"""Template code for video frame processing.""" 
import multiprocessing as mp 
import cv2 

BUFFER_SIZE = 12 
RUNNING = mp.Value("i", 1) 


def get_frames(srcs, q: mp.Queue): 
    """子进程对象。用于视频流解码，并将解码后的图像填充到队列中。""" 
    caps = [cv2.VideoCapture(src) for src in srcs] 
    print("Opening streams...") 
    while RUNNING.value == 1: 
    	for i, cap in enumerate(caps): 
        	_, frame = cap.read() 
            q.put((frame, i)) 
            print("Streaming stopped.") 


def main(): 
    # 设定视频源 
    video_srcs = ['/home/robin/Videos/pose.mp4', '/home/robin/Videos/mask.mp4', ] 
    
    # 构建用于交换数据的队列 
    frame_q = mp.Queue(maxsize=BUFFER_SIZE) 
    
    # 构建进程并启动它 
    p = mp.Process(target=get_frames, args=(video_srcs, frame_q,)) 
    p.start() 
    
    # 预览图像。 
    while RUNNING.value == 1: 
        frame, cap_id = frame_q.get() 
        frame = cv2.resize(frame, (0,0), fx=0.5, fy=0.5) 
        cv2.imshow('{}'.format(cap_id), frame) 
        if cv2.waitKey(1) == 27: 
            RUNNING.value = 0 
            
    print("Closing queue...") 
    frame_q.close() 
    
    print("Joining process...") 
    p.terminate() 
    
    print("All done.") 

if __name__ == "__main__": 
    main()