The diagram is super vague. How are the lyrics encoded? What does the encoder look like inside? What is the input size, input format, output size, output format

The diagram is super vague. How are the lyrics encoded? What does the encoder look like inside? What is the input size, input format, output size, output format? Are the three encoder outputs added? Concatentated? When Mert and m-Hubert combine are they added? Multiplied? Subtracted? Concatenated? I really wish people could make better diagrams.