Caption type size, colour and position must be the viewer's to change
Aliases: caption appearance · closed captions · open captions · burned-in captions
What it is
Correct words are not enough. The line still has to be readable, movable, enlargable. Type size, colour, background, font and screen position belong to the viewer. Burned-in captions (open captions) weld one compromise into the picture: low-vision viewers cannot enlarge it, and the block may cover the row the presenter is pointing at. Closed captions hand appearance to the player or the system. Content and style come apart.
Why it happens
Reading captions is a second visual task. It competes with the picture for place and contrast. The default line is chosen for moderate vision, moderate contrast, and a bottom safe area. Low vision wants larger type and an opaque box. A phone in glare wants more contrast. Colour-coding speakers pushes colour-vision-deficient viewers back to guessing who spoke.
Burn-in is one appearance decision made for everybody. It fails for people at the edge, and the client cannot repair it — the pixels already share a layer with the face. Adjustable style returns the decision to the user agent: system large text, high contrast, a caption panel in the player. What changes is rendering, not a re-encode of the file.
Studying it
Compare fixed versus adjustable style with actual low-vision viewers, or with a controlled simulation (magnification, reduced contrast, colour-vision filters). Measure overlap between the caption block and centres of visual interest — faces, on-screen cards, numerals on a chart.
Independent variables: type size, background opacity, position, burned-in versus closed. Dependent variables: caption reading accuracy, count of covered critical picture elements, how often people actually change the style.
Asking whether the default “looks fine” erases the need to adjust. Opening system text size to maximum and then playing is what shows whether the player handed captions to the system.
Where it stops holding
Cinema prints and some broadcast chains still burn in; the playback end has no style channel. Live character generators expose few parameters — adjustable does not mean an infinite font menu. A viewer who parks captions on the chart the presenter is pointing at still needs to be able to drag them off. Pure audio has no picture to cover; style conflict weakens. Decorative or compositional lettering that is part of the shot is not a closed-caption track and should not pretend to be adjustable.
Applying it
- Ship captions as a separate track. Do not make burn-in the only delivery. If a venue requires burn-in, also offer a closed, adjustable version.
- Expose type size, foreground and background colour, background opacity, and position. The default itself must pass contrast and must not sit on faces.
- Do not identify speakers by red versus green boxes alone; a label or placement must still work without colour.
- How to check: play under system large text and high contrast and see whether captions follow. Drag the block off faces and on-screen type. A burned-in file fails both steps — style was never the viewer’s.