USA unit can shoot 25 fps (well, 24.975 fps)

B

Barry_Green

Moderator
Had a chance to check the mystery, "second" 24fps in the "frame rate hack". For those who know the number sequence, 14 = 24fps, and 15 = ? also 24fps? and 16 = 26fps.

So it's:
13 = 23fps
14 = 24fps
15 = 24fps
16 = 26fps

So that 15=24fps looks curious, doesn't it? Why isn't it 25 fps?

I tested it, and basically it is. The US version, when frame-rate-hacked to 15, delivers 24.975 fps. That's 0.1% variation, just as much as our 23.976 deviates from 24.000.

In other words, it's probably "close enough"!

But, I couldn't get it to record to the card. I got repeated "P2 Micon Errors" when trying to record that frame rate. I had to capture it through DVC Rack to figure out what it really was. So I don't know how useful people may find this, but if someone desperately needed to shoot 25fps on the US HVX, there's definitely a way...
 
Did it with dvc rack?
Barry, as far as i understood, there are no pn modes in dvc rack..am i wrong??
Or does it support all pn framerates?
 
If you shoot in the "p" modes to DVC Rack, it converts the files automatically to being "PN" when it records them. So yes it supports all frame rates automatically.
 
interesting, so I understand that for now it only record 25 direct to laptop via DVrack?
How about FS100 probably not checked so far but interesting because then it would be nice to Run en Gun 25 frames, ENG. isn't it?
 
It would work to FS100 as well, yes.

It may work to card in 720/60p mode, I'm not sure. I couldn't get it to work to the card in 720/24pN mode.
 
Barry,

Kind of a side question, however, part of the HVX PAL/NTSC thing I am finding hard to confirm as true or an invented memory:

1. Does HVX PAL and NTSC 1080 DVCProHD have different underlaying pixels, ie, one has 1440 x 1080 and the other has 1280 x 1080, respectively?

2. If yes, is this a pixel shift thing or other, and is one a technically better image and higher data rate?

3. If no difference, I retract items 1 and 2 (above), and shall seek help from a medical forum.

Thanks in advance Barry. :D
 
See http://en.wikipedia.org/wiki/DV and go down to DVCPro HD.

Since the 50 and 60 Hz variants of 1080 have differing numbers of frames (60 Hz variant has 20% more) then to keep the overall compression per frame similar, the 60Hz variant has a lower horizontal resolution than the 50Hz - 1280 to 1440, as you say.

Nothing to do with pixel shifting - that's a way of improving the luminance resolution somewhat over what the raw pixel count numbers may lead you to believe would be the case. Here we're talking about recording resolutions.
 
harddrive,

Thank you for apprising me of the 50/60Hz difference.

From that information, I distill that 50Hz 1080p25 may be a technically superior image, as it has more horizontal resolution. From memory, the eye is more perceptive and sensitive to vertical resolution. Assuming I have this correct, the horizontal pixel differences between 50/60Hz camera's in 1080 recording, should make less difference to the human eye.

That said, I am not sure if the HVX chip sources a 1440x1080 image? At the time Adam Wilt did his article in DV.com, it was unsure what the HVX chip sensor was producing, if I read the article correctly. Accordingly, if the HVX sensor is producing less than 1440 pixel in the 50Hz PAL version, then how is the 1440 created? At the time of Adam Wilt published the DV.com article, he had "?????" as to the HVX horizontal resolution. Panasonic may have subsequently confirmed/published the HVX resolution for both 50/60Hz camera, and I would appreciated confirmation of same if anyone can confirm?

I have an HVX on order, and for me, it has the most bang for the bucks and suits a lot of what I want to do. I am just interested to see if technically a HVX 60Hz camera, recording say 1080p24, will produce a better images than a HVX 50Hz, in say 1080p25?

HVX rocks :thumbsup:
 
The pixels on the chip, and the recorded resolution, are not the same. They're actually fairly unrelated (think for example of an XLH1, with 1440x1080 pixel CCDs, but recording 720x480 DV from them if you put it in DV mode).

The HVX scans its CCDs into a 1920x1080 matrix and works with the data internally at that frame size. However, there's not quite enough resolution to fill out that full matrix. Panasonic published a web page that showed what they said was the effective pixel resolution, I believe they said they were getting the equivalent of about 1400 x 800 out of it.

So whether the DVCPRO-HD codec records 1280x1080, or 1440x1080, will make very little perceived difference.
 
Barry and harddrive,

[SIZE=+0]Thanks for the information and clarification. Always good to get the facts straight, though I have no issue with the HVX. I am always interested in learning more, and dispelling mixed up information in my punch drunk brain. Can't wait for the HXV to arrive..... :D[/SIZE]
 
TylerD said:
I am just interested to see if technically a HVX 60Hz camera, recording say 1080p24, will produce a better images than a HVX 50Hz, in say 1080p25?
Click to expand...
As you live in Australia, then I'd say the 50Hz variant would be the best choice for you, though if your primary reason for getting it was to transfer to film, then 24p may make a lot more sense. That's for purely practical reasons, nothing to do with recording resolution. As Barry says, the limiting factor is likely to be what the front end of the camera can deliver, rather than the recording format.

A good analogy would be to compare a top end SLR camera with a cheap disposable. They may both use 35mm film (so the same "recording format"), but the cheap camera just won't be able to take advantage of it in the way the SLR can.

Speaking in very general terms, be very wary about putting too much store on simple numbers anyway. You never get a scenario where the response will be perfect up until the equivalent of (say) 1163 pixels, then nothing at 1164 - in practice responses will tail away, and hence the whole concept of modulation transfer function. Camera A with slightly less absolute resolving power than camera B, may actually look sharper if it's mtf is higher at most other resolutions.

Be also wary about manufacturers claims in general. By and large they love to promote numbers when they show their product off well, and then call foul when somebody else brings up other numbers which would put it in a worse light. This is true of many products, not just cameras - it's called marketing.
 
Barry_Green said:
If you shoot in the "p" modes to DVC Rack, it converts the files automatically to being "PN" when it records them. So yes it supports all frame rates automatically.
Click to expand...

Dose this mean you can shoot 720pn varriable framerates over firewire using DVC Rack?

Cheers,

Adam
 
Sorry Barry,

I just did a search and see that you have covered this in another thread.

Man that is so cool I have to get DVC Rack when it comes out!

Dose it work with Pal 720PN files too?

Many Thanks,

Adam
 
You can't have the camera in "PN" mode, of course, it has to be in "P" mode.

I don't know if it has support for the PAL version or not, hopefully the_other_mark will come on and let us know.
 
Barry, I'm new to the HVX thing and I've been stressing about NTSC vs PAL as I work in both formats. Now, it really seems that the NTSC version gives you more flexibility and maybe even a cleaner conversion (60i to 50i for example)
i'm very intrigued though by this hack, but i dont know what dvrack capture is. is that using p2 cards? firewire store??? how does it work? it sounds like something i'll need if i want to do pal stuff on an ntsc
 
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