Techno Help required

[Bullseye]

By no means am I an expert on video and audio but i do know what looks and sounds well. However i just want some clarification on the following. On another forum someone asked the difference between 1080p and 1080i. Now i know p stands for progressive scan so that the image refreshes more quickly. Could someone comment on the following statement.

Basically the only scenario where there is a difference between 1080i and 1080p signal is if you're running a PC game through your set as a PC can produce a 1080p signal at 60 frames a second.

First of all, all TVs are incapable of displaying the 1080i or 1080p signal that originates from TV or movies. The reason is that television and films are shot at 24 frames a second and your TV refreshes its screen 60 times a second. So either your player, or the TV, uses a process called 3:2 pulldown to up the frame-rate. The first frame is doubled, the second frame tripled, the third one doubled, the fourth one tripled, etc... During that process, your TV or player will de-interlace a 1080i signal (meaning there's no difference at all between it and a 1080p signal).

Some 1080p Blu-Ray players actually interlace the signal internally, then de-interlace the signal (internally still). So even if you have a 1080p Blu-Ray player it could still have the step of de-interlacing (and no matter what the 3:2 pulldown is required in either the player or the TV).

So as of now, a 1080p set that only accepts a 1080i signal is absolutely no different for films and Television (and most all video games). The only way it would become an issue is if they start filming movies and TV shows at 60 frames a second, which won't happen for a decade, if ever. A 1080p film at 60 frames per second would take around 3 Blu-Ray discs and require much more bandwidth than Blu-Ray has.

[Colorado Blu Skies]

Originally Posted by Bullseye

By no means am I an expert on video and audio but i do know what looks and sounds well. However i just want some clarification on the following. On another forum someone asked the difference between 1080p and 1080i. Now i know p stands for progressive scan so that the image refreshes more quickly. Could someone comment on the following statement.

I am by no means an expert... but something about that statement seems ignorant. Sorry that I can't be any more helpful than that.

[clyon]

cnet 720p vs 1080i vs 1080p

http://reviews.cnet.com/4520-6449_7-...html?tag=today

[Bullseye]

I also found some infor on this site.
http://ezinearticles.com/?The-1080-H...080p&id=621341

[JohnGalt]

Basically the only scenario where there is a difference between 1080i and 1080p signal is if you're running a PC game through your set as a PC can produce a 1080p signal at 60 frames a second.

Dead wrong. 1080p draws all lines on each pass, 1080i draws every other line every other pass. The only case in which that statement might have some chance of being true is when you have a 1080p television and a 1080i source.

First of all, all TVs are incapable of displaying the 1080i or 1080p signal that originates from TV or movies.

My Pioneer has no problem with this.

The reason is that television and films are shot at 24 frames a second and your TV refreshes its screen 60 times a second.

Film is typically 24 FPS, NTSC television is 29.97, PAL is slightly different, I have no idea what HDTV is, etc. This comment is wrong because the only 24 FPS source you're likely to encounter in your living room is a Blu-ray player. Everything else will be other than 24 FPS.

So either your player, or the TV, uses a process called 3:2 pulldown to up the frame-rate. The first frame is doubled, the second frame tripled, the third one doubled, the fourth one tripled, etc...

True ... if you're sending a 24 Hz source to a set that doesn't feature a refresh rate of 24, 72, 120, or some other multiple of 24. For sets with refresh rates capable of adjusting to a multiple of 24 the 3:2 pulldown never happens and frames are either displayed frame-for-frame (24 Hz refresh), tripled (72 Hz refresh), quintupled (120 Hz refresh), or the like.

During that process, your TV or player will de-interlace a 1080i signal (meaning there's no difference at all between it and a 1080p signal).

True in the very limited circumstance in which a 24 FPS source is sent to a set incapable of refresh rates that are multiples of 24 Hz.

Some 1080p Blu-Ray players actually interlace the signal internally, then de-interlace the signal (internally still). So even if you have a 1080p Blu-Ray player it could still have the step of de-interlacing (and no matter what the 3:2 pulldown is required in either the player or the TV).

This doesn't make much sense. If you interlaced and de-interlaced the signal you'd be right back where you started, no? I don't follow why a player would ever to that.

So as of now, a 1080p set that only accepts a 1080i signal is absolutely no different for films and Television (and most all video games).

I'd have to think about this a bit more but off the top of my head: if my Pioneer, which features a 72 Hz refresh rate capable of 3:3 pulldown on 24 FPS (Blu-ray) sources, accepted only 1080i inputs it would require either a 48 or 96 Hz refresh rate to avoid 3:2 pulldown and its related judder. That's because 2 refresh cycles would be necessary to receive a full frame from a 24 FPS source delivering only an interlaced signal.

So one glaring difference is that a 1080p set that accepts only 1080i inputs would, if like mine its 24 FPS compatibility mode features a refresh rate that's an odd multiple of 24 Hz, be unable to display 24 FPS content without doing 3:2 pulldown which re-introduced the motion judder that 24 FPS compatibility modes are designed to avoid. In other words this could completely defeat the purpose of 24 FPS compatibility modes in some televisions but it would depend on the specific set.

The only way it would become an issue is if they start filming movies and TV shows at 60 frames a second, which won't happen for a decade, if ever.

Won't happen. Bandwidth is a precious commodity and FPS counts for content delivered over the wire or over the air will never move up to unnecessarily high FPS counts.

A 1080p film at 60 frames per second would take around 3 Blu-Ray discs and require much more bandwidth than Blu-Ray has.

Depends on the amount of video compression applied. You could fit many hours of 60 FPS content on a single Blu-ray disc but you might not like the video and audio quality required in order to cram it all on there.

[Bullseye]

Thanks for the feedback guys.