Joined: 15 Jan 2007 Posts: 395 Location: Los Angeles, CA
60i to 24p (was: Highest Quality Footage)
So I'm pretty obsessed with finding ways to make DV footage look it's absolute best. I wanted to run my technique, well, frankly, by Stu, and certainly anyone else, to see what you guys think the drawbacks might be.
I have a Sony TRV27, which is just a regular miniDV camera, 29.97. Right after I bought it, the whole 24p thing hit, but i've been nothing but happy with my camera. Since I only ever watch my movies on DVD, I have no problem with not having 24p.
Anyway, I've tried just turning Interpret Fields to OFF when I import footage into AE. I don't like it. It does wierd things in the motion blur for me.
I was also extremely excited to see "Remove DV Artifacts" on the Rebel CC toolbar included with the book, but for the life of me couldn't see a difference when I applied it. I saw a little bit of difference in the blue channel, but nothing in the main RGB.
The technique I've used for a few years now is this:
1- Import the same footage twice.
2- One Field Interpretation should be set to Lower, one to Upper.
3- Drag one of the pieces of footage to make a new comp, and put the other one on top of that at 50% opacity.
4- then I usually render out an uncompressed quicktime of this, and set a proxy to use the original footage.
The only drawback I've ever found to this techniques is that it doubles up fast moving objects. But, luckily, they're usually moving fast enough that you don't notice it on playback anyway.
Do you guys see any other problems with this workflow? From what it appears to me, it essentially DOUBLES the resolution of DV footage. Try it, and flicker the visibility of the 50% layer on and off, or snapshot it. it's a very obvious smoothing. After some comparisons of stuff, I started throwing an adjustment layer on top as well, with a Sharpen effect of 5-15, depending on the footage.
Any feedback on this technique would be great! I love it, and have had people ask me if I rented a camera, because the footage look better than stuff my friends have shot on Canon XL1's and even some HD.
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Joined: 08 Jan 2007 Posts: 917 Location: San Francisco
Well hype, I have some strong opinions about this, and if they don't jibe with your experience that's certainly OK. But The Guide is about making movies that looks like movies, and that starts with 24p (or 25p). To me, this is not negotiable, as I discuss in The Camera chapter (on your DVD). Even if your ultimate viewing medium is NTSC video, 24p is essential for a proper emulation of a big-budget look (but don't despair, I have a solution for you below that will keep you from needing to buy a new camera).
You are correct that the technique you describe, which is called "field averaging," eliminates some of the spatial artifacts of interlaced footage. But it's a double-edged sword—you trade spatial artifacts for temporal artifacts. The double image you describe is not only an example of such temporal artifacts, it's also an indication that you're using a shutter speed that is faster than you should be for a proper film-like look (if you were using a 1/60 shutter your A field and B field would average together to create continuous motion blur rather than a double image).
But, if you love field averaging, there's a faster and easier way to do it. Import your footage, set Separate Fields to Off, and then add a Box Blur with a vertical-only blur of 1 pixel (at 1 iteration).
And if you like field averaging your 29.97 footage but want a 24p master, just change the comp frame rate to 23.976 (works with either your technique or my simpler one).
But I hate field averaging. The reason I hate it is that, even at 23.976 fps, it doesn't look like film. The smeary, blurry quality of the motion is a dead giveaway that you're seeing some kind of converted video.
So while you're saving up for a 24p camera, here's what I recommend for creating 24p footage from your 60i source:
• Shoot with a 1/60 shutter. Very important, unless you are specifically going for a Saving Private Ryan/Gladiator combat footage look (in which case you'd use a faster shutter).
• Import the footage into AE, and in Interpret Footage > Main, ensure that AE is correctly separating your fields (Upper or Lower, whichever is correct for your footage).
• Turn on Preserve Edges and hit OK.
• Drag the footage to the Create Comp button.
• In the resultant comp, set the frame rate to 23.976.
Believe it or not, this is how the footage in The Green Project was treated, as I shot it with my Sony VX1000 before there was such a thing as a 24p camera. At first the footage will look stroby to your eye, but you'll get used to it.
If you haven't read through the Camera chapter on the DVD, please do. I'm speaking directly to you on page 4.
Last edited by Stu on Sun May 06, 2007 12:32 pm; edited 1 time in total
Mon Jan 15, 2007 6:45 pm
Stu Site Admin
Joined: 08 Jan 2007 Posts: 917 Location: San Francisco
Re: Highest Quality Footage
hype wrote:
I was also extremely excited to see "Remove DV Artifacts" on the Rebel CC toolbar included with the book, but for the life of me couldn't see a difference when I applied it. I saw a little bit of difference in the blue channel, but nothing in the main RGB.
It can be a subtle thing, depending on the footage. You'll see the difference most vividly where colorful objects overlap other colorful objects. Here's the before/after example from the book:
That's the blue channel on the bottom. The good news is, if you're not seeing much difference on a given shot, then you didn't have much of a chroma subsampling artifact problem to begin with!
Joined: 15 Jan 2007 Posts: 395 Location: Los Angeles, CA
Quote:
I have some strong opinions about this, and if they don't jibe with your experience that's certainly OK
I'm totally open to other opinions, that's why I asked! I could never find any solution that looked better, so I stuck with it.
Your quicker, easier frame averaging is great! Kinda bummed that, having just learned it, I'm now going to abandon it for your 60i - 24p. It worked great!
There's something I don't get, though. Is it just removing/dropping frames? Playing back 60i footage at 23.976 means that, since the overall run length is very minimally affected, 6 frames a second are going somewhere, right? And are they taking the sound with them? I don't see how they couldn't. I didn't notice anything strange watching the RAM preview, but it doesn't make sense to me. If it isn't dropping frames, it should lengthen. I'm sticking with it, I just want to understand what's happening.
