Installation is easy. Checkout the Git repository of RETURNN ( Install all dependencies, which are just numpy, h5py, and the backend you want to use (TensorFlow or Theano). You can do so via:

pip install -r requirements.txt

You probably want to use pip3 instead of pip, and you also might want to add the option --user (if you are not using virtualenv).

For TensorFlow, use pip install tensorflow-gpu (pip3 install --user tensorflow-gpu) if you have a Nvidia GPU, and make sure that CUDA and cuDNN can be found.

For Theano, only version 0.9 works (pip install theano==0.9). For Theano usage, make sure that you have this in your ~/.theanorc:

device = cpu
floatX = float32

For some specific datasets or special layers, additional dependencies might be needed, such as librosa. For running the tests, you need nose.

You can also install RETURNN as a framework, via pip (PyPI entry), like:

pip install returnn

See Basic Usage for the basic usage of RETURNN.