'Frame from video is upside down after extracting

My problem here is that when I extracting a video into a frame using opencv, sometimes the frame that I get will flip up which happened to me for both my machine(window) and VM(ubuntu) But some of the video I tested, frames are not flip. So, I wonder what factor or what should be changed/added in my code to make the extract fixed without a flip

def extract_frame(video,folder):
   global fps

   os.mkdir('./green_frame/{folder}/'.format(folder=folder))
   vidcap = cv2.VideoCapture(video)
   success,image = vidcap.read()
   fps = vidcap.get(cv2.CAP_PROP_FPS)
   count = 0
   success = True
   while success:  #os.path.join(pathOut,(name+'.png'))
      cv2.imwrite(os.path.join('./green_frame/{folder}/'.format(folder=folder),"frame%d.png" % count), image)
      success,image = vidcap.read()
      print('Read a new frame: ', success) 
      count += 1

This is the example of frame I get from this code. Which my orginal video that I used is upside down like this:

So, in my case, what I have to changed to make it not flip like my first picture. Is it relate to the resolution or framerate of the video? I tested with a 1280x720 resolution video and all of the frame extracted are flipped upside down but a frame from video with a 568x320 is normal

Thank you

Edit: So, I look at the information of the video and I found out that in the metadata, it has rotate 180 for the video that extract to an upside down frame But when I check with a normal video that produced a non upside-down frame, it does not have rotate:180

So from this, how can I deal with a video that has a rotation?

Solution 1:^[1]

For anyone still looking into this, I was just stuck on the same problem. Turns out some Android phones and iPhones take images/frames in landscape and convert them on the fly according to the exif 'rotate' tag to display the images/frames.

Weird design choice in OpenCV is that cv2.imread(img_file) already reads the image in correct orientation by reading the image's rotate tag, but the cv2.VideoStream's read() method does not do this.

So, to fix this I used ffmpeg to read the 'rotate' tag and rotate the video frame to its correct orientation.(Big thanks to the comments above, for pointing me in the right direction ?)

Following is the code:

Make sure you have ffmpeg for python. (pip install ffmpeg-python)

Create a method to check if rotation is required by the video_file:

 import ffmpeg    

 def check_rotation(path_video_file):
     # this returns meta-data of the video file in form of a dictionary
     meta_dict = ffmpeg.probe(path_video_file)

     # from the dictionary, meta_dict['streams'][0]['tags']['rotate'] is the key
     # we are looking for
     rotateCode = None
     if int(meta_dict['streams'][0]['tags']['rotate']) == 90:
         rotateCode = cv2.ROTATE_90_CLOCKWISE
     elif int(meta_dict['streams'][0]['tags']['rotate']) == 180:
         rotateCode = cv2.ROTATE_180
     elif int(meta_dict['streams'][0]['tags']['rotate']) == 270:
         rotateCode = cv2.ROTATE_90_COUNTERCLOCKWISE

     return rotateCode

Create a method to correct the rotation of the frame in video file:

 def correct_rotation(frame, rotateCode):  
     return cv2.rotate(frame, rotateCode)

Finally, do this in your main loop:

 # open a pointer to the video file stream
 vs = cv2.VideoCapture(video_path)

 # check if video requires rotation
 rotateCode = check_rotation(video_path)

 # loop over frames from the video file stream
 while True:
     # grab the frame from the file
     grabbed, frame = vs.read()

     # if frame not grabbed -> end of the video
     if not grabbed:
         break

     # check if the frame needs to be rotated
     if rotateCode is not None:
         frame = correct_rotation(frame, rotateCode)

     # now your logic can start from here

Hope this helps ?

Solution 2:^[2]

The rotate tag is optional so the check_rotation will fail, This code fix it:

def check_rotation(path_video_file):
    # this returns meta-data of the video file in form of a dictionary
    meta_dict = ffmpeg.probe(path_video_file)
    # from the dictionary, meta_dict['streams'][0]['tags']['rotate'] is the key
    # we are looking for
    rotate_code = None
    rotate = meta_dict.get('streams', [dict(tags=dict())])[0].get('tags', dict()).get('rotate', 0)
    return round(int(rotate) / 90.0) * 90

Solution 3:^[3]

I would just do this in your frame processing loop:

frame = cv2.flip(frame,0)

The 0 flips vertically, see Open CV documentation for more info.

Solution 4:^[4]

Sometimes the following will solve the problem of opening some videos upside-down.

cap = cv2.VideoCapture(path, apiPreference=cv2.CAP_MSMF)

Solution 5:^[5]

When I recently ran into this issue, I found that all that was required was to update to OpenCV v4.5:

This is the related Github issue: https://github.com/opencv/opencv/issues/15499
Here is the commit: https://github.com/opencv/opencv/commit/f0271e54d90b3af62301f531f5f00995b00d7cd6

Sources

This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.

Source: Stack Overflow

Solution	Source
Solution 1
Solution 2	Yonatan Tidhar
Solution 3	Lindsay Fowler
Solution 4	YScharf
Solution 5	agrant3d

'Frame from video is upside down after extracting

Solution 1:[1]

Solution 2:[2]

Solution 3:[3]

Solution 4:[4]

Solution 5:[5]