And you're right, of course, I never bothered to check the shutter speed on my camera (reading that probably sounded like nails on a chalkboard to you! ). But, my camera is more towards the consumer end, not the professional end, so I have very minimal shutter control. I can't find what the default shutter speed is anywhere in the manual or on the camera's menu, but i have a selection of 4 other shutter speeds besides the elusive default one: 1/4, 1/8, 1/15, and 1/30. I'm guessing I should go with the 1/30, since it's as close as I have to 1/48, and then adjust my aperture manually. Does that sound right to you?
Sean
_________________ if it's not fun, what's the point?
www.mackdadd.com
Joined: 08 Jan 2007 Posts: 917 Location: San Francisco
Those shutter speeds are "special effects" shutter modes, where you get a slow frame-rate and a ton of blur, along with 1/2 the vertical resolution. For 60i -> 24p, you want 1/60, no more, no less.
The reason that you don't have any audio problems when going from 29.97 to 23.976 is that you're still playing back your footage at the same speed, you're just refreshing the screen less often. You're not throwing away six frames per second, you're throwing away 12 fields (out of 60).
This is kind of thing After Effects handles with ease, but other frame-based compositing apps would choke on.
Joined: 15 Jan 2007 Posts: 395 Location: Los Angeles, CA
Bummer. Apparently my camera doesn't have a manual shutter, and, after scouring the internet and my user guide, I can't find any kind of listing on what the default is.
So, I guess I'm gonna start saving. Thanks for all the info, and setting me straight!
Hmmm... makes me wanna go back and fix my last two short movies...
Sean
_________________ if it's not fun, what's the point?
www.mackdadd.com
Hey Stu, I'm using an HVX in Filmcam mode.
My shutter is in degrees.
I've been using 200 degrees because some people recommended on DVXUser.com.
What are your thoughts on this?
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Sat Jan 20, 2007 10:49 pm
Stu Site Admin
Joined: 08 Jan 2007 Posts: 917 Location: San Francisco
I have no idea why that would be preferable—I always use 180º with the HVX. But I'd love to be enlightened, could you post a link to the thread?
Joined: 08 Jan 2007 Posts: 917 Location: San Francisco
Here's another case where I have a strong opinion about something that clearly conflicts with some others' experience. Personally, I think the advice referenced in that thread is dangerous and bad for digital cinema.
I rant on in The Guide about the importance of a 180 degree shutter, and it's for a good reason—film cameras are mechanically constrained to this limitation. Every time I hear about some new digitally-shot movie suffering from "looking like video," further investigation reveals that the films in question (Collateral and Apocolypto spring to mind) were at least in part shot with greater-than 180 degree shutters, usually in the name of increased light sensitivity.
I hate this "look" and so do audiences, although they don't know why. But it sets back the digital cinema effort every time someone can't quite put their finger on why a digital movie doesn't quite look like a movie.
What aspiring DV Rebels learn when they first pick up a 24p camera is that 24p strobes like hell. True for the HVX200 and true for film. Cinematographers have been dealing with this for years, and there are rules-of-thumb for acceptable panning speeds and tricks such as making sure you always pan with a moving object. But if you've been shooting silky-smooth 60i video your whole life and you suddenly enter the world of juttery 24p, it's natural that some adjustment, both in shooting style and in viewing the results, will be necessary.
Settings in 24p cameras that take away strobe are taking away the very artifact that makes film film, the very reason you wanted a 24p camera in the first place.
Joined: 08 Jan 2007 Posts: 917 Location: San Francisco
megohead wrote:
Hey Stu. Love the book! what do you think about this mehtod of transforming 60i into 24p from Andrew Kramer of videocopilot.net?
Thanks megohead!
Andrew's technique is no differnt than mine, just a different way of getting there.
To add pixel motion time remapping to my technique, just turn it on for the layer by selecting the layer and choosing Layer > Time Remapping > Pixel Motion. Same rules for previewing and rendering apply from the "Playing with Time" section of The Guide.
Pixel Motion will work great on some shots and badly on others—just turn it off if the results are poor. I didn't use it on The Green Project because there was too much motion in the frame.
Joined: 15 Jan 2007 Posts: 395 Location: Los Angeles, CA
Interesting to me that you suggest pixel motion, Stu, when the comp frame rate version you mentioned seems to work pretty dang good without it. Granted, you do say it works great on some shots and bad on others. Doesn't pixel motion soften frames by removing "grain" (perhaps the artifacting of DV)?
Perhaps it's just an instance of what's more important - cool slow motion, or consistent video artifacting.
Honestly, though, I haven't used pixel motion on video at all, only film frames, where it does definitely remove the grain. Maybe it's not an issue at all on video.
(I keep rereading sections of the book, and re-onlined one of my shorts this weekend. What a phenomenal resource the Guide is!)
_________________ if it's not fun, what's the point?
www.mackdadd.com
Joined: 08 Jan 2007 Posts: 917 Location: San Francisco
Remember, this isn't a slow-motion technique, it's just a frame-rate conversion. As you point out, the difference between using pixel motion and not is very slight.
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I could never find any solution that looked better, so I stuck with it.
). But, my camera is more towards the consumer end, not the professional end, so I have very minimal shutter control. I can't find what the default shutter speed is anywhere in the manual or on the camera's menu, but i have a selection of 4 other shutter speeds besides the elusive default one: 1/4, 1/8, 1/15, and 1/30. I'm guessing I should go with the 1/30, since it's as close as I have to 1/48, and then adjust my aperture manually. Does that sound right to you?