DVD resolution?? Need clarification

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Batman

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Topic # 12821 7-Apr-2007 20:58

Hi ya all!
Got some questions, where i'm trying to get the best out of conventional dvds.

1) Are ALL DVDs (the 16:9 ones) in 852x480 resolution? Why is it that for example King Kong DVD is larger (8gig) and looks better than say Pearl Harbour (4gig)?

2) Assuming that my suspicion is true (well if it isnt then this question naturally wont apply), that some DVDs have a better resolution, how do i get it to play that better resolution on my HD capable LCD? I have thought about buying a DVI (computer out) to HDMI (LCDTV in) and making the DVD play off the computer and watched on tele on HD signal (apparently my video card can send HD signal)? I dont want to spend $30 dollars and find that it wont give me better picture.
Thanks!!

sbiddle

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Reply # 66560 7-Apr-2007 21:28

All DVD's are the same resolution, there is no way to get true HD (minimum 720 lines resolution) from a standard DVD - that's why we now have HD-DVD and Blu-Ray.

How do you have your DVD player hooked up to your TV? If you have a new(er) DVD player it can upscale the DVD to a higher resolution which can make it look a lot better. Typically you can upscale to 625p, 720p and 1080p if you've got a very new DVD player. You'll obviously need to be using a component or HDMI cable to do this.

As to the differences between DVD's it just gets down to the level of compression used. Many try and fit lots of extra things on a single disc and compress the movie to do so.

Spyware

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Reply # 66575 8-Apr-2007 11:00

720 x 480 (NTSC) or 720 x 576 (PAL). Investigate buying a DVD player that can output 576p (rather than 576i) or upscale to 720p or 1080i. See http://en.wikipedia.org/wiki/DVD or http://www.dvddemystified.com/dvdfaq.html.

Ross

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cyril7

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Reply # 66576 8-Apr-2007 11:05

All PAL (ie 50Hz region) discs are 720x576. 16:9 discs are normally encoded anamophically, therefore are still 720x576. A anamorphic image, if displayed on a 16:9 display still has the resolution source of 720x576 but comprises rectangular rather than square pixels.

The figure you mentioned is a typical NTSC derived panel size of 852x480, this comes about from the fact that NTSC discs are 720x480, thus to retain vertical resolution plasma panel manufacturers settled on 852x480 as a panel format. Due to the US market size SD plasma panels of this resolution are also the norm in 50Hz (Pal) regions.

Cyril

stevenz

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Reply # 66586 8-Apr-2007 14:01

As for the difference in movie sizes, King Kong is done the way DVDs _should_ be. The first disk having _just_ the movie on it, and nothing else, with the highest possible encoding bitrate. This means that the movie looks as good as it can with the minimum of encoding artifacts. DVDs which are full of extras sacrifice this space and result in a lower quality for the main movie. As a result, King Kong looks fantastic, pity it's still boring as sin apart from a couple of 1-minute segments...

All video data for DVDs is either 720x576 or 720x480 for PAL or NTSC respectively. The black borders in movies beyond 16:9 (2.35:1 etc) are part of the image, so total resolution remains unchanged.

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Reply # 66592 8-Apr-2007 15:01

hey guys thanks heaps!!!

now here's another questions following all your clarification: what "resolution" is my sony progressive scan (via component output of course) DVD player giving me on my tv?

cyril7

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Reply # 66598 8-Apr-2007 17:04

720x576, nothing more, maybe less depending on what filtering was deployed in the player and in the encoder. Even if it were a upscaling player and outputing 1080i the disc will have been recorded at 720x576 so the viewable resolution will remain the same. The upscaling process would need to increase the pixel frame to 1920x1080, however the end result will still be 720x576, infact slightly less as the upscaling process requires an interpolation filter is applied that normally will reduce the resolution by a small amount.

DVD as with DVB specifies a quite large number of resolutions, the maximum for SD DVD/DVB is 720x576 (or 720x480 for NTSC) so you could be viewing discs that are encoded at lower resolutions. However I have never seen any PAL DVD's that have been encoded less than 720x576.

Cyril

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Reply # 66696 10-Apr-2007 09:58

Spyware: 720 x 480 (NTSC) or 720 x 576 (PAL). Investigate buying a DVD player that can output 576p (rather than 576i) or upscale to 720p or 1080i. See http://en.wikipedia.org/wiki/DVD or http://www.dvddemystified.com/dvdfaq.html.

