# Video speed is very fast

**URL:** <https://forum.opencv.org/t/video-speed-is-very-fast/4269>\
**Category:** Python\
**Tags:** videoio\
**Created:** [July 9, 2021, 1:48pm UTC](https://forum.opencv.org/t/video-speed-is-very-fast/4269 "2021-07-09T13:48:24Z")\
**Posts on this page:** 6\
**Page:** 1

<div class="post-metadata">

**Author:** ![Vansh](https://avatars.discourse-cdn.com/v4/letter/v/53a042/32.png) [@Vansh](https://forum.opencv.org/u/Vansh)\
**Post date:** [July 9, 2021, 1:48pm UTC](https://forum.opencv.org/t/video-speed-is-very-fast/4269/1 "2021-07-09T13:48:24Z")

</div>

I am trying to make an opensource screen recorder app and this is the code i have written till now

```auto
'''Import All the stuff below'''

from tkinter import *
from PIL import ImageGrab
import numpy as np
import cv2
from datetime import datetime
import time

'''Import All the stuff above'''

# Tk() class's instance below
app = Tk()
# Tk() class's instance above

# Vid Name
date_and_time = datetime.now().strftime('%Y-%m-%d %H-%M-%S')
vid_name = f'Simple Recorder {date_and_time}.mp4'
# Vid Name

# Getting screen size below
width = app.winfo_screenwidth()
height = app.winfo_screenheight()
#getting screen size above

vid_writer = cv2.VideoWriter_fourcc('m', 'p', '4', 'v')
captured_vid = cv2.VideoWriter(vid_name, vid_writer, 30.0, (width, height))

while 1:
	img = ImageGrab.grab(bbox = (0, 0, width, height))
	img_np = np.array(img)
	img_final = cv2.cvtColor(img_np, cv2.COLOR_BGR2RGB)
	cv2.imshow('Simple Recorder', img_final)
	cv2.waitKey(33)
	captured_vid.write(img_final)

	if cv2.getWindowProperty('Simple Recorder', cv2.WND_PROP_VISIBLE) < 1:
		break

```

The problem is whenever i run the recorded .mp4 file it is fastforwarded and i have no idea how to handle this problem

can any one help me??  
ThankYou in Advance!!!

---

<div class="post-metadata">

**Author:** ![crackwitz](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.opencv.org/crackwitz/32/14_2.png) [@crackwitz](https://forum.opencv.org/u/crackwitz)\
**Post date:** [July 9, 2021, 2:37pm UTC](https://forum.opencv.org/t/video-speed-is-very-fast/4269/2 "2021-07-09T14:37:53Z")

</div>

check how many frames per second you actually capture and write.

---

<div class="post-metadata">

**Author:** ![furas](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.opencv.org/furas/32/706_2.png) [@furas](https://forum.opencv.org/u/furas)\
**Post date:** [July 9, 2021, 11:47pm UTC](https://forum.opencv.org/t/video-speed-is-very-fast/4269/3 "2021-07-09T23:47:32Z")

</div>

Code

```
VideoWriter(..., 30.0)

```

doesn’t mean that it will create correct video with `30 FPS.`

It only inform video that it has to display 30 frames every second. But if you will generate and write 15 images every second then it will display them in 0.5 second (instead of 1 second) - so it will display it faster. If you will generate and write 60 images every seconds then it will display them in 2 seconds (instead of 1 second) - so it will display it slower.

* * *

You set

```
 waitKey(33) 

```

so it should run loop 30 times in every second

```
1s/33ms = 1000ms/33ms = ~30 FPS 

```

but code needs also time to run `ImageGrab`, convert it to numpy array, etc.  
On my computer it takes ~60-100ms so I can get only 14-15 images every second (if I set `waitKey(1)`).

