720p better than 1080i?

[higgsfield]

Originally Posted by shawty

What I was trying to say is that 1080i should only be relevant if you have a TV with 1980 x 1080 as it will take the 1080i image and upscale it to 1080p (the native resolution of a 1980 x 1080 TV)

Am I correct in therefore concluding the following:-

When "upscaling" 1080i to 1080p, each 1080p frame is assembled from the two interlaced 1080i (540 lines) frames. In the UK, these frames arrive at 50Hz. It is therefore equivalent to 1080p at a frame rate of 25Hz (because it takes 2 1080i frames to construct a 1080p frame).

[SMHarman]

Originally Posted by higgsfield

Am I correct in therefore concluding the following:-

When "upscaling" 1080i to 1080p, each 1080p frame is assembled from the two interlaced 1080i (540 lines) frames. In the UK, these frames arrive at 50Hz. It is therefore equivalent to 1080p at a frame rate of 25Hz (because it takes 2 1080i frames to construct a 1080p frame).

Yes, this comes back to the bandwidth issue, to send more data as you would in 1080p you need more bandwith. An alternative is to send that data half as often, 1080i.

1080p=1980*1080=2138400 pixels per refresh
1080i=1980*520=1029600 pixels per refresh
720p=1280*720= 921600 pixels per refresh
1080i and 720p are very close in their data requirements per frame.

[frattonstation]

well my 1080 37" Samsung picture looked exactly the same when I tried swapping between 1080 & 720.

[higgsfield]

I tried the same. Perhaps there really is little between the two.

SMHarman's post (above) maybe explains the main reason. They are close to equivalent, so the quality of the signal processing in your particular setup will determine which looks best on a case-by-case basis.

In the end, I chose to stick with 1080i, because my screen is 1080, assuming that less DSP will be required to process it.

[Matt D]

Originally Posted by higgsfield

According to that first link, the data rate is higher in the 720p signal as all lines are refreshed every time (e.g. 50k times per second in the UK), whereas the 1080i scheme only refreshes 540 lines each time.

Well, I did say "I may be talking rubbish, lol"

Originally Posted by hokkers999

That's the nub of the problem there and the reason why I say that HD is marketing hype at the moment. There are no end of possibilities for rescaling and in all of the scenarios you have all talked about it happens at LEAST once....

Either the STB does it or your telly does or they both do

When the broadcast is 1080p and the telly is native 1080p then you will have "true" HD broadcasting.

Wake me up when that happens and I'll plonk down my £300 at Dixons for the 75" mega duper whatever

Yup, at the moment, there's always going to be some scaling going on at at least one end.

Unless of course you have a 1080p TV & a Blu-ray / HD DVD player. Super-duper 1080p source, plus higher bitrate than broadcast as well as higher resolution...mmmmmmmmm.....

[Ah, dreams of having a big lounge & a nice big 24fps capable 1080p Samsung or Toshiba... one day hopefully...]

Originally Posted by shawty

Im not arguing about bandwidth, Im arguing about resolutuions. 720p 'should' look better for V+ on TV's with resolutions of 1280 x 720 and 1366 x 768 as if you put it in 1080i, it would need to downscale it. What I was trying to say is that 1080i should only be relevant if you have a TV with 1980 x 1080 as it will take the 1080i image and upscale it to 1080p (the native resolution of a 1980 x 1080 TV)

Wether this works in the real word is a different matter as seen by people on this thread.

And if you put it in 720p, then the STB is downscaling it (plus also the TV then scaling back up slightly, assuming it's 1366*768).

Either setting, *something* is always going to be scaling, TV or STB.


So yeah, real world... which bit of equipment has the better scaling... and of course, the most important, what do *you* think looks best.

Originally Posted by higgsfield

I can understand the irritation, and it may not be optimal - but HD on the V+ looks better than any picture I have seen at home. Later on this year I will invest in a BluRay player - it will be interesting to see whether the true 1080p is a noticeable improvement on the 1080i.

To me, Blu-ray Discs (PS3) & HD DVDs (X360 add-on drive) do look better than broadcast HD via SkyHD, & that's just on my normal 1366*768 HD Ready TV.

I know a couple of people with 1080p sets, capable of 24fps (1080p24), & they find BDs via their PS3s (one of the best BD players available) to be absolutely jaw-droppingly gorgeous.

BDs / HD DVDs don't just have a much better resolution than 1080i broadcast HD, they also have the benefit of a higher bitrate (and, compared to V+, a superior codec).

[SILVER SURFER]

I read the original post thinking I'd get a definitive answer to 720p/1080i-which is best? But all I got was a headache and the belief that there isn't one. I have a 26" panasonic and, whilst not full hd, sitting 8-10ft away I can definitely see a marked difference between sd/hd but hd itself looks exactly the same whether set at 720/1080.
Now where's those asprins!

[Toto]

Originally Posted by SILVER SURFER

I read the original post thinking I'd get a definitive answer to 720p/1080i-which is best? But all I got was a headache and the belief that there isn't one. I have a 26" panasonic and, whilst not full hd, sitting 8-10ft away I can definitely see a marked difference between sd/hd but hd itself looks exactly the same whether set at 720/1080.
Now where's those asprins!

