[Mp4-tech] Frame rate in h.264

[Tuukka Toivonen]

On Mon, 18 Jul 2005, John Cox wrote:
>The table you need to look at is E-6 (under the description of
>fixed_frame_rate_flag).
>
>Once you've worked through all the verbiage what it says is that the
>duration of a field picture is 1x num_units_in_tick/time_scale and the
>duration of a frame picture is 2x num_units_in_tick/time_scale. (If you
>specify pic_struct then other options are available too for 3/2 pull
>down etc.)

Hi, I'm trying to go through this, but I can't find anywhere
what does the symbol \Delta t_{fi,dpb} mean or where it is used?
\Delta t_{o,dpb} seems to be more or less defined in Eqs.
(C-12) - (C-13).
As you refer to Table E-6 I suppose I need to understand
the symbol to understand why
2 * num_units_in_tick / time_scale = frame_time
for progressive video.