Question about speed change

[brian]

You have mixed up two different concepts in your question:

• Frame rate conversion
• Speed change

@owai

but how does it do this? just skip?

In your example, you are only converting the frame rate. If the source clip frame rate is 50fps and the Shotcut Video Mode is 25fps, then Shotcut will skip every other frame.

@owai

but what if a 72 hours time lapse is speedup to 3 minutes?

and same question again if a video is slowed down 4x… and shotcut needs to “create” 4 intermediate frames

Now you are talking about speed change. This depends on how you changed the speed.

If you set the speed parameter in the clip Properties panel, then Shotcut uses simple frame skipping and repeating. Frames will be dropped or duplicated as needed to achieve the speed.

If you used one of the time filters:

• Time Remap Filter
• Speed: Forward & Reverse Time Filter
• Speed: Forward Only Time Filter

They have an image mode with options “nearest” and “blend”. If you choose blend, then the filter will blend images to make new intermediate images. I would not describe this as a motion effect. But it is more like the ratio blending that you described in your question.