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Old August 10th, 2005, 04:56 PM   #1
Barry Wan Kenobi
 
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24P playback on TV

Okay, so get this -- I shot some footage on the HD100 in 24p mode, but I only have a borrowed HD1 here to play it on. I figured I'd be totally out of luck. And, true to form, the HD1 cannot play back the 24p footage. However...

I was viewing the footage on my XBR960 HDTV set, which has firewire ports on it and the ability to control a camera through firewire. So even though the HD1 couldn't play back the clip, the TV set could! The HD1's display said "cannot decode" etc., but the TV still displayed it. So the HD1 is able to transport the sequence, just not decode it itself.

That's probably good news for those who own HD1s, or even the CH1 deck (or whatever it's called) -- even though those products can't play 24P HDV, they probably can be used to digitize 24P HDV.

EDIT: okay, it gets better. I just used the HD1 to capture 24p clips. For software I used the original Pixela HD Capture utility that was bundled free with the HD1. It captured fine, and IINM, it removed pulldown out of the file! I'm not 100% sure on that last part, but I do know this: the clip, when imported to Vegas, reports "23.976 fps". I don't know if the capture program removed the pulldown, or if Vegas 5 just "knows" how to reverse pulldown out of a 60P MPEG-2 24fps transport stream, but either way I am very pleased by that. We've been hearing reports that it'll be a few months before editing programs are integrated with 24p, and I can tell you that right now you can use Vegas 5.0 (note: that's not even 6.0, the HDV update, I'm using 5.0) with the JVC HD Capture Utility and capture 24p HDV files from a JVC HD1 (and presumably from the HD100 as well, of course!)

Last edited by Barry Green; August 10th, 2005 at 05:46 PM.
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Old August 10th, 2005, 05:50 PM   #2
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Hey Barry,

Will that utility work on a mac?
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Old August 10th, 2005, 08:12 PM   #3
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Don't know. I don't have a Mac here, and the CD is long gone (I installed it a couple of years ago when the HD1 first came out, and then pretty much forgot about it).

You could try asking the question in the HD1/HD10 forum here, as I'm sure there are many HD1/HD10 users who are also Mac users, they would have the answer for you.
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Old August 11th, 2005, 10:29 PM   #4
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Hey, hey, hey...!!!

I have asked JVC of the potential to use my CU-VH1 for the new 24P, and they said that it is not posible, so this is a great news. They even said that a firmware update will not be sufficient to make the magic. So, please, let me know for sure if this is true (using Premier Pro 1.5.1 too) so I can keep my small deck and not be in the need to spend money in the new deck. Again, this is a great discovery!!!

Thanks,

Luis
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Old August 11th, 2005, 11:04 PM   #5
Barry Wan Kenobi
 
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I'm certain your deck would not be able to play and display the footage. However, it seems reasonable that it could be used to digitize. So if you have a capture program that supports 24p HDV (such as HDV Rack) you could probably use your deck too, although that's just a guess -- it may not work either (althoug, since the HD1 works, I can't imagine why the CU-VH1 wouldn't work too).
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Old August 11th, 2005, 11:20 PM   #6
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I agree that it will not display the footage since basicaly the deck is a HD-10 without lens. I use Premiere Pro 1.5.1 with Cineform Aspect HD, which already supports 720 24P HDV aquisition and editing, so I think I am covered! The response from JVC big shot guy, in my opinion, was more to protect the new market for the newest, improved HDV deck. It tells me that a simple firmware will suffice... However, I need to salute you for discovering this!!! If I can confirm it with a 24P m2t file, using my workflow and software, I careless if I cannot see it on the LCD display. I will monitor it using my JVC monitor to set the in and out points for capturing.

Is there any way I can get a hold of your m2t file in 24P? I would like to experiment and report the results to everyone that may be in my position on having the small deck and not having $ to buy the deck since will be utilizing the money to get the camera itself.

Thanks again,

Luis
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Old August 12th, 2005, 12:53 AM   #7
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There are three 24p .m2t files available for download in this thread:
http://www.dvxuser.com/V3/showthread.php?t=31678
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Old August 12th, 2005, 04:12 AM   #8
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Quote:
Originally Posted by Barry Green
It captured fine, and IINM, it removed pulldown out of the file! I'm not 100% sure on that last part, but I do know this: the clip, when imported to Vegas, reports "23.976 fps". I don't know if the capture program removed the pulldown, or if Vegas 5 just "knows" how to reverse pulldown out of a 60P MPEG-2 24fps transport stream, but either way I am very pleased by that
I'm fairly sure the i.LINK is outputting 23.98fps not 720p60. Your TV added the pull-down. All ATSC HDTVs must have the ability to handle 23.98/24.

The pulldown must, of course, be added for any analog output from a camcorder. The HD100 does this.
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Old August 12th, 2005, 09:39 AM   #9
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Barry,

After looking at some of your clips, I have a question about the motion smoothing filter. It looks to me that one use for it might be to simulate a shallow depth of field on certain shots... Now, it's not a great approximation, but I did notice that when you panned to follow someone, keeping them roughly in the same place in the frame, That everything else seemed to blur, but the subject stayed sharp...

Again, it's not a great approximation of shallow DOF, but for in certain situations, it wouldn't look too bad...

Your thoughts?
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Old August 12th, 2005, 10:34 AM   #10
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Well... interesting. That's an angle I hadn't thought of.

The panning-while-following-a-subject thing is something that you have to do in film (or 24P video) shooting to eliminate the jarring effects of strobing. But with the JVC's motion smoothing filter, it's basically just blurring a double image together. On a relatively stable object (like the subject in the foreground that you're following) it should have little effect. On the background that's flying by quickly, it should have a more significant effect.

