[HELP] Feature film with duplicate frames

[Miranda]

I have exported a short sample clip but it is 17 GB.

[Selur]

What are you exporting it too? Maybe a shorted sample then?

[Miranda]

It's ProRes 422HQ, approx 15 mins to get a few scene changes. I can convert to mp4?

[Selur]

Yes, just don't change the resolution or color space and don't compress it too much.

Cu Selur

[Selur]

What I would do:

• crop the source 132 top&bottom
  
• mode crop filter above all the frame replacement filters
  
• enable FillDuplicateFrames with debug, this way I can the the difference when moving through the clip
  In the middle you the the average change and in the upper right corner you see whether the current frame is from the input or interpolated.
  

first impression was that everything below 0.0024 was a duplicate.
Note that if you activate any filter before the FillDuplicateFrames filter, you need to adjust the threshold.
At the beginning the threshold seemed fine.
The problem is that if you have duplicates directly before or after a scene change, all these filters will fail, since there isn't anything those filters can do. There is nothing to interpolate between. The best thing they could do would be to keep the duplicates, which they are not aware of. This would require some adjustment to the code of the filter script and some upper threshold.

Side note: Strangely, some of the scene look like nice film scans, while others look like SD upscales.
For the better scenes, some denoising and contrast adaptive sharpening will probably help.

So the sad conclusion is: you can't really do anything about the duplicates directly before or after scene changes.

Cu Selur

[Miranda]

I guess the only thing would be to cut out the dupe frames. I had to do that on another master which had really bad field blending on every scene change. Both masters were probably converted from old interlaced telecine masters and the lab are trying to save money by doing their own sub-par de-interlacing work on them, making them worse. Of course they don't have the original interlaced masters either now.

[Selur]

What do you do with the audio if you cut frames? (contract/compress the audio for one video frame? Probably not noticeable and the first thing that pops into my mind.)

Cu Selur

[Miranda]

In HandySaw you can add a crossfade to each trim.

I also tried the ffmpeg mpdecimate function with limited success. I think it might work if I knew how to use the function correctly.