How to convert 29.97 interlaced to 23.98 progressive with smooth motion

Hi LAFCPUG!

Some material for a project I'm editing has been shot at 29.97 interlaced by mistake.

(There is no "advanced pulldown" or other pulldown in this footage - it's just normally interlaced 29.97 NTSC)

I need it to be 23.98 progressive.

My project is NTSC, 480x720 16:9 anamorphic, 23.98 progressive.

I've tried editing the 29.97 footage into my 23.98 timeline, and Final Cut Just takes out some frames to make it fit, causing motion to look jerky.

I've tried using the Reverse Telecine function and the Conform function in Cinematools to convert the 29.97 interlaced to 23.98 progressive, but I ended up with distorted jagged edges on anything moving in the frame.

Is this conversion possible with cinema tools, without missed frames or jagged edges?

Does anybody know what the right settings are in Cinematools?

I'd be really grateful for any advice and help.

Thanks very much in advance,

Andy Wills

If it's shot at 29.97, there isn't anything to reverse telecine to.

Use Compressor, throw on a DV 24fps setting and turn on frame controls and set retiming to better or best.



www.strypesinpost.com

Woah woah woah. I think you have a typo there, Strypes.

Andy, do not use a DV setting in Compressor unless the rest of your footage is also DV. A lot of people don't realize how truly crappy DV is, as a video format. If you have a timeline that's (to use an example) uncompressed 10-bit, and you insert a DV shot into it, it'll stick out at you like a sore thumb. If you want to use his approach, do as he said, but use a preset that matches the rest of your footage.

There are really four ways to handle this; Strypes' suggestion is one of them, but it may not necessarily be the best possible one.

Option one is reshoot. You might say "Oh, but we can't reshoot," but you really, really can. Trust me. Footage that was shot at the wrong frame rate should be handled just like footage that was shot out of focus. It cannot be fixed in post, period, and must be reshot. It stinks, but that's how it is.

That said, if you really really can't reshoot, like it was an interview and the interview subjected up and died or something, then there are three other options for handling this.

The first other option is to run the footage through a hardware standards converter, like a Teranex or an Alchemist. This isn't free, obviously, 'cause you have to take the stuff to a post house with one of those converters. But if you're dealing with a small amount of material, it won't be very expensive. You'll get results that aren't perfect, but that will probably be quite good. Ask the producer you talk to at the post house if they'll let you run a minute or so through for free first, as a test to see if it'll work. They'll probably say sure.

The second other option is what Strypes suggested. Benefit: It's free. Downside: The results will likely be pretty bad. They may be acceptable if you're lucky; they definitely won't be good. Other downside: This process is unimaginably slow. If you've got a lot of off-frame-rate material, you literally might have to take days to process it all. In that case, you're best off minimizing the amount of off-rate stuff you use in your timeline, and only converting the shots you need with handles.

The third other option is to get creative with it. Material that was shot at 60i with a 180° shutter can be treated like half-resolution footage that was shot overcranked. That is to say, with the right tools it can be conformed to play back at 24 (or 23.976, or whatever) without interpolating it, by treating each field as if it were a half-resolution frame. When you handle the material that way and play it back, it runs two and a half times slower, and looks slightly soft, but is generally not objectionable. If you can find a way to creatively use this stuff as slow-motion, then you're in the clear.

Yikes. I thought I saw DV NTSC. Yea, if you want to convert, convert to whatever format the rest of your footage is. But use Compressor, rather than Cinema Tools. Or, as Jeff mentioned, go hardware if you can (Alchemist/Teranex, etc..).

It really depends on what the subject is. If it's a talking head on a non-busy background, you should be able to get away with Compressor. If it's a lot of action, it's a reshoot.



www.strypesinpost.com

True, it's highly shot-dependent. Something to be aware of before you being is that 60i material converted to 24p tends to look "strobey," because the motion blur is wrong. I did a short about a year and a half ago that mixed 24p footage, overcranked footage intended to play back at about 2:1, and just one shot that was 60i. (It was truly unavoidable, because that just-one-shot happened to be live footage from the pool camera that recorded the president elect's acceptance speech on election night.)

I was able to get away with it to the client's satisfaction, but man was it ugly. The shot only lasted about two seconds, and it was just a guy delivering a line at a podium, but it looked really weird because of the motion blur.

That, as well as other factors. Most standards converters today rely on optical flow. Although it's really cool and you can get away with a lot of things, there are certain circumstances that prevent it from working as well as it should. Eg. amount of action, whether there are objects moving in different directions, multiple planes within a shot, moving speculars, amount of video noise, amount of blur, etc... Also, the more the algorithm has to guess the more errors it tends to make (eg. time warp at 4% of normal speed vs time warp at 50% of normal speed footage)

That said, I wonder if anyone has seen the hardware converters fail on some of the trickier shots (eg. erratic motion blur).



www.strypesinpost.com

Hey, Andy, I'm trying to understand your question.

Quote
Andy
My project is NTSC, 480x720 16:9 anamorphic, 23.98 progressive.

