There are quite a few examples on how to use LSTMs alone in TF, but I couldn't find any good examples on how to train CNN + LSTM jointly. From what I see, it is not quite straightforward how to do such training, and I can think of just one option.
I believe the simplest solution (or the most primitive one) would be to train CNN independently to learn features and then to train LSTM on CNN features without updating the CNN part, since one would probably have to extract and save these features in numpy and then feed them to LSTM in TF. But in that scenario, one would probably have to use a differently labeled dataset for pretraining of CNN, which eliminates the advantage of end to end training, i.e. learning of features for final objective targeted by LSTM (besides the fact that one has to have these additional labels in the first place).
Is there any other way to do it? I haven't been able to find any example in tensorflow.