Reimplement support for rknn detector

[MarcA711]

This PR is not complete. I just want to get some early feedback.

One thing that bothers me is that some parts (especially the prerequisites and setup parts) of the video processing and object detection docs overlap.
Compare https://github.com/MarcA711/frigate-rockchip/blob/1e1a11ae2bffab188e788e742c9ef0f801c7d002/docs/docs/configuration/hardware_acceleration.md?plain=1#L367-L397
and https://github.com/MarcA711/frigate-rockchip/blob/1e1a11ae2bffab188e788e742c9ef0f801c7d002/docs/docs/configuration/object_detectors.md?plain=1#L317-L346

Any suggestions how to handle this better?

Generally, it would be better for the user to describe the configuration for both video processing and object detection in one place. Now, the user has to find two pages. But I think this is again rockchip specific and difficult to fix without breaking other stuff.

Moreover, was it considered to move the post-processing part of all detectors in one file? As far as I know every detector implements its own post-processing for each supported model. However, post-processing of the same model (like yolo-nas, yolox etc.) should be the same so there is some duplicate code.

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[NickM-27]

If there are commonalities then you could put that in the installation section of the docs then have the hardware and object detector link to that as a prerequisite for specific setup

as far as post processing goes, it could make sense to have a util.py in detectors that handles this

[MarcA711]

as far as post processing goes, it could make sense to have a util.py in detectors that handles this

I agree. I will try to implement post-processing for all detectors. I will use the mode: model_type: config option that is already implemented to handle this. But I will also include a way to return the pure detections (similar to how its already done) to allow the detectors to handle post-processing differently (e.g. using opencl on GPU).

[MarcA711]

This is now ready to merge

[blakeblackshear]

I think it's best to add some information about the license on your repo where you published the models. Also, probably best to note that here as well. We wouldn't want someone using Frigate for commercial purposes to assume that these models are free for commercial use.

[blakeblackshear]

Lastly, how painful would it be to update this so the models are downloaded at runtime? That prevents frigate from actually redistributing the models itself.

[MarcA711]

Good idea. I will add notes in my repo and frigate and I will exclude the models from the image. Maybe I will add some other models (maybe yolox) to the image later.

[MarcA711]

I added a note to my repo, the docs and to the logger on each start, so that the user knows about the license situation.

I also excluded the models from the image.

[MarcA711]

I see that Frigate 0.14 is coming out soon. Are there any plans for a beta phase? When should I finish my bigger changes so that they make it in that version?

[NickM-27]

I don't know that I would call it "soon". There should be a beta within a week or two, and I am sure there will be at least a few betas to follow that.

[MarcA711]

This PR is ready to merge from my side.