[Jim Arco]

Well, I hadn’t had my first coffee yet…

With time-warp you want to get more frames to work with / slow the video down. So… you need to time-warp to 50% or 25%, then time-stretch by the same amount.

[Jim Arco]

Forgot to mention:

The technique I listed was from an idea provided to me by Chris Wright when I was looking for a better method for frame rate conversions for Super8 film.

Jim

[Jim Arco]

Time-stretch by small amounts seems to work strangely in AE. I have had some luck by first time-warping the video to 200% or 400%, then time-stretch the result (in another comp) by the appropriate amount to get to the speed I need. Make sure pixel-motion is on and add motion shutter blur if needed.

This gives AE more frames to work with and would change your time-stretch to a larger amount, 47% or 23.4% for instance. Time-warp can be messy with interlaced footage, so you might have to do some other work there.

[Jim Arco]

Right now, I want to take super-8 18 fps and make it more smooth for a DVD at 24fps. The source was captured a frame at a time and is a tif sequence, so it is truly an 18fps image sequence. (At least I think that S8 is 18fps. This is silent S8 and maybe that was shot at 16fps?)

BTW, I first saw your recipe for 30–>24 a few months ago when searching for a better solution for some other frame-rate conversion I was doing. After spending an hour or two on the math, I just used your recipe, figuring I’d come back to the lesson some other time. When I saw your posting yesterday, I figured it was time and began crunching numbers with no success – it just never occurred to me that 99fps was as high as AE could go.

Sometimes the simplest answer is the best answer.

[Jim Arco]

Chris,

Your technique seems to work quite well.

Can you help me understand the math involved here? If I timewarp 59.94fps by .60545403, I get 99fps. Then if I timestretch the resulting footage by .60545403, I get right back to my 59.94fps original (albeit with differences “invented” by AE during the two conversions) which I can then output to 23.976.

But why 99fps? What is the relationship between 99 and 23.976 that makes this work?

BTW – I am trying to work out the math to use the same technique on an image sequence from some super-8 film at 18fps.

Jim

[Jim Arco]

…just to add my two-cents worth…

If the lines you describe are dropouts – white lines with no picture information at all – the tool you are looking for is called a drop-out compensator. Pro level tape decks included these as an option. They were available on some high-end VHS decks.

You could try using a second video copy below the main video. Use luma keying on the top layer to detect the white lines; blur the lower layer and/or offset it a few line vertically.

The blue screen problem is probably caused by the tape deck thinking that the noise is a copy protection technique. Also, playing damaged video on VHS decks with TBC sometimes makes the video worse. The noise on the tape can fool the TBC to generate sync pulses at the wrong time, resulting in jitter or roll. You may want to switch off the TBC or try a different player.

All of this is from the Library of Ancient Video History; your mileage may vary.

[Jim Arco]

…another BIG thank you….

The addition of the “tolerance” sliders, and the “draft mode” was a great idea. Methinks you may have a marketable product here! Then again, maybe I’m the only one trying to improve video that was shot in the stone-age.

Jim

[Jim Arco]

I’m pretty sure you’re not sitting there waiting for my questions – but it almost seems like it.

You are correct, by ‘edge-enhancement’ I mean the artifact that is produced by most camcorders. Edge-enhancement can be from oversharpening, or even an edge-finding algorithm that produces an outline around objects in an image. It seems the less expensive the camera, the more edge-enhancement the manufacturer wants to add (probably to make up for the lack of any real resolution.) We have been using a combination of find edges and compound blur to reduce the artifacts in footage from older/inexpensive camcorders.

Once again, Chris, you’ve given me another way to think about solving the problem. Depending on the source material your solution seems to work better (quite a bit better in some cases.)

Seems to also have the added bonus of reducing some of the noise and/or compression artifacts.

Thanks for sharing.

Jim
ColorBurst Video

[Jim Arco]

Thanks for taking the time to respond. It’s not really too late, I have other projects that might need the technique one day.

I followed your directions, but I must be doing something wrong. In my project, I go to the project tab, copy the sequence, open a new project and click on the project tab. When I paste the sequence into a new project, I just get the linked material on the timeline. I would like to get my original edited timeline back.

I am using CS4.

Jim

[Jim Arco]

OK Chris, you’ve done it again! I just replace the ‘missing image’ file with my footage and blown-out highlight detail comes back. Sorta like creating detail from an thin air, I guess.

Your magic is appreciated. Thanks again.

Jim

Wanna tackle that overzealous edge-enhancement typically found on footage from consumer-grade camcorders….? 😉