1080i tv res question

skysnapper · 22 Feb 2006 at 14:32

What is the native resoution for this?

Im looking into getting a 42inc plasma/lcd/dlp

I pretty new to this hdtv stuff and Getting a bit confused as what res is need to display 1080i properly

i have seen mentioned in threads displays with a 1366 x 768 res can display 1080i it but i was kind of under the impression that you would need a res of 1920 x 1080

Surely if it was not doing a 1:1 pixel per pixel the picture wouldn't look as sharp.

However this planels that display 1920 x 1080 appear to be very rare or extremely expesive.

or is 1366 x 768 sufficient and anything higher would only be any benefit if you were plugging in a pc :confused:

Bomag · 22 Feb 2006 at 19:38

1080i is interlaced and therefore only displays 540 lines per field. A standard 1366*768 HDTV plays 1080i without any problems. Also as there is no 1080p TV standard the few TVs whcih do have 1920*1080 screens down convert 1080p PC input to 1080i and then back to 1080p

Raider · 22 Feb 2006 at 21:47

Proper 1080p LCDs and Plasmas are only just about to be released in Japan. It'll be Summer at least before they appear here. No rush really since the only thing that will output at 1080p in the next 6 months will be the ultra top-of-the-line Blu-Ray players. Most Blu-Ray players, and I believe all initial HD-DVD players will only output at 720p.

A PC monitor with 1920x1080 res doesn't equal 1080p automatically!

So no need to worry for at least a year.

Sclodion · 22 Feb 2006 at 21:54

if you purchase a display with a native 1920 x 1080 (or 1920 x 1200) display that can be driven via DVI, it is capable of displaying a 1080p signal (but only through the DVI or VGA input) - the tuner will not be capable of decoding a 1080p source.

This means that if you used an external decoder, you could potentially recieve 1080p should it ever be broadcast. or an HD DVD player, but you have the HHCP content protection issue to deal with.

The price of 1080 native screens is very expensive as you've noticed, even in the US wher ethey have content to drive sales, they are still an expensive proposition.

But the price will come down with sales volumes and the LCD glass makers will get better and therefore cheaper at producing the displays.

Bomaq - a native 1080 screen with a VGA or DVI input will not convert a pc input to interlaced.
Also if 720p was broadcast, it would be decoded by the tuner as a progressive signal, not an interlaced one.

Bomag · 22 Feb 2006 at 22:19

Sclodion

Unless they have suddenly changed the design of all the existing 1080 HD TVs since Christmas none (or at least those less than £3k) will accept a 1080p PC signal via DVI or via vga without down converting to 1080i.

Hi res PC monitors such the Dell 2405/2407/3007 don't have this problem, but then they are not TVs

Sclodion · 22 Feb 2006 at 22:30

Bomag said:
Sclodion

Unless they have suddenly changed the design of all the existing 1080 HD TVs since Christmas none (or at least those less than £3k) will accept a 1080p PC signal via DVI or via vga without down converting to 1080i.

Hi res PC monitors such the Dell 2405/2407/3007 don't have this problem, but then they are not TVs

I'm not going to disagree with you, maybe i've never seen / used one at less than the price point that you specify, but to me, a native 1080 screen will support 1920 x 1080 or 1920 x 1200 native progressive input with 1:1 pixel mapping.

The only thing that should define the set as capable of supporting interlaced format is the tuner. I don't believe i've ever seen an LCD glass at any resolution thats not capable of being driven progressive as well as interlaced.

Bomag · 22 Feb 2006 at 22:48

I am not saying the LCD panels are not progressive themselves but that the scaling hardware of HD TVs is not capable of transfering a 1080p signal to the panel without down coverting it. Once somebody agrees a 1080p TV standard then will start to be supported. I presume this is one of the reasons 1080p support is apparently missing from first gen HD-DVD/Blueray players.

Also I don't think that running PCs with HD TVs is high on the priority of TV makers. As far as I am aware only LG and Hitachi give full screen 1:1 mapping via DVI. Most others either only accept 720p which is upscaled or 4:3 ratio 1024*768 at 1:1

Sclodion · 22 Feb 2006 at 23:09

1080p is a SMPTE defined HD format. the reason it is not implemented is one of bandwidth.

It would take substantially more bitrate to broadcast 1080p than 1080i (nigh on double per frame). The ATSC decided to standardise on 1080i to manage the bandwidth issues. As such no tuners are manufactured to recieve 1080p as its not likely to be broadcast. (at least not in MPEG2, things may change with the bit rate savings made moving to mpeg4 avc or WM9 HD as the broadcast format)

However 1080p will be possible from DVD players via DVI with HDCP or HDMI should the manufacturers choose to do so. (its possible from PCs now on the DVI / VGA input, but the HD content protection will prevent this being used for displaying native HD content from DVD until HDCP enabled gfx cards are released)

Also a true 1080 res screen has no scaling when displaying either 1080i or 1080p content. deinterlacing and displaying an image encoded as interlaced on a progressive output is not the same as scaling (image resize).

As a consumer, anything that is not 1:1 pixel capable 1920 x 1080 is not a native 1080 HD display, its only an HD capable display.