Flickering video for tkinter video - python-3.x

Question

I am trying to make a simple play/pause application in tkinter. Basically I want to show a video and have a play/pause button underneath.
So, after some research I found this suitable post to show a video using tkinter and opencv:
to show video streaming inside frame in tkinter
When using the code, given in the accepted answer to show a video, there is no problem and I don't see any flickering. Here is the code:
# import the necessary packages
from __future__ import print_function
import tkinter as tk
from PIL import ImageTk, Image
import cv2
root = tk.Tk()
# Create a frame
app = tk.Frame(root, bg="white")
app.grid()
# Create a label in the frame
lmain = tk.Label(app)
lmain.grid()
# Capture from camera
cap = cv2.VideoCapture(r'PATH_TO_VIDEO_FILE')
# function for video streaming
frame_number = 0
def video_stream():
global frame_number
cap.set(cv2.CAP_PROP_POS_FRAMES, frame_number)
success, frame = cap.read()
cv2image = cv2.cvtColor(frame, cv2.COLOR_BGR2RGBA)
img = Image.fromarray(cv2image)
imgtk = ImageTk.PhotoImage(image=img)
lmain.imgtk = imgtk
lmain.configure(image=imgtk)
lmain.after(1, video_stream)
frame_number += 1
video_stream()
root.mainloop()
Now, I slightly altered the code to be able to use the grid manager and add a play button:
# import the necessary packages
from __future__ import print_function
import tkinter as tk
from PIL import ImageTk, Image
import cv2
class PhotoBoothApp:
def __init__(self, path_to_video):
# initialize the root window
self.window = tk.Tk()
self.window.title("Video_Player")
self.videocap = cv2.VideoCapture(path_to_video)
self.frame_number = 0
# Initalize
self.videocap.set(cv2.CAP_PROP_POS_FRAMES, self.frame_number)
success, self.frame = self.videocap.read()
cv2image = cv2.cvtColor(self.frame, cv2.COLOR_BGR2RGBA)
self.img = Image.fromarray(cv2image)
self.imgtk = ImageTk.PhotoImage(image=self.img)
# Show frames
self.picture_label = tk.Label(self.window, image=self.imgtk, relief=tk.RIDGE).grid(row=0, column=0)
self.btn_next_image=tk.Button(self.window, text="Play", width=50, bg ="green",command=self.video_stream).grid(row=1,column=0)
self.window.mainloop()
def video_stream(self):
self.videocap.set(cv2.CAP_PROP_POS_FRAMES, self.frame_number)
sucess, frame = self.videocap.read()
cv2image = cv2.cvtColor(frame, cv2.COLOR_BGR2RGBA)
img = Image.fromarray(cv2image)
self.imgtk = ImageTk.PhotoImage(image=img)
self.picture_label = tk.Label(self.window, image=self.imgtk, relief=tk.RIDGE).grid(row=0, column=0)
# Update Frame Number to display
self.frame_number = self.frame_number + 1
self.window.after(1, self.video_stream)
ph = PhotoBoothApp(r'PATH_TO_FILE')
The problem is that when I execute the above code, the video flickers as if tkinter need to reload something in-between frames. I have no clue why this happens.
P.S. This post here Flickering video in opencv-tkinter integration did not help me.

Answer 1

You need to make two changes: split your self.picture_label line to create a proper reference to your Label object, and then use self.picure_label.config(...) to change the image.
class PhotoBoothApp:
def __init__(self, path_to_video):
# initialize the root window
...
self.picture_label = tk.Label(self.window, image=self.imgtk, relief=tk.RIDGE)
self.picture_label.grid(row=0, column=0)
...
def video_stream(self):
...
img = Image.fromarray(cv2image)
self.imgtk = ImageTk.PhotoImage(image=img)
self.picture_label.config(image=self.imgtk)
# Update Frame Number to display
self.frame_number = self.frame_number + 1
self.window.after(1, self.video_stream)
ph = PhotoBoothApp(r'PATH_TO_FILE')