Frame rate change to digitized 8mm film

mark-y wrote on 9/4/2023, 10:21 AM

The frame rate for Regular8 and Super8 film is 18 frames per second.

Your digitized scans are either interpolated or simply sped up slightly (10%) to 20fps. You need to know which before undertaking corrective action. If they are interpolated, it's a can of many worms and you are better off leaving it alone. Slowing down 20->18 fps is relatively simple in Vegas, but personally I wouldn't bother. Most old movies run a bit fast, anyway. 🙂

DMT3 wrote on 9/4/2023, 10:51 AM

The BEST way is to render it out as a frame sequence from a 20fps project.. Then reimport to a 18 or 16 fps project.

3POINT wrote on 9/4/2023, 1:42 PM

The BEST way is to render it out as a frame sequence from a 20fps project.. Then reimport to a 18 or 16 fps project.

I think that isn't necessary. In Vegas you can directly import a 20fps video at projectframerate. Projectframerate can be 16 or 18fps. Just right click 20fps video in media tab and choose import at projectframerate.

DMT3 wrote on 9/4/2023, 3:47 PM

@3POINT I have never tried it that way, but if it imports without interpolation, then that is better.

mark-y wrote on 9/4/2023, 4:10 PM

Why don't you upload a sample of your 20fps original footage to Drive or Dropbox, so folks can look at it.

It does make a difference whether it was sped up, interpoloate, or has some form of frame cadence. Each would require a different approach, if unbaking the cake is even a viable option

douglas_clark wrote on 9/4/2023, 4:13 PM

I have used ffmpeg to change frame rate to 16 fps, when the scanner records with another frame rate. I have the following in a batch file "fixfps16.bat". I use it for .mov files containing ProRes video.

ffmpeg -i %1 -codec copy -an -r 16.00 temp.avi
ffmpeg -i temp.avi -codec copy %2

Execute the batch file with input filename as the first argument and output filename as the second argument. Maybe it will work for you.

It's been a while so I do not remember if this only works for .mov files, or will also work for other container/codecs. The first line copies the file to a temporary .avi without reencoding, but sets a new framerate on the output file. The second is necessary because it didn't work copying directly .mov to .mov. There are surely ffmpeg experts here who can explain what this is doing better than I can.

kplo wrote on 9/5/2023, 1:30 PM

"The frame rate for Regular8 and Super8 film is 18 frames per second."

@mark-y

The frame rate for Regular 8 is 16fps. When Super 8 came out, the silent speed was changed to 18fps.

mark-y wrote on 9/5/2023, 6:19 PM

Ok, I understand 16fps. If @douglas_clarkedited] has time, I would still like to see some 20fps on Drive or Dropbox to determine the other parameters I mentioned and maybe make a test.

wwaag wrote on 9/5/2023, 9:18 PM

@Harry-Britton

Could you upload some sample footage? Also, what machine are you using--something like a Wolverine?

fr0sty wrote on 9/6/2023, 12:22 AM

One thing you need to keep in mind... few displays out there can actually display your video at 16fps (only displays that support variable display rates, like freesync, and even then it relies on the software being used to play the file back also being capable of playing the file at that rate), they are going to upscale the framerate to 24, 29.97. or 59.94/60fps. So, it may work out better for you to instead do the interpolation yourself, so you have control over exactly how well that upscaling of the framerate is going to be done, vs. relying on the display device/playback software to do a good job of it.

Try setting VEGAS to "optical flow" resample mode in project settings, this will eliminate jitter from uneven frame scaling, and set the frame rate to a standard rate (I'd do 24/23.976 fps, as this requires the least amount of interpolation, but 29.97 is compatible with more devices). Sometimes optical flow can introduce artifacts, but when it works correctly, it produces a smoother image vs. the blurry, frame doubled or jittery look that the other resample modes have. Try the other modes only if optical flow introduces unwanted artifacts.

If you plan on this video being viewable on standard TVs, this is the approach you're going to want to take.

douglas_clark wrote on 9/6/2023, 4:27 AM

Ok, I understand 16fps. If @douglas_clark has time, I would still like to see some 20fps on Drive or Dropbox to determine the other parameters I mentioned and maybe make a test.

@mark-y I don't have any 20fps footage. Mine was 16.216 fps -> 16.00 fps. (ProRes 422 HQ).

mark-y wrote on 9/6/2023, 6:19 AM

Sorry, wrong tag! @Harry-Britton

Harry-Britton wrote on 9/6/2023, 7:49 AM

Hi Folks: Thanks for the replies. I just tried matching project rate on the import, and I see 16 frames per second when advancing frame by frame, but I think the video is still too fast. I'm going to try to cut the speed in half to verify what is happening. I don't have a short clip. They're all about 3 minutes and 180 megs or so..

I'll keep you posted.

Thanks

Dexcon wrote on 9/6/2023, 8:08 AM

On YouTube, there are many YT channels that have taken hand-cranked film footage from the very late 1800s and early 1900s and have transformed that footage into 60 fps with stabillisation, colorisation etc - like this one -

Maybe add a comment on a YT channel or so asking the YT creator how they increased what was probably 16 fps (apparently the minimum fps at which the human eye perceives continuous motion) to 60 fps without massively speeding up the video. Needless to say, the original footage one hundred plus years ago wasn't filmed at 60 fps.

