Regarding Read Only Setting in getParamImpl()

[BruceChanJianLe]

Hi everyone, I am trying to implement "Parameters On Set Parameter Callback" feature, which I can update the parameters through a callback function. However, it seems like if I use the GetParam method, the declared parameter is set to a read only state.

Is there a special reason why it is set to read only?

It is set at this line here.

filters/include/filters/filter_base.hpp

Line 134 in 5507bc5

desc.read_only = true;

If I set param through the terminal, I will get this output.

Setting parameter failed: parameter 'filter1.params.output_frame' cannot be set because it is read-only