I've tried editing the 29.97 footage into my 23.98 timeline, and Final Cut Just takes out some frames to make it fit, causing motion to look jerky.

1) If your project is 720x480 anamorphic 16:9, then the horizontal field is less than 720 lines.

2) If your 29.97 footage is Standard 29.97 DV then it's probably 4:3, and 720x480 non-anamorphic.

So it would seem to me that your 29.97 DV footage might be better quality in comparison. Beside making it into 23.98 fps you will need to crop it to 720x405 and then squeeze it into an anamorphic frame size of 720x480 (in other words stretching the height from 405 to 480 and leaving the width at 720 pixels.)

Now as to converting the 29.97 fps footage to 23.98 fps -- here strypes and Jeff are experts at doing this sort of thing. However, this is one of my biggest headaches because I've never figured out how to do it on my own using FCP Studio 5.04.

In my experience it has been all the different problems of dealing with this conversion. Jeff has gone into several considerations in dealing with the frame rate and the options. Strypes also mentioned the subject matter variations.

So, here is the question: if your shot is 29.97 fps and it was shot as 60i and, let's say, shutter angle set at 120, then what you have is 60 half fields and twice the normal sharpness (shutter angle 60 being the normal "blur" resolution -- normal blur in the sense of what looks best for motion picture projection).

Then if you used "blend fields" in converting the 60i to 30p (29.97fps), you'd end up with the normal blur amount, and as your shutter angle was 120, sharpness of the shot would not be worse than the normal 60 degree shutter angle of normal photography.

So what my assumption would be is that the 29.97fps original footage wouldn't suffer too much in comparison.

I appreciate further comments on these assumptions, because I don't have extensive knowledge of these matters.

Quote

Beside making it into 23.98 fps you will need to crop it to 720x405 and then squeeze it into an anamorphic frame

That's really bad advice, Vic. Anamorphic optics do not work that way. Besides, Andy didn't say anything about having to mix aspect ratios, so either all his footage is anamorphic, or he already has that taken care of. Let's try not to confuse the issue.

Quote

if your shot is 29.97 fps and it was shot as 60i and, let's say, shutter angle set at 120

I'm afraid that's not accurate either. You're confusing shutter speed with shutter angle. I don't have time to give a full explanation right now, but you can google up the details. Suffice to say that at 60 fields per second, you'd get a 1/120th shutter from a 180° shutter angle.

Quote

then what you have is 60 half fields and twice the normal sharpness (shutter angle 60 being the normal "blur" resolution -- normal blur in the sense of what looks best for motion picture projection

No, I'm sorry, that's also not right. By convention, shutters are always set to 180°, which gives you a shutter speed that's half your frame rate. At 24 frames per second, you'd have a 1/48th shutter. At 60 frames per second, you'd have a 1/120th shutter. It's the ratio of shutter speed to frame rate that determines motion quality, and Andy didn't say anything about not using a 180° shutter. So his motion quality will be fine when played back at 60 fields per second. It will also be fine if he plays it back at 24 frames (instead of fields, using vertical interpolation) per second, because it's still a 180° shutter regardless of the speed at which you look at the frames. It will not be fine if he digitally processes his footage so it plays back in real time but at a different frame rate. Even with the best possible digital frame-rate conversion, he'll end up with footage that's running at 24 frames per second but that was shot with a 1/120th shutter instead of 1/48. This is called a short shutter, and will give the footage a stroboscopic or juddery look that won't match the other footage.

Quote

Then if you used "blend fields" in converting the 60i to 30p (29.97fps), you'd end up with the normal blur amount

There are three things wrong with this sentence. One, Andy is working in 24, not "30p." Two, "blend fields" is a speed-changing function, not a frame-rate-conversion function ? and you should never use it anyway, as it always products unacceptable results. And three, your suggestion wouldn't work anyway for the reasons I described above.

I appreciate your willingness to help out, Vic, but please check your facts before posting next time, okay?

Thanks, Jeff. I've been watching too much slalom lately; I just went for it, you know what I mean? One of my Norwegian friends advised me the first time I tried slalom, "It's not how fast you go down the hill; it's how you go down the hill."

I was just trying to understand what the 29.97 to 23.98 conversion process entails.

There are six extra frames there. Per second.

Beside the two shutter speeds there are so many other factors, and here is where it's difficult to figure out what an editor is supposed to do. I've heard Teranex and Alchemist mentioned before. I wonder what those "boxes" do. But that will be too much to ask for, and I'm not asking for an explanation of how they work; but the question of the original post is how the conversion can be done with what's available to a FCP editor -- always a topic of interest, as some of us don't have the means to use a post house with our own personal projects.

I'm trying to help; but also I'm trying to figure out whether to shoot a feature in 60i with my Sony Z1U. I need to find a viable way of converting 60i and 29.97 to 23.98 fps without having to buy a $60,000 camera.

> I need to find a viable way of converting 60i and 29.97 to 23.98 fps without having to buy a
>$60,000 camera.

