Cleaning other people's mistakes (frame rates)

Marty111 wrote on 2/9/2019, 10:08 PM

Hi everyone !
I'm having an issue with frame rates. I though that I got everything right, now I know how to deal with frame rates, so I won't make mistakes anymore. But it turns out that I have to edit other people's work, and those people did messed up with frame rate a great deal. So I have for instance a 29fps video that originally had less frames, it means some frames are repeated in the source video I have. I know how to clean this manually, frame by frame, but it's quite a lot of work. I wonder if there is a more automated way to clean it. Might some special plugin be able to remove repeated frames ?

Thank you !

Comments

Musicvid wrote on 2/10/2019, 12:53 AM

Start here, section C, and upload a sample and all file properties.

https://www.vegascreativesoftware.info/us/forum/important-information-required-to-help-you--110457/

wwaag wrote on 2/10/2019, 1:24 AM

@Marty111

There are many free tools available for doing this, but not inside editors such as Vegas. You will have to use open source software such as Avisynth and VirtualDub. Do a search for "avisynth find duplicate frames" to get started. If you are already familiar with Avisynth, it should be easy. If not, it's a steep learning curve, but probably quicker than doing it manually. A good resource is the Restoration sub-forum at VideoHelp.com. Good luck.

Musicvid wrote on 2/10/2019, 2:32 AM

I'm thinking it may be a flavor of soft or hard pulldown, and contingent on that, may be able to manipulate in Vegas or Handbrake. I agree, Avisynth is the most powerful free tool.

Do you know, is it originally film source? That sample would tell us quite a lot about its former life.

One quick check for soft pulldown "might" be to change its project frame rate to 24p, and step through the frames. Seems plausible.

Handbrake has some built in IVTC functionality. tries to identify cadence, and is also great for soft-flagged DVD movies using "Constant Frame Rate" and "Same as Source" together.

Marty111 wrote on 2/10/2019, 3:09 AM

It's old historical footage that has been compiled on youtube.

Musicvid wrote on 2/10/2019, 3:15 AM

Well, that's easy, give us a link.

Marty111 wrote on 2/10/2019, 5:20 AM

Well nothing special, just an additional frame every 5 or 6 frames, it depends :

This one for instance @ 4mn02s :

Marty111 wrote on 2/10/2019, 5:23 AM

Two identical frames following each other. Sometime (though more rarely) frame aren't exactly the same because some compression has been added therefore modifying them, but you can still see that it's a frame rate conversion issue.

Marty111 wrote on 2/10/2019, 5:28 AM

Apparently now adobe première has support for variable frame rate. It would solve most issues for people who compile different sources, and we should see in the future less butchered videos on youtube.
I don't know what codec and container it uses though, nor if youtube will stream this format.

Marty111 wrote on 2/10/2019, 5:37 AM

you would have to download the video to see the issue, it goes unnoticed unless you study frame by frame but it's annoying when there's a good resolution, speed, action, transitions.

Musicvid wrote on 2/10/2019, 8:21 AM

Marty, I understand completely. It's a form of pulldown, which may not be completely reversible.

Mechanical film captures used a projector having a five bladed shutter, creating precisely the result you describe. Digital transfers do this internally with interpolation at the frame or field level, depending on dozens of factors. We're getting a progressive result through god-knows how many iterations, so don't hold your breath. We're good at figuring out what was done, but not-always-so-good at putting the toothpaste back in the tube. Best case would be soft pulldown which preserves the native frame integrity, and instead works with flags for dvd production. Unfortunately, I am now 99% certain that is not the case.

I'll get back to you, knowing that the result would play less smoothly than your download, if anything can be done. Sincr it's historical footage, be most sure to check at archive.org to see if there is an earlier generation available. This saved my sanity trying to convert the kinescope of the original live broadcast of The Fantasticks, ca. 1965.

wwaag or johnmeyer (if he does another fly-by), will undoubtedly have a script or two as well. I started doing film transfers at my job in 1990, and both of those guys are way more advanced than me.

Marty111 wrote on 2/10/2019, 10:45 PM

Thanks all of you for all your suggestions, I'll give them a try.

Musicvid wrote on 2/11/2019, 4:51 AM

I think later today or tomorrow I'll have something to show you.

Musicvid wrote on 2/12/2019, 4:01 PM

@Marty111

It turns out this is simple as microwave popcorn using Handbrake.

Since I use an older version, your controls may be placed slightly differently.

I downloaded the 320p version from Youtube for my test. it is sharper.

Marty111 wrote on 2/12/2019, 9:39 PM

Oh my god... Thank you so much ! How did you get rid of the additional frames ? I'm not sure to understand.

I downloaded the clip you repaired :)

Musicvid wrote on 2/12/2019, 9:54 PM

Do you not see the specific Handbrake settings I prepared for you in three separate images?

It does the trick in a couple of minutes.

If you have not yet downloaded Handbrake and examined the user interface, please do so first.

https://handbrake.fr/

Good luck with your project!

Marty111 wrote on 2/14/2019, 11:20 PM

Thank you Musicvid !

Musicvid wrote on 2/15/2019, 6:59 AM

BTW, it does appear to have been transferred using a five blade aerial projector. The "screen" was just a resolving point in space, upon which a video camera focused from the opposite perspective (from behind the imaginary "screen"), flipping the image and slaved to the shutter. Cadence, as in your film, is ABCDDEFGHH...

Worked quite well when it worked, but the projector required daily maintenance and calibration. Film fps in those days was 15-24. The whole purpose was to make 24 fps film play nicely with 29.97I television. PAL conversion was a lot simpler -- just speed up the projector to 25/24, roughly 4%. No, European orchestras did not play everything half a semitone higher, or faster.

Now, PAL to NTSC conversion is at the obvious 6:5 ratio, but the reinterlace (576->480) and horizontal standards conversion can look messy, as in the old French Open broadcasts. Tracers, anyone?

Telecine is a fascinating contrivance, but some types are impossible to undo in post. You are lucky to have frame integrity compared to some software that mashes fields to make a "frankenframe" at scene cuts.