In SpeechT5, the input to the decoder part of the model is reduced by a factor 2. In other words, it throws away every 
other timestep from the target sequence. The decoder then predicts a sequence that is twice as long. Since the original 
target sequence length may be odd, the data collator makes sure to round the maximum length of the batch down to be a 
multiple of 2.
 

data_collator = TTSDataCollatorWithPadding(processor=processor)