While generally colorisation hasn't been a strong point of these YT videos, frame rate and stabilisation has usually been quite good.

Harry-Britton wrote on 9/6/2023, 8:11 AM

OK. I create a project with 4 fps. I import the 20 fps media without changing the project to the media rate. What I see is a choppy video played at 4 fps but the speed is the same. That is, I'm seeing every 5th frame.

Harry-Britton wrote on 9/6/2023, 8:20 AM

Looks like rendering 4fps uncompressed is skipping lots of frames, too. Length of clip is the same.

Harry-Britton wrote on 9/6/2023, 8:29 AM

I just tried to convert to AVI, 4fps with VLC, and it remains 20FPS.

How would I convert/export to a series of frames?

3POINT wrote on 9/6/2023, 8:36 AM

OK. I create a project with 4 fps. I import the 20 fps media without changing the project to the media rate. What I see is a choppy video played at 4 fps but the speed is the same. That is, I'm seeing every 5th frame.

You should import the 20fps at projectframerate. Right click 20fps video in media tab and choose "add at projectframerate". Now video will play full frames at projectframerate.

EricLNZ wrote on 9/6/2023, 6:01 PM

16 fps (apparently the minimum fps at which the human eye perceives continuous motion)

@Dexcon Actually no. At 16fps the flicker would be unwatchable. 8mm projectors have a three bladed shutter so you actually see each frame three times. So effectively you see 16 x 3 = 48 images per second which we perceive as continuous motion. But it's still only 16 original frames per second. Surprisingly movement is smooth but that's because the grain structure of film is very different to the fixed pixel images of digital.

16mm film was shot at 24 fps and the only 16mm projector I've encountered had a two bladed shutter. 24 x 2 = 48 (again).

wwaag wrote on 9/6/2023, 6:55 PM

Here's the split-screen version of an 8mm true 16fps (created from individual 1480x1080 png's) clean up demo I did a few years ago. For anyone interested in film restoration, the place to go for help is the Restoration subforum on VideoHelp. I used a number of Avisynth scripts written by John Meyer, one of the early Vegas scripting guru's. Not the best in the world, but it does illustrate pretty decent dirt and grain removal with stabilization.

The original footage was shot in Austria.

You can download the "unalterred" footage here. https://www.dropbox.com/scl/fi/n7ltzyghxpj60ir1b6e0s/8mmDemoSplitScreen.mp4?rlkey=imcmlwfntjrld91hpx2zpel4b&dl=0

mark-y wrote on 9/6/2023, 7:20 PM

+1 @wwaag

@johnmeyer also has some work he did a while back on his Youtube channel.

Former user wrote on 9/6/2023, 9:03 PM

So, the clips length will grow on the timeline, but each frame and the number of frames will remain unchanged. It sounds easy, but not working for me. It would be ideal if I could change the play rate to 80%, which would be 20 to 16 FPS.

Are you doing the following?

If you are and you're getting duplicate frames that would indicate your video is VFR instead of CFR. Vegas is very bad at handling VFR footage, instead of reading all frames available it will duplicate frames. You would have to use a transcoder such as shutter encoder to create a CFR version and bring that into Vegas instead.

fr0sty wrote on 9/6/2023, 9:14 PM

It's all going to get converted to 24, 30, or 60fps anyway, depending on the display.

Dexcon wrote on 9/7/2023, 7:16 AM

@EricLNZ ...

Actually no. At 16fps the flicker would be unwatchable.

This seems to be a rather disputed issue with quite a lot of different opinions. In the early silent era, hand-cranked cameras were shot at around 16 fps - a Wikipedia page about early film (which also mentions 2 or 3 blade projection) - suggests that the fps in the hand-cranked camera era was somewhere between 16 - 20 fps. One of the reasons for this is that that was the physical limit of cranking speed for the camera operator.

Projectors were also hand-cranked. In fact, one of my uncles (who I never met) was a silent era projectionist in Sydney who I heard enjoyed a generous donation of tomatoes from the audience if/when the film broke mid-session.

But more particularly, the following webpage explains human "persistance of vision" where the human eye retains an image for longer than an image actually exists - https://www.masterclass.com/articles/persistence-of-vision-explained. The pertinent sentence in this article is:

However, research suggests that the human eye struggles to differentiate between more than twelve images in a single second

And this Wikipedia page also somewhat supports this - https://en.wikipedia.org/wiki/Frame_rate which states:

The human visual system can process 10 to 12 images per second and perceive them individually, while higher rates are perceived as motion.

But then another Wikipedia article notes that it was suggested in the past by one early researcher who concluded that something like 48 fps was needed to appreciate smooth motion. I think that this conclusion can readily be discounted.

So there are lots of different opinions about the subject.

Nonetheless, the point of my comment was that there are heaps of YT channels that convert silent era film into (often) 60 fps and perhaps the OP can contact them to ask how they achieve smooth video in current day NLEs using hand-cranked 100 years old film footage.