[M4IF Technotes] confusion about modulo_time_base, vop_time_increment, ...

Christoph Lampert chl math.uni-bonn.de
Wed Aug 7 11:49:35 EDT 2002


Hi,
I still have problem understanding the correct specifications
for writing timecodes to the VOP header.
First there is modulo_time_base, it consists of a number of 
1s followed by a 0, one 1 for every second that passed since the last
GOV header or last module_time_base of the previously decoded I-, S- or
P-VOP. 
Am I right, that this does not mean elapsed "full seconds", but is some
kind of "carry" flag, when the ticks-counter "overflows"?  
So if we talked minutes and hours, it would be 1 when the clock jumps from
0:59 to 1:00, right? 
In real life, the chances of this value ever getting 2 is very small,
correct? 
And then, there is vop_time_increment: 
It has a value in [0,vop_time_increment_resolution) and the last comment
on it is "The local time base in the units of seconds is recovered by
dividing this value by the vop_time_increment_resolution."
That's simply wrong, isn't it? You will always end up with 0 when dividing
this value by vop_time_increment_resolution... but what _is_ really meant? 
Thank you for your help,
Christoph 
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