Why is the 24p option buried in the 1080i video?

E

euge04

Active member
After all this camera can supposedly do why can't it record 1080 24p files directly to the p2 card?

Wouldn't it be able to fit more video in the 24p form? What is the technological reason for this? Is there degradation of the video image converting a 1080i 2:3:3:2 image to 24p? With my experience with the DVX100 I have found footage converted from the advanced pull down method to 24p for editing converted back to 60i to look a little degraded.

Thanks!
 
Interesting question... Good (smart) start, welcome! And comparatively with 25p/50i? Is there any difference? I'm not sure but I think that in 25p/50i there isn't 2:3:3:2 pull down or am I wrong?
 
Emanuel said:
Interesting question... Good (smart) start, welcome! And comparatively with 25p/50i? Is there any difference? I'm not sure but I think that in 25p/50i there isn't 2:3:3:2 pull down or am I wrong?
Click to expand...

There is no need for pulldown in PAL because the framerates are +/- the same, with caveats.

The need for pulldown in NTSC has to do with greatly different framerates.
 
It's the nature of the specs of the 1080 DVCpro 100 codec... it only allows for (in NTSC land) 1080 to be 29.97i interlaced video... they can't break the specs of what the standardized codec allows... (or rather, they won't break the specs...)

And the 24p is recorded same as 24p would be with the DVX, or a film to tape transfer would do, and no there's no degradation. This is real progressive, even if it's stored in an interlaced manner.


Regards,

Jim Arthurs
 
Jim Arthurs said:
they can't break the specs of what the standardized codec allows... (or rather, they won't break the specs...)
Click to expand...


The fact that they "won't" break the specs is one thing that makes this camera so attractive. The inclusion of a 24 frame 1080P option would essentially be a new codec, or at least a new version of the DVCProHD codec.

DVCProHD allows for 1080i, therefore the HVX records a 24P signal with a pulldown added in the same exact way that the DVX works to get 24P into a 60i signal.

This means that any footage which the HVX records will work seamlessly with any editing workflow which can handle DVCProHD footage today. DVCProHD has been around for years, and editing systems have supported it for a long time.

By not breaking the spec Panasonic can insure a smooth post workflow with existing solutions, as opposed to the myriad of compatability issues we are seeing with all the different flavors of HDV that are coming out today.
 
So it does record 24p onto the cards?

So it does record 24p onto the cards?

The camera is recording 24p onto the cards? If I get a P2 card and drag it onto my computer it will be in 24p and not 60i?

That way I can edit in 24 and then add the pulldown later or create 24p DVDs?

Why not add an extra spec to the codec? It would save space.
 
you'll need to remove the pulldown manually after you've brought the footage into your NLE(something like Cinema Tools with FCP will do it).
 
euge04 said:
Why not add an extra spec to the codec? It would save space.
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They can save space without adding anything to the codec if what David said is correct. I believe the Firestore units can strip frames from the output of a DVX and only record 24Fps, so I don't see why Panasonic/P2 Cards can't do it, either. Point is, the codec doesn't have to change. Which brings me to this question: Does the HVX actually record 24p with the pulldown already removed, in other words, "native" 24p files in 1080p/i/whatever?
 
Not as far as I know. I asked Jan about that and I believe I was told that no, it records the full 60i data stream with either 2-3 or 2-3-3-2 pulldown inserted.

Dropping the pulldown frame would have saved some space, but not nearly as much as it does in 720p -- in 1080, storing only the 24 active frames would result in a space savings of 20%. But in 720p, storing only the 24 active frames saves 60%. So it makes a huge difference in 720, but not such a big difference in 1080.
 
Is it true that this method implies any degradation of the video image converting a 1080i 2:3:3:2 image to 24p?
 
No, converting a 1080i 2-3-3-2 image to 24p involves no change to the video whatsoever.

As far as the FireStore, all I've heard recently is that it records the 60i or 60p data stream from the firewire port. Which I think is quite disappointing if true; I really really really hope they don't lame out and just capture the raw stream, but that they employ some drive intelligence to parse the data stream and only record the active frames.

Then again, I'm not altogether convinced that they'll stick to firewire streaming -- maybe they'll go the extra mile and make a P2-card interface instead of plugging into the firewire port. I think that would be at least 3,000 times smarter. The firewire port is inherently a little fragile and prone to disconnecting at the worst possible times -- but with the HVX, they have another alternative. I sincerely hope they use it. They could make the product great.

