Boundary frames do not stretch correctly when changing clip speed to very low values (e.g., 0.05x)

Bug
1

Hi everyone, thanks for the great work on Shotcut. I ran into a couple of issues that look like bugs. I’d appreciate it if you could take a look.

System Info:

  • Shotcut Version: 26.2.26

  • Operating System: Windows 11 Pro

  • Hardware: Ryzen 9 9950X3D, RTX 5090

Description: There is a consistent issue when slowing down a clip (slow-motion). When I change the speed of a clip in the Properties panel (e.g., to 0.05x), the first and last frames of the segment do not stretch proportionally with the rest of the frames. The middle of the clip behaves as expected, but the boundaries seem to have a different duration or “glitch” in their timing. This is 100% reproducible at extreme low speeds.

Steps to Reproduce:

  1. Cut a segment and drag it to the V1 track.

  2. Select the clip and open Properties.

  3. Change the speed to 0.05x.

  4. Check the first and last few frames of the clip.

Expected Result: All frames, including the start and end frames, should be stretched equally according to the speed ratio.

Actual Result: The start and end frames do not match the expected slow-motion duration, causing a visual inconsistency at the clip boundaries.