Best tv for pc resolution
 

On 1 Oct, 18:16, Colin Stamp wrote:
On Mon, 01 Oct 2007 01:48:04 -0700, "

btw, you seem convinced that it's the horizontal pixel count that
matters -

Yep - convinced by personal experience.

if you think for one second about the analogue signal,
you'll realise it's the pixel clock that defines the bandwidth
required. This is roughly proportional to the pixel count per second
(not exactly, because blanking and sync varies with display mode in a
not quite proportional way on "old" modes).

But if you increase your one second of thought to maybe two or three,
you'd realize that the situation is more complex than bandwidth alone.
With no pixel sync on the interface, and a display with discrete
pixels that need to be addressed individually, timing becomes
crucially important too.

OK, I can see how that might be possible.

There's a line sync, so that lets vertical resolution off the hook.
Horizontally though, you're into trying to locate the middle of a
pixel when your last proper timing reference might have been nearly
two thousand pixels ago. Any bandwidth limitations will make matters
worse by tightening the margin for error on finding the exact centre
of each pixel.

Oscillators that can acheive the necessary accuracy over the required
temperature range are certainly available, but how many video cards
and TVs have them fitted?

I understand how conventional TVs sync, and in that domain the
absolute accuracy of the pixel clock is irrelevant (within reason; but
VHS works!).

I have no idea how LCD PC monitors sync, but let's assume the worse.
If LCDs assume a perfect pixel clock, but trigger blindly and without
"fly wheel" circuitry from the H and V syncs, then the pixel clock
needs to be wrong by 1 part in 2000 to shift a pixel at the end of the
line at 1920x1080.

It would be possible to make a graphics card that's that bad. However,
it would be easy to make one that's well within those constraints.

In other words, there's no magic: it's easy to make VGA work at
1920x1080p50, but graphics cards with a poor quality clock might not.
That's assuming LCDs work in the worst way possible. I have my doubts
about that.

Not to mention that DVI/HDMI outputs connected to DVI/HDMI inputs can
have issues too!

Cheers,
David.

Best tv for pc resolution
 

On Wed, 03 Oct 2007 02:28:27 -0700, "
wrote:

On 1 Oct, 18:16, Colin Stamp wrote:
On Mon, 01 Oct 2007 01:48:04 -0700, "

btw, you seem convinced that it's the horizontal pixel count that
matters -

Yep - convinced by personal experience.

if you think for one second about the analogue signal,
you'll realise it's the pixel clock that defines the bandwidth
required. This is roughly proportional to the pixel count per second
(not exactly, because blanking and sync varies with display mode in a
not quite proportional way on "old" modes).

But if you increase your one second of thought to maybe two or three,
you'd realize that the situation is more complex than bandwidth alone.
With no pixel sync on the interface, and a display with discrete
pixels that need to be addressed individually, timing becomes
crucially important too.

OK, I can see how that might be possible.

There's a line sync, so that lets vertical resolution off the hook.
Horizontally though, you're into trying to locate the middle of a
pixel when your last proper timing reference might have been nearly
two thousand pixels ago. Any bandwidth limitations will make matters
worse by tightening the margin for error on finding the exact centre
of each pixel.

Oscillators that can acheive the necessary accuracy over the required
temperature range are certainly available, but how many video cards
and TVs have them fitted?

I understand how conventional TVs sync, and in that domain the
absolute accuracy of the pixel clock is irrelevant (within reason; but
VHS works!).

I have no idea how LCD PC monitors sync, but let's assume the worse.
If LCDs assume a perfect pixel clock, but trigger blindly and without
"fly wheel" circuitry from the H and V syncs,

Even if it was possible to do that reliably, it would be far more
expensive than just paying out for oscillators that were up to the
job.

then the pixel clock needs to be wrong by 1 part in 2000 to shift a
pixel at the end of the line at 1920x1080.

That seems like a good starting point, giving a tolerance of +/-
250ppm, but it assumes the samples can be taken right up to the border
with the next pixel, which would require infinite bandwidth. In
practice, you'd need to restrict the samples to somewhere near the
centre of the pixel to avoid the slope into adjacent pixels. Let's
take a stab in the dark, and limit ourselves to the middle 20%. That
takes the accuracy to +/-50ppm. Then you'll need to allow for the
accuracy of the oscillator at the other end of the link. Assuming
they're both equally accurate, you're left with +/- 25ppm.


It would be possible to make a graphics card that's that bad. However,
it would be easy to make one that's well within those constraints.