And while we're at it, I so strongly encourage them to design it to use interchangeable hard disks.

They could get this right and make a great product. If they don't, I am sure they will find sales to be less than they hoped.

C'mon, Focus, do the right thing...
 
Thanks for your answer, Barry. As you probably figure out, I'm a little bit concerned about 24p possible degradation (film-out purposes), so what will be the consequences of a synchro scan shutter speed of 1/50 @ 24p? (for shooting without fluorescent lights flickering) Grain increase? Noise? Regarding yours resfest reports - I think Jarred said it - the image is very CLEAN. Clean enough @ 1/50 in 24p?
 
The DVX currently shoots 24p at 1/50th. There are no "consequences" to be worried about.

As for the rest, we'll have to wait until we have a production model in our hands before being able to guess.
 
Thanks again Barry, your wise words are useful as always. Besides this particular concern, I only ask you 'cause a friend/an associate said to us that maybe 1/50 will produce increase the grain or even some noise. Sure, we must wait HVX [(A) also HVX will shoot currently 24p @ 1/50th?] but in DVX is there any visible grain/noise effect? [(B) or any difference comparatively with another shutter speeds?]

<PS> Unfortunately, I never did work with this piece of technology that we already know that is this cam.
 
1/50th is the default shutter speed on the DVX @ 24Fps. This is probably to match the 1/50th shutter speed on Aaton's with a 172.8-degree shutter angle @ 24Fps or maybe even to match the 1/50th shutter speed of a 180-degree shutter angle @ 25Fps.

I shot our family get together tonight and the house was full of compact fluorescent light bulbs. None of them flickered. The new fluoros are pretty good. I wouldn't worry about flickering...
 
Thanks Brian (it's your first name isn't it? Pardon if not but I think that I'm not wrong...) for your help.

I ask about the flickering problem because, as Barry knows, I think to buy the HVX 24p/60i for use in Europe (PAL with that question of 50Hz - different electricity system comparatively US).

Although I don't know DVX, I understood it (the default shutter speed on the DVX). Will it be in HVX @ 24p?

I'd like only to understand the tolerance concerning the grain/noise factor/coefficient if one day I'd need to correct any fluorescent lights flickering in PAL land with HVX 24p/60i @ 1/50.
 
I shot in Romania a couple of months back and had to deal with some really awful low frequency magnetic ballast flourescents, and YES, I can verify that a 1/50th shutter speed eliminates the flicker. If I recall correctly, 1/25th is what I actually used because the light levels were so low and 1/25th makes for a brighter picture. I needed that.

There is zero effect on video noise from using a 1/50th shutter. Likewise, zero difference with 1/25th. What will it take for you to believe us?
 
Thanks Brian for your testimony. Of course, I believe in your practice. I'm not a guy from the technology, nevertheless a background in this "things" of the moving image. Maybe better in terms of language(s) & aesthetics and so on. But your personal experience is very important like your comment about the detail of the 1/25th shutter. There are sometimes these particular "things" that do all the difference between an option for A or B instead of C. And as I told you before I heard another person that put a but on this possible problem. About 1/25th, following your words, that was a brighter picture with it. A relevant point I suppose for your option.
 
"Converting" 1080i to 24P involves no change to the video???

"Converting" 1080i to 24P involves no change to the video???

Barry_Green said:
No, converting a 1080i 2-3-3-2 image to 24p involves no change to the video whatsoever.
.
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Technically gifted people tell me that camera CCD sensors are usually read out in either interlace or progressive. Not both. When Panasonic describes reading out a 1080i image in 24P, I get confused.

Sony apparently reads out the Z1 CCD's at 24fps. The resulting Cineframe (if that's what it's called) seems to get universally poor reviews. JVC seems to read the HD100 CCD's progressively, and it's understandable how the progressive image could be read out in sequential alternating lines to yield a simulated interlaced result. But how does the HVX produce both native interlaced and native progressive images? (Sorry, "Just like the DVX" is an insufficient reply.) I can imagine a de-interlacing process merging two interlaced fields and compensating the motion differences to yield a progressive result, or a native progressive device creating a simulated interlaced output???

How is it possible to yield native HD progressive and native HD interlaced output from the same CCD's??
 
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