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uk.tech.digital-tv (Digital TV - General) (uk.tech.digital-tv) Discussion of all matters technical in origin related to the reception of digital television transmissions, be they via satellite, terrestrial or cable. Advertising is forbidden, with no exceptions.

Analogue TV vs DTV Picture Quality -- which is best?



 
 
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  #21  
Old April 30th 05, 02:46 PM posted to uk.tech.digital-tv
Ben
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Posts: 774
Default Analogue TV vs DTV Picture Quality -- which is best?

Martin Underwood wrote:
One other point: do we ever see truly analogue pictures these days? Or do
most channels use digital production (recording, mixing etc) these days,
albeit using much higher bit-rates within the studio than are used for
broadcating.


Given that programmes are played out from digital tape or hard drive,
and distributed to the transmitter by a digital microwave link, I
wouldn't have thought you'd get to see 100% analogue any more. Question
Time always looks like its been through an analogue stage to me, but
you've still got that digital stage aswell.
The bit rate for uncompressed video is about 270Mbps (or 100 times what
they're trying to squeeze freeview down to), although I believe
compression at 50Mbps or so is virtually lossless.
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  #22  
Old April 30th 05, 02:48 PM posted to uk.tech.digital-tv
DAB sounds worse than FM
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Posts: 929
Default Analogue TV vs DTV Picture Quality -- which is best?

Ben wrote:
DAB sounds worse than FM wrote:
Ben wrote:


It's not at all, because some people do have good reception.


Well I don't!



What a coincidence that you take the point of view that you do.....

IME, I think you're in a small minority, though, because I've lived in a
few places and apart from when I've had to use a set-top aerial when
living on the ground floor I've always had good reception.


reception problems like snow and
ghosting are part of the transmission system.




Snow and ghosting are not transmitted, so they're reception
issues/problems.


But the picture you get to watch is the one that you receive, not the
one that was transmitted.



Picture quality and reception quality are 2 different things. End of
story. For example, I am not going to be told by someone that has ****
FM reception that FM sounds crap when I have good FM reception and know
it sounds miles better than DAB.


In the case of digital they are one and the
same, in the case of analogue they can be very different.



Bull****. If someone lives in a borderline coverage area for DTT and
they get loads of pixellation due to there being too many bit errors
then that is a reception problem, not a picture quality problem.


What you're asking for
is a comparison of what digital actually looks like versus what
analogue would look like if you could bypass the transmission
network and just walk up to the TV studio and plug your telly into
a socket on the wall. Its not real.




Bull****.

Fk this, I cannot be arsed. I asked a simple question, and I receive
answers to different questions.


Oooh, get her! OK then, my answer to your original question is that
even if you could somehow magically remove all the snow and ghosting
from an analogue picture (WHICH YOU CAN'T!!!),



I'm not saying you can magically remove all the snow, but snow is not
transmitted, so snow is caused by poor reception.


digital is still
better because its not riddled with those horrible PAL artefacts that
look much worse than a bit of MPEG compression.



I disagree, and so do others on this thread.



--
Steve - www.digitalradiotech.co.uk - Digital Radio News & Info

Find the cheapest Freeview, DAB & MP3 Player Prices:
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  #23  
Old April 30th 05, 02:48 PM posted to uk.tech.digital-tv
DAB sounds worse than FM
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Default Analogue TV vs DTV Picture Quality -- which is best?

Martin Underwood wrote:
"DAB sounds worse than FM" wrote in message


What you're asking for
is a comparison of what digital actually looks like versus what
analogue would look like if you could bypass the transmission
network and just walk up to the TV studio and plug your telly into
a socket on the wall. Its not real.



Bull****.

Fk this, I cannot be arsed. I asked a simple question, and I receive
answers to different questions.



You are asking a question about a very artificial situation: given a
perfect transmission medium (with no losses, added noise, digital
glitches), do analogue pictures look better than digital pictures or
vice versa.



I think the vast majority of people get good analogue TV reception. So
it's not even artificial, it's reality for the vast majority of people.

Basically, why should someone with poor **RECEPTION** be allowed to tell
someone with very good reception that the picture quality of analogue TV
isn't very good, when the person that does have very good reception
knows it is a lot better than what they're being told?

Basically, you HAVE TO treat the underlying picture quality and the
reception quality as 2 different issues or you end up with a nonsensical
discussion.

