FA-77953 / Subtitle cue timing / Member archive

Cue snapping to video frame grid: overlap push test · case 03

Consecutive snapped cues share frames and flicker on screen together.

Member previewVariant 3 · 3 implementations · 9 checks per implementation

Case contract

For fps "N" or "N/D", frame k starts at k*1000*D/N ms. Each cue [start,end] (sorted) gets start frame floor(start*N/(1000*D)) and end frame ceil(end*N/(1000*D)), at least one frame long. A cue whose start frame precedes the previous cue end frame is pushed to that end frame (and kept at least one frame long). Output [a,b,ms(a),ms(b)] with ms(k)=floor(k*1000*D/N).

Why this case matters

Subtitle timing defects shift, hide or overlap captions that viewers depend on for comprehension and accessibility.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
regression: overlap push test	`[[150, 153, 5005, 5105], [152, 153, 5071, 5105], [153, 154, 5105, 5138]]`	`[[150, 153, 5005, 5105], [153, 154, 5105, 5138], [154, 155, 5138, 5171]]`	Failed

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