Investigate Whisper.writer parameters

[alundgard]

Run different parameter combinations on a media test item and observe the vtt output formatting, attending to subtitle accessibility guidelines and readability.

Whisper.writer parameters

Subtitle formatting parameters are input to the writer (obtained by whisper.utils.get_writer), and not the model (model.transcribe). NB: To use these writer parameters, word_timestamps must be set to True as input to model.transcribe.

• max_line_width: the maximum number of characters in a line before breaking the line (default: None)
  • Accessibility guidelines recommend a maximum of 42 characters per line.
• max_line_count: the maximum number of lines in a segment (default: None)
  • Accessibility guidelines recommend a maximum of 2 lines per segment.
• max_words_per_line: the maximum number of words in a segment (default: None)
  • Line width indeterminate.

Preliminary parameter testing and vtt output: Pre-pilot parameter testing (Local).

Questions

• max_words_per_line may improve readability by breaking caption segments on complete sentences (see the Relevant links below). Should we use this parameter instead of max_line_width=42 and max_line_count=2?
• What happens if all three of the above parameters are specified simultaneously?

Relevant links

• Improve default line lengths in subtitle files · openai whisper · Discussion sul-dlss/common-accessioning#314 · GitHub
• How to Customize Subtitles with Whisper - CodePull

[alundgard]

This Whisper output contains caption segments that are too long. Although they appear on the screen long enough to read them, accessibility guidelines recommend a max of 42 chars per line, and a max of 2 lines per segment.

https://sul-purl-stage.stanford.edu/jr745nr3367