Set your V+ Output to 720 then, dead simple.

[SILVER SURFER]

Yes that's what I had it set at before the 1080i supporters put some doubt in my mind.
Thanks

[higgsfield]

If your TV is not full HD, you'll get some picture degradation with 1080 resolutions as the TV will have to downscale. If you couple that with the fact that the 1080 out of the V+ box is only interlaced, you are far better off with the progressive scanned 720p format in this instance.

That said, if you can't tell the difference, it doesn't really matter, does it?!

[SILVER SURFER]

True. Thanks anyway.

[Hugh Sawyer]

If it helps, the shop that sold me a Pioneer 50" PDP 508xd, advised me to use 720p; that seems fine.
What I myself would like to know is, why does the V+ Settings menu say (in the field 'V+Box HiDef output') - "Undefined" ? There is no option to change to 720 or 1080 - not that it seems to matter, as the HD quality is quite good.
Perhaps there is a Virgin expert engineer out there, who can solve this curious situation?

[kirk1690]

Originally Posted by Matt D

I think you have misunderstood the article.



Key word: Broadcasting.

They are not saying that you should set your box to 720p instead of 1080i, they are saying that 720p is a better format for broadcast than 1080i.

Although it's a bit late for them to be deciding this, seeing as all HD broadcasts are currently 1080i...








SkyHD, BBC HD, C4 HD = 1080i, not 720p, & certainly not 1080p.



One argument for setting your box to 1080i, even if your TV is native 720p:

The HD content itself is 1080i. If you set the STB to 1080i, it does not have to do any scaling, & simply outputs the original 1080i to the TV, which the TV then downscales & deinterlaces to its native 720p (well, more likely 768p) resolution.

This should be better than having the STB set to 720p. As, if set to 720p, the STB has to downscale & deinterlace the 1080i source to 720p, only for the TV to then have to scale it back up slightly to 1366*768 (the most common HD Ready resolution).


Although of course it depends on which is best at scaling - your STB, or your TV.


I find having my SkyHD set to 1080i to be better on my particular Sammy TV. Others will find different.

---------- Post added at 21:56 ---------- Previous post was at 21:52 ----------




Indeed.


The box may be better at scaling than the TV, or vice versa.

e.g. perhaps


Box better at scaling: set the box to the TV's optimal resolution, letting the box handle the scaling.

TV better at scaling: set the box to the source's resolution, & let the TV do the scaling.

JUST WATCH THE BLOODY PROGRAMMES !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!

[march.brown]

Originally Posted by SMHarman

But it depends on the ability of the TV and other devices to up and downscale.
576i upscaled to 1080i and downscaled to 720p may look better than
576i straight to 720p depending on the hardware involved.

Simple answer is ''Try both 720 and 1080 and pick the better'', using the HDMI output on the V+.

To see the differences , view from four or five feet using channel 108 (BBC HD) ... Check also that the EPG is clear enough to read easily on both ... Mine is a better picture on 1080 but a slightly less clear EPG ... Since I prefer the better picture , I choose the 1080 ... I simply let my eyes be the judge at a close distance of about four feet ... I then watch TV at my normal distance of eleven feet.

I realise that at eleven feet you can't tell the difference between 720 and 1080 , but at close distance the 1080 wins on my particular set-up ... If you can't see any difference in the picture , pick the better EPG quality ... You don't really have to get technical to pick the better one.

Obviously the settings on the TV make a big difference , but I assume everyone has already adjusted the Brightness , Contrast , Colour , Hue , Backlight , Sharpness , etc to suit their own viewing conditions.

Techies may have their own methods , but for Mr or Mrs average , just trust your eyes and pick the better picture.
.

[multiskilled]

Originally Posted by march.brown

Simple answer is ''Try both 720 and 1080 and pick the better'', using the HDMI output on the V+.

To see the differences , view from four or five feet using channel 108 (BBC HD) ... Check also that the EPG is clear enough to read easily on both ... Mine is a better picture on 1080 but a slightly less clear EPG ... Since I prefer the better picture , I choose the 1080 ... I simply let my eyes be the judge at a close distance of about four feet ... I then watch TV at my normal distance of eleven feet.

I realise that at eleven feet you can't tell the difference between 720 and 1080 , but at close distance the 1080 wins on my particular set-up ... If you can't see any difference in the picture , pick the better EPG quality ... You don't really have to get technical to pick the better one.

Obviously the settings on the TV make a big difference , but I assume everyone has already adjusted the Brightness , Contrast , Colour , Hue , Backlight , Sharpness , etc to suit their own viewing conditions.

Techies may have their own methods , but for Mr or Mrs average , just trust your eyes and pick the better picture.
.

Exactly! Your the one watching it, choose the one you think is better, not the one that somebody else who doesn't watch it, thinks is better.

[march.brown]

Does it matter about 720 and 1080 after Saturday ?

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