Or using a better source video. As there's no way the original film was interlaced.

I'm now imagining a low-paid 1930s film job called "interlacer" which consisted of taking every frame and drawing tiny, perfectly straight black lines on it, with a tiny fineliner and a tiny ruler, on odd and even rows, every next frame.

I know of a company that did the opposite to handle 2:3 pulldown for rotoscoping. They had a photoshop action that would select every other line, copy&paste to a new doc, collapse the empty space, and then paint the frame. Then, do that a second time for the other half. Finally, more actions to recombine.

I couldn't make this up. My jaw just hit the floor when it was explained to me the first time. I still shake my head typing it up to post here.

I had to look this up: https://en.m.wikipedia.org/wiki/Three-two_pull_down

What tool should have been used to do that conversion (in reverse)? To their credit, it sounds like they solved the problem and moved on.

They solved the problem by increasing the work unnecessarily. So to explain the issue with more detail and not requiring peeps to jump to wikipedia, 2:3 pulldown is how 24fps film was converted to 29.97 fps interlaced video. This increases the number of frames roughly 20%, but it does this by repeating fields of the original progressive data. When you step through this 29.97 video frame-by-frame, you will see a repeating pattern of 3 progressive frames followed by 2 interlaced frames. To do this asinine made up workflow, they then increased the number of frames again. Instead, they should have done an inverse telecine (IVTC), which reverses the 2:3 pulldown returning 24 fps progressive frames. When rotoscoping, you definitely do not want to be creating additional frames "just because". Applying a small amount of logic should have suggested that these interlaced frames are odd since the orgininal source had nothing but clean progressive frames. If this was introduced in the conversion to video, surely it can be undone.

They, as you, decided it was acceptable to do whatever needed to be done at whatever expense rather than taking 10 minutes to find the proper workflow which would have saved them money. A simple phone call to the company they used to transfer the film to video would have been able to explain to them how to do this in less than 5 minutes. I know because I worked for the company doing the film transfer and had helped several other clients with the video for film post workflows. Today, it's even easier because there's like a bazillion write ups on how to do this posted on the web.

Edit: I didn't answer the question directly after pontificating. IVTC is the process that needed to be applied. Many many tools exist(ed) for this. The tools at this company's disposal would have been After Effects, Avid, etc. Later more tools became available like AVISynth, FFMPEG, and other dedicated tools were created by people to tackle this directly.

A flow like this could have been someone's job security.

Analogue video (e.g. television) interlacing did actually begin in the 1930s, a few years before the Hindenburg disaster. But the original disaster footage would have been shot on film (not interlaced of course), cut into newsreels and then converted to a television signal via telecine.

Supposedly the original newsreals still exist, preserved by the National Film Registry: https://en.wikipedia.org/wiki/Hindenburg_disaster_newsreel_f...

Original film may have flickered, or the playback process to capture may have induced flicker.

What is missing is object continuity with respect to color. That would quiet things down tremendously. Right now it is as if every object gets re-painted from one frame to the next in a completely new (and often garish or wildly incorrect) color.

I believe there already is quite some continuity, otherwise the colors would flicker much stronger from frame to frame. In the video it varies smoothly from frame to frame.

There are many instances of frame-to-frame discontinuity that I can't explain other than by a lack of object detection and labeling. It would be less wrong to use the color from the previous frame even if the lighting changes than to use an entirely different hue for the same object.

Only things like TV screens and other displays (and some interesting objects covered with micro surfaces that can cause light interference) can change color that rapidly given the same color incident light.

I think they get that not because of putting in that constraint, but only because subsequent frames are similar. That makes the coloring algorithm pick similar coloring.