main.py

import time
import datetime
import os
import argparse
from itertools import repeat
from pathlib import Path

import cv2
import numpy as np

if os.name == 'nt':
    from utils.win32 import enable_virtual_processing

ASCII_CHARS = np.array([x for i in ['@', '#', 'S', '%', '?', '*', '+', ';', ':', ',', '.'] for x in repeat(i, 5)])
TERMINAL_ROWS, TERMINAL_COLUMNS = os.get_terminal_size()


parser = argparse.ArgumentParser(
    prog='ascii_player',
    description='Converts a video into an ASCII representation, frame-by-frame'
)
parser.add_argument('-v', '--video', required=True, help='An absolute path to the video to convert')
args = parser.parse_args()


def sleep_until(target: datetime.datetime) -> None:
    now = datetime.datetime.now()
    if now > target:
        return

    time.sleep((target - now).total_seconds())


def convert_to_greyscale(image: np.ndarray) -> np.ndarray:
    return cv2.cvtColor(image, cv2.COLOR_RGB2GRAY)


def load_frame(frame: np.ndarray) -> str:
    frame = cv2.resize(frame, (TERMINAL_ROWS, TERMINAL_COLUMNS), interpolation=cv2.INTER_LINEAR)

    frame //= 5  # type: ignore
    final_display = ASCII_CHARS[frame]

    return '\n'.join(''.join(row) for row in final_display)


def display_frames(final_display: list[str], frame_rate: int) -> None:
    time_between_frames = 1 / frame_rate

    # this ensures each frame is printed at the desired frame rate
    target_frame_display = datetime.datetime.now()

    for frame in final_display:
        print('\x1b[2J')
        print(frame)

        target_frame_display += datetime.timedelta(seconds=time_between_frames)
        sleep_until(target_frame_display)


def main():
    video = cv2.VideoCapture(str(Path(__file__).parent / args.video))

    frame_rate = int(video.get(cv2.CAP_PROP_FPS))
    total_frames = int(video.get(cv2.CAP_PROP_FRAME_COUNT))

    print(f'There are {total_frames} frames in this video.')

    frames: list[np.ndarray] = []

    start = time.perf_counter()
    for frame_num in range(total_frames):
        print(f'Progress : Converting frame {frame_num + 1} of {total_frames} to greyscale', end='\r')

        # more_frames represents whether or not a valid frame has actually been retrieved
        # i.e. `False`` is returned when frame 322 is reached of a 321 frame video
        more_frames, frame = video.read()
        assert more_frames  # this should never raise an AssertionError

        frames.append(convert_to_greyscale(frame))
    end = time.perf_counter()

    print(f'Progress : Converting frame {frame_num + 1} of {total_frames} to greyscale (took {end-start:.2f} seconds)')  # type: ignore

    final_display: list[str] = []
    start = time.perf_counter()
    for frame_num, frame in enumerate(frames, start=1):
        print(f'Progress : Loading frame {frame_num} of {total_frames}', end='\r')
        final_display.append(load_frame(frame))
    end = time.perf_counter()
    print(f'Progress : Loading frame {frame_num} of {total_frames} (took {end-start:.2f} seconds)')  # type: ignore

    display_frames(final_display, frame_rate)


if __name__ == '__main__':
    on_windows = os.name == 'nt'
    # Windows' command prompt (cmd) does support ANSI escape sequences
    # however, this is only for itself, and not programs running on it,
    # thus, we'll need to enable it ourselves.
    system_has_native_ansi = not on_windows or enable_virtual_processing()

    if system_has_native_ansi is False:
        raise OSError('Native ANSI is not enabled, which is required for clearing the terminal.')

    main()