Upscaling/Downscaling output via "Rescale Output" vastly improves frame render time when Virtual Camera is running.

[ninbura]

Operating System Info

Windows 11

Other OS

No response

OBS Studio Version

30.2.2

OBS Studio Version (Other)

No response

OBS Studio Log URL

https://drive.proton.me/urls/4FCVACQ1KC#wisNreIefBOl

OBS Studio Crash Log URL

No response

Expected Behavior

OBS should have the lowest average frame rendering time when streaming at the same resolution as your canvas. Regardless of whether Virtual Camera is running.

Current Behavior

OBS reports less than 1/2 the average frame rendering time when output is scaled vs non-scaled while Virtual Camera is running. This is true even when upscaling the output. One would assume that performance would decrease, not increase, when upscaling the output.

Steps to Reproduce

1. Set base canvas to 2560x1440.
2. Start virtual camera if it's not running.
3. Verify that "Rescale Output" is disabled in "Output" settings.
4. Observe frame render time before streaming.
5. Start streaming to YouTube.
6. Observe frame render time.
7. Stop streaming.
8. Stop Virtual Camera.
9. Enable rescale output & set resolution to 3840x2160.
10. Start Virtual Camera.
11. Observe frame render time before streaming.
12. Start streaming to YouTube.
13. Observe frame render time.
14. Contrast upscaled frame render time with native frame render time.

Anything else we should know?

I would like access to whatever pipeline grants this performance uplift without the need to scale. I want a base canvas of 3840x2160, and to stream at 3840x2160 without my average frame rendering time doubling. Unfortunately, this "hack" doesn't work when trying to "re-scale" your output to the same resolution as your canvas. I need to keep Virtual Camera enabled as this is how I stream to Discord & Microsoft Teams. I consistently stream to YouTube & one of the aforementioned applications simultaneously.

video demonstration

https://github.com/user-attachments/assets/d62a5ca5-063d-43fa-95a8-75980c88dd6c

test stream links

• 2560x1440 (no scaling | 2.8ms render time)
• 3840x2160 (scaling | 1.4ms render time)