tf.keras.losses.ctc

CTC (Connectionist Temporal Classification) loss.

y_true A tensor of shape (batch_size, max_length) containing the true labels in integer format. 0 always represents the blank/mask index and should not be used for classes.
y_pred A tensor of shape (batch_size, max_length, num_classes) containing logits (the output of your model). They should not be normalized via softmax.