Correct me if I'm wrong, but the only advantage to having a progressive scan DVD player is to enable reverse 3:2 pulldown on NTSC discs? What improvement would progressive scan (ie 576p25 as opposed to 576i50) make to DVD PAL feature films?

cyril7

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Reply # 66699 10-Apr-2007 10:19

Tom has a point, there is no advantage to PAL replay at 576p, this is why there were no progressive pal players for a long time. There is a distinct and definite advantage to having NTSC DVD's of film material progressively replayed from the DVD player in an attempt to correctly reconstruct the 3:2pulldown process.

Upscaling players have little advantage also, in my view. Unless you have a 1080 native display then all you are doing is putting the image through an unessesary and often damaging scaling process. Better of to feed the display with 576i and let it do a one of scale to its native resolution rather than have it go 576>1080>displaysize as each rescale introduces its own filtering and image artifacts.

Cyril

TomAckroyd

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Reply # 66708 10-Apr-2007 11:12

cyril7: Tom has a point, there is no advantage to PAL replay at 576p ...
Cyril

Interestingly, according to the Wikipedia entry on "Progressive scan":
"The perceived vertical resolution of an interlaced image is usually equivalent to multiplying the active lines by about 0.6. This means that, when viewing progressive sourced material, a progressive display will show a more detailed image, when compared to an interlaced one, even if both have exactly the same display resolution."

There is no source given for this. And the discussion has this comment:
"This is called the "Kell factor". I'd read before that it is .6 for interlaced displays and .9 for progressive. However I did a google search to verify this, and found all sorts of conflicting info with no one description predominating"

It would be interesting to do a side-by-side comparison. But interlacing on a CRT will have quite different subjective effects to that on a flat screen display. Also, bear in mind progressive scan on a traditional CRT defeats the object, as the signal sent by the DVD will be PAL, so re-interlaced.

cyril7

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Reply # 66709 10-Apr-2007 11:18

Yes a CRT will defeat the improvement, and a digital display is going to have to perform deinterlacing to show the image anyway, so unless your DVD player has a demostratably superiour deineterlacer to your display then its wasted effort. In most cases newer displays have quite good deinterlacers.

Cyril

TomAckroyd

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Reply # 66714 10-Apr-2007 12:33

cyril7: ... a digital display is going to have to perform deinterlacing to show the image anyway, so unless your DVD player has a demostratably superiour deineterlacer to your display then its wasted effort. In most cases newer displays have quite good deinterlacers.

Cyril

Do you really mean de-interlace, or do you mean "grab interlaced frame from DVD and put both fields together to create one progressive frame with all the information from the original"? Deinterlacing a film frame throws away half the info, or at least half the vertical resolution.

Tom

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Reply # 66716 10-Apr-2007 13:07

Film is obviously Weave deinterlaced, ie both half fields are stitched back together, so vertical resolution is retained. A lot of plasma panels until recently did not detect film (read progressive) sources and so used Bob deinterlace where only one feild is used thus halving vertical resolution. The newer Panasonics and other better brands have good film detection routines that let them Weave film and bob or even better motion adapt both weave and bob interlace video sources.

Up until even a couple of years even better brands only used bob for all material, yuck.

Cyril

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Reply # 66734 10-Apr-2007 17:30

Upscaling players have little advantage also, in my view. Unless you have a 1080 native display then all you are doing is putting the image through an unessesary and often damaging scaling process. Better of to feed the display with 576i and let it do a one of scale to its native resolution rather than have it go 576>1080>displaysize as each rescale introduces its own filtering and image artifacts.

i agree 100%. bought an upscaler before and returned it on the same day because the picture looked so so bad (you could somewhat blame the chip on the LG player but still, i didnt want to go that path again!)

richms

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Reply # 66757 10-Apr-2007 21:54

The dvds may support 576 lines, but when mastered they have to reduce the effective resolution to about 2/3rds of that because otherwise there will be unacceptable line flicker on interlaced displays. The only source of full res seems to be the menus that come out of most of the make your own dvd softwares.

Sadly, this should have being addressed by the dvd spec to mandate that the players have vertical flicker filtering for interlaced crt display, but like hdtv in the US, it was just a little bit early to be concerned with the huge shift insales to flat digital panels, so we are stuck with this being done in production.

also on progressive ntsc playback the 3:2 pulldown becomes a 3:2 candence in frames, since you end up with 24 frames after deinterlacing, so the motion is still crap, the only solution is if the display panel does it itself and is smart enough to swap frames at 24 or 48FPS, and I haven't seen any that still dont suffer from shudder on ntsc sources except for the philips pixel plus ones, and they just look like your watching it when drunk so hardly a good display.

Richard rich.ms