User talk:85.193.217.247

Generally, in the television industry which deals with both audio and video, lip sync error is referred to as audio to video timing error, rather than video to audio timing error. I believe that this is because most of the time video signal processing creates the video delay that creates the lip sync error. That is a common situation and given the common error (which I'll call 30ms here by example) where audio leads which is commonly referred to in a positive sense, e.g. lip sync error is 30ms, thus implying a positive error number means that the audio is advanced (because of the common culprit video processing delay). Generally nobody ever says it is positive 30 ms, just 30ms. When the error is in fact negative most people say there is an audio delay of 30 ms rather than lip sync error is negative 30 ms. In any event the people in the industry who deal with both audio and video, as compared to those who deal mainly with audio (e.g. the Audio Engineering Society or AES) refer to audio to video timing error or audio/video error or A/V error and several versions thereof.

One rather old (and by now likely somewhat outdated in terms of maximum acceptable error), which has been referred to by highly authoritative and well respected industry leaders as "The Only International Standard on A/V Sync" . is BT.1359. On page 1, under considering, statement g) "that subjective evaluations show that detectability thresholds are about +45 ms to -125 ms and acceptability thresholds are about +90 ms to -185 ms on the average, a positive value indicates that sound is advanced with respect to vision," followed immediately below under recommends, 2 "that the timing difference in the path from the output of the final programme source selection element* to the input to the transmitter for emission should be kept within the values +22.5 ms and -30 ms, a positive value indicates that sound is advanced with respect to vision. **" I won't speculate as to whether the AES/EBU definition which is pointed to is a typo, carelessness, ignorance, disagreement, or something else, but I submit that a widely read, international recommendation by a standards group which is concerned with the broadcasting of both audio and video would be the better authority. I note in passing, if one departs from the standard audio to video timing error convention where a positive error means audio leads and instead talks about video to audio error, then I would expect for a positive error to mean that the video leads. TVtech (talk) 22:10, 9 March 2018 (UTC)

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