• New Patreon Tier and Early Access Content available. If you would like to support AVForums, we now have a new Patreon Tier which gives you access to selected news, reviews and articles before they are available to the public. Read more.

Three Quick Questions

B

Bryce Curdy

Guest
My screen has a resolution of 1280 x 768. Will 720p or 1080i broadcasts tend to look better? Which would look better on a 1920 x 1080 display? Are Blu Ray and HD-DVD going to be 1080p?
 

Welwynnick

Distinguished Member
Hello Bryce,

I think you have summarised pretty much half of all the debates in this forum. Have a look through the recent threads. Any replies to your questions would be the same as what has already been written a hundred times.

Nick
 

Ambient Fish

Active Member
'Lo Bryce, you come from the North Lanarkshire area?, I think I might know you from the Crown Hotel.
 

richjthorpe

Active Member
Bryce Curdy said:
My screen has a resolution of 1280 x 768. Will 720p or 1080i broadcasts tend to look better?
Depends on your LCDs ability to scale but it would be easier to remove lines from 1080i than it would be to make up lines for 720 to 768.
Bryce Curdy said:
Which would look better on a 1920 x 1080 display?
Between 720p and 1080i ?
Bryce Curdy said:
Are Blu Ray and HD-DVD going to be 1080p?
Maybe, but many folk are saying it will be 720p.

Richie
 

NicolasB

Distinguished Member
richjthorpe said:
Depends on your LCDs ability to scale but it would be easier to remove lines from 1080i than it would be to make up lines for 720 to 768.
No, just the reverse: deinterlacing 1080i is far more difficult than upscaling 720p. What most screens will do is treat each 1080i field as if it were a single 1920x540 frame, and resize that, rather than reconstructing the original 1920x1080 frames.

On top of that, even perfectly deinterlaced and downscaled 1080i viewed on a 1280x768 screen now has a resolution of only 1280x768. If it uses the dodgy deinterlacing method described above, it will effectively be 1280x540, which is actually visibly lower res than 720p. The difference in resolution is thus at best negligible and at worst actually tilted in 720p's favour. And 720p has double the frame-rate. So it will look a great deal better - much smoother motion.

On a 1920x1080 screen, if you have a proper film-mode deinterlacer, then 1080i material will look stunning.
 

Stephen Neal

Distinguished Member
NicolasB said:
On top of that, even perfectly deinterlaced and downscaled 1080i viewed on a 1280x768 screen now has a resolution of only 1280x768. If it uses the dodgy deinterlacing method described above, it will effectively be 1280x540, which is actually visibly lower res than 720p. The difference in resolution is thus at best negligible and at worst actually tilted in 720p's favour. And 720p has double the frame-rate. So it will look a great deal better - much smoother motion.

Err - surely if you are treating 1080i as 540p then the frame rate becomes identical to 720p...

1920x1080/50i treated as 1920x540p will effectively be 50 x 540p frames every second - as each 540 line field is treated as a frame. As each field in a full 50i source can have motion between it and a previous or following field, it delivers the same motion rendition as 720/50p... (i.e. 50 distinct "snapshots" each second)

The difference is that if you treat 1080/50i as a 1080/50i signal, your vertical resolution varies between 540p and around 800p (not 1080p) depending on the motion in the scene. If you ignore the >540p vertical resolution by ignoring the interlacing, then you compromise the vertical resolution on static scenes - but the motion rendition is pretty much the same as 720/50p.

It is important to remember that when 25p source material isn't being used, 1080/50i delivers 50 discrete images a second, not 25. The two fields of each 1080/50i "frame" don't have to be taken at the same time, and with non -25p sources they aren't.

These days, many1080i capable CCD cameras are effectively based on 1080/50p (or 4320/50p) sensors, and so each 1080/50i field is sourced from a DIFFERENT 1080/50p source frame (the 50p to 50i conversion may be integrated into the CCD clocking though). It is only 25p source material where both fields come from the same source frame.
 

cyberheater

Well-known Member
Bryce Curdy said:
Which would look better on a 1920 x 1080 display? Are Blu Ray and HD-DVD going to be 1080p?

It depends on how far you are away from your screen.

If you sit more then 2 x screen width then your eyes cannot tell the difference between 720P or 1080p.
 

The latest video from AVForums

Fidelity in Motion's David Mackenzie talks about his work on disc encoding & the future of Blu-ray
Subscribe to our YouTube channel
Support AVForums with Patreon

Top Bottom