Sorry.


--
Steve - www.digitalradiotech.co.uk - Digital Radio News & Info

Find the cheapest Freeview, DAB & MP3 Player Prices:
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  #24  
Old April 30th 05, 02:52 PM posted to uk.tech.digital-tv
tony sayer
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Posts: 5,001
Default Analogue TV vs DTV Picture Quality -- which is best?

In article , Tony
writes
DAB sounds worse than FM wrote:
So, which do people think is best in terms of picture quality: analogue
TV or DTT?


Hmmm, well I am old enough to remember those that were suspicious of
transitor
amplifiers and wanted to stay with the "warmth" of valve amplifiers.


Yes choose your coloration

The truth is that there has yet to be a perfect reproduction system and
there is a natural tendancy to tolerate and ignore the artefacts of the
system you are used to, while over-stating the unfamiliar artefacts of
the new system.


Not necessarily

As regards analogue TV, I have invested in enough aerial and masthead
amplifier technology to ensure a pin sharp analogue picture for channels
1 to 4 (and a very snowy channel 5 - but then we're not meant to receive
it anyway).

The same aerial gives excellent digital reception.

Our main living room has a 32" Philips with Pixel Plus fed by a Thomson
DT1000 set to RGB over a SCART. There is no contest for which is the
better picture. The analogue is of course in stretch-o-vision and looks
flat compared with the much improved colours from the digital system. We
never use the analogue tuner except by mistake.


Well we see the reverse the colours on analogue are so much better. When
you get a good studio shot its remarkable...

In the family room is an older Sony 24" fed by an ex-ITV Digital Philips
box, again set to RGB. Here the difference is less pronounced, but
again, the colours are better from the digital box. I suspect the Sony
has a better PAL decoder than the Philips TV.


Yes they do vary, and I don't think there made as well as what they
ought be anymore. After all like safety on cars not a major selling
point. Witness the ****ty pics that the likes of Comet and curry's use
to demo TV's...

If I set the output of the old ITV Digital boxes to composite video then
you see a different result - the digital picture appears inferior both
on colour and definition and is probably due to a relatively poor PAL
encoder in the box compared with the one used by the TV station.

My guess is that a lot of the comments on analogue being better than
digital come from setups which use composite video (or even RF) to
connect the digibox to the TV.


Either way the piccys the same on the tests I've done....

Remember, what is happening in the digibox is that the original digital
picture (in Y-UV) is going through a PAL encoder to merge the UV
components into a single chroma signal, a low pass filter to chop the Y
component above 4 MHz or so and then the two are merged together. The
quality of the signal sent to the TV is totally dependent on how good
these encoders and filters are, and I would not be surprised if the
basic encoders in the digiboxes are a lot poorer than the ones used for
TV transmission.

Hence, expect broadcast analogue TV to be better than a digibox feeding
a TV with composite video.

On the other hand, Y-UV to RGB is a relatively simple conversion than
even cheap electronics find difficult to get wrong, so you would expect
and do get a much better picture this way.

Yes, greedy TV companies can reduce the bit rate to below acceptable and
get digital TV a bad name (and the answer to that is (a) complain and
(b) don't watch them). On the other hand, a DTT transmitter is repoted
to need only 50KW ERP to cover the same area as a 1MW analogue
transmitter and delivers something like 4 to 9 channels compared with
one. Which is better for the environment?


That argument isn't quite so simple, as that really does anyone take
into account Aerial gain figures. The don't generate 1MW they get that
by aerial gain!...

With the right setup, digital TV has the potential to deliver a much
better picture than analogue. If it does not then don't blame the
technology - it's the TV company wots to blame!


Yes it could if there were sufficient bits, as usual;!...

--
Tony Sayer

  #25  
Old April 30th 05, 03:00 PM posted to uk.tech.digital-tv
DAB sounds worse than FM
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Posts: 929
Default Analogue TV vs DTV Picture Quality -- which is best?

Ben wrote:

Snow and ghosting are not transmitted, so they're reception
issues/problems.


But the picture you get to watch is the one that you receive, not the
one that was transmitted. In the case of digital they are one and the
same, in the case of analogue they can be very different.