25ppm is way too accurate to achieve with an unadjusted discrete
oscillator of the type that are on many video cards. Those cards will
*probably* still work, particularly at lower horizontal resolutions,
but it isn't anywhere near guaranteed.

In other words, there's no magic: it's easy to make VGA work at
1920x1080p50, but graphics cards with a poor quality clock might not.
That's assuming LCDs work in the worst way possible. I have my doubts
about that.

It is easy to make one that's guaranteed to work, but it takes a
little bit of extra money. It becomes far more difficult if you've got
a bean-counter looking over your shoulder.


Not to mention that DVI/HDMI outputs connected to DVI/HDMI inputs can
have issues too!

No doubt, but that's not at issue here.

Cheers,

Colin.

Best tv for pc resolution
 

Colin Stamp wrote:
On Tue, 02 Oct 2007 22:24:54 GMT, "ThePunisher"
wrote:

also what makes you think analogue signals can't be pixel
perfect over VGA?

*Can't* be pixel perfect? I don't recall ever saying that anywhere. I
can't imagine myself ever saying it since it's never been my view.

You did when you said you've seen a pc work perfectly at 1600x1200 on a crt
monitor but start to smear badly when displaying 1380x720 [sic] on a lcd,
you put it down to the output not being pixel perfect.

Perhaps you could point out where your mis-interpretation occurred.
I'd be happy to try to help you understand your mistake.

Cheers,

Colin.

Quote:
"The 15-pin analogue VGA connector that's standard on PCs isn't really
capable of
doing 1080p resolution properly."

Even though you've been told by a few people that it can easily do it, ever
though the problem might be at your end?

--
ThePunisher

Best tv for pc resolution
 

On Thu, 04 Oct 2007 23:57:37 GMT, "ThePunisher"
wrote:

Colin Stamp wrote:
On Tue, 02 Oct 2007 22:24:54 GMT, "ThePunisher"
wrote:

also what makes you think analogue signals can't be pixel
perfect over VGA?

*Can't* be pixel perfect? I don't recall ever saying that anywhere. I
can't imagine myself ever saying it since it's never been my view.

You did when you said you've seen a pc work perfectly at 1600x1200 on a crt
monitor but start to smear badly when displaying 1380x720 [sic] on a lcd,
you put it down to the output not being pixel perfect.

Well, I guess you're talking about the quote below...

On Tue, 25 Sep 2007 20:19:09 +0100, Colin Stamp
wrote:

It's hit-and-miss in that some systems will work and some won't. If
you have one that works then that's wonderful - for you and you alone.
But then again, we don't know that it works even for you.
I've even seen one 1380X720 setup that's pixel-perfect until the PC
starts to warm up, then starts to smear after half an hor or so.
Flat-panel displays are *much* less forgiving than CRTs in this
respect. The output *has* to be pixel-perfect or it shows up really
badly.

Are you seriously suggesting that you read all that and still came
away with the impression that I was saying that no LCD can work when
driven via VGA?

That's actually quite an impressive bit of mis-understanding.


Perhaps you could point out where your mis-interpretation occurred.
I'd be happy to try to help you understand your mistake.

Cheers,

Colin.

Quote:
"The 15-pin analogue VGA connector that's standard on PCs isn't really
capable of
doing 1080p resolution properly."

Ah, that's slightly more understandable. All you've done wrong here is
fail to notice the words "really" and "properly" in the sentence. I
put them there for a reason. Notice how they change the meaning.
A couple of other people made the same mistake, so you're not alone. I
wouldn't fret too much about it.

Even though you've been told by a few people that it can easily do it, ever
though the problem might be at your end?

What problem? You're still operating under the same mis-understanding
as before. "Can easily do it" and "Can't always do it" can happily
both be true.

Cheers,

Colin.

Best tv for pc resolution
 

Colin Stamp wrote:
On Thu, 04 Oct 2007 23:57:37 GMT, "ThePunisher"
wrote:

Colin Stamp wrote:
On Tue, 02 Oct 2007 22:24:54 GMT, "ThePunisher"
wrote:

also what makes you think analogue signals can't be pixel
perfect over VGA?

*Can't* be pixel perfect? I don't recall ever saying that anywhere.
I can't imagine myself ever saying it since it's never been my view.

You did when you said you've seen a pc work perfectly at 1600x1200
on a crt monitor but start to smear badly when displaying 1380x720
[sic] on a lcd, you put it down to the output not being pixel
perfect.

Well, I guess you're talking about the quote below...

