Captioning

Every video and audio file in ALEX requires closed captioning. This is not just an inclusive practice generally, but an important part of our accessibility requirements.

Writing captions

When creating caption files, make sure they include:

  • Accurate spelling
  • Correct grammar and punctuation
  • Speaker identification (for multiple speakers)
  • Non-speech sounds (for important sounds)
  • Verbatim text (as close as possible, within reason)

It can be helpful to refer to the project’s script and writers for questions related to formatting (for example: “health care” vs. “healthcare”).

ALEX loosely follows the Netflix standards for adding captions to video. The important rules are:

  • Captions do not exceed 20 characters-per-second
  • Captions do not exceed 42 characters-per-line
  • Captions do not exceed 2 lines of text at a time
  • Captions have a minimum on-screen duration of 0.83 seconds
  • Captions have a maximum on-screen duration of 7 seconds
  • Either 2 frames or 12 frames or more minimum gap duration (between captions)

Creating caption files

The process we use to create captions is as follows:

  1. Create a separate Premiere project for captioning and store this project in your project folder
  2. Import the video you want to caption into a timeline
  3. Use Premiere’s Transcribe feature to transcribe the video
  4. Correct any mistakes in the transcription
  5. Create captions from the transcription using the “Subtitle default” preset (it can be helpful to tweak the preferences in this preset)
  6. Edit captions as needed in the timeline and captions panel
  7. Export your captions as an SRT file
  8. Use EditingTools.io’s Subtitle Tool & Converter to convert the SRT file to VTT
    1. Set the framerate to the framerate of your video (either 24 or 30)
    2. Apply the following settings (see below for screenshot):
      1. Check the following fixes:
        1. Remove empty subtitles
        2. Merge identical subtitles
        3. Extraneous whitespace removal
        4. Fix invalid tags
        5. Remove subtitles with a length of 0 frames
      2. Check “Check subtitle guidlelines” against Netflix (for adults)
      3. Under “More Options” check the following:
        1. Set minimum gap duration between subtitles: 2 frames at your framerate
    3. Hit “Generate” and review the changelog for any errors that require fixing in Premiere
  9. Once your SRT-to-VTT conversion is complete and not displaying any errors in the changelog, download your VTT caption file and place it alongside your deliverables in your project folder