helpers.py

import os
import cv2
import tensorflow as tf
import numpy as np
import yaml

from typing import List

with open('config.yml', 'r') as config_file_obj:
    yaml_config = yaml.safe_load(config_file_obj)

dataset_config = yaml_config['datasets']
VIDEO_DIR = dataset_config['video_dir']
ALIGNMENTS_DIR = dataset_config['alignments_dir']

vocab = [x for x in "abcdefghijklmnopqrstuvwxyz'?!123456789 "]
char_to_num = tf.keras.layers.StringLookup(vocabulary=vocab, oov_token="")
num_to_char = tf.keras.layers.StringLookup(
    vocabulary=char_to_num.get_vocabulary(), oov_token="", invert=True
)


def load_video(path: str) -> List[float]:
    """
    adapted original loading code using this tutorial about openCV
    https://learnopencv.com/read-write-and-display-a-video-using-opencv-cpp-python/
    """
    cap = cv2.VideoCapture(path)
    frames = []
    ret = True

    while cap.isOpened():
        ret, frame = cap.read()

        if ret is True:
            frame = tf.image.rgb_to_grayscale(frame)
            frames.append(frame[190:236, 80:220, :])
        else:
            break

    cap.release()

    mean = tf.math.reduce_mean(frames)
    std = tf.math.reduce_std(tf.cast(frames, tf.float32))
    return tf.cast((frames - mean), tf.float32) / std


def load_alignments(path: str) -> List[str]:
    with open(path, 'r') as f:
        lines = f.readlines()

    tokens = []
    for line in lines:
        line = line.split()
        if line[2] != 'sil':
            tokens = [*tokens, ' ', line[2]]

    return char_to_num(tf.reshape(
        tf.strings.unicode_split(tokens, input_encoding='UTF-8'), (-1)
    ))[1:]


def load_data(tf_path):
    # print('PATH', tf_path, type(tf_path))
    path = tf_path.numpy().decode('utf-8')

    # get dirname of dir
    dir_name = os.path.basename(os.path.dirname(path))
    # get filename of the current path
    base_filename = os.path.basename(path)
    base_name = os.path.splitext(base_filename)[0]
    new_base_path = os.path.join(dir_name, base_name)

    # file_name = path.split('/')[-1].split('.')[0]
    # File name splitting for windows
    video_path = os.path.join(VIDEO_DIR, f'{new_base_path}.mpg')
    alignment_path = os.path.join(
        ALIGNMENTS_DIR, f'{new_base_path}.align'
    )

    try:
        frames = load_video(video_path)
    except Exception as e:
        print('BAD_VIDEO', video_path)
        raise e

    alignments = load_alignments(alignment_path)
    return frames, alignments


def mappable_function(path:str) -> List[str]:
    result = tf.py_function(
        load_data, [path], (tf.float32, tf.int64)
    )
    return result