Hey qian - the 255 FPS @ 400P figure shown on the OV9282 sensor page(I assume you are reffering to that) refers to the supported sensor mode on RVC2, but it should not be interpreted as guaranteed end-to-end FPS for a DepthAI v2 pipeline streaming frames to the host.
In practice, DepthAI v2 host-side throughput is usually lower and depends on the full pipeline and measurement method, including USB speed, host transfer, XLink settings, and whether frames are being displayed or otherwise processed on the host. So seeing around 190 FPS in a single-mono 400P test on DepthAI 2.32 is plausible and does not necessarily indicate a problem.
If you can share your exact test script, device model, reported USB speed, and whether you are measuring device timestamps or host-received frames, we can help check whether your setup is already close to the practical limit or if there are a few settings to improve it.
Thanks,
Oskar
