尝试使用 opencv 和 tkinter 录制视频时获取 6kb avi 文件

Question

我有一个多帧/多页 Tkinter 应用程序，在一个页面/帧中，我有一个相机框架，当我导航到该页面时，它会启动相机和星星捕捉现在我想录制该视频，但当我尝试录制它时我得到了一个 6kb 的 ```avi`` 文件，它根本不工作而且似乎已损坏。

我的代码

class FrontCameraPage(tk.Frame):
    def __init__(self, parent, controller):
        tk.Frame.__init__(self, parent)
        self.controller = controller

        self.label = tk.Label(self, text="FRONT CAMERA", font=MediumFont, bg="white").grid(row=0, column=0, columnspan=2, sticky="nsew")
        self.cameraFrame = tk.Frame(self, bg=gray)
        self.cameraFrame.grid(row=1, column=0, sticky="nsew")
        self.buttonFrame = tk.Frame(self, bg="white")
        self.buttonFrame.grid(row=1, column=1, sticky="nsew", padx=(10, 0))


#creating buttons and frames --
        self.end= tk.Button(self.buttonFrame, text="STOP", font=small_Font, bg=dark_blue, fg="White")
        self.end.grid(row=2, column=0, ipadx=10, pady=(0, 5))
        self.end['command'] = self.stop_capture

        self.cancelButton = tk.Button(self.buttonFrame, text="Cancel", font=small_Font, bg=dark_blue, fg="white")
        self.cancelButton.grid(row=3, column=0, ipadx=10)
        self.cancelButton['command'] = lambda: controller.show_frame(someOtherPage)

#----------------------------------------------------------------------------------------------

        # setup callbacks for switching in and out events starts and stops when I change frames
        self.bind('<<SwitchIn>>', self.start_capture)
        self.bind('<<SwitchOut>>', self.stop_capture)

        self.capture = None  # task id for the capture loop
        width, height = 200, 200
        self.cap = cv2.VideoCapture(0)
        self.cap.set(cv2.CAP_PROP_FRAME_WIDTH, width)
        self.cap.set(cv2.CAP_PROP_FRAME_HEIGHT, height)


        self.fourcc = cv2.VideoWriter_fourcc('M', 'J', 'P', 'G')
        self.out = cv2.VideoWriter('output.avi', self.fourcc, 20.0, (width, height))        
        self.lmain = tk.Label(self.cameraFrame)
        self.lmain.pack()

    def start_capture(self, event=None):
        if self.capture is None:
            self.show_frame()
            print('capture started')


    def stop_capture(self, event=None):
        if self.capture:
            self.after_cancel(self.capture)
            self.out.release()
            self.capture = None
            print('capture stopped')


    def show_frame(self):
        ret, frame = self.cap.read()
        if ret:
            frame = cv2.flip(frame, 1)
            cv2image = cv2.cvtColor(frame, cv2.COLOR_BGR2RGBA)
            img = Image.fromarray(cv2image)
            #----------------------------------------------------------------
            self.out.write(cv2image)
            #----------------------------------------------------------------
            self.imgtk = ImageTk.PhotoImage(image=img)
            self.lmain.configure(image=self.imgtk)
        self.capture = self.after(10, self.show_frame)

Answer 1

这是因为self.cap.read()返回的实际帧大小与创建视频写入器时的大小不匹配。

调用self.cap.set(...)后需要使用self.cap.get(...)获取实际帧大小：

class FrontCameraPage(tk.Frame):
    def __init__(self, parent, controller):
        tk.Frame.__init__(self, parent)
        self.controller = controller

        ... 

        width, height = 200, 200
        self.cap = cv2.VideoCapture(0)
        self.cap.set(cv2.CAP_PROP_FRAME_WIDTH, width)
        self.cap.set(cv2.CAP_PROP_FRAME_HEIGHT, height)

        # get the final frame size
        width = int(self.cap.get(cv2.CAP_PROP_FRAME_WIDTH))
        height = int(self.cap.get(cv2.CAP_PROP_FRAME_HEIGHT))

        self.fourcc = cv2.VideoWriter_fourcc('M', 'J', 'P', 'G')
        self.out = cv2.VideoWriter('output.avi', self.fourcc, 20.0, (width, height))
        ...