This report details investigations at the Communications Laboratory of the Human perception of Sound to Vision mistiming measured at sub-frame intervals.
Sound to Vision timing problems have existed ever since sound came to the movies, however the recent advent of digital television systems have caused various delays to be imposed on the timing of the separate Audio and Visual components through the production, transport, storage and presentation processes associated with television.
Correct timing is currently described as the relative time between 1 field (16-20 ms) sound advance to 2 fields (32-40 ms) sound delay for the various world television standards.
Under a special Rapporteur to ITU Working Party 11A we have conducted expert subjective evaluations of critical news reader material for various adjusted Sound to Vision mistimings.
Important conclusions of the work described in this report are:
There remains scope for further work on the sound/vision timing subject focusing on film based source material, non-speech events and typical production tolerances where post syncing is involved.