What does ImageMagick do when converting DNG to MOV?

[zfmobil]

Hello nice girls and guys!

I have a question. I need to generate short video-clips from a bunch of DNG files that are generated from my Highspeed camera. In the folder with the DNGs I use this command:

magick -verbose *.dng movie.mov

This works fine, I get the clip as I need it. As far as I can see, ImageMagick does this in four steps.

STEP 1: for each DNG in the folder it prints something like this:
frame_XXXXXX.dng DNG 1920x1080 1920x1080+0+0 16-bit sRGB 3.95898MiB 2.609u 0:00.254

STEP 2: Magick does something several seconds without printing a message

STEP 3: each DNG is converted to a JPG in the systems TEMP folder, for each DNG I get a message like this:
frame_XXXXXX.dng=>e:/Temp/magick-19392lf1AXFsSkxK784.jpg[84] DNG 1920x1080 1920x1080+0+0 16-bit sRGB 501404B 0.047u 0:00.054

STEP 4: finally, it collects the JPGs from STEP 3 and combines them into the movie via FFMPEG

I wonder if I could improve performance here. While STEP 1 and STEP 2 are relatively slow and I don't get what they do, STEP 3 and STEP 4 are quite fast. So here is my question: If the DNGs are being converted to JPGs in STEP 3 and then put together into the clip in STEP 4, is there any chance to avoid STEP 1 and 2?

I don't care about White balance and so on. Most important thing for me is to see what happens in the clip.

Thanks a lot! Martin

[zfmobil]

Still have no solution. But if someone stumbles upon this: I recognized that FFMPEG can work on DNGs directly, which is much much faster, since it uses the GPU. Unfortunately the clips are very dark and greenish. But this is REALLY fast.

The command line is:

ffmpeg -r 25 -f image2 -i frame_%06d.dng -vcodec libx264 -crf 25 -pix_fmt yuv420p preview.mp4

If someone has an answer to my initial question, I'd be still very happy. But even more I'd be happy if someone knew how to make FFMPEG work correctly with the DNGs.