [MUSIC] or [LAUGHTER] should be added in square brackets and where it aids understanding qualify this, for example [DRAMATIC MUSIC]
  • All actual words should captioned, regardless of language or dialect.
  • Use of slang and accent should be preserved and identified.

Clipomatic – for iOS 10.0 or later. Compatible with iPhone, iPad and iPod touch:

Clipomatic is a smart video editor that turns everything you say into live captions. All you have to do is hit the magical record button, speak clearly and your words will appear as stylish captions right on your recording. Caption a video in 40 languages using just your voice: select the speech recognition language right in the app.

Adding captions to a Sakai video:

If you upload video to a Sakai site, and that video includes sound, you should include a text alternative, such as captions. WarpWire is the video platform available to embed video media into Sakai sites; information about how to upload subtitle files to accompany videos is available here –

Uploading Media – Associated Files:

When uploading media you can attach associated documents to the media.

There is also the option of uploading a captions file. The following file extensions can be uploaded: *.smi, *.rt, *.ssf, *.srt, *.ttxt, *.sub, *.txt, *.xml.

SubRip Text File Format:

The SubRip file format is perhaps the most basic of all subtitle formats. SubRip (SubRip Text) files are named with the extension .srt, and contain formatted plain text. The time format used is hours:minutes:seconds,milliseconds. The decimal separator used is the comma, since the program was written in France. Subtitles are numbered sequentially, starting at 1.

Subtitle number
Start time –> End time
Text of subtitle (one or more lines)
Blank line

You can use a plain text editor, such as Notepad (Start > All Programs > Accessories), to create a .srt file.

SubRip .srt File Example Syntax

00:00:20,000 --> 00:00:24,400
Altocumulus clouds occur between six thousand

00:00:24,600 --> 00:00:27,800
and twenty thousand feet above ground level.

Tools for creating, editing, and converting text-based subtitle files:


When uploading a video to YouTube, there are three ways that you can add captions:

  1. Uploading a caption file with timecodes
  2. Uploading a transcript of the audio
  3. Having captions generated automatically.

You can learn more about Closed Captions and Subtitles on YouTube with Creator Academy best practices or in their YouTube Captions and Subtitles video. Alternatively you can visit YouTube Help for step-by-step instructions.


When uploading a video to Vimeo, you also have three options for adding captions:

  • Upload: If you already have caption files, upload them in any of the supported formats.
  • Editor: launch Amara’s editor and create your own files without leaving Vimeo.
  • Purchase: purchase subtitling and captioning services provided by Amara.

Visit the Vimeo Captions and Subtitles FAQ for step-by-step instructions.


The Amara captioning tool works independently of how your video is hosted in the Internet.  It provides a very simple workflow which makes the addition of captions relatively painless.

The video must already be uploaded to the Internet, for example on a video hosting site such as Vimeo or YouTube or on your own server.

Using Stream:

Start with a ‘local’ copy of the video you want to create captions for.

Open ‘Stream’ – this is a component of UNC Office 365

  • Create – Upload Video – drag and drop or browse to select the target video file – the following file types are among those accepted:
    • FLV (.flv), MXF (.mxf), GXF (.gxf), MPEG2-PS, MPEG2-TS, 3GP (.ts, .ps, .3gp, .3gpp, .mpg), Windows Media Video (WMV)/ASF (.wmv, .asf), AVI (Uncompressed 8bit/10bit) (.avi), MP4 (.mp4, .m4a, .m4v)/ISMV (.isma, .ismv), Microsoft Digital Video Recording(DVR-MS) (.dvr-ms), Matroska/WebM (.mkv), WAVE/WAV (.wav), QuickTime (.mov)
  • Click ‘Publish now’
  • Now navigate to ‘My content’ / ‘Videos’ and wait until the uploading file reaches 100%
  • It will take a little time for the Subtitle file to be ‘autogenerated’ – click on the pencil to edit and look to see if ‘Captions –  Download file’ shows – if so click Download file and rename the file with an .srt extension.

Download and open Handbrake

  • Select the original video (File, open single video file’
  • Click the Subtitles tab and select the .srt file you just created
  • Check ‘Burn In’
  • Create a new file name for your combined video + subtitle file (eg original_filename_subbed) in your desired destination
  • Click ‘Start Encode’ wait until Queue Finished replaces the incremental green bar indicating that encoding is taking place – bottom left-hand corner of screen.

Using Otter –

The free app, available for iOSAndroid, and the web, records audio and converts speech to text on the fly using voice recognition algorithms. It also synchronizes the audio with the text during playback, so you can tap on any word to hear exactly what was being said at the time. While Otter’s algorithms do not produce perfect transcriptions, with the right recording conditions it can be accurate enough to give you a headstart, certainly for transcriptions if not for subtitles.

Free use is capped at 600 minutes (10 hours) of recording per month; premium users can pay $10 per month (or $80 per year, or $3 per month for students) to increase the recording limit to 100 hours and add some advanced exporting options, including audio exporting.