[opendtv] Re: source programme quality
- From: "Barry Wilkins" <barry.barrywilkins@xxxxxxxxx>
- To: opendtv@xxxxxxxxxxxxx
- Date: Mon, 28 Apr 2008 17:01:45 +1200
Yes, I am surprised also. 576i is 576i but nevertheless my screen has a good
scaling engine (so I am told) and I use the "pixel plus" technology of the
screen to further enhance the image.(I can turn this on or off) It enhances
edge detail and gives a perception of better resolution.
I looked carefully at various scenes from the continuously running wildlife
HD demo program running on Freeview HD and compared between screens. I
looked for motion artifacts, and general clarity/ detail. Colour depth was
not something I was concerned about yet I always see better colour balance
on my set up because of the tendency of shop displays to be set with over
saturated colour for "effect".
As I mentioned, I am expecting to be further impressed if I see a high end
screen operating directly on HDMI but in the shops where these screens exist
they run a common switched line to all screens via component or composite
hence if the source were the FreeviewHD STB then the common feed will only
be 576i (they do not loop through the HDMI). The only screen I confirmed
that was connected directly to the HDMI STB output gave the inferior image
to my screen.
Also, I should mention, the STB will allow you to set the output on HDMI to
either 720p or 1080i or "auto". Component is permanently 576i. Incidentally,
the Singapore version of this same STB has different firmware that enables
the component outputs at full HD 720p/1080i. Our version gets nobbled!
Enterprising fellows have installed the singapore version of firmware here
and enabled the HD on component but found the EPG does not function
correctly then.
Barry Wilkins
On Mon, Apr 28, 2008 at 1:25 PM, Tom Barry <trbarry@xxxxxxxxxxx> wrote:
> I am actually surprised by this. It does seem true that a good DVD at
> 480p can have as much detail as bad 1080i or 720p HD, though decent HD also
> exists, at least for slow moving scenes.
>
> But when you add the interlace factor of 576i I'm surprised the difference
> is not fairly obvious. Something seems wrong here and HD (sans low bit-rate
> artifacts) should seem obviously better than 576i.
>
> - Tom
>
>
>
> Manfredi, Albert E wrote:
>
> > Barry Wilkins wrote:
> >
> > The situation here to start with is that we have a mix of SD
> > > at 576i, HD at 720p and HD at 1080i source content. This is
> > > all transmitted as either 720p or 1080i via upscalers where
> > > needed.
> > >
> >
> > Hi Barry. Here are my observations as a viewer (not a broadcaster):
> >
> > My new LG TV tells me in what mode a broadcast is being transmitted.
> > Assuming it is correct, all of our programs here are *not* upconverted,
> > as yours appear to be.
> >
> > Typically, but not always, the -1 subchannel of each multiplex is
> > transmitted as 720p or as 1080i, and the program content may be HD or
> > upconverted SD. The other subchannels are typically transmitted as 480i.
> > It appears to be that when SD content is upconverted, it is transmitted
> > as 4:3 rather than 16:9, just judging from the detail in the image. It
> > seems that all true HD content is 16:9. (One of our local stations
> > transmits five 480i multicasts only, nothing upconverted.)
> >
> > Some supposedly SD source material can look exceedingly
> > > good, i.e. better than my best looking PAL SD dvd from my
> > > collection.
> > >
> >
> > Certainly has been my experience here as well. And some SD looks very
> > similar to analog TV broadcast, minus the ghost. It's strikingly bad
> > compared to other SD material.
> >
> > The HD source material at 1080i, i.e. Boston Legal for
> > > instance, is extraordinarily good imagery. So is some
> > > Aussie HD content.
> > >
> > > To complicate this issue is the fact that my screen is
> > > only 1024 x 1024 42" with no HDMI. I use the component
> > > inputs from the STB which down scales the image to 576i.
> > > Nevertheless, I can clearly differentiate between the
> > > better image quality on my screen and that of a 42" LCD
> > > connected directly via HDMI to the same type of STB
> > > running the same demo HD programme content.
> > >
> > > What I am getting at here is that in 3 weeks of looking,
> > > I have not been able to find a demonstration of HD
> > > source material received on a STB connected via HDMI to
> > > a 1080 x 1920 resolution LCD/plasma screen that improves
> > > over what I am seeing.(And I am delighted in what I see).
> > > If and when I do see a significant difference from a
> > > better screen set-up I shall be "over the moon" knowing I
> > > can make a difference by upgrading the screen later..
> > >
> >
> > I believe it. Your LCD panel should be more than adequate. If I
> > understand what you're comparing, you have determined that OTA HDTV, via
> > HDMI, on a 1024p panel is about as good as OTA HDTV on a 1080p panel.
> >
> > First off, tests in the past have shown that 720p and 1080i are roughly
> > comparable in quality. So, if you find that converting either of these
> > to 1024p (1.05 Mpel) gives results similar to converting to 1080p, I
> > wouldn't be a bit surprised. IMO, if there's any reason to go up to 1920
> > X 1080 in a 42" display, it would be to view BluRay disks, from a 1080p
> > player, up close. For broadcast TV, shouldn't provide any meaningful
> > improvement.
> >
> > There is a small difference, though, that I have noticed. In comparing
> > 1366 X 768 (also 1.05 Mpels) to 1080p panels from the same manufacturer,
> > and standing close in, concentrating on brightly lit parts of the scene,
> > the 1080p screen looks smoother. In the 768p screen, standing close, you
> > can see individual pixels more readily. I pointed this out to my wife,
> > and she noticed it too. But at normal seating distance, with the 42"
> > panel, the individual pixels disappear. Exactly as the math says they
> > should.
> >
> > Also, what HD I see is easily better than the quality of
> > > image viewed at any of the local cinemas. So what has
> > > been the general impression of the image quality of the
> > > best ATSC content. Are you all very impressed? How close
> > > does it get to Blue Ray quality at 1080i? What screen
> > > resolutions are you viewing this on?
> > >
> >
> > I've been impressed ever since first seeing HD in stores. Most people
> > are, as far as I can tell. Most comments I've seen are that live sports
> > are especially impressive as HD.
> >
> > Bottom line: I always take negative comments from habitual critics with
> > a huge grain of salt.
> >
> > Unrelated example: last night, we went to see "88 Minutes," with Al
> > Pacino. It got some pretty bad reviews, but we went in spite of these.
> > Well, it was a great movie. Plenty of suspense, perfectly fine acting. I
> > have no idea what drug those moron critics were on, but no doubt they
> > will dissuade many people from going to see it. Their loss.
> >
> > Bert
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> >
> --
> Tom Barry trbarry@xxxxxxxxxxx
>
>
>
>
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