Start with the information in the frame
Caption placement needs to serve both the text and the programme. Identify persistent lower thirds, demonstrations, on-screen names and other important visual regions. A technically valid cue position can still obscure the detail the speaker is explaining.
Start with ordinary readable placement and add positioning complexity only where the content needs it. A single lower-third conflict does not necessarily justify custom placement on every cue. Keeping the exceptional regions explicit makes later picture revisions easier to review.
Use a representative cue sample
Prepare an owned sample containing a short cue, a longer cue, simultaneous information where needed and a passage with the actual graphic collision. Include the scripts and punctuation the production uses. Review the sample at the intended media size, not only in a caption editor's large preview.
The WebVTT specification defines cue settings and regions, but rendering support and the complete player layout still need destination review. The version checked here is the W3C Candidate Recommendation Draft of 20 May 2026, a work in progress. Do not treat it as proof of universal implementation.
Test the viewer's presentation context
Review normal playback and the viewing modes the destination actually offers. Caption size preferences can change line wrapping and occupied space. A position that suits the author's default display may conflict with another essential graphic when the text is larger.
For a hypothetical demonstration with a control near the bottom edge, compare moving the exceptional cue and moving the production graphic. Choose the solution that preserves meaning and remains usable. Record the reason instead of leaving an unexplained coordinate adjustment.
Keep the delivery maintainable
Retain the editable caption source and a list of intentional placement exceptions. If the picture is cropped or reframed, revisit those exceptions. Do not assume that a track approved for one aspect treatment remains appropriate for another.
Accept syntax, timing and readability separately. A parser can establish one kind of correctness; it cannot decide whether the audience can read two competing pieces of information. The final review should name the actual destination and state any untested renderer or viewing mode.
Questions answered
Does valid positioning syntax prove captions avoid important graphics?
No. Review the rendered programme with its actual visual content.
Will one fixed placement work for every caption-size preference?
Do not assume it. Include relevant viewer settings and presentation sizes in the review.
Sources & further reading
Official references for the subjects discussed. Service terms and device software can change.