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Old June 7th, 2006, 12:02 AM   #1
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JVC 720 60p to 24p "overcrank" clip

Hey all,

A friend of mine and I shot a little bit with his JVC and the XL-H1 yesterday. We captured the JVC's analog 60p output (Kona SDI/Sheer codec) with the intention of doing an "overcrank" slow motion effect from it. I think it turned out pretty damn good. The clips were converted to PhotoJPEG QT 720p format to be accessible on the pc side. They're very close in quality to the uncompressed originals.

Shot 1/100 shutter:

The 24p slow mo version:

http://www.realm.cc/upload/Elton/JVC...rieSlow-1.movx

Here's the 60p "live" output version:

http://www.realm.cc/upload/Elton/JVC...Irie60p-1.movx

Right click and save, remove the "x" from the file name after downloading to make it a QT .mov


btw, I'm an H1 user but I must say the JVC is a great performer.

I wanted to post these clips for you guys to see what the 60p output can really look like when recorded and processed properly.

I'll probably have to take the clips down in a day or two as they are GIGANTIC 100+ MB files so download while you can.

Barlow

Last edited by Barlow Elton; June 7th, 2006 at 11:03 AM.
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Old June 7th, 2006, 04:47 AM   #2
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maybe the links are broke

but nothing is downloading??
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Old June 7th, 2006, 05:23 AM   #3
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Seems to work now.

Last edited by Barlow Elton; June 7th, 2006 at 11:03 AM.
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Old June 7th, 2006, 08:44 AM   #4
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Quote:
Originally Posted by Barlow Elton
I have the links to these clips posted on one other forum and they work. Maybe the links were broken here due to that.

Sorry 'bout that. Didn't mean to offend. I thought it would be of interest to the JVC folks.
Barlow,

I tried downloading and my download window said 'file doesn't exist'. Could you re-check the links for errors.

-gb-
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Old June 7th, 2006, 11:04 AM   #5
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Quote:
Originally Posted by Greg Boston
Barlow,

I tried downloading and my download window said 'file doesn't exist'. Could you re-check the links for errors.

-gb-
Rechecked. I think it works now.
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Old June 7th, 2006, 01:34 PM   #6
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WOW! Beautiful clips!

These are gorgeous! Great job!

Can you please tell me exactly what you did to get the "overcrank" slow-mo effect? Thanks!
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Old June 7th, 2006, 04:32 PM   #7
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Very nice. It's got that characteristic softness of having the iris wide open, but it's still nice. Do you recall what the f-stop was?

Am I understanding correctly that you captured this directly to your computer with a Kona card?

The 1/100th shutter works really well. On some 60pSDHDV tests Iíve done I used 1/250, but the background could get a little juddery that way. 1/120 is probably ideal (accessed using variable shutter).

Thanks for posting.
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Old June 7th, 2006, 06:00 PM   #8
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Oh cool - Barlow posted it here. He captured directly using the Kona SDI card/G5. Iris was F2.8. ND filter was set to the middle one. He actually wanted 1/120 shutter but I'm still a beginner so I thought 1/100 to 1/250 were my choices.

Chad, I need to try your settings for slomo. This is from HDV via firewire, right? I desperately need good slow motion tomorrow but I'll be using HDV tape.
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Old June 7th, 2006, 07:33 PM   #9
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Quote:
Originally Posted by Perry Shumway
These are gorgeous! Great job!

Can you please tell me exactly what you did to get the "overcrank" slow-mo effect? Thanks!
Thanks Perry. I hadn't seen any examples of JVC 720 60p from the analog uncompressed out yet, so I bugged George to go out for a test shoot with me, just to satisfy the curiosity.

Since this seems to be one of the stronger JVC communities, I figured some of you might get a kick out of it.

The Breakdown:

What we did was run the component analog RCA outs of the HD100 into my Kona LH card, which has analog HD input and can record all flavors of HD. I captured via FCP to a new codec I've been using called Sheer Video which is actually lossless and bit for bit the same as uncompressed. The quality of the codec is amazing . It took about a 42MBs data rate to sustain capture, and believe it or not my internal Western Digital 320GB 8MB cache SATA drive kept up with it. We got away with it, but I'm pretty sure I was recording to the faster part of the drive. I think longer sustained captures might've dropped frames here and there. To be comfortable, you really need a 2 drive SATA raid.

The clips were converted to PhotoJPEG at high quality, which is actually better than DVCProHD and maintains full raster sampling. So what you're seeing is true 4:2:2 720p in a clean and efficient codec.

