RE: [9fans] A prick into the wasps' nest ;-)

["Nigel Roles" <nigel@9fs.org>]

> factors involved.  if we assume that TV is 26 (iirc) frames/second
> there is phosphor persistance on the the screen (let's forget about
> LCD's) and (iirc) there's retinal persistance.  so, dropping a
> few frames  doesn't really matter.  oh yeah, it's interleaved as well.
> 
> they may not even be watching when the frames are dropped.
> 

Even if I softly drop a few words here and there, this is still
recognisably rubbish.

The frame rate is 25Hz for PAL, or 30Hz for NTSC (29.97 for pedants).
SECAM is also 25 Hz.

There is some persistance (sic), but the human eye/brain
is extremely sensitive to missing frames, or disturbed frame timing,
so it is arguable that persistence makes a timing error worse.
You only have to watch a someone walk across the shot on a decent
DVD player and then compare it will your typical soft decoder on
a Windows laptop to know that seeing all the fields at the right
time is a really important.

Interleaving only helps reduce apparent flicker. Each field represents
a different point in time, so missing a field, or replacing one
with a copy of the previous one is ruinous. Swap the fields and
everything looks furry. 100Hz TVs don't just
display each field twice; they have a DSP in there to
sort out the motion compensation and synthesise the missing fields.
My 100Hz TV still screws up on fast scrolling credits (horizontal
and vertical).

Stick to what you know, Boyd.
Except the guns; it's really, really tedious.