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Add captions to audio or video

Page history last edited by Monica 2 years, 10 months ago

Captions are text that display over audio or video in the online player. A caption file contains both text and information about when each line of text should be displayed.  To improve accessibility, it is recommended to include a text transcription for audio content or provide captions for video. Either SRT or VTT closed caption formatting is supported. Closed caption files should be uploaded with the same filename as the source video file (e.g. myvideo.mp4.srt).

 

To display your media in browser (instead of downloading), use MP3 format for audio or MP4 for video.

 

Required

  • MP3/MP4 format for streaming media online 

  • Filename can not contain blank spaces or special characters e.g.  ~ ! @ # $ % ^ & * ( ) ` ; < > ? , [ ] { } '  ; recommend using dash or underscore instead.

 

Recommended

  • Less than 1GB file size. (May need to request programming ingest for larger file sizes.)

  • Filename less than 32 characters (Otherwise the filename may be truncated)

  • Include duration info in bitstream description and dc.format.extent

  • Include technical specifications or digital provenance in dc.digitial.specifications

  • Create custom Video thumbnail

  • Use recommended descriptive practices

 

 

Transcriptions

RDSA is configured to display the caption file as a separate file viewable by an end-user. This file may act as a transcription but with time codes included. It is recommended to include a transcription file as well as captioning for multimedia content. 

 

Benefits:

  • Transcripts allow anyone that cannot access content from either web audio or video to read a text transcript instead. 
  • Transcripts make multimedia content searchable by search engines and users.
  • Beyond the spoken words, a transcript should include descriptions of important audio information (like laughter) and visual information (such as someone entering the room). 

 

Source: WebAIM: Captions, Transcripts, and Audio Descriptions, https://webaim.org/techniques/captions/ 

 

To add captions for audio and video files:

 

1) Create caption file using either WebVTT (.vtt) or SubRip (.srt) format. 

  • WebVTT is a World Wide Web Consortium standard for displaying timed text in connection with the HTML5 <track> element.  See simple instructions on how to create a WebVTT file.

 

  • SubRip is widely supported Microsoft Windows format. Most subtitles distributed on the Internet are in this format

 

2) File naming pattern.

To enable captions, both the time-media and caption filenames must be appended with "_caption".  The caption (e.g. *.vtt) file must use the same filename as the source media file.

 

For example:

 

File Type Filename 
Video  MyVideo_caption.mp4 
Caption  MyVideo_caption.mp4.vtt 

 

3) Upload both the time-media and caption files to the Original Bundle in RDSA

The media filter program will run over night and the next day your captions should appear over audio or video.

 

EXAMPLERICE CHORALE Wednesday, November 28, 1984 (audio performance) Shepherd School of Music https://scholarship.rice.edu/handle/1911/81757

 

Notes:

  • For Audio files using captions, the window size of the player is enlarged to better display text overlay.
  • For pre-existing video items, may request programmer to change the filename directly in database to avoid having to re-upload the video/audio files. 

 

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