[mythtv-users] OT: Aspect ratio broadcast rant

f-myth-users at media.mit.edu f-myth-users at media.mit.edu
Sat Feb 20 22:05:12 UTC 2016


    > Date: Fri, 19 Feb 2016 08:08:16 -0500
    > From: Eric Sharkey <eric at lisaneric.org>

    > On Fri, Feb 19, 2016 at 12:41 AM,  <f-myth-users at media.mit.edu> wrote:
    > > It looks great, but is only possible in display systems (such as CRTs)
    > > which don't actually have fixed, indivisible pixels in the Y axis of
    > > the actual display.  This wouldn't work the same for an LCD, for example.

    > But SD LCDs are pretty rare.  Most people with LCD TVs are going to
    > have higher resolution display (720 lines at least).  The display is
    > going to be scaling the image digitally to fit the actual number of
    > pixels it has and if all that's available is an SD signal, an
    > anamorphic encoding will give the display the most information with
    > which to create the picture.

By "it," I meant "compressing the same number of lines into a smaller
space on the screen."  I'm sure having more available scanlines on an
LCD helps the situation, but it's not quite the same mechanism, and
it's easy to see that depending on the exact ratios, you might have to
do rounding if the squeezed vertical lines don't work out to be integral
multiples of the LCD's available scanlines, and that in turn may make
the vertical axis look blurrier than the true squeeze available to a
CRT.  That's why I said it wouldn't work the same on an LCD.

Of course, I have no argument that even having to interpolate
scanlines across nonintegral mismatches in an LCD is superior to
simply not using anamorphic at all, which throws away the available
resolution -before transmission- and only gives you 300 (ish) lines
total no matter how many scanlines the display has available, whether
it's a squeezed CRT or an interpolated (or not) LCD.  But I've never
seen either of the two cable broadcasters I've used ever do it that
way, and I don't believe their STBs can do it, either, given that
I looked for such capabilities in their menus.


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