So yeah, I do believe you may be on to something. It may indeed introduce a bit of that shallow-DOF look. I'd have to experiment with it a lot more to be comfortable with it and trust it -- right now I think of "motion smoothing" as a bad gimmick, a way to make your high-def footage blurry (isn't that what you always wanted? Blurry HD?) But if used in controlled circumstances, perhaps it would add value.

Shallow-DOF is easier to get with the HD100 than most other cameras if you just have room to back up and zoom in. The telephoto reach makes it a lot easier to accomplish the shallow-DOF look. But in close quarters it's just as limited as any other 1/3" camera. The motion smoothing may indeed help with that, I don't know.

I think the test would be "motion smoothing" against just using 1/30 or 1/24 shutter speed. Both are going to add blur, but the slow shutter speed is going to add smooth blur, vs. motion smoothing which makes a double image. You may be able to get the effect you're looking for through the slower shutter speed, without the odd visual effect of the motion smoothing filter.
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Old August 12th, 2005, 10:56 AM   #11
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I'm with you for the most part Barry, I think it's a gimmick that will have very limited use... I was just fishing for one of them I guess...

I'm holding off on the prosumer HD camera barrage that's going on... looking for what will benefit me the most in the long run. I'll just file this under "something to look into further"...
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Old August 12th, 2005, 02:45 PM   #12
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Quote:
Originally Posted by Barry Green
I think the test would be "motion smoothing" against just using 1/30 or 1/24 shutter speed. Both are going to add blur, but the slow shutter speed is going to add smooth blur, vs. motion smoothing which makes a double image. You may be able to get the effect you're looking for through the slower shutter speed, without the odd visual effect of the motion smoothing filter.
The Motion Filter does NOT make the double image. Sampling at 30fps inherently creates an eye-tracking artifact that causes you to SEE a double image.

Setting the shutter-speed to 1/30 adds motion blur to everything which HELPs but does not eliminate double images. You SEE two images with blur between them. Many do this with the HD1/HD10.

All the MF does is -- FOR OBJECTS WITH RAPID MOTION -- take a sample of THAT OBJECT from the last available frame (remember we have 60 frames available) and add the image to the to be recorded frame.

Non-moving objects don't get anything added. The result is a frame recorded to tape that has two images (1/60th second apart) for rapidly moving objects -- and only one for all other objects.

The process of adding the second image is not simple addition. It is done in a way that creates a smooth blur BETWEEN the two images.

The result is clever, but may not be convincing. Rapidly moving objects have artificial motion blur so they do NOT strobe. They look like you used 1/30th second shutter-speed.

SLOWER moving objects are captured at 1/60 so they are not blurred as they would be if you used 1/30th. This should keep them clear.

Of course, there will be a range of motion which is too slow to be blurred artificially, yet fast enough to cause the EYE to see a double image. These kinds of objects will appear to stobe.

The clip we have is likely a worst case situation. Overall rapid motion caused by fast panning plus an object that CHANGES speed at each end -- note how sharp he becomes when he hangs in the air for a moment -- plus the natural motion wobble introduced by hand held camera movement.

A film person would use a fluid head to shoot this. And that is the lesson we learned from the first generation of JVC. 30fps is, like film, a LOW temporate rate medium. It is NOT like 60Hz interlace video! The MF simply helps rduce strobing -- but it does not eliminate the need to shoot as you would film.

And that means fluid heads and steadicam -- or an understanding of how to shoot LOW TEMPORAL RATE MEDIA.

JVC has been very clear that ONLY from the analog outputs do you get 720p60. All recorded material is 30fps video. This should be no surprise to anyone who has followed the last 2 years of HDV posts.
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Old August 12th, 2005, 10:28 PM   #13
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Quote:
Originally Posted by Steve Mullen
The Motion Filter does NOT make the double image. Sampling at 30fps inherently creates an eye-tracking artifact that causes you to SEE a double image.
Given that Barry wrote "it's basically just blurring a double image together" earlier in the same message I don't think there should have been any misunderstanding of what he meant. Just substitute "blend" for "make" in the sentence and move on.

Don
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Old August 13th, 2005, 09:27 PM   #14
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Quote:
Originally Posted by Don Crockett
Just substitute "blend" for "make" in the sentence and move on.Don
Sorry -- words do have specific meaning.

MAKE: means create 2 distinct images in each frame. This is an eye-tracking artifact we get with the HD1/HD10. It is very clearly 2 cars, 2 people. In reality the two images are created IN YOUR BRAIN not in the camera.


BLEND: means create 1 blurred image in a frame. This is what we get from the HD100. It is the point of the MF.

Perhaps you aren't as ready to move on as you think. :)
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Old August 13th, 2005, 10:35 PM   #15
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The camera DOES make double images when the motion smoothing filter is on. It clearly, distinctly, and absolutely does. It appears that what it does is take two frames and overlay one at 50% opacity over the other. Two images. That's what it does. And you can clearly and easily see it in the still that I posted.

And it matches with the description JVC has given for how motion smoothing works -- to takes two 60p frames and combines them to make one 30p frame. So obviously, you get two images in one. Double images.

I have the same pan in "motion smoothing" and "not motion smoothing" modes. In the "motion smoothing" one, there's two images in the frame. In the non-motion smoothing one, there's one image per frame.

This has nothing to do with something happening in anyone's brain. It's right there in the image! You can see it in the still frame. This has nothing to do with persistence of vision or motion blur or any other explanation -- a detailed examination of the frames will show exactly what it's doing.
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