What lip-sync (sound/picture) timing tolerance does EBU R37 set for a broadcast programme, and what is the stage-by-stage versus end-to-end figure?

Problem: an edit or AI-dubbed/AI-generated-audio deliverable needs a defensible number for 'is the audio in sync'. Conditions: broadcast or broadcast-style delivery; R37 is a 2007 EBU recommendation measured under EBU R28 viewing conditions. Method: R37 gives two figures. (1) Accuracy at each stage of the chain: audio from 5 ms early (sound before picture) to 15 ms late (sound after picture). (2) At any output intended for emission, the overall end-to-end difference should lie within Table 1: sound before picture up to 40 ms, sound after picture up to 60 ms. It says the values come from subjective tests of when lip/speech asynchrony becomes perceptible to 50% of observers, that perceptibility depends on content and viewing distance, and that HD needs particular care. It also says audio and video should be kept coincident in the file and not advanced or retarded to compensate for downstream delays, and that concurrent flash/blip (1 kHz tone, one frame) header markers are the measurement reference and should be retained even in file-based chains. Example (inference, label): an AI-dubbed track placed 3 frames (125 ms at 24 fps) late would be far outside either figure; 1 frame (41.7 ms at 24 fps) late sits inside the 60 ms end-to-end limit but outside the 15 ms per-stage limit. Failure modes: treating the 40/60 end-to-end figures as a per-stage budget; mixing sign conventions with ITU-R BT.1359 (see relationship). Limitations: broadcast TV norm, not a film or social-platform specification; dubbed speech is not tested separately; 2007 document. Curator qualifications: All cited documentation excerpts located on the live pages by curator GET; no video sources. Limitations: Figures are for television programme chains under R28 viewing conditions; the document itself says perceptibility depends on content and viewing distance. The frame-count example is my arithmetic, not a source statement. Evidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.

{
  "citations": [
    {
      "url": "https://tech.ebu.ch/docs/r/r037.pdf",
      "note": "Recommends: accuracy per stage; Table 1; Recommends: file-based chains"
    }
  ]
}