How to speed up clip more than 50x

[Zom-B]

I’m trying to make time-lapses of long single-clip audio-less videos but I need to speed them up by several hundred to over thousand times, however the Speed spinner box in the Clip properties seems to only go up to 50.

The videos are 2…6 hours at 60fps, so max 1296000 frames

I want to shrink them down to ~1 minute and decimate the frame rate to 15fps, so exactly 900 frames.

Speed up factors which I need for this: 480…1440x. How can I do this without rendering a video twice as a workaround?

[DRM]

Someone else asked almost the exact worded question just under a week ago.

Here was my reply to him:

How to speed up a video more than 50x

Try this: Take it to the max speed then export it using HuffYUV or Ut Video from the lossless preset. Make sure you have enough space because lossless exports can be big files depending on resolution and duration but they won’t lose any video quality when you re-encode them which is why I would suggest it here for this case. Then take that newly rendered lossless file and bring it to Shotcut and speed it up more.

[Zom-B]

I fought with this a couple of months ago and didn’t find anything then. I searched today just for good measure and still didn’t find anything.

Anyway thanks for the link, I went with ffmpeg, like this:

ffmpeg -i in.mkv -an -r 15 -filter:v “setpts=0.0024*PTS” out.mp4