TTML2 comments on roll-up and paint-on captions

In my opinion, the approach taken for supporting roll-up and paint-on modes (2 important caption styles in the US) could be simplified by having explicit regions attributes, as in tts:paintmode=”rollup” or tts:paintmode=”painton”. For rollups, the scrolling style could also be designated as “smooth” or “discrete”.

This approach would simplify the conversion of 608/708 captions to TTML, and eliminate the complexity and clutter of overlapping cues and timed <span> tags.


Glenn Goldstein
SVP, Chief Technology Convergence Officer
Viacom MTS