Should captions follow shot changes, and what numbers do Netflix and BBC give?

Problem. A caption that straddles a cut looks like a flash or lingers over a new shot. Conditions. Edited video where shot boundaries are known (an EDL, or shot detection run on the picture). Method. Documented: BBC says avoid subtitles that straddle a shot change by splitting the sentence or delaying the next one, merge subtitles for short shots if the merged event then ends at the second shot change, and authoring tools may use automated shot detection. Netflix: if dialogue starts on or within half a second after a cut, set the in-time to the first frame of the shot; if an out-time is within half a second before a cut, extend it to the cut keeping a 2-frame gap; if dialogue ends before a cut and no subtitle follows, still end 2 frames before the cut; as a last resort the out-time may be 12 frames after the cut provided no lingering effect. Failure modes. Snapping to cuts can shorten a caption below minimum duration or push reading speed over the cps limit; BBC lists this as a reason to give less time only as a last resort and to prefer merging. Limitations. The rules assume human judgement ('apply good judgment'); YouTube and social upload files carry no shot data. Inference: for a pipeline, run shot detection on the video (not covered by these sources), then apply the half-second snap windows before the gap and duration checks. Curator qualifications: All cited documentation excerpts located on the live pages by curator GET; no video sources. Limitations: Shot-sync is a broadcast/streaming craft rule; no source says viewers of social video benefit. Evidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.

{
  "citations": [
    {
      "url": "https://www.bbc.co.uk/accessibility/forproducts/guides/subtitles",
      "note": "6.3 Avoid straddling shot changes; 6.3; 2: Timing to the shot change; 1: Timing to audio; researcher reasoning"
    },
    {
      "url": "https://partnerhelp.netflixstudios.com/hc/en-us/articles/360051554394-Timed-Text-Style-Guide-Subtitle-Timing-Guidelines",
      "note": "6.3 Avoid straddling shot changes; 6.3; 2: Timing to the shot change; 1: Timing to audio; researcher reasoning"
    }
  ]
}