CTCLoss
class torch.nn.CTCLoss(blank=0, reduction='mean', zero_infinity=False)
The Connectionist Temporal Classification loss.
Calculates loss between a continuous (unsegmented) time series and
   a target sequence. CTCLoss sums over the probability of possible
   alignments of input to target, producing a loss value which is
   differentiable with respect to each input node. The alignment of
   input to target is assumed to be "many-to-one", which limits the
   length of the target sequence such that it must be \leq the input
   length.
Parameters:
      * blank (int, optional) -- blank label. Default 0.
  * **reduction** (*str**, **optional*) -- Specifies the reduction
    to apply to the output: "'none'" | "'mean'" | "'sum'".
    "'none'": no reduction will be applied, "'mean'": the output
    losses will be divided by the target lengths and then the mean
    over the batch is taken. Default: "'mean'"
