Convert 1080i/30 footage to "true" 720p30p footage?

F

filmguy123

Veteran
Can you record 1080i/30p, and then use it for "true" 720p30p footage by downrezzing in post (ie, in FCP, putting it into a 720p30p timeline)? Will this render the footage as true 30p footage (and not double the 30 progressive frames to fit into the 1080i's interlaced standard?)


Also, won't this give a higher resolution since the HVX downscales the image when shooting 720p30p mode?

The other reason I am wondering is, for those cameras (consumer models, of the sony FX1) that only shoot 1080i but do 30p - to match footage shot on the HVX at 720p30p, could this footage be used perfectly with it and look the same visually?
 
You're talking about two completely different processes.

The HVX does not shoot 1080i and then convert it to 30p; the FX1 and other models with a "Frame" or "Cineframe" mode do that. The HVX shoots actual, full-res 30p and then splits it up into fields to record it in a 1080i stream. All resolution is preserved. The FX1, etc., shoots 1080i and converts it in camera to 30p, thus reducing its vertical resolution by up to half.

The 1080/30p shot by the HVX is "true" 30p.

In my experience, 1080/30p downrezzed to 720/30p in post looks just like 720/30p, maybe a little bit sharper. But the difference won't be stark. The HVX does downrez when shooting 720p, but it does so FROM 1080p.
 
OK, I see. So a consumer 1/3 CMOS camera that does 1080i/30p can basically also do 720p30p, if you downrez it in post? (although vertical resolution might be reduced? or will downrezzing from the higher resolution anyway negate any affects of the other cameras using an interlaced capture method to create faux 30p?)
 
Don't confuse the two -- there's 1080i, and there's 1080p. 30p is 1080p.

Panasonic made a mistake by putting "1080i/24p" and "1080i/30p" in the Recording Setup menu; it refers to the method of recording, but many, many people read it as referring to the method of shooting, and think the HVX shoots interlaced and converts to progressive. It doesn't. It shoots progressive.

If you have a camera which shoots 1080/30p, then yes, you can downrez the footage in post to 720p. Yes, you'll lose resolution by doing it, but that's because 720p is lower-rez. But it may still be a little sharper than footage that was native 720p. But you may not see any difference.

Footage which is 1080i, as in, actually interlaced, will never have more than about 770 lines of actual vertical resolution, because it's interlaced. (1080p footage can have the full 1080 lines.) You compound the issue by converting the 1080i to progressive, because in order to do it, you must give up some vertical resolution -- and when you're starting at about 770, giving up the resolution by as much as half can take you down to less than 400 lines of vertical resolution. (You'll still have the full horizontal rez, though.)
 
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