Solved by ptrblck in post #2 
              
              
                I’m unsure where the 29 comes from. Do you mean 129 or 20 or are the “29 columns” created in a special way? 
If it’s a typo and you would like to use the 20 channels as the temporal dimension, you could initialize the RNN via batch_first=True, which would expect an input in the shape [batch_size, se…