Large glass-to-glass latency with Blackfly S USB3

[nicshackle]

Describe the bug
I have a Blackfly S BFS-US-16S2M connected over USB3 to a powerful computer running Ubuntu 22.04. If I point the camera to a blinking pattern on the screen, and then open the aravis monitor next to the blinking pattern, I notice a significant latency (not measured, but probably in the 100-200ms range). Is this normal?
Attached is a screen recording of the blinking dot, alongside the viewer. The camera is pointed at the red blinking dot.
flashing_dotshort.webm

To Reproduce

• Build aravis from source (release 0.8.31)
  • with meson configured to enable introspection, viewer, usb.
• Blackfly S BFS-US-16S2M connected over USB 3
• Point the camera at a blinking pattern on the computer monitor
• Open aravis viewer
  • Pixel format: Mono8, Binning:1x1, Region size: 1440x1080 (also tried with smaller region sizes; same result)
  • Nothing set to auto; exposure set to 12uS, gain set to 47
  • fps at 199Hz

Expected behavior
Less latency

Camera description:

• Flir
• Blackfly S BFS-US-16S2M
• USB3

Platform description:

• Aravis version 0.8.13
• OS: Ubuntu 22.04
• x86_64, i9-14900K, GTX4080

Additional context
Trying with Spinnaker SDK (& spinview), I see the similar latency. Also tried setting the buffer to "newest only" (see https://www.flir.com/support-center/iis/machine-vision/application-note/understanding-buffer-handling/)

[EmmanuelP]

Hi,

Arv-viewer is mostly a debugging tool. The latency may increase if the gstreamer based video output can not keep up with the incoming frames from aravis.

What is the CPU use ? Did you try to lower the frame rate ?