Re: Sony model numbers

"Paul D.Smith" <paul_d_smith@xxxxxxxxxxxxx> wrote:

Sorry, I wasn't very clear. Surely it's the BluRay player that is
outputting 24fps and the TV that would be expected to simply display what
it's given. It would seem odd if a TV (which in this case is basically a
monitor) was rejigging the framerate to either 25 or 30 before displaying
it. This would appear to require MORE work that simply displaying 24fps, as
presented by the player.

To explain this, I need to distinguish between the maker of the bare LCD
display component, and the maker of the flat-panel TV.

Makers of LCD displays will only design and qualify them for a specified
drive frequency. Usually the frequency tolerance is wide enough to allow
the display to be driven at 50Hz or 60Hz, and most TV makers allow their
TV to switch between the two. This isn't too bad for 24fps sources,
because the TV will usually run at 60Hz and alternately display frames
twice then thrice, and although this increases the flicker a bit, most
people won't notice that.

Unfortunately, because it costs money to put an LCD through its
qualification testing, there's still some LCDs that will *only* run at
60Hz. Although the LCDs almost certainly *could* be driven at 50Hz
without any problems, the TV maker can't risk that because they'll have
no legal comeback on the LCD maker if the LCD fails when being driven
outside of its specified tolerance. The Toshiba 40XF355DB, which is a
highly desirable TV for its remarkably narrow frame is a case in point,
and converts our 50fps broadcasts to 60Hz internally with a noticeably
jolting image.

In some cases, the LCD maker has been persuaded to re-qualify their
50/60Hz displays for 48Hz as well, and thus the TV can simply display
each 24fps frame twice (which is indistinguishable from 24fps on an LCD).
Also, 100/120Hz LCDs are just starting to appear, and those simply
display each 24fps frame five times.

With interlaced it might have done more because I'm told that Americans,
used to 30 half-frames per second, can actually spot the flicker of a 25
hfps UK screen so I suppose it would be worth "uprating" to 30hfps for them.

No, that just makes the image jolt visibly. Unlike CRTs, there is no
visible flicker of a static image on an LCD. The problems relate only to
moving images, and they're best displayed without conversion from the
original camera rate.

--
Dave Farrance
.

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