Scaling image size in event view scales playback speed reciprocally in 1.37.64 20241021 build (jammy, focal)

[MarsRover]

Hello.
In MJPEG mode scaling image size in event view scales playback speed reciprocally (with linear scale factor squared).
For example, camera (and recording) original resolution is 2560x1440, when I set scale to "Max 1280", which is linear 1/2, my actual playback speed goes ~4x and I need to set rate to 1/4x to get more or less 1x playback.

Browser: latest Chrome on Windows 10

[iconnor]

That's weird. Scaling happens after any timing choices... the only thing I can think of is that it is faster because it is able to be faster... due to less cpu use... but I'm not seeing any of that here. All event and live streams involving zms are scaled to the displayed resolution or less for the exact purpose of saving cpu/bandwidth.

[iconnor]

Actually the scale dropdown doesn't seem to be doing anything here at the moment. I'll dig in.

[MarsRover]

Actually the scale dropdown doesn't seem to be doing anything here at the moment. I'll dig in.

It does scale the video. But not only frame size )
I have time with seconds on camera OSD so I can tell

[MarsRover]

1.37.65~20241031 (focal) - problem persists

[iconnor]

https://github.com/ZoneMinder/zoneminder/issues/4184

Hopefully someone else can reproduce it. I can't.

[MarsRover]

Maybe one needs slow channel, say 2-3 Mpbs, to reproduce it, I'm not sure.

And maybe this video will clarify the problem

I've found out that it happens only when B/W settings are Low or Medium. When I set B/W to High, the bug is gone.