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Digitize Super 8 film to 18fps or 25/30fps?

I am finally going to digitize old Super 8 films.

The service uses Rank Cintel 4K scanner which scans frame by frame to ProRes 422HQ 1080p format (I guess they add black borders to the 5.79 x 4.01 mm Super 8 frame to fit it to the 1920x1080 ratio). That costs somewhat and I'd like to do it properly (I do know the input quality is very low but I'd like to squeeze every possible detail out of those old films).

Frame rate is one thing I am still concerned about. Super 8 is 18fps while the local TV standard is 25fps and mobile devices are forcing 29.97/30fps to the mix.

Initially I planned to let them save to ProRes 422HQ @ 18fps. But they recommend 25fps because 18fps is incompatible with TV standards and editors.

I plan to edit the footage and export it as .mp4 watch it mainly on a computer monitor or an iPad and occasionally on an OLED TV. I think computer monitors should have no trouble with 18fps, right? But I am not sure about modern TVs.

Should I let them scan at 18fps, 25fps or even 30fps? Is 18fps asking for trouble in Final Cut Pro 10.4.8 and on a TV?

I can spot uneven movements when watching footage converted 25<->30fps by duplicating or skipping frames. I have successfully mixed some 25 and 30 fps clips in the same project via Final Cut's "Automatic Speed" which does not skip or duplicate frames but instead shortens or lengthens the clip respectfully.

I was planning to do the 18->24/30fps conversion by adding duplicate frames in Final Cut later, IF necessary. Adding duplicate frames should be easier than removing them, right? But would that work because Final Cut lacks 18fps setting and I'm not sure if even editing its exported .xml project file works anymore.

What do you think?

Posted on Jan 20, 2020 12:27 PM

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Matti Haveri Author

Level 6

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Posted on Feb 8, 2020 11:40 AM

The service did the test clips for me.

Neither Apple ProRes nor the usual applications (FCP, Premiere, After Effects, DaVinci Resolve) do not seem to support 18fps (*). So the service exported each scanned frame to a 25fps 1920x1080 ProRes 422 HQ file (actual image area is 1444x1080 with 238 pixel black borders on both sides). That ”raw” ProRes material is further edited so the 139% fast-motion (18fps played at 25fps) frame rate was not important at this step.

I can edit and slow down the clips in Final Cut Pro X to their normal speed. For such a (Super 8) 25fps project, 72% ”slow-motion” yields the normal speed (18/25 = 0.72). That same 72% applies also when that 25fps ProRes clip is dropped to a 30, 50, or 60fps project while a 24fps project needs 75% to keep the project length exactly the same with normal speed. In each such project just the correct number of frames are added with the desired method (duplicate, blend, optical flow). No extra generation loss.

The service routinely makes also a 25fps H.264 25Mbps MP4 delivery version with 18->25fps conversion with a chapter every 3 minutes with the correct speed and duplicated frames (these are silent films but they used their usual 71.85% “slow-motion” that fits Super 8 audio to the total project length so the actual frame rate is then about 17.9625fps).

I now recalled that one old Super 8 project was actually shot at 12fps for a comic effect. If needed, I can now easily adjust its speed to normal with minimal extra fps conversion artifacts with a 48% slow-motion in FCP.

The quality was good (the low-res demo clip link in my earlier post is old and was not done with their current Rank Cintel 4K hardware).

(*) With great effort and lots of trial and error I managed to make an animated 60 second 18fps MP4 test pattern clip via Photoshop, FCP, QuickTime Player 7's 24fps Image Sequence with a pattern of duplicated frames, that were then stripped off via VLC's conversion to 18fps. My LG OLED TV played it OK.

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28 replies

Jan 21, 2020 12:21 AM in response to betaneptune

it should not accelerate at all. If a technique like pull down is used it creates an additional frame every 3 that is blended and the timeline is kept the same. This is what you want otherwise there is on added value to this process you convert them at 18 fps and then manage yourself...

