cv2.CAP_GSTREAMER

cv2.CAP_GSTREAMER是OpenCV库中的一个常量，用于指定使用GStreamer作为视频解码方式。通过设置cap = cv2.VideoCapture('filesrc location=road.mp4 ! decodebin ! videoconvert !appsink sync=false', cv2.CAP_GSTREAMER)，可以使用GStreamer来解码名为"road.mp4"的视频文件。

相关问题

给下列代码添加注释：def reach_cb(msg): global reached reached = msg.data def socket_cb(msg): global color color = msg.data def nothing(x): pass def imgRead(imgQueue): # %% 从摄像头读取数据 # cam = cv2.VideoCapture(0) global old_angle cam = cv2.VideoCapture(gstreamer_pipeline(flip_method=0), cv2.CAP_GSTREAMER) if not cam.isOpened(): print("Unable to open camera") else: print('Open camera success!') sub_reached = rospy.Subscriber('/reached',Bool,reach_cb) done_pub = rospy.Publisher('/done',Bool,queue_size=10) sub_color = rospy.Subscriber('/detector_trafficlight', Bool, socket_cb) # true检测红色，false检测蓝色 cmd_vel_pub=rospy.Publisher('/ackermann_cmd',AckermannDrive,queue_size=10)

# 定义一个回调函数，用于接收/reached话题的消息，并将消息数据保存到全局变量reached中
def reach_cb(msg):
    global reached
    reached = msg.data

# 定义一个回调函数，用于接收/detector_trafficlight话题的消息，并将消息数据保存到全局变量color中
def socket_cb(msg):
    global color
    color = msg.data

# 定义一个空函数，用于占位，不执行任何操作
def nothing(x):
    pass

# 定义一个函数，用于从摄像头读取图像数据
def imgRead(imgQueue):
    # 使用gstreamer_pipeline函数打开摄像头并获取摄像头对象cam
    cam = cv2.VideoCapture(gstreamer_pipeline(flip_method=0), cv2.CAP_GSTREAMER)
    # 判断摄像头是否成功打开
    if not cam.isOpened():
        print("Unable to open camera")
    else:
        print('Open camera success!')
    # 创建一个订阅器，订阅/reached话题，当有新消息时，调用回调函数reach_cb处理消息
    sub_reached = rospy.Subscriber('/reached', Bool, reach_cb)
    # 创建一个发布器，用于向/done话题发布消息，消息类型为Bool，队列大小为10
    done_pub = rospy.Publisher('/done', Bool, queue_size=10)
    # 创建一个订阅器，订阅/detector_trafficlight话题，当有新消息时，调用回调函数socket_cb处理消息
    sub_color = rospy.Subscriber('/detector_trafficlight', Bool, socket_cb) # true检测红色，false检测蓝色
    # 创建一个发布器，用于向/ackermann_cmd话题发布消息，消息类型为AckermannDrive，队列大小为10
    cmd_vel_pub = rospy.Publisher('/ackermann_cmd', AckermannDrive, queue_size=10)

[ WARN:0@12.577] global C:\b\abs_d8ltn27ay8\croot\opencv-suite_1676452046667\work\modules\videoio\src\cap_gstreamer.cpp (862) cv::GStreamerCapture::isPipelinePlaying OpenCV | GStreamer warning: GStreamer: pipeline have not been created (python.exe:10308): GLib-GIO-WARNING **: 21:20:09.250: Unexpectedly, UWP app `Microsoft.ScreenSketch_11.2303.17.0_x64__8wekyb3d8bbwe' (AUMId `Microsoft.ScreenSketch_8wekyb3d8bbwe!App') supports 29 extensions but has no verbs Traceback (most recent call last): File "D:\学习\作业\pythonProject\代码\traditional\extract_hand_video.py", line 57, in <module> main() File "D:\学习\作业\pythonProject\代码\traditional\extract_hand_video.py", line 38, in main key = cv2.waitKey(8) KeyboardInterrupt

这个警告表明GStreamer捕获器无法创建管道。这通常是由于没有正确设置GStreamer环境或缺少必要的元素库引起的。您可以尝试重新安装GStreamer或确保您的环境正确设置。另外，您的代码中还出现了一个 KeyboardInterrupt 错误，这可能是由于用户在程序运行时按下了 Ctrl+C 组合键导致的。为了避免这个错误，您可以在代码中添加一个 try-except 块来捕获该异常并进行处理。