On Tue, 25 Sep 2007 20:19:09 +0100, Colin Stamp
wrote:

It's hit-and-miss in that some systems will work and some won't. If
you have one that works then that's wonderful - for you and you
alone. But then again, we don't know that it works even for you.
I've even seen one 1380X720 setup that's pixel-perfect until the PC
starts to warm up, then starts to smear after half an hor or so.
Flat-panel displays are *much* less forgiving than CRTs in this
respect. The output *has* to be pixel-perfect or it shows up really
badly.

Are you seriously suggesting that you read all that and still came
away with the impression that I was saying that no LCD can work when
driven via VGA?

No I didn't, or else I would have said that.

That's actually quite an impressive bit of mis-understanding.

No mis-understanding on my part.


Perhaps you could point out where your mis-interpretation occurred.
I'd be happy to try to help you understand your mistake.

Cheers,

Colin.

Quote:
"The 15-pin analogue VGA connector that's standard on PCs isn't
really capable of
doing 1080p resolution properly."

Ah, that's slightly more understandable. All you've done wrong here is
fail to notice the words "really" and "properly" in the sentence.

No I haven't.

I put them there for a reason. Notice how they change the meaning.

No, they don't.

A couple of other people made the same mistake, so you're not alone.

No, they didn't.

I wouldn't fret too much about it.

I'm not.

Even though you've been told by a few people that it can easily do
it, ever though the problem might be at your end?

What problem? You're still operating under the same mis-understanding
as before.

No, I'm not.

"Can easily do it" and "Can't always do it" can happily both be true.

That's true, it's a pity you didn't say that in the first place. Instead of
trying to be a smart **** you should try looking up some words in a
dictionary, start with "really" and "properly"

BTW what screen uses that resolution of 1380x720?

--
ThePunisher

Best tv for pc resolution
 

On Sat, 06 Oct 2007 01:59:01 GMT, "ThePunisher"
wrote:

Colin Stamp wrote:
On Thu, 04 Oct 2007 23:57:37 GMT, "ThePunisher"
wrote:

Colin Stamp wrote:
On Tue, 02 Oct 2007 22:24:54 GMT, "ThePunisher"
wrote:

also what makes you think analogue signals can't be pixel
perfect over VGA?

*Can't* be pixel perfect? I don't recall ever saying that anywhere.
I can't imagine myself ever saying it since it's never been my view.

You did when you said you've seen a pc work perfectly at 1600x1200
on a crt monitor but start to smear badly when displaying 1380x720
[sic] on a lcd, you put it down to the output not being pixel
perfect.

Well, I guess you're talking about the quote below...

On Tue, 25 Sep 2007 20:19:09 +0100, Colin Stamp
wrote:

It's hit-and-miss in that some systems will work and some won't. If
you have one that works then that's wonderful - for you and you
alone. But then again, we don't know that it works even for you.
I've even seen one 1380X720 setup that's pixel-perfect until the PC
starts to warm up, then starts to smear after half an hor or so.
Flat-panel displays are *much* less forgiving than CRTs in this
respect. The output *has* to be pixel-perfect or it shows up really
badly.

Are you seriously suggesting that you read all that and still came
away with the impression that I was saying that no LCD can work when
driven via VGA?

No I didn't, or else I would have said that.

That's actually quite an impressive bit of mis-understanding.

No mis-understanding on my part.

Hang-on, I'm seeing a pattern starting to emerge here...


Perhaps you could point out where your mis-interpretation occurred.
I'd be happy to try to help you understand your mistake.

Cheers,

Colin.

Quote:
"The 15-pin analogue VGA connector that's standard on PCs isn't
really capable of
doing 1080p resolution properly."

Ah, that's slightly more understandable. All you've done wrong here is
fail to notice the words "really" and "properly" in the sentence.

No I haven't.

Yep. There's that pattern again. Stop trying to start some kind of
"Oh no I haven't" - "Oh yes you have" style pantomime.


I put them there for a reason. Notice how they change the meaning.

No, they don't.

I said stop it.


A couple of other people made the same mistake, so you're not alone.

No, they didn't.

There you go again.


I wouldn't fret too much about it.

I'm not.

*Please* stop it.


Even though you've been told by a few people that it can easily do
it, ever though the problem might be at your end?

What problem? You're still operating under the same mis-understanding
as before.

No, I'm not.

This is getting silly now.


"Can easily do it" and "Can't always do it" can happily both be true.

