python: 'cv2.' -> 'cv.' via 'import cv2 as cv'

doc/py_tutorials/py_gui/py_video_display/py_video_display.markdown

@@ -6,7 +6,7 @@ Goal
 
 -   Learn to read video, display video and save video.
 -   Learn to capture from Camera and display it.
--   You will learn these functions : **cv2.VideoCapture()**, **cv2.VideoWriter()**
+-   You will learn these functions : **cv.VideoCapture()**, **cv.VideoWriter()**
 
 Capture Video from Camera
 -------------------------
@@ -22,25 +22,25 @@ the second camera by passing 1 and so on. After that, you can capture frame-by-f
 end, don't forget to release the capture.
 @code{.py}
 import numpy as np
-import cv2
+import cv2 as cv
 
-cap = cv2.VideoCapture(0)
+cap = cv.VideoCapture(0)
 
 while(True):
     # Capture frame-by-frame
     ret, frame = cap.read()
 
     # Our operations on the frame come here
-    gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
+    gray = cv.cvtColor(frame, cv.COLOR_BGR2GRAY)
 
     # Display the resulting frame
-    cv2.imshow('frame',gray)
-    if cv2.waitKey(1) & 0xFF == ord('q'):
+    cv.imshow('frame',gray)
+    if cv.waitKey(1) & 0xFF == ord('q'):
         break
 
 # When everything done, release the capture
 cap.release()
-cv2.destroyAllWindows()
+cv.destroyAllWindows()
 @endcode
 `cap.read()` returns a bool (`True`/`False`). If frame is read correctly, it will be `True`. So you can
 check end of the video by checking this return value.
@@ -55,9 +55,9 @@ video) and full details can be seen here: cv::VideoCapture::get().
 Some of these values can be modified using **cap.set(propId, value)**. Value is the new value you
 want.
 
-For example, I can check the frame width and height by `cap.get(cv2.CAP_PROP_FRAME_WIDTH)` and `cap.get(cv2.CAP_PROP_FRAME_HEIGHT)`. It gives me
-640x480 by default. But I want to modify it to 320x240. Just use `ret = cap.set(cv2.CAP_PROP_FRAME_WIDTH,320)` and
-`ret = cap.set(cv2.CAP_PROP_FRAME_HEIGHT,240)`.
+For example, I can check the frame width and height by `cap.get(cv.CAP_PROP_FRAME_WIDTH)` and `cap.get(cv.CAP_PROP_FRAME_HEIGHT)`. It gives me
+640x480 by default. But I want to modify it to 320x240. Just use `ret = cap.set(cv.CAP_PROP_FRAME_WIDTH,320)` and
+`ret = cap.set(cv.CAP_PROP_FRAME_HEIGHT,240)`.
 
 @note If you are getting error, make sure camera is working fine using any other camera application
 (like Cheese in Linux).
@@ -66,26 +66,26 @@ Playing Video from file
 -----------------------
 
 It is same as capturing from Camera, just change camera index with video file name. Also while
-displaying the frame, use appropriate time for `cv2.waitKey()`. If it is too less, video will be very
+displaying the frame, use appropriate time for `cv.waitKey()`. If it is too less, video will be very
 fast and if it is too high, video will be slow (Well, that is how you can display videos in slow
 motion). 25 milliseconds will be OK in normal cases.
 @code{.py}
 import numpy as np
-import cv2
+import cv2 as cv
 
-cap = cv2.VideoCapture('vtest.avi')
+cap = cv.VideoCapture('vtest.avi')
 
 while(cap.isOpened()):
     ret, frame = cap.read()
 
-    gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
+    gray = cv.cvtColor(frame, cv.COLOR_BGR2GRAY)
 
-    cv2.imshow('frame',gray)
-    if cv2.waitKey(1) & 0xFF == ord('q'):
+    cv.imshow('frame',gray)
+    if cv.waitKey(1) & 0xFF == ord('q'):
         break
 
 cap.release()
-cv2.destroyAllWindows()
+cv.destroyAllWindows()
 @endcode
 
 @note Make sure proper versions of ffmpeg or gstreamer is installed. Sometimes, it is a headache to
@@ -95,7 +95,7 @@ Saving a Video
 --------------
 
 So we capture a video, process it frame-by-frame and we want to save that video. For images, it is
-very simple, just use `cv2.imwrite()`. Here a little more work is required.
+very simple, just use `cv.imwrite()`. Here a little more work is required.
 
 This time we create a **VideoWriter** object. We should specify the output file name (eg:
 output.avi). Then we should specify the **FourCC** code (details in next paragraph). Then number of
@@ -111,30 +111,30 @@ platform dependent. Following codecs works fine for me.
 -   In Windows: DIVX (More to be tested and added)
 -   In OSX: MJPG (.mp4), DIVX (.avi), X264 (.mkv).
 
-FourCC code is passed as `cv2.VideoWriter_fourcc('M','J','P','G')` or
-`cv2.VideoWriter_fourcc(*'MJPG')` for MJPG.
+FourCC code is passed as `cv.VideoWriter_fourcc('M','J','P','G')` or
+`cv.VideoWriter_fourcc(*'MJPG')` for MJPG.
 
 Below code capture from a Camera, flip every frame in vertical direction and saves it.
 @code{.py}
 import numpy as np
-import cv2
+import cv2 as cv
 
-cap = cv2.VideoCapture(0)
+cap = cv.VideoCapture(0)
 
 # Define the codec and create VideoWriter object
-fourcc = cv2.VideoWriter_fourcc(*'XVID')
-out = cv2.VideoWriter('output.avi',fourcc, 20.0, (640,480))
+fourcc = cv.VideoWriter_fourcc(*'XVID')
+out = cv.VideoWriter('output.avi',fourcc, 20.0, (640,480))
 
 while(cap.isOpened()):
     ret, frame = cap.read()
     if ret==True:
-        frame = cv2.flip(frame,0)
+        frame = cv.flip(frame,0)
 
         # write the flipped frame
         out.write(frame)
 
-        cv2.imshow('frame',frame)
-        if cv2.waitKey(1) & 0xFF == ord('q'):
+        cv.imshow('frame',frame)
+        if cv.waitKey(1) & 0xFF == ord('q'):
             break
     else:
         break
@@ -142,7 +142,7 @@ while(cap.isOpened()):
 # Release everything if job is finished
 cap.release()
 out.release()
-cv2.destroyAllWindows()
+cv.destroyAllWindows()
 @endcode
 
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