Develop Reference

OpenCv - output video is not playing

I want to write a video using OpenCv and process every frames in different seconds.
I am using cv2.VideoWriter, but the output file shows only the first frame of my video and it is not playing. I wanted to add text on the first frame and it did it, but it doesn't continue with the rest of the video.
As you can see from the code below, it creates a new output file for the new processed video.
It does create the mp4 file, but only showing first frame with the added text and it is not playing.
Any suggestion why this is happening?
Here is my code, I am using Spyder and windows.
fps = int(round(cap.get(5)))
frame_width = int(cap.get(3))
frame_height = int(cap.get(4))
fourcc = cv2.VideoWriter_fourcc(*'mp4v')
out = cv2.VideoWriter(output_video_file,fourcc,fps,(frame_width,frame_height))
while(True):
# Capture frame-by-frame
ret, frame = cap.read()
if ret:
if cv2.waitKey(28) & 0xFF == ord('q'):
break
if between(cap, 0, 10000):
font = cv2.FONT_HERSHEY_COMPLEX_SMALL
cv2.putText(frame,'hello',org=(10,600),fontFace=font,fontScale=10,color=(255,0,0),thickness=4)
pass
# Our operations on the frame come here
out.write(frame)
# Display the resulting frame
cv2.imshow('frame',frame)

Exactly I could not find the problem in your code because you did not give the between function. However you may try following snippet:
import cv2
import numpy as np
cap = cv2.VideoCapture(0)
if (cap.isOpened() == False):
print("Unable to read camera feed")
frame_width = int(cap.get(3))
frame_height = int(cap.get(4))
fps = int(round(cap.get(5)))
out = cv2.VideoWriter('output.mp4', cv2.VideoWriter_fourcc(*'mp4v'), fps, (frame_width, frame_height))
while (True):
ret, frame = cap.read()
if ret == True:
cv2.putText(frame, 'hello',
org=(10, 300),
fontFace=cv2.FONT_HERSHEY_SIMPLEX,
fontScale=5,
color=(255, 0, 0),
thickness=4)
out.write(frame)
cv2.imshow('frame', frame)
if cv2.waitKey(1) & 0xFF == ord('q'):
break
else:
break
cap.release()
out.release()
cv2.destroyAllWindows()

How can I change a single frame in a video using OpenCV?

I have a video that I built using OpenCV VideoWriter.
I want to change a specific frame with a different one.
Is there a way to do it without rebuilding the entire video?

I am changing the third frame by making all pixels to zeros.
import numpy as np
import cv2
cap = cv2.VideoCapture(0)
fourcc = cv2.VideoWriter_fourcc(*'XVID')
out = cv2.VideoWriter('output.avi',fourcc, 20.0, (640,480))
frame_number = -1
while(True):
frame_number += 1
ret, frame = cap.read()
if frame_number == 3: # if frame is the third frame than replace it with blank drame
change_frame_with = np.zeros_like(frame)
frame = change_frame_with
out.write(frame)
gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
cv2.imshow('frame',gray)
if cv2.waitKey(1) & 0xFF == ord('q'):
break
cap.release()
out.release()
cv2.destroyAllWindows()
If you do not want to go through all the frames again:
import numpy as np
import cv2
cap = cv2.VideoCapture(0)
fourcc = cv2.VideoWriter_fourcc(*'XVID')
out = cv2.VideoWriter('output.avi',fourcc, 20.0, (640,480))
frame_number = -1
while(True):
frame_number += 1
ret, frame = cap.read()
if frame_number == 3: # if frame is the third frame than replace it with blank drame
change_frame_with = np.zeros_like(frame)
frame = change_frame_with
out.write(frame)
break # add a break here
else:
out.write(frame)
gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
cv2.imshow('frame',gray)
if cv2.waitKey(1) & 0xFF == ord('q'):
break
cap.release()
out.release()
cv2.destroyAllWindows()
But the above solution will not write all the other frames after 3 to the whole new video

This might help you :)
import cv2 as cv
vid = cv.VideoCapture('input.mp4')
total_frames = last_frame_number = vid.get(cv.CAP_PROP_FRAME_COUNT)
fourcc = cv.VideoWriter_fourcc(*'avc1')
writer = cv.VideoWriter("output.mp4", apiPreference=0,fourcc=fourcc,fps=video_fps[0], frameSize=(width, height))
frame_number = -1
while(True):
frame_number += 1
vid.set(1,frame_number)
ret, frame = vid.read()
if not ret or frame_number >= last_frame_number: break
# check these two lines first
if frame_number == changeable_frame_number :
frame = new_img_to_be_inserted
writer.write(frame)
# frame = np.asarray(frame)
gray = cv.cvtColor(frame, cv.IMREAD_COLOR)
# cv.imshow('frame',gray)
if cv.waitKey(1) & 0xFF == ord('q'):
break
vid.release()
writer.release()
cv.destroyAllWindows()