You don't. Unless you have a good reason where you need to go to 24p (eg. film out). Lots of cameras shoot 25p, and they don't cost US$60K. I'm sure many of those do 24p too. You could look at the Panasonic prosumer range.

The reason why you can't do 24pA on the Z1, is precisely because it shoots to HDV. You can't ingest and remove a pulldown when your frames are stuck in a GOP.



www.strypesinpost.com

Quote

it's difficult to figure out what an editor is supposed to do

The editor isn't supposed to do anything; this is not an editorial issue. That's why I said what I said up yonder: Off-frame-rate material should be treated just as if it'd been shot out of focus. It's an on-set mistake, and should be corrected by re-shooting. You wouldn't shoot a whole scene out of focus and then ask an editor to run a sharpness filter on it to fix the problem. You'd fire your 2AC, get the actors and crew back and reshoot the scene. Or rewrite around it if you could.

Quote

how the conversion can be done with what's available to a FCP editor

It can't be. Period. Let us have no misunderstandings about this: It is a physical impossibility to take 60i video and turn it into 24p. It cannot be done, any more than you can take an egg and turn it into bacon.

What is possible is to use some of the more obscure tools and techniques available to turn 60i video into something usable. Maybe. Depending on what you need that something to be. You can scramble the egg, or you can fry it, or you can hard-boil it, and any one of those might be acceptable. But nothing you do will ever make it bacon.

Quote

I need to find a viable way of converting 60i and 29.97 to 23.98 fps without having to buy a $60,000 camera.

That's absurd. Soderbergh shot "Full Frontal" entirely in DV on an XL1, a camera that retailed for less than $5,000 when it was brand new. Danny Boyle did the same thing for "28 Days Later." You don't need to spend five figures to purchase a camera that shoots the correct frame rate, for cryin' out loud. You can get one at a local pawn shop. Hell, you can get a brand new HVX200 for less than $6,000, and that'd give you HD!

I just looked it up. You can rent an entire Red One camera kit including lens, batteries, rails and a handful of CF cards for as little as $5,000 for a month. And that's for a frickin' cine camera! Unless you've planned an 8-month shooting schedule, the idea of plopping down $60,000 to buy a camera to shoot an indie feature is risible.

Quote
strypes
The reason why you can't do 24pA on the Z1, is precisely because it shoots to HDV. You can't ingest and remove a pulldown when your frames are stuck in a GOP.

Thank you for pointing this out to me.

Quote
Jeff Harrell
Let us have no misunderstandings about this: It is a physical impossibility to take 60i video and turn it into 24p. It cannot be done

This is a life saver for me. Thanks, man, for pointing this out to me.

The only question left is if a 35mm film shot in 24 fps is telecined to HDV tape, turning it into 29.97 fps, is it possible to convert it to 23.98 in FCP?

I'm thinking the answer is no, and therefore I have to re-telecine it and have the transfer house transfer it to 23.98 uncompressed 10bit and put it on a fire wire external drive for me.

>The only question left is if a 35mm film shot in 24 fps is telecined to HDV tape, turning it into
>29.97 fps, is it possible to convert it to 23.98 in FCP?

Yes. But you need to capture as ProRes to get rid of the GOP, then reverse telecine, preferably before you edit.



www.strypesinpost.com

Sorry, I goofed. It was telecined to DVCAM, not HDV.

Do me a favor, Vic? We're happy to answer your questions, but just to keep things tidy, let's stick to Andy's question in this thread. Would you mind starting a separate thread for your questions? Thanks much.

It's too complicated, Jeff. I don't have a handle on how to word the question.

Quote
Andy
How to convert 29.97 interlaced to 23.98 progressive with smooth motion

Sometimes the best answer to a complicated question is accidental. I think here the addition of "with smooth motion" produced the results. No, it is impossible to do the conversion "with smooth motion"!

So it's too complicated to ask how to turn 29.97 into 23.98 when these are approximate values anyway, and what do they entail anyway? Then it will take a long thread with so many issues of shutter angles (do digital cameras without spinning shutters have shutter angles? I know the Arri 20D does), then there are other issues as well: shutter speeds, number of pixels, GOPs, and a myriad of other digital complications that require a PhD in astrophysics or whatever to explain why normal people don't want to shoot with a Super 8 magnetic stripe camera to get the film look. LOL

Dear All

Thanks very much for your helpful advice.

I used compressor, as Strypes recommended, selecting the codec that matches my original material, and it worked fine for me.

When there was really fast blurred movement some artefacts occurred, but I swear to goodness, no one will ever notice them amidst the swooshing blur.

On steady shots there was no problem at all.

I turned the re-timimg and field interpolation controls to the maximum, and the re-sizing to the minimum, as there was no re-sizing involved.

It took a few hours to process a couple of minutes of footage. Everyone is happy now, my film is on it's way to Baselight, and it was a lot cheaper than re-hiring everyone and bulldozing tons of snow out of the way to make a re-shoot possible.

Cheers!

All the best

Andy