import tensorflow as tf
from tensorflow import keras

def CTCLoss(y_true, y_pred):
    batch_len = tf.cast(tf.shape(y_true)[0], dtype = "int64")
    input_length = tf.cast(tf.shape(y_pred)[1], dtype = "int64")
    label_length = tf.cast(tf.shape(y_true)[1], dtype = "int64")

    input_length = input_length * tf.ones(shape = (batch_len, 1), dtype = "int64")
    label_length = label_length * tf.ones(shape = (batch_len, 1), dtype = "int64")

    loss = keras.backend.ctc_batch_cost(y_true, y_pred, input_length, label_length)
    return loss