1080i vs 720p

N

Nonsense

Active member
Here are several questions that get me confused.

True or False?

1) The HVX cannot shoot 1080p, just 1080i.

2) 1080i has a siginifcantly higher resolution that 720p, but 720p is more commonly used with the HVX because it shows motion in a more fluid manner.

3) Progressive scan is prettier than interlaced fields because...there are no interlaced fields in progressive scan.


Thank you very much.

I hope you can ace my test.

Please include a "why" section for question 3.
 
1. The HVX images 1080i video progressively and encodes it in interlaced half-frames because that's the only broadcast format that exists.

2. Yes, 1080i has a higher resolution than 720p, but the HVX derives both 720p and 1080i video from the same progressive image regardless of which output resolution is selected. Resizing and encoding to the selected recording format is the very last step.

3. Yes, because there is more vertical detail, fewer motion artifacts, and absolutely no jaggies.
 
Even though the HVX can shoot in the higher rez 1080, from what ive read the actual boost in image quality is barely anything. 13% or something like that isn't worth space on a P2 card unless you really need it. Ide even shoot in 720p then 1080p for a shot or so just to reframe something if I had to because the detail woudl probably match pretty well.
 
Nonsense said:
1) The HVX cannot shoot 1080p, just 1080i.
Click to expand...
Completely false.

2) 1080i has a siginifcantly higher resolution that 720p, but 720p is more commonly used with the HVX because it shows motion in a more fluid manner.
Click to expand...
Completely false.

3) Progressive scan is prettier than interlaced fields because...there are no interlaced fields in progressive scan.
Click to expand...
True.
 
1. It's more properly called 1080psf/25(30) - progressive carried in an interlaced stream, and hence fully compatible with 1080i/25(30) from a TRANSMISSION viewpoint. Note it can be seamlessly reconverted back to 1080p/25, something 1080i/25 cannot, psf is a straightforward reordering of the p line sequence - easily undone.

2. The 1080 frame has a higher POTENTIAL ABILITY to resolve detail than the 720 one, but that depends on the input to it - lens, chips, electronics etc. By and large, all 1/3" cameras are limited mainly by their front end, and none really capable of filling a 1080 container, resolution wise. (Neither are many 2/3", for that matter!) You really need to specify frame rates when you refer to motion fluidity - by 720 do you mean 720p/25 or 720p/50? In general 1080i/25 is likely to have the same fluidity of motion as 720p/50.

3. Again, the statement needs qualification - 1080i may look better than 720p under some circumstances. (Capable of more resolution - dependent on lens, chip etc - especially horizontally.) And tests have shown that whilst they may look similar in a lightly compressed form, a progressive format may stand up to very high levels of compression better than an interlaced one, such as may be used for bandwidth restricted broadcast.

EDIT - the above is intended in a very general sense - not HVX specific. That especially applies to 3.
 
Last edited:
Wow, those were all great answers. Thanks! Except for you Barry, you didn't answere the "why" part for question three.

Everyone gets an A.

Except Barry. He gets a B+.

I'm kidding. Barry you always get an A.

-M
 
Barry: I never thought I'd hear you give a five word answer to such a complex question. Erudiate for us, please.
 
Imagine that -- brevity! :) Well, 1 has been answered a thousand times before, so no need to go into it again.

2 -- well, let's just say that that's false. 1080i has more spatial resolution, 720/60p has more temporal resolution, and the net result is that they both push about 60 million pixels per second through the TV; they net out at about the same. And the reason people choose 720 on the HVX all boils down to two factors: recording time on the P2 card, and variable frame rates.

As for 3, no need to go into why, because he said exactly why. Progressive looks better because there are no fields, it's a continuous progressive picture. 720/60p slays 1080/60i for sports coverage specifically because of that.
 
You must log in or register to reply here.
Back
Top