Harsh, "aliased" sound with digital TV converter box.

"Albert Manfredi" wrote in message
...
On Mar 7, 7:55 pm, "Mike" wrote:

On this side of the pond, we don't have SCART.

Ah I didn't realise that, I had assumed that as it was incorporated on all
of the stuff sold by major Japanese and north American manufacturers in
Europe and elsewhere that it was pretty much a universal standard.

The irony is that not only from the performance angle it actually makes
equipment cheaper and easier to install because they don't have to fit an
RF
modulator.


TVs sold in the US are mostly HDTVs now. Have been for some time. So
they are virtually all equipped with component (Y, Pb, Pr) and HDMI
inputs, and they are also provided with composite and S-video. Some
also have RGB, especially those models that might possibly be used as
PC monitors. A few of each variety. Makes the connector board somehwat
intimidating to many, I'm sure.


Something like SCART would make life simpler. On the other hand, these
nice, combined connectors have a way of becoming obsolete. Like the
DIN connectors used in European stereo equipment back when. The newer
digital video interfaces might just have to be added alongside SCART,
for example.


Just like the U.S. there have also been millions of flat panel digital HDTV
receivers sold here in the UK over the last few years (far too many IMO
considering the amount of perfectly good and serviceable modern W/S CRT
stuff which is being dumped in waste disposal sites) however despite being
equipped with HDMI sockets most (all?) will still have several SCART sockets
fitted as standard.

One also has to take into consideration the amount of kit that has been
produced with SCART conectivity since its introduction, maybe hundreds of
millions of devices, therefore in all honesty I don't see it disappearing
for a very very long time to come.

Also of course, if the cold winds of recession start to bite around the
world giving people more pressing priorities than rushing out and spending
their hard earned cash on new toys, then it's anyone's guess how much longer
its life will be prolonged :0)



Bert

"Albert Manfredi" wrote in message
...
On Mar 6, 8:57 pm, "William Sommerwerck"
wrote:

If B-Y and R-Y _truly_ represent B and R _saturation_, then the only HF
detail in these signals will be that representing changes in saturation --
not changes in luminance.

QED, anyone?

Even assuming your assumption to be correct, all of the black and
white luminance information NOT sent with the B-Y and R-Y must still
be transferred. Moving it over to the Y does not mean you have reduced
any bandwidth requirements. I fail to understand why you keep
confusing yourself with tangential discussions.

Whether _my_ reasoning is correct has nothing to do with your reasoning. The
issue is not the bandwidth of the Y signal, but the bandwidth of the color
signals -- and whether one can choose color signals that make better use of
the available bandwidth.

"Smarty" wrote in message news:[email protected]

Imagine a blue screen with a gradient or checkerboard of blue values
only, as an example. Alternating squares of light and dark blue, or a
smooth transition from light to dark, or any conceivable variation of
blues
including steps, ramps, wedges, bars, etc.

This blue signal B will contain, before conversion into NTSC, lots of
high frequency content, if the transitions are abrupt / small, and little
or no high frequency content if it the blue field is solid or smoothly
transitioning.

Now imagine what the luminance component Y of this signal would look
like, namely, an envelope exactly the same in amplitude (since red and
green are zero) and exactly the same in spectral / frequency components
as the blue signal.

NOW........subtract the two (as in B-Y).........

Note that the difference would be precisely, exactly zero at all times.
Their instantaneous values, being precisely the same, cancel each
other entirely.

Your mental experiment is wrong. As the color-difference signal represents
saturation, and a blue field has at least _some_ saturation, the resulting
signal _can't_ be zero.

Here's the error in your reasoning... You're ignoring the way the Y signal
is derived.

Ignoring absolute luminance levels, the situation you describe is B = 1, R =
G = 0. The Y signal isn't 1, it's

0.30 R + 0.59 G + 0.11 B

Therefore, the B-Y signal must have an amplitude of 0.89, not zero.

On Sat, 8 Mar 2008 03:44:31 -0800, "William Sommerwerck"
wrote:


"Albert Manfredi" wrote in message
...
On Mar 6, 8:57 pm, "William Sommerwerck"
wrote:

If B-Y and R-Y _truly_ represent B and R _saturation_, then the only HF
detail in these signals will be that representing changes in saturation --
not changes in luminance.

