Invisible <voi### [at] devnull> wrote:
> Quadrupling the number of pixels doesn't necessarily mean that the 
> *compressed* signal takes more bandwidth.

  It depends on the video contents and the codec.

  If you take, let's say, a 640x480 video and quadruple its size to
1280x960 (using some interpolation filtering), you won't need significantly
more bitrate eg. on MPEG-4 to get the same picture quality. That's because
the larger version doesn't contain any more information than the smaller
one (any additional bitrate you might need comes mostly from other overhead
caused by the larger video size).

  However, if your *original* video is 1280x960, at full detail, then it
will contain significantly more information than the 640x480 version. Most
of this extra information will get mangled if you use the same bitrate as
you did with the smaller video (assuming the bitrate was pretty optimal for
it to begin with). You will need more bitrate to retain that extra
information as much as possible (although not four times as much, of course).

  This is so for MPEG-4. Digi-TV (at least here) uses MPEG-2 (the same as
DVDs use). I don't know how well that handles larger video resolutions
compared to smaller ones.

> Then again, since we replaced our old CRT with a shiny new LCD, suddenly 
> I notice that just about *everything* on TV has DCT artifacts all over 
> it. (I guess the CRT was too blurry to show this.) It's quite annoying.

  Most digital TV broadcasts use significantly lower bitrates than DVDs,
which is why most digital TV broadcasts have significantly more visible
artifacts.

-- 
                                                          - Warp

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scott wrote:

> Virgin have a system called On Demand in the UK.  Here in Germany we 
> have T-Home.  Obviously you need a fast internet connection (about 6 
> MBit/s or higher IIRC) to receive broadcast quality video.
> 
> http://en.wikipedia.org/wiki/IPTV
> http://en.wikipedia.org/wiki/Video_on_Demand

Hmm, interesting.

I know the BT Vision system is supposed to allow you to download video 
content to watch later, but I'm not aware of any system which can manage 
it in realtime. (Certainly not just using a normal PC...)

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Fredrik Eriksson <fe79}--at--{yahoo}--dot--{com> wrote:
> On Mon, 26 Apr 2010 17:15:28 +0200, Invisible <voi### [at] devnull> wrote:
> >
> > Ooo, here's a random thought: Do you think there will ever be a day when  
> > the Internet becomes fast enough to watch TV-quality video in realtime?
> >
> > When do you think that day will be?

> About five years ago.

  At what quality?

  Certainly if your bandwidth is enough to transfer a full double-layer
DVD (ie. about 8 gigabytes) in 2 hours, then it would be enough to *watch*
that DVD in real-time over the internet. Not many people have such huge
bandwidths, though.

-- 
                                                          - Warp

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> I know the BT Vision system is supposed to allow you to download video 
> content to watch later, but I'm not aware of any system which can manage 
> it in realtime. (Certainly not just using a normal PC...)

Many TV company websites let you watch TV live via your PC at varying levels 
of quality.  I have certainly seen a few that exceed digital SD broadcast TV 
(a friend was watching american football streamed over the net in HD 
quality, I had it through my laptop hooked up to the TV - definitely better 
than watching it on normal SDTV).

How about BBC iPlayer, what's the quality like on that? (I can't access it 
outside the UK)

YouTube also streams video at resolutions up to 1080p, you just need a fast 
enough internet connection to watch it in real time as it's downloading. 
IIRC the best digital TV broadcast streams use about 6 mbit/s, so that 
should give you some idea what internet speed you need.

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scott wrote:
>> I know the BT Vision system is supposed to allow you to download video 
>> content to watch later, but I'm not aware of any system which can 
>> manage it in realtime. (Certainly not just using a normal PC...)
> 
> Many TV company websites let you watch TV live via your PC at varying 
> levels of quality.  I have certainly seen a few that exceed digital SD 
> broadcast TV.

Seriously??

> How about BBC iPlayer, what's the quality like on that? (I can't access 
> it outside the UK)

Pitiful. Utterly pitiful.

I mean, forgetting the minor detail that it's plain unusuable at certain 
times of day, the picture quality is abysmal. (The sound isn't bad though.)

Also, if you use the iPlayer client (rather than just the Flash thing on 
the website), it appears to turn our PC into a peer-to-peer client, 
constantly uploading and downloading data even when iPlayer isn't 
running. (It installs a background service which starts at boot.)