error while saving video file using open cv

program:
import numpy as np
import cv2
cap = cv2.VideoCapture(1)
fourcc = cv2.VideoWriter_fourcc(*'VID')
out = cv2.VideoWriter('output.avi',fourcc, 20.0, (640,480))
while(True):
ret, frame = cap.read()
gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
out.write(frame)
cv2.imshow('frame',gray)
if cv2.waitKey(1) & 0xFF == ord('q'):
break
cap.release()
out.release()
cv2.destroyAllWindows()
error:
Traceback (most recent call last):
File "D:/ANIKET/python projects/img_process.py", line 5, in <module>
fourcc = cv2.VideoWriter_fourcc(*'VID')
TypeError: Required argument 'c4' (pos 4) not found
i m trying to save the video file.
but i m getting this error.
plz tell me what i am doing wrong

you can also use -1 as an default argument. It had worked in my case.
import numpy as np
import cv2
cap = cv2.VideoCapture(0)
# Define the codec and create VideoWriter object
#fourcc = cv2.VideoWriter_fourcc(*'XVID')
out = cv2.VideoWriter('output.avi',-1, 20.0, (640,480))
while(cap.isOpened()):
ret, frame = cap.read()
if ret:
gray = cv2.cvtColor(src=frame, code=cv2.COLOR_BGR2GRAY)
out.write(gray)
cv2.imshow('frame', gray)
if cv2.waitKey(1) & 0xFF == ord('q'):
break
else:
break
cap.release()
out.release()
cv2.destroyAllWindows()

This code addresses both your original issue (replacing *'VID' with *'XVID') as well as your subsequent issue in the comment to your question:
import numpy as np
import cv2
cap = cv2.VideoCapture(0)
# Define the codec and create VideoWriter object
fourcc = cv2.VideoWriter_fourcc(*'XVID')
out = cv2.VideoWriter('output.avi',fourcc, 20.0, (640,480))
while(cap.isOpened()):
ret, frame = cap.read()
if ret:
gray = cv2.cvtColor(src=frame, code=cv2.COLOR_BGR2GRAY)
out.write(gray)
cv2.imshow('frame', gray)
if cv2.waitKey(1) & 0xFF == ord('q'):
break
else:
break
cap.release()
out.release()
cv2.destroyAllWindows()
Feel free to tell me if this works as you intended and point out any remaining issues!

Opencv-python cannot write video file

I am trying to save a video file with opencv3 in python. The video that I want to save comes from another video file which I modify for tracking purposes. What I get is an empty .avi file, and I don't understand why.
If it helps, I'm on OSX.
Thanks for the help.
Here is the relevant part of the code:
import cv2
import numpy as np
cap = cv2.VideoCapture('Vid.avi')
width = int(cap.get(cv2.CAP_PROP_FRAME_WIDTH))
height = int(cap.get(cv2.CAP_PROP_FRAME_HEIGHT))
fourcc = cv2.VideoWriter_fourcc(*'XVID')
out = cv2.VideoWriter('output.avi', fourcc, 20.0, (width-110, heigh-210))
while (cap.isOpened()):
success, frame = cap.read()
if success:
hsv_frame = cv2.cvtColor(frame,cv2.COLOR_BGR2HSV)
mask = cv2.inRange(hsv_frame,lower,upper) #lower and upper are defined in another part of the code
hsv_res = cv2.bitwise_and(hsv_frame,hsv_frame, mask= mask)
out.write(hsv_res)
cv2.imshow('Video', hsv_res)
if cv2.waitKey(50) & 0xFF == ord('q'):
break
cap.release()
out.release()
cv2.destroyAllWindows()

opencv python- not able to write videos

I tried as given in the to tutorial, but I am not able to open the video. I guess there is some problem with the fourcc thing in OpenCV-Python. My code was as follows:
import numpy as np
import cv2
cap = cv2.VideoCapture(0)
#fourCc = cv.VideoWriter_fourcc(*'XVID')
fourCc = cv2.VideoWriter_fourcc('X','V','I','D')
out = cv2.VideoWriter('output.avi',fourCc,20.0,(640,480))
while(cap.isOpened()):
ret, frame = cap.read()
if ret==True:
frame = cv2.flip(frame,0)
out.write(frame)
cv2.imshow('frame',frame)
if cv2.waitKey(1) & 0xFF == ord('q'):
break
else:
break
cap.release()
out.release()
cv2.destroyAllWindows()
It does create a file named output.avi (of non-zero size), but I am not able to play it, even using VLC.
NOTE: The same thing in C++ is working fine