Matti Haveri Author

Level 6

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Feb 9, 2020 4:53 AM in response to betaneptune

Thanks for the tips:

I could indeed convert my 18fps H.264 .m4v file to 18fps ProRes 422 .mov file via Finder's Services. I now noticed that Final Cut Pro X 10.4.8 Inspector (cmd-4) at the upper right reports it to be 23.98fps but at the left above the film strip 18fps is correctly reported. Confusing. Anyway, the calculations are correct so Automatic Speed makes it play unique (not duplicated) frames in any FCP project (in a 24fps project at 133% speed, in a 25fps project at 139% speed, in a 30fps project at 167% speed and so on).

And I could indeed export the imported clip from the FCP browser as 18fps ProRes 422 HQ file. It just didn't previously cross my mind that I could export via that route because I was so used to exporting only projects from the timeline. What I can't do is make a 18fps Final Cut Pro project and export that.

I don't know in what codecs or maybe more importantly what frame rates the service's scanner can export. They did say that outputting TIF codec was one option but the file sizes would then be unpractically large. Creating brand-new 18fps files seems to be difficult.

I am hesitant to ask them diverting from their proven workflows because that might yield undesired results.

Feb 26, 2020 1:27 PM in response to Matti Haveri

Greetings,

Thanks for the info.

I'm still a bit puzzled why your transfer company has a problem with frame rates. Yeah, it'd be great for the editing programs to be able to do 16 and 18 fps. Regular 8mm was a 16 fps deal? Or sometimes 16?

And it's not like you and I are the only ones with 18 fps footage! The company I used told me it's just a number in the metadata in the file. You could make it 97 if you wanted.

BTW, the link for the ruby argument attached the )" to itself, so I initially got the old 404 bit. Please post links cleanly with no attached characters.

OK.

Matti Haveri Author

Level 6

19,664 points

Feb 27, 2020 12:27 AM in response to betaneptune

Yes, I noticed that part of the Terminal command for the "Homebrew" installation was incorrectly interpreted as a link (the editing window for the message had then closed but obviously you sorted it out. I now put those Homebrew, ffmepg and mkvtoolnix installation commands and the frame rate conversion commands in the additional text in this message. I hope they are not as badly mangled there. One command in one line).

Just for fun I tested m4v files converted 6.25, 12, 12,5 and 18fps on my LG OLED TV. It could play them all but at least those very non-standard 6.25 and 12.5fps had disturbing jerky movements. 18fps played OK.

Terminal commands

Feb 8, 2020 6:45 PM in response to Matti Haveri

I just checked out the Automatic Speed function. ****, I could have used that on a particular clip when I needed to do noise reduction at 18 fps, as there were problems doing it at 29.97. So I actually opened the clip in the timeline -- something I really don't want to do! I'll know for next time.

Feb 9, 2020 2:24 PM in response to Matti Haveri

"I now noticed that Final Cut Pro X 10.4.8 Inspector (cmd-4) at the upper right reports it to be 23.98fps but at the left above the film strip 18fps is correctly reported. Confusing."

Is your project at 23.98? That would explain the upper-right corner. But 18 fps should appear if you select the clip in the browser, or if you look in the table in the browser after adding the "video frame rate" column. But "at the left above the film strip"? I don't see anything there. What version of FCP are you using?

Note that if you open the clip in the timeline via Clip>Open Clip, you will see the clip's frame rate. I don't recommend editing a clip directly like this except in very unusual circumstances.

Matti Haveri Author

Level 6

19,664 points

Feb 10, 2020 11:50 AM in response to betaneptune

That confusing 23.98p Inspector (cmd-4) info for a 18fps imported media clip is at the upper right (before any project is even created to the timeline -- see attached screenshot). But the Browser's Frame Rate column (and that info at the upper left) correctly show 18 fps.

