1080i, 720p or 720pn?

simone.p

simone.p

New member
my first time looking for help on the web
I'll maybe sound a bit ignorance but... i red people saying that 1080i has 15-20% more quality then the 720p but i even knew that progressive increase vertical resolution and if i will have to end on film with the interlaced fields won't i have more problems that if i shoot with the progressive "frames"?
and yet which is the difference in between 720p and 720pn?
which are the advantages and disadvantages of the two kinds?
if 720p is not "n" (native) does it mean it is an interlaced shot transformed after in a progressive one?

thank you everibody for your precious help
simone
 
720pN can only be recorded to the P2 cards although the FS-100 in the PN mode can essentially mimic this capability.

pNative is more efficient in that no duplicate frames have to be removed, and it's more space efficient because no duplicate frames are stored on the cards.

The other thing pN mode gives you is instant feedback on how your variable-frame-rate clips look. Record in pN, play back, and you'll see the effect instantly (vs. recording in 720P mode, where you'd need to extract the frames in post before you know how the effect looks).
 
Nice to see some italians here!

As David explained 720p is always shot in 50p then is pulled down to 25 if you choose 720p25. I Love 720pN because it's Native resolution and it's real frame shot: 12 to 60 variable. So if you shoot 50f you'll get a lovely slow motion!...on 25f timeline.

I think you're right about 720p 25 (or pN25) better for film, shorts and I must say for Lcd Monitors as they don't like that much interlaced video especially on vertical pan's. But I'm not into film transfer techniques so somebody else could be more helpfull on this.

But the if your output is to be displayed on an HD Broadcasting program 1080i50 could be better for fast camera movement or hand held camera.

Ciao,

rap
 
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If you're planning to go to film, 1080p is really the way to go. Aside from the 20% more resolution, the big thing is less compression. 720p compresses the horizontal quite a bit and has overall more compression than 1080p. I forget who but someone did some tests on the technical board to show how much less compression 1080p has. If you're just planning to release on a DVD or even for HDTV it won't make much difference but, if you're going for film, 1080p is the way to go.

Now, the way the HVX200 records 1080p is by embedding (not sure if that's the right word) the progressive frames onto an interlaced signal. If you're using FCP or Edius, you can have them automatically remove the redundant frames so you can edit onto a 1080p signal. Avid has 1080p workspaces but can't do frame extractions yet so you'll have to extract them before bringing them in if you want full progressive (though they claim they're working on getting frame extractions working). You can use other software like Raylight to extract the redundant frames. You'll also have to do this for other editors like Vegas or Premiere.
 
Interesting...
so you saying that the HVX is shooting 1080p25 then interlace to 50i?
Then FCP can remove (how?) the redundant frames...Why redundant?
I've red another thread where somebody was telling the same story, pointing out that to deinterlace 1080i is very simple as is 25p interlaced. I've tried to deinterlace 1080i50 and it's true! Deinterlaced 1080i looks great, no lines or artifacts as in Pal/Ntsc deinterlaced.
So now I've a question:
If 1080i is shot progressive then interlaced, what's the difference shooting 1080p25 or 1080i50 (as in pal), does fields in 1080i once deinterlaced differ form 1080p? For what I understood: NO... two fields in 1080i are the same as a frame in 1080p. So it isn't shot in 50 different fields.

And a new one:
I've tested some shots in 720pN50 for two reason: one for slowmo, the other to have REAL different frames from the doubled 720p50.
What I noticed in a test was that if pan shots or horiz tracking shots in 720pN50 where edited in a SD timeline then speed'em up 200%, the result was nice as in SD interlaced shots, instead same takes, shot in 720p25 or pN25 when downconverted had problems of that "jumping" (don't know how do you say in english: jittering?) effect in pan and horiz tracking.

So finally, if we shoot for downconverting to SD which is the best, smooth motion, format? Either for SD DVD or broadcasting? (assuming that we shoot HD to keep an HD master for HD future uses...)
Instead going to film is better 1080i or P, if you don't need variable frame rate. Is it?


Rap
 
The HVX shoots 1080/50p, then splits those progressive frames into fields.

You can't make a 1080/50i look out of 1080/25p. It has to have enough motion samples. Internally an HVX200E is working at 1080/50p (even though it can't record that much info).
 
Thanks Barry (waiting for the book...),

So if I deinterlace 1080i50 I get 1080p25?
There is a way so to get 1080p50 out of 1080i50 maybe speeding down 50% and the deinterlace it?

Just guessing...

rap
 
thank you david, rap, barry for your help. very interesting first time within the community

ciao s
 
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