> YouTube also streams video at resolutions up to 1080p, you just need a 
> fast enough internet connection to watch it in real time as it's 
> downloading. IIRC the best digital TV broadcast streams use about 6 
> mbit/s, so that should give you some idea what internet speed you need.

I've yet to see anything on YouTube which even approaches TV quality.

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>  Certainly if your bandwidth is enough to transfer a full double-layer
> DVD (ie. about 8 gigabytes) in 2 hours, then it would be enough to *watch*
> that DVD in real-time over the internet. Not many people have such huge
> bandwidths, though.

That "only" comes out at around 9 MBit/s, a lot of people nowadays have 
internet speeds getting on for that.

Anyway, there are also compression algorithms that are a lot more efficient 
than the one used on DVDs. So in theory you could get DVD quality with a lot 
less than 9 MBit/s if you use a better compression algorithm.

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> I've yet to see anything on YouTube which even approaches TV quality.

You did find a video that supports HD resolutions, and switch YouTube to use 
that resolution, and watch full-screen?  Search "1080p demo" to easily find 
some.

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scott <sco### [at] scottcom> wrote:
> Anyway, there are also compression algorithms that are a lot more efficient 
> than the one used on DVDs. So in theory you could get DVD quality with a lot 
> less than 9 MBit/s if you use a better compression algorithm.

  MPEG-4 Part 10 (also know as H.264) can compress DVD video to at least
1/4th of the size without any visible loss of quality, so what you are
saying is certainly true.

  However, MPEG-4 is still such a new technology that not many companies
nor devices support it well yet. (H.264 also requires quite a lot more
computing power to decompress than MPEG-2, which means that viewing
devices need to be more expensive.) Of course since we are talking about
internet broadcasting here, and thus people wathing on their PC's, that's
mostly a non-issue.

  Digital TV could have benefited from using MPEG-4 instead of MPEG-2, but
it didn't. It's a bummer.

-- 
                                                          - Warp

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Invisible escreveu:
> http://www.xkcd.com/732/
> 
> This puzzles me too.

yeah, my only conclusion is that you and the author of XKCD both use 
(blurry) glasses.  Perhaps that even may explain his simple art style... :D

> I mean, if you're going to force everybody to buy a new TV, new 
> receiver, new type of disk and a new machine to play it, why it increase 
> the resolution *significantly*? Why only increase it by a small amount? 
> I don't understand that.

It *is* a significant increase and it looks specially good on big Full 
HDTV screens in the living room, not a small 19 inches PC monitor.  BTW, 
mine here at work is a 19 inch LG monitor and is running at the maximum 
resolution of 1600x900 pixels.  That is below 1080p.

You won't even want to know what I ran back in 2004.  Humor demands 
exaggeration. :)


> (And hell, half the equipment and content that says "HD" on it isn't 
> even full resolution anyway... Why allow half a dozen resolutions when 
> it would have been far simpler for the designers and less misleading for 
> the public if they allow only one resolution?)

Because, say, games at full HD may have to cut geometry or frame rate 
here and there to fit comfortably?

> Hell, when I was at uni ten years ago we had computers exceeding these 
> resolutions. With Windows NT 4.0, Service Pack 4. Has technology not 
> moved on since then? It's not like there's any technical challenge to 
> using a higher resolution, after all...

Regarding the iPhone resolution:  obviously huge TV screens have far 
"bigger" pixels than that on a iPhone display.  Literally.  From the 
distance of your sofa, though, you don't notice them individually.  Just 
as a guy doesn't notice any lack of pixels at a tiny iPhone display.

> PS. I am similarly baffled by the current fashion for "widescreen" TVs. 
> Given that 99.998% of all video content ever created is in 4:3 aspect, 
> what the hell is the advantage of buying a TV with a 16:9 aspect?? I 
> don't understand.

Yeah, why sell color TVs in a time when 99.98% video content ever 
created is B&W?  This is one of your "obviously impossible" kinda 
comments, ain't it?

-- 
a game sig: http://tinyurl.com/d3rxz9

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On Mon, 26 Apr 2010 18:04:34 +0200, Warp <war### [at] tagpovrayorg> wrote:
>
>   Digital TV could have benefited from using MPEG-4 instead of MPEG-2,  
> but it didn't. It's a bummer.

Over here we have already started the switch to MPEG-4.

Depending on where in Finland you live, you might even be able watch some  
of it (with a compatible receiver of course).



-- 
FE

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