Re: 480p or 1080i


"Randy Yates" <yates@xxxxxxxx> wrote in message
news:m31wx2gywc.fsf@xxxxxxxxxxx
"Jeff Rigby" <jeffg212@xxxxxxxxxxx> writes:

"Bob Engelhardt" <bobengelhardt@xxxxxxxxxxx> wrote in message
news:PYKdnXoGONfIZYvZnZ2dnUVZ_tWdnZ2d@xxxxxxxxxxxxxx
Jeff Rigby wrote:
...
HDMI Best Digital HD (usually the best but depends on
which converts digital to analog better the STB or the TV)...

"converts digital to analog better"? Why is there a conversion to
analog?
Bob

Because we don't see digital.

With "digital TV" you get errors caused by fast moving objects and
media sources made with other resolutions converted to HD. These errors
have to be smoothed out.

If you are comparing DVI or HDMI with component cables you are comparing
the
conversion to analog by either the STB or the TV. If you have a true
digital TV or one that does a better better job in converting digital to
analog the DVI or HDMI is the better way to get the information to the
TV.

You're confusing two different issues here, Jeff.

A gross oversimplification of an HDTV receiver block diagram consists
of an MPEG2 decoder (compressed digital input, uncompressed digital
output) followed by D/A conversion (uncompressed digital input, analog
output).

The MPEG2 decoder decodes what was produced by the MPEG2 encoder.
It is the MPEG2 encoder that produces errors due to fast-moving objects.

The D/A conversion stage is what's being compared above with respect to
DVI/HDMI versus component video (or lower). A DVI/HDMI interface requires
the settop box to perform the MPEG2 decoding and then transfers the
uncompressed digital information to the TV, and the TV is responsible
for D/A conversion. When using the component video interface out of
settop box, the settop box performs both the MPEG2 decoding AND the
D/A conversion.

However, in neither case would D/A conversion produce the "fast-moving
object" artifacts you refer to.
No, you are correct and I fully understood this issue, I just skipped a step
I felt unnecessary to include. The errors caused by the mpeg decoding of
fast moving objects are there before and after the D/A conversion. They
need to be corrected. Which does a better job at smoothing these out, the
STB or the TV. IN most cases, a TV does NO further processing of a
component video signal but DVI or HDMI will go through the video processing
in the TV.


Instead, D/A conversion errors could result
in things like

a. improper color balance (mismatched conversion)
b. decreased video SNR (spurs or other nonlinear effects in D/A
conversion)
c. decreased video resolution (limited bandwidth)

References

[1] High-Definition Multimedia Interface Specification Version 1.2a
--
All true Randy and I should have specified that we are talking about digital
television transmissions not the TV itself. In that case my statement is
correct. The device that does a better job of the conversion to analog
(correcting idealization of fast moving objects and cleaning up poor media)
is the device that should be allowed to do so. If it's the STB then you
should use component cables if it's the TV then you should use DVI or HDMI
cables.


.

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