That's true,

Hallelujah! The penny has dropped at last!

it's a pity you didn't say that in the first place.

Apologies. My newsreader is strictly plain-text only. I wasn't able to
write it in a 50pt crayola-style font or anything. Instead, I had to
rely on people properly reading my posts. By the time you made your
second post on this thread (your first remotely meaningful post, that
is), I had already clarified the point at-least once and everyone knew
exactly what I meant (even if they didn't agree with it). Everyone
except you, that is. You need to try to keep up-to-date a little bit
better, otherwise you'll end-up in all sorts of problems.

Instead of trying to be a smart ****

Do I detect a little tetchyness in your tone? I thought you said you
weren't fretting about this. Is it the condescending tone I use with
you that you don't like? I'm afraid that if you act like a child when
dealing with me, I'll treat you like one. For instance, opening a
discussion with me using nothing but the words "What a load of
********." will generally get you off on the wrong foot.

you should try looking up some words in a
dictionary, start with "really" and "properly"

Right - done that. They're both in there. I suspected as much, to be
honest.

BTW what screen uses that resolution of 1380x720?

Thankyou for pointing out that error (twice now - it must have been
really bugging you). The exact resolution wasn't that important so I'm
afraid I guessed it to save the trouble of finding it out properly.
The actual value is 1360X768. I'm deeply ashamed of what I've done and
I unreservedly apologize to anyone who might have been misled by this
grave error of judgement. I hope we can now both draw a line under the
whole sordid "guessed-resolution" affair.

Now that's over with, let's check a few of your posts for mistakes....
Oh dear, you're hardly in a position of strength here, are you?

Cheers,

Colin.

Best tv for pc resolution
 

Colin Stamp wrote:

Hang-on, I'm seeing a pattern starting to emerge here...

That would be a pattern of me answering your statements.

it's a pity you didn't say that in the first place.

Apologies. My newsreader is strictly plain-text only.

Yes, I see how having a plain text newsreader prevents you from typing words
like
"Can't always do it"


Instead of trying to be a smart ****

Do I detect a little tetchyness in your tone?

No, I thought you were a **** from the start.

I thought you said you
weren't fretting about this. Is it the condescending tone I use with
you that you don't like? I'm afraid that if you act like a child when
dealing with me, I'll treat you like one. For instance, opening a
discussion with me using nothing but the words "What a load of
********." will generally get you off on the wrong foot.

Yep, the truth hurts doesn't it.


BTW what screen uses that resolution of 1380x720?

Thankyou for pointing out that error (twice now - it must have been
really bugging you). The exact resolution wasn't that important

Actually it was important as running a non native resolution on a lcd screen
can cause some strange problems.

--
ThePunisher

Best tv for pc resolution
 

"ThePunisher" wrote in message
...
Colin Stamp wrote:

Hang-on, I'm seeing a pattern starting to emerge here...

That would be a pattern of me answering your statements.

it's a pity you didn't say that in the first place.

Apologies. My newsreader is strictly plain-text only.

Yes, I see how having a plain text newsreader prevents you from typing
words like
"Can't always do it"


Instead of trying to be a smart ****

Do I detect a little tetchyness in your tone?

No, I thought you were a **** from the start.

I thought you said you
weren't fretting about this. Is it the condescending tone I use with
you that you don't like? I'm afraid that if you act like a child when
dealing with me, I'll treat you like one. For instance, opening a
discussion with me using nothing but the words "What a load of
********." will generally get you off on the wrong foot.

Yep, the truth hurts doesn't it.


BTW what screen uses that resolution of 1380x720?

Thankyou for pointing out that error (twice now - it must have been
really bugging you). The exact resolution wasn't that important

Actually it was important as running a non native resolution on a lcd
screen can cause some strange problems.

--
ThePunisher
Nice, friendly little group, innit?????

Best tv for pc resolution
 

Chas Gill wrote:
Nice, friendly little group, innit?????

Why I should break you fuc... oh, hello :-)

--
ThePunisher

Best tv for pc resolution
 

On Sun, 07 Oct 2007 16:53:25 GMT, "ThePunisher"
wrote:

Well, it was fun for a bit and it's tempting to reel you in some more,
if only to see if I can get a few more carefully thought through and
well presented expletives from you, but I guess it was really time to
stop some days ago. In any case, I've just noticed that Top Gear has
turned up on the disk of the Topfield. I don't care what they say
about Clarkson, he's still more interesting than you...

Don't forget to take the last word, by the way. I'm looking forward to
it :o)

Cheers,

Colin.