* * *

This code measures time and display how many FPS you should use in `VideoWriter`

Because `.mp4` doesn’t work on my computer so I use `.avi`

```python
import tkinter
from datetime import datetime
from PIL import ImageGrab
import numpy as np
import cv2
import time

#video_name = datetime.now().strftime('Simple Recorder %Y-%m-%d %H-%M-%S.mp4')
video_name = datetime.now().strftime('Simple Recorder %Y-%m-%d %H-%M-%S.avi')

# getting screen size
app = tkinter.Tk()
#app.iconify() # minimize window to icon on taskbar
#app.withdraw() # hide window without icon on taskbar
width = app.winfo_screenwidth() # //4
height = app.winfo_screenheight() # //2
app.destroy()

#video_format = cv2.VideoWriter_fourcc(*'mp4v') # .mp4
video_format = cv2.VideoWriter_fourcc(*'MP42') # .avi 
video_writer = cv2.VideoWriter(video_name, video_format, 15.0, (width, height))

while True:
    start = time.time()
    
    img = ImageGrab.grab(bbox=(0, 0, width, height))
    img = np.array(img)
    img = cv2.cvtColor(img, cv2.COLOR_RGB2BGR)
    cv2.imshow('Simple Recorder', img)
    
    end = time.time()
    diff = (end-start)*1000
    print('time: {:6.2f} ms | {:5.2f} FPS'.format(diff, 1000/diff ))
    
    cv2.waitKey(1)
    
    video_writer.write(img)

    if cv2.getWindowProperty('Simple Recorder', cv2.WND_PROP_VISIBLE) < 1:
        break

```

Better method would be to run `ImageGrab`, numpy.array, `cvtColor` in separated thread and later in `while`-loop use `cv2.waitKey(33)` to control how often to write image to file. If there will be no new image then it will write previous image but at least it will write 30 frames every second.

Somewhere on `PyImageSearch` was even example how to use `threads` to get ~120FPS from WebCam.

Maybe later I create version with threads

---

<div class="post-metadata">

**Author:** ![Vansh](https://avatars.discourse-cdn.com/v4/letter/v/53a042/32.png) [@Vansh](https://forum.opencv.org/u/Vansh)\
**Post date:** [July 10, 2021, 7:35am UTC](https://forum.opencv.org/t/video-speed-is-very-fast/4269/4 "2021-07-10T07:35:28Z")

</div>

Thankyou for your support,

I manage to get the fps i want (because of you)

but a new problem has came!!

i completed the code part of the software and now when i convert .py file to linux executable i get the executable with no errors  
but  
whenever i hit the record button on the gui i get an error saying somthing like this

```auto
qt.qpa.plugin: Could not find the Qt platform plugin "xcb" in "/tmp/_MEIdKXjK0/cv2/qt/plugins"
This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.

Aborted (core dumped)

```

what is this about??

---

<div class="post-metadata">

**Author:** ![berak](https://avatars.discourse-cdn.com/v4/letter/b/85f322/32.png) [@berak](https://forum.opencv.org/u/berak)\
**Post date:** [July 10, 2021, 7:47am UTC](https://forum.opencv.org/t/video-speed-is-very-fast/4269/5 "2021-07-10T07:47:44Z")

</div>

> [@Vansh](#):
>
> what is this about??

we might have no idea. a qt, not an opencv problem ;(

---

<div class="post-metadata">

**Author:** ![furas](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.opencv.org/furas/32/706_2.png) [@furas](https://forum.opencv.org/u/furas)\
**Post date:** [July 10, 2021, 5:18pm UTC](https://forum.opencv.org/t/video-speed-is-very-fast/4269/6 "2021-07-10T17:18:06Z")

</div>

Using `print(cv2. __file__ )` you can find folder with source code and there should be subfolder `plugins/platforms/` with `libqxcb.so` which you may need to add to config file when you convert to executable.

On my Linux Mint it is

/usr/local/lib/python3.8/dist-packages/cv2/qt/plugins/platforms/libqxcb.so