Exciting thread to read, like it a lot!
I'm not sure what Frigate can do but my approach is to only analyze images from my cameras if there has been a movement detected. I would try to do the same if I would use Frigate to avoid load on both the CPU and the object detection "thing" (the "thing" being the TPU or an other object detector) as well as reducing an eventual recording to hold only "interesting" frames that can be studied afterwards
Give you a description of my setup that is working very well since years, lately updated with a RPi5 for the TFlite object detection part
My cameras are pretty old now, just usb types but with a decent resolution and night vision capability, for sure a later generation is better. All cameras are providing 1024x768 images that are continuously analyzed by the Motion software (running as a service), just looking for motion in unmasked areas. If and when motion is detected, images are sent further to the next step, the object detection analyze.
This is the "flow" so to say:
Cameras -> Motion (motion detection, masking, etc) -> images with motion via MQTT -> TFlite etc in RPi5 (object detection, drawing bounding boxes, recording etc) -> Node-RED if defined objects are detected (Telegram, Dashboard etc etc)
The object detection is running TFlite using the CPU of the RPi5. Since it is only analyzing images that has been considered "of interest", the total CPU load is very limited (I do not monitor the CPU load, only the RPi5 temperature and it is really stable, around 53 degrees C). Furthermore, a daily videorecording is built with all images that are received, makes it simple to check afterwards what happened during the time before, during and after the event
(just for info, the TFlite is using the Python library. It does also support the TPU but I do not have such)
Additionaly: I'm not so convinced about that cropping of 320x320 parts. I let my analyzer run analyze on the full image and it works really well detecting people objects. If you crop, isn't there a risk you will loose some objects in a "wide screen" image? Or will there be multiple crops made from a single image? Myself I tried to resize the whole image to 320x320, also while keeping the aspect ratio, the detection confidence went down