Two types of High Definition?

On 04/07/2006, John Russell wrote in message [email protected]
2.news.uk.tiscali.com:

MPEG4, the HD compression used, is similar to MPEG2 used to compress
standard broadcasts. It is not an absolute, it allows different
bitrates/quality levels to be used.

Agreed, but you missed out a key point: MPEG4 is inherently a far better,
faster, more efficient, better-looking method of compression. Also, it
scales to different size displays far better than MPEG2.

Simon.
--
http://www.hearsay.demon.co.uk

On 06/07/2006, Matt Overton wrote in message
:

Any idea why Sky are using 1080i for movies? Seems rather pointless.

You object to the increased spatial resolution?

Considering other HD countries seem to use both formats for best
results, it seems odd that we're going down the just 1080i route,

Nobody said we are. The two companies which are currently making test
transmissions are each performing tests that appeal to them right now.

Simon.
--
http://www.hearsay.demon.co.uk

You wouldn't see any difference between the two.

Matt Overton wrote:
Any idea why Sky are using 1080i for movies? Seems rather pointless.
You object to the increased spatial resolution?

Considering other HD countries seem to use both formats for best results, it
seems odd that we're going down the just 1080i route, especially as ISTR
there's a bandwidth saving (and it's not like satellite channels to be
generous with bandwidth)
Now if they actually bothered with 1080p, that'd be worth while!

Wdino wrote:
Matt Overton wrote:
Considering other HD countries seem to use both formats for best
results, it seems odd that we're going down the just 1080i route,
especially as ISTR there's a bandwidth saving (and it's not like
satellite channels to be generous with bandwidth)
Now if they actually bothered with 1080p, that'd be worth while!

You wouldn't see any difference between the two.

Why not?

Exactly the same information is provided with i as for p in all formats.
The only difference is that i does it using alternate fields. All modern
TV sets integrate that information so that it is displayed in the same
form as p anyway.
Most people would not notice the only artifacts that can be present, in
the rapidly changing parts of the picture. For most scenes this is
blurred anyway.

Pyriform wrote:
Wdino wrote:
Matt Overton wrote:
Considering other HD countries seem to use both formats for best
results, it seems odd that we're going down the just 1080i route,
especially as ISTR there's a bandwidth saving (and it's not like
satellite channels to be generous with bandwidth)
Now if they actually bothered with 1080p, that'd be worth while!

You wouldn't see any difference between the two.

Why not?

Wdino wrote:
Exactly the same information is provided with i as for p in all
formats. The only difference is that i does it using alternate
fields. All modern TV sets integrate that information so that it is
displayed in the same form as p anyway.

There's the rub. Deinterlacing requires inventing data that was not present
in the source - immediately falsifying your assertion that the same
information is provided in both cases. This is a non-trivial process, and is
always going to be worse than having the real information to display.
Whether people will see the difference will depend on the sophistication of
the deinterlacer and on the type of source material being viewed, but you
cannot reasonably claim that there will never be any difference!