I am not pretty sure whether I implement it right or wrong but you can add your CNN model before the LSTM inforward function. However it will be very slow while training. Therefore I am not doing that because seems like train that separately give not much different accuracy and faster. Make sure you slice tensor the do CNN on it after that concate to feed to LSTM. I am still trying to find my previous code but seems like it has been deleted while I formatted my disk. Sorry.