「Python案例」字符图像，让字符跳动起来！

STRING = "Ñ@#W$9876543210?!abc;:+=-,._"

def gray2ascii(gray):
    h, w = gray.shape[0:2]
    ascii_img = np.zeros((h, w), dtype="<U1")
    idxs = np.round(gray / 255.0 * len(STRING))
    idxs = idxs.astype(np.int32)
    for i in range(h):
        for j in range(w):
            ascii_img[i, j] = STRING[-idxs[i, j]]
    return ascii_img

def extract_frames(video_path, callback):
    video = cv2.VideoCapture(video_path)
    num_frames = int(video.get(cv2.CAP_PROP_FRAME_COUNT)) 
    for _ in tqdm(range(num_frames)):
        _, frame = video.read()
        if frame is not None:
            callback(frame)
        else:
            break

WRITER = None 
def write_frame(frame, out_path, fps=30):
    global WRITER
    if WRITER is None:
        size = frame.shape[0:2][::-1]
        WRITER = cv2.VideoWriter(
            out_path,
            cv2.VideoWriter_fourcc(*'mp4v'),  # 编码器
            fps,
            size)
    WRITER.write(frame)