I was surprised that the service routinely uses 71.85% slow-motion to convert the unique-frame-fast-motion 18->25fps ProRes 422 HQ to normal speed instead just using 72% (18/25 = 0.72). So the effective Super 8 frame rate is then 17.9625 fps. They said that Super 8 audio needs that fine adjustment to keep it in sync in long projects and even that detail somehow relates to mains frequency of electric grids. I accepted that little oddity even for my silent project because 18->25fps conversion isn't so evenly spaced as 18->24/30fps conversions are (112 or 221 duplicate frame patterns). Is a similar fine adjustment needed for Super 8 audio in 29.97/30fps conversions?? (They give me also the unique-frame ProRes version so I can do whatever % fps conversion I want in the future).

It is strange that brand-new 18fps files seem to be so difficult to create.

Is it really so difficult or impossible to edit a modern video file's metadata to some other frame rate and duration without duplicating/skipping frames and re-encoding the video?

Feb 10, 2020 3:30 PM in response to Matti Haveri

23.98 is the default speed for a project. What version of FCP do you have? In mine they're always both the same. If I click on a clip in the browser I get the speed of the clip in the browser for both. If I put focus on the timeline area I get the project speed for both. I can't reproduce having different speeds at the same time. I'm using FCP 10.4.6.

I don't know anything about a 71.85% conversion factor. I don't have any Super 8 sound film, so I can't answer that part, either.

I don't know why they can't put whatever frame rate they want in the metadata portion of the file. Doing it after the fact would be hard if it's written in binary.

Feb 10, 2020 3:41 PM in response to betaneptune

I found a way to reproduce it. If I press Cmd-J I get the project speed in the upper right-hand corner and it stays at 18 fps on the left. That's probably what you have. So click on an 18 fps clip in the browser and then press Cmd-J.

Jan 21, 2020 1:15 AM in response to Interceptor121

@Interceptor121:

My point was to exercise caution because of the word you yourself used: "should". You don't want them to have done an expensive transfer and then have it come back different from what you expected! I myself chose 18 fps and would do so again. Final Cut can do the telecine, dropdown, or WTFIC bit. You need to make sure first that they know what you want them to do or how it should come out.

I don't understand your second sentence.

Feb 8, 2020 4:08 PM in response to Matti Haveri

Thanks for keeping us informed!

Matti Haveri wrote:

The service did the test clips for me.

Neither Apple ProRes nor the usual applications (FCP, Premiere, After Effects, DaVinci Resolve) do not seem to support 18fps (*). So the service exported each scanned frame to a 25fps 1920x1080 ProRes 422 HQ file (actual image area is 1444x1080 with 238 pixel black borders on both sides). That ”raw” ProRes material is further edited so the 139% fast-motion (18fps played at 25fps) frame rate was not important at this step.

Who does this "further editing"? You or them? And why is it not important?

Also, Apple ProRes 422 does support 18 fps. I have 18 fps clips in the browser. So Final Cut supports it in the browser just fine, but projects cannot be set to that frame rate. Copy that clip to the timeline and it will be converted to whatever other rate your project is set to.

I can edit and slow down the clips in Final Cut Pro X to their normal speed. For such a (Super 8) 25fps project, 72% ”slow-motion” yields the normal speed (18/25 = 0.72). That same 72% applies also when that 25fps ProRes clip is dropped to a 30, 50, or 60fps project while a 24fps project needs 75% to keep the project length exactly the same with normal speed. In each such project just the correct number of frames are added with the desired method (duplicate, blend, optical flow). No extra generation loss.

I do not understand this part. OK, you get a 25 fps transfer with no dropped or duplicated frames. And it will run 25/18 too fast in a 25 fps project. So you slow it by 0.72 with the retime function. But how can that same number (0.72) work for any other frame rates? Also, if you go from 25 to 24, you will need to drop frames. But this all depends on the 139% fast motion step above, which I do not fully understand and do not see how it cannot be important.

[Rest of quote post omitted.]