Okay then, let's take a more extreme example, and an example that I've
seen you comment on: HDTV. If someone suggested that HDTV had poor
picture quality because their signal was blighted by poor reception,
would you agree that HDTV has poor picture quality, or would you
(correctly) sum up that their problems were due to poor reception, and
in fact HDTV has good picture quality (assumption of appropriate bit
rate levels)?

Take it even further and fast forward to ultra-HDTV with 4,096 lines and
some idiot complained that ultra-HDTV looks crap because they can't get
good reception, yet everybody else is absolutely raving about it. Who is
right? Is it the person unlucky enough to have poor reception, or the
people that are viewing it as it is meant to be seen?


--
Steve - www.digitalradiotech.co.uk - Digital Radio News & Info

Find the cheapest Freeview, DAB & MP3 Player Prices:
http://www.digitalradiotech.co.uk/fr..._receivers.htm
http://www.digitalradiotech.co.uk/da...tal_radios.htm
http://www.digitalradiotech.co.uk/mp...rs_1GB-5GB.htm
http://www.digitalradiotech.co.uk/mp...e_capacity.htm


  #26  
Old April 30th 05, 03:15 PM posted to uk.tech.digital-tv
:::Jerry::::
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Posts: 185
Default Analogue TV vs DTV Picture Quality -- which is best?


"Dr Zoidberg" wrote in message
...
DAB sounds worse than FM wrote:
DAB sounds worse than FM wrote:

snip

I should state that reception problems on analogue should be

ignored,
because they are not problems with picture quality -- they're
reception problems.


But as the majority of analogue viewers don't get "best" reception

they
**do** have static , ghosting etc and are very real factors in

people's
decision.

What's the point in comparing a digital signal that they do get with

an
analogue one that they might in theory get if they lived somehwhere

else


Well said, the problem with Steve is that it's all about theory with
him, he doesn't seem to be able to live in the real world were
reception problems DO colour people decisions about analogue and DTT
reception.


  #27  
Old April 30th 05, 03:26 PM posted to uk.tech.digital-tv
Conor
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Posts: 579
Default Analogue TV vs DTV Picture Quality -- which is best?

In article , DAB sounds worse
than FM says...

I don't actually watch analogue TV at the moment because it would mean
unplugging and re-plugging in aerials, so I only watch DTT. I don't
really have a problem with DTT's picture quality, but my recollection is
that analogue TV's picture quality was always better.

It was and so was analogue satellite.

Easy way to compa

1) On gradual gradient colour changes.
2) When looking at a picture of a fast moving waterfall.

For 1) the analogue signal will produce a nice smooth change of colour.
The digital will show a slightly pixellated one as it has a more
limited colour pallete.
For 2) The analogue signal will show a moving waterfall in perfect
detail. The digital one will show up VERY pixellated and even blocky.


--
Conor

"Of all the things I've lost, I miss my mind the most." O.Osbourne.
  #28  
Old April 30th 05, 03:27 PM posted to uk.tech.digital-tv
Conor
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Posts: 579
Default Analogue TV vs DTV Picture Quality -- which is best?

In article , news says...


Digital

Are you blind?


--
Conor

"Of all the things I've lost, I miss my mind the most." O.Osbourne.
  #29  
Old April 30th 05, 03:39 PM posted to uk.tech.digital-tv
Martin Underwood
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Posts: 46
Default Analogue TV vs DTV Picture Quality -- which is best?

"tony sayer" wrote in message
...
In article ,
Martin Underwood writes
"DAB sounds worse than FM" wrote in message
...
Ben wrote:
Loz wrote:
"DAB sounds worse than FM" wrote in message
...


I should state that reception problems on analogue should be
ignored, because they are not problems with picture quality --
they're reception problems.

This is not a meaningful comparison,


It's not at all, because some people do have good reception.


reception problems like snow and
ghosting are part of the transmission system.


Snow and ghosting are not transmitted, so they're reception
issues/problems.


What you're asking for
is a comparison of what digital actually looks like versus what
analogue would look like if you could bypass the transmission network
and just walk up to the TV studio and plug your telly into a socket
on the wall. Its not real.


Bull****.

Fk this, I cannot be arsed. I asked a simple question, and I receive
answers to different questions.




What a sensible reply

You are asking a question about a very artificial situation: given a
perfect
transmission medium (with no losses, added noise, digital glitches), do
analogue pictures look better than digital pictures or vice versa.

