I’m developing a TV enconder, and I need to extract information from my
input data, and this will be used to determine the parameters of other
blocks on the flow graph.
How can I change the value of a variable of the python (or grc)
environment
from the block general_work() method?
I’m developing a TV enconder, and I need to extract information from my
input data, and this will be used to determine the parameters of other
blocks on the flow graph.
How can I change the value of a variable of the python (or grc) environment
from the block general_work() method?
Well, you generally cant call a python function from c++… but heres a
few ways that may accomplish what you need:
Using swig directors is a possibility. Rather than figure out the
intricacies of directors, gnuradio already makes use of them in the
gr.feval_* class, which you can use to call into a python object. Your
general_work() calls the feval object in c++; and then feval object
(from python) directly calls into other variables in the python-domain
of your flow graph.
Another possibility is passing messages into a message queue object.
A python thread can pop the messages and act upon them.
A related possibility, depending upon how your block operates would
be to have a python thread periodically poll the getter methods of your
custom block and act upon those values. There is already a block in grc
that will poll another block’s getter function and update a variable.
And if thats not possible for performance reasons, you might consider
a hybrid approach where you write general work in python, but you call
into a function implemented in c++; where this function processes the
input data and returns the “determined parameters”, which you can act on
in python.
-Josh
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