How to rotate a video with OpenCV

Question

How do you rotate all frames in a video stream using OpenCV? I tried using the code provided in a similar question, but it doesn't seem to work with the Iplimage image object returned cv.RetrieveFrame. This is the code I currently have: ``` import cv, cv2 import numpy as np def rotateImage(image, angle): if hasattr(image, 'shape'): image_center = tuple(np.array(image.shape)/2) shape = image.shape elif hasattr(image, 'width') and hasattr(image, 'height'): image_center = (image.width/2, image.height/2) shape = np.array((image.width, image.height)) else: raise Exception, 'Unable to acquire dimensions of image for type %s.' % (type(image),) rot_mat = cv2.getRotationMatrix2D(image_center, angle,1.0) result = cv2.warpAffine(image, rot_mat, shape, flags=cv2.INTER_LINEAR) return result cap = cv.CaptureFromCAM(cam_index) #cap = cv.CaptureFromFile(path) fps = 24 width = int(cv.GetCaptureProperty(cap, cv.CV_CAP_PROP_FRAME_WIDTH)) height = int(cv.GetCaptureProperty(cap, cv.CV_CAP_PROP_FRAME_HEIGH…

Accepted Answer

If you are just after a 180 degree rotation, you can use `Flip` on both axes,

replace:

```
frame = rotateImage(frame, 180)
```

with:

```
cv.Flip(frame, flipMode=-1)
```

This is 'in place', so its quick, and you won't need your `rotateImage` function any more :)

Example:

```
import cv
orig = cv.LoadImage("rot.png")
cv.Flip(orig, flipMode=-1)
cv.ShowImage('180_rotation', orig)
cv.WaitKey(0)
```

this: becomes, this:

How to rotate a video with OpenCV

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