I took the 60p captures and brought them into Cinema Tools to conform the frame rate to 24fps instead of 60fps, (technically went from 59.94 to 23.98) which just like the HVX yields true "overcrank" slow motion. If you download the 60p shot you can try this yourself, if you have Cinema Tools or Nattress Standards converter FCP plug-in. IMHO, I think the slow mo shot looks a great deal like very good Super16.

I have a few other nice slow motion clips but that one should give you an idea of the potential of the analog output. With frame rate software conversion tools, it's also possible to get the 60p to "overcrank" at different speeds like 48fps, etc. You can also use tools like Twixtor to interpolate synthetic frames from the 60 you've captured and probably get a convincing 120 fps slow mo look too.

I think the new 250 camera will be very cool having 60p recorded to tape.

Last edited by Barlow Elton; June 7th, 2006 at 08:07 PM.
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Old June 7th, 2006, 09:15 PM   #10
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Thanks for the detailed description, Barlow. What was your zoom set to? It still seems like it's got that soft purple feel around the edges due to the iris being further open and more zoomed in. I find if you're beyond 40mm on the zoom you need to be at an F4 or greater on the iris to keep it sharp. In general F5.6-F8 is the sweet spot I think. Though this sucks for us film-makers who crave shallow depth of field!

It's probably my computer, but I've never been able to edit anything set to the JPEG codec. Of course that was back when I was editing 1080i, so maybe things would be diff. with 720p. I'm on a PB G4 1.25Ghz w/ a FW800 LaCie drive. I don't like Apple's Intermediate codec because it shows just a tiny bit more macroblocking than DVCProHD, but it lowers the resolution and takes up more space... Everything's a trade-off.

George: 60pHDV-SD is simple with this camera. Just switch over to 60/30 timebase and then to HDV60pSD. Set your shutter to 1/100th or 1/250 (or 1/120 if you want to go into variable speed shutter and get the technically correct shutter based on twice the frame rate - 24p = 1/48, 60p = 1/120. This looks the most natural, but it's all subjective. 1/100 will be slightly blurrier on fast motion, 1/250 will stop most action and give you the "Gladiator" type of slow-mo --very little motion blur). Then record 60p, capture mt2 file in your desired way, transcode to a 60p stream of your desired codec (if uprezzing to HD, be sure to do so at this point as MPEG Streamclip does a great job here). Then conform your clip using Cinema Tools or whatever you have to 24p.

We've actually got a couple of slow-mo portions in our upcoming short. The tests we did outdoors look great when uprezzed to HD. You also have the option of using PAL for 540 or so lines of resolution, but 50p instead of 60. I prefer to get it as slow as possible and taking the hit on resolution. It still looks nice and for DVD release, you won't be able to tell the difference.

Does anyone know how to shoot so that you can play part of the clip at normal speed, but then suddenly slip into a silky smooth slow mo? It's a very popular effect and looks to be done pretty effortlessly (no high end tricks). Whenever I try it, the playback at 24fps normal speed looks very stuttery because of the higher shutter speed, but the slow-mo is fine. Any ideas?
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Old June 7th, 2006, 10:43 PM   #11
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I think Joe's filters has a pretty good plug-in to do ramped slow motion. I don't think any of the low cost HD cameras can do ramped slow mo in camera.

That's pretty cool to be able to shoot SD60p and uprez reasonably well to 720p.

George shot the clip so I don't know exactly what his zoom was at but I think it was pretty close to max.
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Old June 7th, 2006, 10:49 PM   #12
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It think it would have been interesting to have recorded 30p to tape and compared the analog capture to the HDV, or at least compare the frames that weren't thrown away. See how much you lose by adding that extra analog step in there. Or perhaps see how much you lose going to HDV, who knows.
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Old June 7th, 2006, 11:34 PM   #13
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It's a lot like the Canon. The HDV holds up very well compared to the uncompressed but there is a slight loss of color resolution that is barely perceivable.
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Old June 7th, 2006, 11:44 PM   #14
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Thanks, Chad I'll try those settings for slow motion. The zoom was definitely close to max most of the time we were shooting. Next time we do this, I'll stay within the sweet spot of the zoom and close down the iris a little bit more. I was absolutely amazed when Barlow showed me the H1 footage resolutionwise.

Barlow, anytime you're ready :-)
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Old June 8th, 2006, 01:22 AM   #15
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By contrast, here is a 30p clip slowed down.

Click here for WMV

It's not nearly as smooth but still effective. The clip is excerpt from our latest doc titled "Separated".
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