Incorrect audio shape

[ebezzam]

When applying browserinterface.change_config, the first buffer sent to the callback does not have the correct shape (buffer size, number of channels) but subsequent ones do. Need to apply a check as in examples/frame_processing.py.

[fakufaku]

After talking with @NTag , it seems this is caused because a few audio blocks are received before the configuration is actually changed. We could change this by having a check of the stream parameters (I see some of the scripts now have it).

@NTag also pointed out that we can have a call back on change of configuration events as in the original frame_processing.py example.