QED, anyone?

Even assuming your assumption to be correct, all of the black and
white luminance information NOT sent with the B-Y and R-Y must still
be transferred. Moving it over to the Y does not mean you have reduced
any bandwidth requirements. I fail to understand why you keep
confusing yourself with tangential discussions.

Whether _my_ reasoning is correct has nothing to do with your reasoning. The
issue is not the bandwidth of the Y signal, but the bandwidth of the color
signals -- and whether one can choose color signals that make better use of
the available bandwidth.


I haven't been following this thread, but has anybody yet mentioned
the ratio of rods to cones in the eye? There is simply no point in
making the colour information wideband, because the eye can't resolve
it anyway.

d

--
Pearce Consulting
http://www.pearce.uk.com

"Don Pearce" wrote in message
...

I haven't been following this thread, but has anybody yet
mentioned the ratio of rods to cones in the eye? There is
simply no point in making the colour information wideband,
because the eye can't resolve it anyway.

This is, broadly speaking, true, but it is only indirectly connected with
the reason for using color-difference signals rather than color primaries.

On Sat, 8 Mar 2008 04:15:17 -0800, "William Sommerwerck"
wrote:

"Don Pearce" wrote in message
...

I haven't been following this thread, but has anybody yet
mentioned the ratio of rods to cones in the eye? There is
simply no point in making the colour information wideband,
because the eye can't resolve it anyway.

This is, broadly speaking, true, but it is only indirectly connected with
the reason for using color-difference signals rather than color primaries.


well of course. That came about from the need to make systems backward
compatible with existing monochrome receivers. I'm sure they took
their cue from the Zenith GE stereo audio system.

d
--
Pearce Consulting
http://www.pearce.uk.com

"Don Pearce" wrote in message
...
On Sat, 8 Mar 2008 04:15:17 -0800, "William Sommerwerck"
wrote:

I haven't been following this thread, but has anybody yet
mentioned the ratio of rods to cones in the eye? There is
simply no point in making the colour information wideband,
because the eye can't resolve it anyway.

This is, broadly speaking, true, but it is only indirectly connected
with the reason for using color-difference signals rather than color
primaries.

well of course. That came about from the need to make systems
backward compatible with existing monochrome receivers. I'm sure
they took their cue from the Zenith/GE stereo [FM] audio system.

I hope you're joking, Mr. Pearce.

And as I've repeatedly pointed out, the color signals could have been
primaries, rather than color-difference signals, and still fit within the
required bandwidth.

On Sat, 8 Mar 2008 04:36:07 -0800, "William Sommerwerck"
wrote:

"Don Pearce" wrote in message
...
On Sat, 8 Mar 2008 04:15:17 -0800, "William Sommerwerck"
wrote:

I haven't been following this thread, but has anybody yet
mentioned the ratio of rods to cones in the eye? There is
simply no point in making the colour information wideband,
because the eye can't resolve it anyway.

This is, broadly speaking, true, but it is only indirectly connected
with the reason for using color-difference signals rather than color
primaries.

well of course. That came about from the need to make systems
backward compatible with existing monochrome receivers. I'm sure
they took their cue from the Zenith/GE stereo [FM] audio system.

I hope you're joking, Mr. Pearce.

And as I've repeatedly pointed out, the color signals could have been
primaries, rather than color-difference signals, and still fit within the
required bandwidth.


Really? Ok.

d
--
Pearce Consulting
http://www.pearce.uk.com

On Mar 8, 7:41*am, (Don Pearce) wrote:
On Sat, 8 Mar 2008 04:36:07 -0800, "William Sommerwerck"





wrote:
"Don Pearce" wrote in message
...
On Sat, 8 Mar 2008 04:15:17 -0800, "William Sommerwerck"
wrote:

I haven't been following this thread, but has anybody yet
mentioned the ratio of rods to cones in the eye? There is
simply no point in making the colour information wideband,
because the eye can't resolve it anyway.

