Invisible nous apporta ses lumieres en ce 2007/11/22 04:15:
> That's interesting. I was in some shop the other day, and they had a 
> huge LCD with "HD Ready" splashed all over it, and huge cardboard signs 
> saying "WOW! LOOK AT THE DIFFERENCE!" And I remember thinking "...I 
> can't see any difference."
> 
> I mean, let's face it, HD is only 4x the imagine resolution. If you 
> compare the two side by side you'd probably notice. But if you just look 
> at an HD TV, there really isn't much to notice. The picture is very 
> slightly more crisp, but that's about it.
Do you mean 4x the total numbet of pixels, or 4x the number of LINES?
4x the pixels == double the pixels per lines and double the lines.
4x the lines is more like 16x the resolution!

> 
> Certainly it hardly seems worth paying £7,000 just for a very slightly 
> more crisp picture. I could buy a *car* for that amount of money! Hell, 
> I could almost buy a copy of *Oracle* for that!
You are slightly outdated! HD prices have come down a LOT in just 2 years.

-- 
Alain
-------------------------------------------------
You know you've been raytracing too long when you look at waterfalls, dust, 
rain, snow, etc, and think: "If only I had a fractalized, vector based 
particle-system modeler with collision detection!"

Post a reply to this message

Invisible nous apporta ses lumieres en ce 2007/11/22 07:55:
> scott wrote:
>>> Must take some serious MPEG compression to fit that onto a disk - 
>>> even a bluray disk has only finite storage capacity.
>>
>> 50 GB max IIRC.
> 
> Well, let me see...
> 
> 1,920 pixels x 1,080 pixels = 2,073,600 pixels / frame
> 
> 3 bytes / pixel x 2,073,600 pixels / frame = 6,220,800 bytes / frame
> 
> 25 frames / second x 6,220,800 bytes / frame = 155,520,000 bytes / second
> 
> Approx 148.31 MB / second. (Woah, that's some transfer rate!)
> 
> 8.69 GB / minute.
> 
> 512.40 GB / hour. So only 10x bigger than the disk. ;-)
> 
Now, each non-key frame only contains the difference from the preceding one. 
Normaly, every frame is compressed. The end result is that you have compression 
ratio well over 10, it can get in the 20 to 50 time.
They probably use MPEG2, it gives you about twice the compression of regular 
MPEG (MPEG1), with a slightly beter quality.

-- 
Alain
-------------------------------------------------
You know you've been raytracing too long when you think it's a failing of the 
universe that the large software companies like Corel or Fractal Design do NOT 
export to POV primitives.
George Erhard

Post a reply to this message

Alain wrote:
> They probably use MPEG2, it gives you about twice the compression of 

I believe they do. At least for standard def DVD.

Post a reply to this message

And lo on Thu, 22 Nov 2007 11:50:12 -0000, Invisible <voi### [at] devnull> did  
spake, saying:

> scott wrote:
>>> That's interesting. I was in some shop the other day, and they had a  
>>> huge LCD with "HD Ready" splashed all over it, and huge cardboard  
>>> signs saying "WOW! LOOK AT THE DIFFERENCE!" And I remember thinking  
>>> "...I can't see any difference."
>>  They were probably feeding in some crappy HD or worse even SD  
>> material... NExt time take along a copy of the pixar shorts on blu-ray  
>> and ask them to play that on a 1080p TV.  It will knock you out!
>
> They were running National Geographic HD. (Doesn't mean they had an HD  
> decoder of course...) Lots of long short of mountains, jungles, big  
> savanas and stuff that's clearly meant to make you go "wow". It honestly  
> didn't look much different to what I get on my 7 year old TV at home.

Remembering that all the training they've had in electronics is to  
remember to ask "So you want the extended warranty on that?". It's scary  
at times watching HD televisions being fed an input via an unshielded  
multifeed or from an HD Box via a SCART connector.

>>> I mean, let's face it, HD is only 4x the imagine resolution.
>>  "only".  What resolution do run your desktop in?  Now imagine dividing  
>> that by 4.  It wouldn't be pretty...
>
> As far as I know, a normal TV operates at something like 300x200 or so.  
> That means that 4x would only be 600x400 - still extremely low.

As has already been mentioned PAL has 625 lines with normally only 576  
active lines.