However it's very difficult for people to judge, because the only way they
see analogue or digital pictures is as they receive them - with added
analogue noise and ghosting or with glitches caused by digital dropouts.


Yes quite its like saying product A is better than B because you can run
it off a bit of crap...


I'm not sure what point you're making here. My point is that the verdict of
anyone who says that A is better/worse than B is not able to judge on the
true nature of A and B because both suffer some degradation during the
transmission process: hence the comment by someone earlier in this thread
that to judge purely on the encoding mechanism, you need to go to the
transmitter and plug directly into the analogue and digital signals, to cut
out the broadcast degradation.

I live close enough to a transmitter that I get almost noise-free and
ghosting-free analogue reception and almost glitch-free digital
reception -
so I'm able to give a reasonably accurate answer to the question that you
asked.

One problem remains, however: my TV gives very different colour and
contrast
depending on whether I view digital pictures as RGB or PAL, so I cannot
switch the PAL decoder out of "the equation"


Don't TV do this anyway on RGB, after all why do they remain in circuit
a PAL decoder decodes a composite input?.


I may not have made my point very well. The only way for *me* to compare
analogue and digital is to compare analogue PAL with digital that's been
converted to PAL. My TV unfortunately renders RGB inputs as very high
contrast and very high saturation if correctly adjusted for PAL signals. If
I wind down the contrast and saturation to the point that they are
tolerable, PAL signals are very flat and almsot monochrome. My *perception*
is that when adjusted to give a good RGB picture, the digital/RGB signal is
sharper and crisper than the corresponding analogue picture because it
hasn't been low-pass filtered and doesn't have PAL dot-patterning on
saturated colours (especially reds) or on vertical edges. But it's only a
perception because I don't have a way to alternate between analogue and
digital/RGB to compare them; hence the need to compare analogue and
digital/PAL.

My TV definitely switches the PAL decoder out of circuit when I give it an
RGB input - there's no dot-patterning. When I said "out of the the equation"
I was alluding to the fact that like-for-like comparisons can only be made
on my set between analogue and digital/PAL. If my TV had a way to set the
contrast/saturation for PAL and RGB so they are indistinguishable (apart
from PAL artifacts) I could make a true comparison.


This blockiness is not an inherent failure of the digital process as such,
just an artifact caused by too low a bit rate. The clipping of highlights
probably *is* inherent in the digital process and would not be cured
purely
by increasing the bit rate. Instead it's a problem with the encoding: the
A-to-D converter has its white point set too low when should be set so
that
255 represents the very brightest (highest voltage) that an analogue
signal
can ever attain.


Don't they do this anyway;?...


My perception is that there's more clipping of highlights on digital/PAL
than with analogue - but suppose it could be due to a non-linear response
in the digital box's PAL encoder.


  #30  
Old April 30th 05, 03:47 PM posted to uk.tech.digital-tv
Ben
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Posts: 774
Default Analogue TV vs DTV Picture Quality -- which is best?

DAB sounds worse than FM wrote:
Snow and ghosting are not transmitted, so they're reception
issues/problems.


But the picture you get to watch is the one that you receive, not the
one that was transmitted. In the case of digital they are one and the
same, in the case of analogue they can be very different.




Okay then, let's take a more extreme example, and an example that I've
seen you comment on: HDTV. If someone suggested that HDTV had poor
picture quality because their signal was blighted by poor reception,
would you agree that HDTV has poor picture quality, or would you
(correctly) sum up that their problems were due to poor reception, and
in fact HDTV has good picture quality (assumption of appropriate bit
rate levels)?

Take it even further and fast forward to ultra-HDTV with 4,096 lines and
some idiot complained that ultra-HDTV looks crap because they can't get
good reception, yet everybody else is absolutely raving about it. Who is
right? Is it the person unlucky enough to have poor reception, or the
people that are viewing it as it is meant to be seen?


The difference here is that due to the level of forward error correction
used, digital TV is an all-or-nothing medium. You get exactly what was
transmitted or you get nothing (or nothing usable anyway). If analogue
TV used frequency modulation you'd get a similar effect due to the noise
rejection characteristics of FM receivers but it doesn't, it uses
amplitude modulation, so nomatter how good your signal is you'll never
receive exactly what was transmitted. Characteristics of the propagation
channel are part of the system and there's no getting away from it.
 




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