This is, broadly speaking, true, but it is only indirectly connected
with the reason for using color-difference signals rather than color
primaries.

well of course. That came about from the need to make systems
backward compatible with existing monochrome receivers. I'm sure
they took their cue from the Zenith/GE stereo [FM] audio system.

I hope you're joking, Mr. Pearce.

And as I've repeatedly pointed out, the color signals could have been
primaries, rather than color-difference signals, and still fit within the
required bandwidth.

Really? Ok.

d
--
Pearce Consultinghttp://www.pearce.uk.com- Hide quoted text -

- Show quoted text -

ok we are beating this to death..

Color DIFFERENCE signals fundamentally require the same BW as the
color primary signals, other wise you do loose information. But the
eye does have less color resolution so if you need to minimize the BW
usage, full BW luma with reduced BW color resolution is a good
compromise.

Now encoding the color as DIFFERENCE also makes sense because it is
then easy to manipulate the BW of the color independently without
effecting the luma and also becasue there is often less ENERGY (not
less BW) in the difference signals so when you have to combine the
color info with the luma in a backwardly compatable COMPOSITE signal,
there is less chance for interference between the two.

The analogy to stereo is very good. There is less energy in L-R but
not less BW. If you needed to conserve BW you might consider reducing
the BW of L-R and that would give less seperation at high frequencies
instead of less BW of the main L and R. The logic is the same in
video.

Reducing the BW of the resolution of the color signals is a good
compromise. Encoding and trasnmitting the color as DIFFERENCE makes
it easy to manipulate and there is less energy in the DIFFERENCE
signals.

Mark

On Mar 8, 9:23 am, Mark wrote:
On Mar 8, 7:41 am, (Don Pearce) wrote:



On Sat, 8 Mar 2008 04:36:07 -0800, "William Sommerwerck"

wrote:
"Don Pearce" wrote in message
...
On Sat, 8 Mar 2008 04:15:17 -0800, "William Sommerwerck"
wrote:

I haven't been following this thread, but has anybody yet
mentioned the ratio of rods to cones in the eye? There is
simply no point in making the colour information wideband,
because the eye can't resolve it anyway.

This is, broadly speaking, true, but it is only indirectly connected
with the reason for using color-difference signals rather than color
primaries.

well of course. That came about from the need to make systems
backward compatible with existing monochrome receivers. I'm sure
they took their cue from the Zenith/GE stereo [FM] audio system.

I hope you're joking, Mr. Pearce.

And as I've repeatedly pointed out, the color signals could have been
primaries, rather than color-difference signals, and still fit within the
required bandwidth.

Really? Ok.

d
--
Pearce Consultinghttp://www.pearce.uk.com-Hide quoted text -

- Show quoted text -

ok we are beating this to death..

Color DIFFERENCE signals fundamentally require the same BW as the
color primary signals, other wise you do loose information. But the
eye does have less color resolution so if you need to minimize the BW
usage, full BW luma with reduced BW color resolution is a good
compromise.

Now encoding the color as DIFFERENCE also makes sense because it is
then easy to manipulate the BW of the color independently without
effecting the luma and also becasue there is often less ENERGY (not
less BW) in the difference signals so when you have to combine the
color info with the luma in a backwardly compatable COMPOSITE signal,
there is less chance for interference between the two.

The analogy to stereo is very good. There is less energy in L-R but
not less BW. If you needed to conserve BW you might consider reducing
the BW of L-R and that would give less seperation at high frequencies
instead of less BW of the main L and R. The logic is the same in
video.

Reducing the BW of the resolution of the color signals is a good
compromise. Encoding and trasnmitting the color as DIFFERENCE makes
it easy to manipulate and there is less energy in the DIFFERENCE
signals.

Mark

Sadly, this painfully prolonged thread continues with a total
disregard for widely-known principles on William's part. He has
completely dismissed statements by a half-dozen other posters who have
pointed out the correct nature of color video processing and continued
to insist that only he was correct. When challenged to provide support
for his position, he has been unable to cite a single reference. It
would seem likely that William also believes that the earth is flat
and that the sun revolves around it.