>
> I think we've established that the shop was overpriced. ;-)

You seem to have a few of those :-)

-- 
Phil Cook

--
I once tried to be apathetic, but I just couldn't be bothered
http://flipc.blogspot.com

Post a reply to this message

>> They probably use MPEG2, it gives you about twice the compression of 
> 
> I believe they do. At least for standard def DVD.

The bluray standard allows MPEG2, h264 or VC-1 to be used.

Post a reply to this message

scott wrote:
>>> They probably use MPEG2, it gives you about twice the compression of 
>>
>> I believe they do. At least for standard def DVD.
> 
> The bluray standard allows MPEG2, h264 or VC-1 to be used.

Had to look them up. Cool.

Post a reply to this message

scott wrote:
> The bluray standard allows MPEG2, h264 or VC-1 to be used.

h264 is pretty impressive, even if it does require a Cray to run at 
realtime speeds.  my own attempt to rip a VHS tape to an AVI resulted in 
an initially 22-GB file (6.25 hours @ 640x480x24fps), and I was able to 
use h264 to compress it to ~3 GB with almost no noticeable reduction in 
quality (not that the quality was terribly great to begin with...)

-- 
Tim Cook
http://home.bellsouth.net/p/PWP-empyrean

-----BEGIN GEEK CODE BLOCK-----
Version: 3.12
GFA dpu- s: a?-- C++(++++) U P? L E--- W++(+++)>$
N++ o? K- w(+) O? M-(--) V? PS+(+++) PE(--) Y(--)
PGP-(--) t* 5++>+++++ X+ R* tv+ b++(+++) DI
D++(---) G(++) e*>++ h+ !r--- !y--
------END GEEK CODE BLOCK------

Post a reply to this message

Alain wrote:
> Invisible nous apporta ses lumieres en ce 2007/11/22 04:15:
>> I mean, let's face it, HD is only 4x the imagine resolution. If you 
>> compare the two side by side you'd probably notice. But if you just 
>> look at an HD TV, there really isn't much to notice. The picture is 
>> very slightly more crisp, but that's about it.
> Do you mean 4x the total numbet of pixels, or 4x the number of LINES?
> 4x the pixels == double the pixels per lines and double the lines.
> 4x the lines is more like 16x the resolution!

I mean 4x the number of pixels (2x lines + 2x columns).

>> Certainly it hardly seems worth paying £7,000 just for a very slightly 
>> more crisp picture. I could buy a *car* for that amount of money! 
>> Hell, I could almost buy a copy of *Oracle* for that!
> You are slightly outdated! HD prices have come down a LOT in just 2 years.

Yeah, but the shop isn't going to draw you eye to the *cheap* models, 
are they? ;-)

Post a reply to this message

> I mean 4x the number of pixels (2x lines + 2x columns).

http://en.wikipedia.org/wiki/Image:Common_Video_Resolutions.svg

I was looking for that before but couldn't find it...

Also I found a few screen-caps:

This is from normal digital terrestial TV:

http://www.oreillynet.com/mac/blog/images/0604DoraCreds2b-x.jpg

This is from some US HD channel:

http://www.bur.st/~anthony/dba/160206/stateoftheunion_1.jpg

Now, if you can't tell the difference...

Post a reply to this message

scott wrote:
>> I mean 4x the number of pixels (2x lines + 2x columns).
> 
> http://en.wikipedia.org/wiki/Image:Common_Video_Resolutions.svg
> 
> I was looking for that before but couldn't find it...

Ah yes, it's coming back to me now... Some "HD" TVs only actually 
support the lowest HD resolution, and some support higher ones. (I 
wonder if the same goes for "HD" transmissions and "HD" disks?)

> Also I found a few screen-caps:
> 
> http://www.oreillynet.com/mac/blog/images/0604DoraCreds2b-x.jpg
> http://www.bur.st/~anthony/dba/160206/stateoftheunion_1.jpg
> 
> Now, if you can't tell the difference...

These images look different to me. (I notice one is photographic and the 
other isn't...)

All I said was I was in a shop looking at one of their fantastic HD TVs 
and there was little if any apparent difference. Yeah, the picture was a 
little bit sharper, but nothing to get excited about.

I see three possibilities:

1. The TV they were proudly displaying was actually rubbish.

2. The signal they were feeding it with was naff.

3. There's little actual difference between HD and SD.

These possibilities do not appear to be muturally exclusive.

Post a reply to this message