Need Clarification 720p vs 1080-24p

kgb

kgb

Active member
I was on a trip back from NAB in Vegas last weekend. I had a bit of a debate with a producer about the HVX and resolutions. I've owned the HVX since September, and have since been using 1080, 24pn for my short films. I was wondering if someone could offer an opinion...

The crux of the argument was that shooting on any higher resolution than 720p on the HVX was pointless, in his words. And he claimed that I was the first person that offered a differing opinion from his cinematographer friends. I remember attending various tech seminars where they said that the HVX was essentially capturing 720p to the CCD's, and if you shot at 720p, you'd be capturing the truest signal path to the hardware. Any truth to that?

I was set to shoot my short on 720p when I tried switching to 1080/24pn and noticed the increased frame size and extra stop or so of light. I told the producer that this, and he still thought I was misinformed. He kept referring to it as 1080i, which is not the case with 24p, correct? I thought it was a progressive field mode.

Thanks in advance.
 
He is wrong.

The HVX does all internal processing of the image at 1080 and resamples it from there to fit the selected recording mode. If you are recording 720, that is derived from a 1080 image, as is 480.
 
I don't know much about the specifics but 1080 is supposed to be about 15% sharper than 720.

HVX doesn't have 1080/24pn, it has 1080/24pa (progressive advanced). It captures 24 progressive frames throught the 60i signal.
 
While it's true that the HVX CCD's don't resolve the full res of 1280x1080 (dvcpro HD 1080 resolution), there are several advantages to shooting 1080p24A, even if you do end up using boatloads of P2 space compared to 720pn. Most people agree that by shooting at 1080, you get about 10-15% more resolution. More importantly, there is a bit less compression for similar data: 24 frames at 40Mbps vs 24 frames at 100Mbps, and visually speaking, I've found that 1080 doesn't suffer from the dramatic ringing and blockiness problems in the red channel that are present in 720p footage, a fact I attribute to the greater bit rate of dvcpro 1080. I think that what is also useful is that 1080 in the DVCPro codec records full raster 720, since 720 uncompressed is 1280 x 720 so it downconverts nicely, especially if you were going to do an uncompressed online edit down the line.
 
Well, being that the sensor resolutions are about that of the Canon XL2's, I see the legitimacy of his argument. The HVX incorporates pixel-shifting, which is more or less what 3rd party products do to blow up progressive SD video to HD resolutions (i.e. Red Giant's InstantHD). I haven't tested uprezzed 720p -> 1080p vs. in-camera 1080p, but I wouldn't be taken by surprise if they were identical.
 
The other thing that the producer missed is that even 1080 on the HVX is still a true progressive image.

It is embedded in a 1080i video stream as two fields, but it was still captured and processed progressively, and there are no interlacing artifacts.
 
Zack Vohaska said:
The HVX incorporates pixel-shifting, which is more or less what 3rd party products do to blow up progressive SD video to HD resolutions (i.e. Red Giant's InstantHD).
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Pixels shifting and scaling are not at all the same thing. Pixel shifting creates additional sampling points by offsetting the green CCD.
 
hmmmm

hmmmm

It would be interesting to get Barry Green to weigh in on this.

In his book he says "720P has less visible artifacting and performs better under heavy compression" than 1080i. This is in addition to the fact that 720P is always presenting a full frame of detail as opposed to 1080's half frames (fields) of detail.

Barry if I am taking your words drastically out of context please let me know.
 
Zack Vohaska said:
Well, being that the sensor resolutions are about that of the Canon XL2's, I see the legitimacy of his argument. The HVX incorporates pixel-shifting, which is more or less what 3rd party products do to blow up progressive SD video to HD resolutions (i.e. Red Giant's InstantHD).
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With all due respect, this opinion is entirely incorrect. Pixel Shift (aka Spatial Offset) is not a digital up-rez technique.

Instead of arguing theory, all one has to do is look at the actual footage. It's plainly obvious to see that 1080 just looks better than 720. It's sharper and with less compression.
 
Barry if I am taking your words drastically out of context please let me know.
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Drastically out of context in the terms that I was talking about 720p vs. 1080i. When talking about 720p vs. 1080p, 1080p wins every time. 720/60p is noticeably cleaner and better than 1080/60i, but 1080/24p is better than 720/24p, and 1080/30p is better than 720/30p.
 
this is a noob question - but is 1080 24p mode (not advanced) equivilant to this concept because of the pulldown it performs?
 
I still don't get it. Can someone please give me a straight forward, simple answer.

My HVX does not have 1080p in the record set up menu.
Obviously I want to shoot 1080p over 720p.
But since I do not see a way to shoot 1080p, I've elected to shoot in 720p over 1080i.
So my question is quite simply this: can the HVX shoot in 1080p or not?
Some say it can. How?

