#------------------------------------------------------------------------------
#This Python + OpenCV code adjusts the frame rate per second (FPS) of a video.
#You can use it to create a video for slow-motion or fast-motion display. Some-
#times the FPS of videos need to be equalize to play to side-by-side. The audio
#is not preserved and you need to add the audio --- though the audio shall also 
#should be adjusted to be in synch with the video frames. Output from this code 
#is same as FFmpeg command: ffmpeg -i in.mp4 -filter:v fps=10 -y out.mp4
#------------------------------------------------------------------------------
import cv2
#Read the input videos and specify name of the output video
Vid = "v1.mp4"
Out = "newFPS.mp4"
newFPS = 10

cap = cv2.VideoCapture(Vid) 
if (cap.isOpened() == False):
  print("Error opening the video file, exiting!")
  exit()

h = cap.get(cv2.CAP_PROP_FRAME_HEIGHT)
w = cap.get(cv2.CAP_PROP_FRAME_WIDTH)
size = (int(w), int(h))

fourcc = cv2.VideoWriter_fourcc('m','p','4','v')
videowriter = cv2.VideoWriter(Out,fourcc,newFPS,size)

while (True):
        cap.set(cv2.CAP_PROP_FPS, newFPS) 
        ret,frame = cap.read()
        if ret == True:
        	videowriter.write(frame)
        else:
        	break
        
cap.release()
cv2.destroyAllWindows()