Downconvert 1080p to 720p will cut 15-20% of the 960 x 540 resolution??

I

iFilm7

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Downconvert 1080p to 720p will cut 15-20% of the 960 x 540 resolution??

in 1080p it records 960 x 540 right? but if you downrez resolution to 720p the useful pixels or something would be only 80-85% of 960 x 540 right?

but ive heard you'll get better results when recording 1080p than 720p?
 
First of all, it's not 960x540 resolution, so everything about your premise is faulty.

The HMC150's imaging block is three chips that work together, using spatial offset technology, to deliver a 1440x810 image. It records 1920x1080, so that 1440x810 gets stretched up into a 1920x1080 frame. If you record as 720p, it downscales 1440x810 down to 1280x720.

You get better results from 1080p vs. 720p for two reasons:
1) 1440x810 is more than 1280x720
2) 960x540 chroma samples is a lot more than 640x360.
 
Given those two reasons, should i first 'edit/key the greenscreen' or do those after converting down to 720p?
and when i do convert down to 720p does my chroma samples (which is a necessity for green screen work) go down from 960x540 also?
EDIT: also if you record as 1080p with the 1440x810, and down rez it in post, wouldn't it downrez the 1440x810 also?

thanks for correcting me (:
 
I'm shooting a film with the HMC150 and we're using 1080p. Our little hard drive that could is getting filled up way more than we thought it would after transferring the date to FCP. What do you guys know about down-converting footage to 720p? Is it worth it for the disk space?
 
Stang68 said:
I'm shooting a film with the HMC150 and we're using 1080p. Our little hard drive that could is getting filled up way more than we thought it would after transferring the date to FCP. What do you guys know about down-converting footage to 720p? Is it worth it for the disk space?
Click to expand...

If my target output was 720p I would shoot at 720p when ever possible.

If my target output is 1080p I shoot at 1080p.

For DVD you can shoot at either.

For green screen I shoot 1080p every time.
 
Stang68 said:
I'm shooting a film with the HMC150 and we're using 1080p. Our little hard drive that could is getting filled up way more than we thought it would after transferring the date to FCP. What do you guys know about down-converting footage to 720p? Is it worth it for the disk space?
Click to expand...

i would shoot 1080p all the time, and then downconvert to 720p for output. it would give you the best chromatic resolution.
if you need slow mo shoot in 720p
 
Stang68 said:
I'm shooting a film with the HMC150 and we're using 1080p. Our little hard drive that could is getting filled up way more than we thought it would after transferring the date to FCP. What do you guys know about down-converting footage to 720p? Is it worth it for the disk space?
Click to expand...
It would be simplier and faster to simply buy an additional Hard Drive. They are getting cheaper.

Me, I have a lot of hard drives, so, this is not a problem!
 
Thanks, guys! We've decided to keep the 1080p. I'm going to invest in a LaCie 1TB drive for the rest of the production. I have had great experience with LaCie over the years.
 
In PH Mode the 720p files and the 1080p files are the same size. So shooting in 720p is not going to save disc space. I would just buy a new drive.
 
hey barry, i was wondering if this logic made any sense to you:

720 mode possibly more sharper than 1080 because,

1440x810 stretched up into a 1920x1080 frame is proportionately lesser than 1440x810 downscaled onto a 1280x720 frame, unstretched.

Correct me if I'm wrong, which I hope I am.
 
zeroblank said:
In PH Mode the 720p files and the 1080p files are the same size. So shooting in 720p is not going to save disc space. I would just buy a new drive.
Click to expand...

That depends on the files. Once transcoded (e.g. to ProRes 422) the 720p is no longer wrapped in a 1080p container so the files are smaller, so will save disc space.

If you are targeting 720p you are getting a less than optimal image resize from 1080p footage. You are shrinking by 1.5. You can't get half a pixel, so it's down to how well the software interpolation works in your NLE. This means you need to shoot 1080p vs 720p and see the actual output. It's not hard - it only takes a few minutes, so it really is worth doing.

If you are shooting only for the potential benefits of the extra color space then by all means shoot in 1080p, but before you really make the decision, do some of your own tests (rather than relying on contradictory postings here) to ascertain if you can actually see any difference. If you can't then it's possibly a waste of time, and shooting 720p/60 would give you more options in terms of slow-mo etc.

I've done my own tests, which is why I prefer 720p if I know I am targeting a 720p output. For anything else I choose 1080p.
 
zeroblank said:
In PH Mode the 720p files and the 1080p files are the same size. So shooting in 720p is not going to save disc space. I would just buy a new drive.
Click to expand...

Yes, but if you're referring to Stang68's post, when you use FCP, you have to convert to Pro-Res, and then resolution *does* make a difference in terms of file size. Same with DVCProHD or Cineform.
 
zeroblank said:
In PH Mode the 720p files and the 1080p files are the same size. So shooting in 720p is not going to save disc space. I would just buy a new drive.
Click to expand...
It's not the camera files that's the problem. He's converting the files into prores files (or AIC) and those are massively much bigger than the camera-original files. And while I don't use that program or its codec, I think it's probably reasonable to assume that a prores 720/24p file would be smaller than a prores 1080/24p file.
 
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