I2S parallel output in slave mode

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I have recently managed to port this nice project to latest esp-idf: viewtopic.php?t=3256

This works very well.
However if I try to switch the external clock (slave mode), then there is no output.
The Technical Reference says that arbitrary combination of input/output vs. master/slave is possible at least in serial mode. However the documentation is not so clear if both master and slave modes are available in parallel output mode.

Could anyone please provide me with a working code example for I2S parallel output in slave mode?