Matti Haveri Author

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Feb 9, 2020 2:13 AM in response to betaneptune

The service made two ProRes versions for me: A) unique frames at 25fps and B) 18->25fps conversion with duplicate frames (112 12 112 12 112 112 12 duplicate frame pattern). They exported the MP4 25fps delivery version from "version B". I can myself make "version B" by dropping "version A" to a 25fps FCP project timeline, doing a 71.85% slow-motion the service routinely uses, and exporting it as ProRes 422 HQ. So now I'm wondering whether I want them to do deliver "version B" because it bloats the archive more than 2x. But maybe I get also "version B" because someone in the future might not have the editing tools I now have.

The service tried to make 18fps (I believe they used FCP and After Effects). They could export at 18fps (not sure whether it was ProRes or MP4) but they said that the exported file played at the wrong frame rate anyway or that the file didn't otherwise seem to be correct. I tried to find info about the ProRes spec and the applications and 18fps support seems severely lacking. FCP sees the 18fps MP4 clip I mentioned in my previous post as 23.98fps and behind the scenes seems to treat it as 18fps in its calculations so it can import 18fps but exporting back to 18fps seems nearly impossible.

How did you get a ProRes 18fps clip? I read that some older FCP versions could be hacked to make 18fps by editing the .xml project file or something like that.

So to play it safe we settled for a standard proven workflow. I can use that ProRes "version A" as a master file if I need to re-edit the project to match various frame rates with minimal fps conversion generation loss.

I first thought that I'd have to slow down a 30fps FCP project to 60% (18/30 = 0.6). But if I drop "version A" 25fps ProRes clip to a 30fps timeline, FCP duplicates frames to keep its duration and 100% speed the same. So also in the 30fps project a 72% "slow-motion" is needed for normal speed (then frames are duplicated in a steady 221 221 pattern because in effect a 18->30fps conversion is made). That same 72% applies also to 50fps and 60fps projects. (FCP sees "version A" ProRes clip's speed as 100% while in reality it is fast-motion ~139% (25/18 ~ 1.39) from Super 8's 18fps. ~1.39 x 0.72 = 1).

(On the other hand, FCP does 25->24fps conversion by doing a 96% (24/25 = 0.96) slow-motion behind the scenes while misleadingly still showing 100% speed thus making the clip slightly longer (obviously this is the standard way of doing 25<->24fps conversions). So such a 24fps project needs 75% (0.96 x 0.75 = 0.72) slow-motion to keep the duration exactly the same -- frames are then duplicated in a steady 112 112 pattern because in effect a 18->24fps conversion is made).

Feb 9, 2020 2:42 AM in response to Matti Haveri

@Matti Haveri

I'll check the rest of your post later, but this is how I got 18 fps ProRes 422.

I dragged an 18fps Motion JPEG A file into the browser. If you enable the Video Frame Rate you can see what the frame rate is. In my case it's 18. I can also convert an 18 fps Motion JPEG A file with the Finder by right-clicking the file and then Services > Encode Selected Video Files. Enter your settings and go! (Be sure to wait for the file size to grow. There is no "Done" notification of any type.)

While it's 18 fps in the browser, it will be converted to something else in the project's timeline. You could use the Automatic Retime function to eliminate adding frames when you copy the clip to the timeline, but then it will run too fast.

I don't know why they're having trouble exporting at 18 fps. It's just a datum in the metadata in the video file. You could make it 3 if you want. I got mine transferred that way (at 18) and it came out as desired. And with no blended frames.

Here's a snapshot of the QT7 Pro Info pane of a movie I converted using the Finder method (High Sierra OS). I believe you can also export clips directly from the browser. What you can't do is make a project at 18 fps. But it has nothing to do with ProRes 422. Maybe the HQ version is limited in that way. IDK. BTW, you need the HQ version for Super 8? What type of film was it, if you don't mind me asking. Kodachrome? Ektachrome? Other?

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Digitize Super 8 film to 18fps or 25/30fps?