I've never gotten a STRAIGHT answer on this.
Can anyone break it down for me? In concrete, step by step terms?

If I could shoot 1080p with the HVX I'd be ok with holding off on the RED for awhile.
 
It records 1080p the same way the DVX100 records 24p in 480p.

Using the 2:3:3:2 advanced pulldown.

Because the DVCPRO HD codec does not have a native 1080p setting, it feeds the 24p frames into an advanced interlaced stream. When imported into an editor those extra frames are removed and bam, you're editing in 100% true, honest to god 1080p.
 
Ok, so... I should have recorded in 1080i and removed pulldown in editing. Why didn't anyone tell me this? Let me guess... because 720p allows me to record variable frame rates? Fu ck variable frame rates! I want to tell a story here -- and I want to do it with the best possible tools. If 1080p gets me a noticeably better image, I'd be an idiot to shoot in 720. Slo mo and time lapse are fun to play with, but I'm interested in making movies and telling stories -- not in getting hung up on a lot of fancy shmancy gimmickry.
 
Yeah, wherever possible I'll shoot 1080 24pa and uprez my fandangle slow mo/time lapse 720pn to 1080.

99 % of the time people shoot 720pn because you can get a lot of HD footage on an 8gb card - about 18 minutes I think. Very, very handy in a lot of situations.
 
tmnt said:
99 % of the time people shoot 720pn because you can get a lot of HD footage on an 8gb card - about 18 minutes I think. Very, very handy in a lot of situations.
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I was surprised to find that I got about 21 minutes of 720/24Pn on an 8 GB card.
 
Ted Spencer said:
I was surprised to find that I got about 21 minutes of 720/24Pn on an 8 GB card.
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Think of it this way.

Whether you're recording 1080p or 720p, you're recording at a data rate of 100 Mb/s. So, an equal number of frames would take up an equal amount of space.

But when you're recording 720p/24pN, you're only recording 24 fps, as opposed to the 60 fps (fields or frames) of either 1080 or the 720 P modes, so you're only recording 40% of the data. 40% of the data means 2.5 times the recording time. And 20 is 2.5 x 8.

--

The worst thing Panasonic could have done is put all those "1080i/Whatever" in the menu screens, because it confuses EVERYBODY, and a lot of people think that because the menus say that, it can't record 1080p. But in 24p and 30p, it does.
 
tmnt said:
Yeah, wherever possible I'll shoot 1080 24pa and uprez my fandangle slow mo/time lapse 720pn to 1080.
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What is your preferred method of uprezzing 720P footage to 1080P?

David Jimerson said:
The worst thing Panasonic could have done is put all those "1080i/Whatever" in the menu screens, because it confuses EVERYBODY, and a lot of people think that because the menus say that, it can't record 1080p. But in 24p and 30p, it does.
Click to expand...

I agree. That confused me for awhile in the beginning. 1080i? 1080P? Which is it?? But nowadays I understand . . .
 
David Jimerson said:
So, an equal number of frames would take up an equal amount of space.
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Well, not exactly -- because 1080 is stored as 60 fields (or in common nomenclature, 29.97 "frames") but 720/60p is actually 60 distinct frames. So you could say "for an equal amount of time, equal amount of space" or something, but when comparing 100-megabit 720/60p vs. 100-megabit 1080/60i, you'd have twice as many frames in 720 than you would have in 1080. 1080 frames are spatially larger and take up twice as many bits per 720p frame; that's why you can fit twice as many 720p frames in the same bandwidth as half as many 1080i "frames".

The worst thing Panasonic could have done is put all those "1080i/Whatever" in the menu screens, because it confuses EVERYBODY, and a lot of people think that because the menus say that, it can't record 1080p. But in 24p and 30p, it does.
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Ooooh, I so agree. Having that little "i" in there has caused more confusion than anything else. But the simplest/easiest way to break it down is:
1080i/24pA *is* 1080/24P. It's pure progressive footage, once your editor strips out the pulldown.

1080i/25P *is* actual genuine 1080/25P.

And 1080i/30P *is* actual genuine 1080/30P.
 
Now looking back panasonic was right to keep the Chipset dimensions a secret. Look how much confusion it causes. Juan from Reelstream said it best. he said, Think of the HVX's 3RGB 960x540 CCD's as the RGB components from a Bayer pattered 1920x1080 Single chip CCD. Apparently if you count the RGB pixels from thoes chips you wind up with 960x540 per color. In essence, the pixel shift is making a 1920x1080 "singe chip" with big pixels, because the RGB components are seperated physically, on different chips, as opposed to being seperated electronically by the DSP on a Single CCD imager.
 
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