BBC HD critised in The Independent

In message , "Dave Plowman (News)"
wrote

Surely it's one of the most basic of production techniques to make sure
other parts of the picture don't detract from the important part? Usually
done by the correct choice of lens and exposure to give the required depth
of field. And of course avoiding having distracting things happening in
the background. But is the same in principle no matter what the medium.


But shouldn't this be done by the director and cameraman at the time of
shooting the scene and not by some accountant trying to force more
channels into the limited bandwidth which requires at post production
higher compression and/or heavy low pass filtering?

The discussion here appears to be that the BBC are claiming the new
encoders produce a "better" picture because the background becomes
de-focused - but only as a result of the new encoders and a reduction in
transmission bit rates.

--
Alan
news2009 {at} admac {dot} myzen {dot} co {dot} uk

On Sat, 12 Dec 2009 11:41:35 +0000, Kay Robinson
wrote:

full HD being 1290x1080

1920x1080

Ken wrote:
On Sat, 12 Dec 2009 11:41:35 +0000, Kay Robinson
wrote:

full HD being 1290x1080

1920x1080


I assumed it was a typo.

--
Adrian

At 11:07:40 Sat, 12 Dec 2009, Roderick Stewart wrote in article
en.co.uk:
In article , John Legon wrote:
I may be completely wrong, but isn't the notion of "picture depth"
associated with contrast and richness of colour? If an image lacks
contrast then people say it looks "flat". Conversely, high contrast
images have "depth". HD is not simply about sharpness...

HD is just television with more lines. Signal levels and colorimetry
are just the same as they always were, and vision control (when they
bother with it at all nowadays) is done in exactly the same way.

So there's no increase in "dynamic range" with HD?

One obvious flaw with SD as often broadcast is the compression which
affects the number of colours that can be displayed. Typically, the
continuously varying hues of a blue sky appear step-wise as a finite
number of different shades, with distinct boundaries.

When Danielle Nagler said "HD is not simply about sharpness, it is about
picture depth" I assumed she meant maintaining the contrast and colour
range, which might be said to give "picture depth" while have nothing to
do with picture sharpness. Throwing backgrounds out of focus by reducing
the depth of field is surely not what she had in mind?

--
John Legon

John Legon wrote:

So there's no increase in "dynamic range" with HD?

One obvious flaw with SD as often broadcast is the compression which
affects the number of colours that can be displayed. Typically, the
continuously varying hues of a blue sky appear step-wise as a finite
number of different shades, with distinct boundaries.


Someone correct me if I have this wrong but surely that's a standard
JPEG-style artefact caused by lack of bandwidth - the codec can't send
all the detail, so reckons that as this block is nearly the same colour
all over, that'll do.

Andy

"Andy Champ" wrote in message
. uk...
John Legon wrote:

So there's no increase in "dynamic range" with HD?

One obvious flaw with SD as often broadcast is the compression which
affects the number of colours that can be displayed. Typically, the
continuously varying hues of a blue sky appear step-wise as a finite
number of different shades, with distinct boundaries.


Someone correct me if I have this wrong but surely that's a standard
JPEG-style artefact caused by lack of bandwidth - the codec can't send all
the detail, so reckons that as this block is nearly the same colour all
over, that'll do.

Andy

That is exactly what I perceive on BBC HD broadcasts now - large blocks of
colour look 'fuzzy' / blocky.
BBC say the new encoders are 'revealing new detail', but for any of us who
have encoded video into MPEG4 or H264, it looks to me like any video encoded
with too low a bitrate - large blocks of one colour are the first thing that
the encoder thinks it can save some bandwidth on.
Ms Nackers comparison with MP3 reminds me that MP3 encoders are based on
'Psycho-acoustics', or removing audio that you don't notice. But bitrate
still makes a big difference.
I wonder what the video encoder sales reps call it - psycho-vision? Sounds
about right.

In article , Kay Robinson wrote:
[...]
If I recall correctly it was
Eastman-Kodak that estimated that to create a digital image equal to
25ASA you would need a camera capable of around 400 megapixels. We're
a long way off at present but will eventually get there (it can be
done now but the size of the camera and the cost would run in £m).

That might be true, but it would be pointless because it would be
recording vastly more detail than anyone would see in a typical viewing
situation. Film happens to record excess information because of the way
it works and there has never been any extra cost in doing so. However,
if you need to record and broadcast a signal electronically, extra
information requires extra transmission bandwidth and extra storage
capacity, and this has a price. Broadcast television pictures are
designed to be viewed at a particular distance from the screen, at
which the line structure is just beyond the limit of visual acuity, so
there is no point wasting money recording and broadcasting detail which
will not be seen.
[...]

I recall watching a BBC documentary in which it was said that to get
the best full HD it was neccessary to use film and convert to digital
at the required definition.
[...]

It certainly seems to be the case that better fine detail is captured
by photographing at a higher resolution than the final version will
need, and then downconverting. SD produced from an HD camera usually
looks better than from an SD camera, and you can confirm this by doing
your own experiments with digital stills cameras of various
resolutions. Maybe to get really good HD, we need to design a camera
which has greater resolution than HD and then downconvert it
afterwards. Using film would be one way of doing this, but not the only
possible one.

Rod.
--
Virtual Access V6.3 free usenet/email software from
http://sourceforge.net/projects/virtual-access/

A lot of what is said here is above my head.
Now what is simple to me is we all agree was BBC HD was ok now it not.

What I can't understand is the BBC thinking the opposite. They seem to be
telling me the Emperor has got a new suit of clothes on, when he hasn't!
They truly believe this HD transmission is very good.

Regards
David

In article , David
wrote:
A lot of what is said here is above my head. Now what is simple to me is
we all agree was BBC HD was ok now it not.

What I can't understand is the BBC thinking the opposite. They seem to
be telling me the Emperor has got a new suit of clothes on, when he
hasn't! They truly believe this HD transmission is very good.

some 30 years ago, I had to go and see the head of Ceefax about his
reception. His BBC2 pictures were so noisy, I couldn't bear to watxch
them. "That's not a very good picture" I remarked. "I wouldn't know, I'm
only a journalist" he replied. He obviously never noticed the pictures in
the studios where he worked.
(and he had been "science correspondent" in his previous job - I assume
because he could pronounce long words correctly ;-)

--
From KT24

Using a RISC OS computer running v5.11

David wrote:
A lot of what is said here is above my head.
Now what is simple to me is we all agree was BBC HD was ok now it not.

What I can't understand is the BBC thinking the opposite. They seem to
be telling me the Emperor has got a new suit of clothes on, when he
hasn't! They truly believe this HD transmission is very good.

Actually David, I quite like your suggestion you posted in uk.tech.tv.sky, in
response to someone quoting this article:-

http://news.sky.com/skynews/Home/UK-...15497982?f=rss

Of course Sky have spun the issue to their benefit, and even perhaps imply
that BBC HD looks better via them, than Freesat, which of course is nonsense,
because it's exactly the same signal.

However, as you suggested,it might be worth complaining to Sky about the
quality of BBC HD. Sky do have performance and quality criteria that have to
be met before a channel is allowed on their platform. They certainly won't
want what are perceived as 'damaged goods' as part of their service. It would
be interesting if they received enough complaints, and/or there's any more
'bad press' over BBC HD, so see if they'd remove the service from the EPG. (I
think that's unlikely, but it would certainly give the Beeb a poke in the eye).


--
Mark
Please replace invalid and invalid with gmx and net to reply.

www.paras.org.uk