What is all this new math concerning home video?

Question

I hear that 1080i = 740 p is that true?

So if my tv is a 1080 i and I watch a blu-ray player it is actually playing at 780p?

correct?

Answer 1

First, if your TV is of the fixed-pixel type (LCD, plasma or DLP) then it is not 1080i--it is either 720p (or 768p or other p) or 1080p.  The only TV display that is 1080i is the CRT.  Consumer-level CRT sets cannot display 720p--the sweep rate is too high for the CRT.   As a result, all fixed-pixel sets will accept 480i, 480p, 720p and 1080i.  Some will accept 1080p as well (that is becoming more common).  The only source for 1080p is a blu-ray player.  Broadcast TV is either 720p (Fox, ABC) or 1080i (the rest).  Standard DVD is 480i or 480p.

Things get even more complicated when you try to figure out which has higher resolution, and which looks better.  Specifically, a 1080i picture shows you a 540 x 1920 pixel image every 1/60 of a second.  A 720p picture shows you a 720 x 1280 picture every 1/60 second.  Which is  better?  The answer is it depends on the image: If the image is not moving, the 1080i frames will superimpose and you will see the full 1080 x 1920 pixel frame.  However, if the image moves between frames, the edges will be only 540 and will not look smooth.

But wait! It gets even more complicated.  CRT displays accept and show 1080i, but no consumer-level CRT can actually resolve 1080 lines on the screen!  So even in a stationary image, the actual visible resolution is not 1080 lines (more like 800 lines).  On the other hand, fixed-pixel displays CAN show all 1080 lines and can offer full resolution.

To go to the next level of confusion, the newer fixed-pixel sets can process the two 540 frames of a 1080i picture to produce a pretty good representation of a full 1080-line frame, even if the image is moving!  So the latest set really do come close to meeting the full potential of HDTV at its maximum resolution.

Finally, regardless what the screen can show, the set can not show any more detail than what the input image carries.  So if you feed 480i into a 1080p set, the image you look at will be 1080p, but not have any more resolution than the original 480-line picture,

This is probably more detail than you asked for, but it is a way of showing that your question is not a simple one.

Finally, if you have a blu-ray player, and your TV can accept 1080p, set the player for that format.  If the TV can only accept 1080i, the set that as the player output.  If you set your blu-ray to 720p, see the above paragraph on 480i input for the answer.

Answer 2

No.  Blue ray is formated to send image resolutions to 1080p, the highest and just above 1080i. Your TV being a 1080i unit will accept and decode up to 1080 images sent through only an HDMI cable where the video signal ( DVD player is DVD HD or Blue Ray formated. 780p is about 1/2 the resolution of a 1080. The human eye and ear in most cases cannot tell the difference between a 1080i vs. a 1080p image or sound.

Answer 3

no 1080i and 720p are close in resolution but different. if your display is 1080i it most likely would be better to set the output of the bd to 1080i. most 720p displays will accept 1080i input and most 1080i displays will accept 720p and convert to native resolution. some do it better than others.

its best to experiment to find out what is the best setting for you display.