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AttributeError: 'NoneType' object has no attribute 'shape'

opencv#python

asked 2019-02-26 05:37:44 -0600

Abdu
1 ●1 ●2 ●3

Hi all! I need your help regarding the following code. My goal is to read and show the video with a resolution modification.


import cv2
 cap = cv2.VideoCapture("C:/Users/user/Desktop/Foot_Detection/ball_tracking_example.mp4")
 def rescale_frame(frame, percent=30):
    width = int(frame.shape[1] * percent/ 100)
    height = int(frame.shape[0] * percent/ 100)
    dim = (width, height)
    return cv2.resize(frame, dim, interpolation =cv2.INTER_AREA)
 if (cap.isOpened() == False):
    print("Error opening video stream or file")
 while (cap.isOpened()):
    # Capture frame-by-frame
    ret, frame = cap.read()
 frame = rescale_frame(frame, percent=30)
    if ret == True:
 cv2.imshow('Frame', frame)
 if cv2.waitKey(25) & 0xFF == ord('q'):
            break
 else:
        break
 cap.release()
 cv2.destroyAllWindows()

After executing the above code, the video displayed on my screen till the end. However, I have got the following error:


Traceback (most recent call last):
  File "C:/Users/user/Desktop/Foot_Detection/FootDetection.py", line 24, in <module>
    frame = rescale_frame(frame, percent=30)
  File "C:/Users/user/Desktop/Foot_Detection/FootDetection.py", line 10, in rescale_frame
    width = int(frame.shape[1] * percent/ 100)
AttributeError: 'NoneType' object has no attribute 'shape'

I tried to install the codec for mp4 and to the video path is correct. Could you please assist me in this matter? Thank you in advance.

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Comments

checking the ret value is mandatory, since it will tell you, when the movie's over.

berak ( 2019-02-26 07:38:08 -0600 )edit

Nope, berak. What does the error tell you? AttributeError: 'NoneType' object has no attribute 'shape'

supra56 ( 2019-02-26 08:08:16 -0600 )edit

again, the last frame will be empty (None)

(and this is one of the main differences between capturing from a webcam or a video file, please go and check)

berak ( 2019-02-26 08:11:57 -0600 )edit

Nope. The frame is not empty. I already tested it.. There are no differences between webcam and file.

supra56 ( 2019-02-26 08:42:02 -0600 )edit

@Abdu, can you take another look at the code in your question, and try to repair the broken formatting ?

(whitespace matters in python ...)

berak ( 2019-02-26 13:39:17 -0600 )edit

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2 answers

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answered 2019-02-26 07:35:50 -0600

supra56

943 ●9 ●6

updated 2019-02-26 08:48:19 -0600

I am using OpenCV 4.0.1, using raspberry pi 3. Do not put outside of while condition block. And do not used this else: break. Because it will disappeared window. The correct code like this:

import cv2

cap = cv2.VideoCapture("C:/Users/user/Desktop/Foot_Detection/ball_tracking_example.mp4")
def rescale_frame(frame, percent=30):
    width = int(frame.shape[1] * percent/ 100)
    height = int(frame.shape[0] * percent/ 100)
    dim = (width, height)
    return cv2.resize(frame, dim, interpolation =cv2.INTER_AREA)
if (cap.isOpened() == False):
    print("Error opening video stream or file")
while (cap.isOpened()):
    # Capture frame-by-frame
    ret, frame = cap.read()
    frame = rescale_frame(frame, percent=30)
    if ret == True:
        cv2.imshow('Frame', frame)
        if cv2.waitKey(25) & 0xFF == ord('q'):
            break


cap.release()
cv2.destroyAllWindows()

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Comments

Good tutorial to learn. tutorial

supra56 ( 2019-02-26 07:39:04 -0600 )edit

please check ret* **before** callingrescale_frame()`

(else you run into the same problem as the original question (and nothing is resolved))

berak ( 2019-02-26 08:13:22 -0600 )edit

NOPE! Everything outside of while condition block.

supra56 ( 2019-02-26 08:47:09 -0600 )edit

@supra56 your link is not up to date. Good link it's here You must check ret valeur in cap.read()

LBerger ( 2019-02-26 09:43:29 -0600 )edit

Thank you for your answers. @supra56 your code shows me the same error.

Abdu ( 2019-02-26 11:01:07 -0600 )edit

@Abdu. Are you running on python 2 or python 3?

supra56 ( 2019-02-26 12:54:12 -0600 )edit

@supra56 Python 3.7

Abdu ( 2019-02-27 03:31:56 -0600 )edit

Did you try link from @LBerger? Wondering, what's your opencv version?

supra56 ( 2019-02-27 03:45:01 -0600 )edit

Yes, I tried the code in the link of @LBerger, the error persists.

Abdu ( 2019-02-27 03:55:58 -0600 )edit

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answered 2019-02-27 04:20:33 -0600

Abdu
1 ●1 ●2 ●3

I was able to solve the problem. I just need to figure out how to loop:


import numpy as np
import cv2
cap = cv2.VideoCapture('C:\Sample3.mp4')

def rescale_frame(frame, percent=30):

    width = int(frame.shape[1] * percent/ 100)
    height = int(frame.shape[0] * percent/ 100)
    dim = (width, height)
    return cv2.resize(frame, dim, interpolation =cv2.INTER_AREA)

while True:
    ret ,frame = cap.read()
    if type(frame) == type(None):
        break
    frame25 = rescale_frame(frame, percent=25)
    cv2.imshow('frame25',frame25)
    if cv2.waitKey(1) & 0xFF == ord('q'):
        break
cap.release()
cv2.destroyAllWindows()

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Comments

what's about

if not ret:
    break

instead of

if type(frame) == type(None):
    break

and you don't check if video file is opened :

if not cap.isOpened():
    print("Cannot open video file")
    exit()

LBerger ( 2019-02-27 04:38:28 -0600 )edit

@Abdu . Following example freom @LBerger.

supra56 ( 2019-02-28 06:59:21 -0600 )edit

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AttributeError: 'NoneType' object has no attribute 'shape'

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