Menu
I want to capture video from a webcam and save it to an mp4 file using opencv. I found example code on stackoverflow (below) that works great. The only hitch is that I'm trying to save it as mp4, not avi. Part of what I don't get is that the 'XVID' argument passed to the FOURCC writer is supposed to be, I think, an mp4 codec (from this link). If I change the filename to 'output.mp4' it tells me that the tag is invalid, so I have to believe that the XVID codec is actually making an avi file. Is this a stupid question? How do I write to an mp4?
I have found links showing how to convert an avi to an mp4 after the fact but that seems inefficient. Seems like I should be able to do it during the initial write.
import numpy as np import cv2 cap = cv2.VideoCapture(0) # Define the codec and create VideoWriter object fourcc = cv2.cv.CV_FOURCC(*'XVID') 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) # write the flipped frame out.write(frame) cv2.imshow('frame',frame) if cv2.waitKey(1) & 0xFF == ord('q'): break else: break # Release everything if job is finished cap.release() out.release() cv2.destroyAllWindows() 
427
In this Python OpenCV lesson we are going to learn How to Play Mp4 Videos in Python OpenCV, before this we have learned that how you can read avi videos in opencv, you can use an mp4 video or you can use camera, the same code will be implemented with camera or mp4 video.
In this article, we will discuss how to write to a video using OpenCV in Python. Import the required libraries into the working space. Read the video on which you have to write. Create a output file using cv2.VideoWriter_fourcc () method output = cv2.VideoWriter (“path”,cv2.VideoWriter_fourcc (*’MPEG’),30, (1080,1920))
The problem such as OpenCV: FFMPEG: tag 0x5634504d/'MP4V' is not supported with codec id 13 and format 'mp4 / MP4 (MPEG-4 Part 14)' OpenCV: FFMPEG: fallback to use tag 0x00000020/' ???' maybe that your output video size is not the same as original video. You can look over the frame size of video first.
VideoWriter_fourcc ('M', 'J', 'P', 'G') in Python. VideoWriter::fourcc ('M', 'J', 'P', 'G') in C++. The video codec specifies how the video stream is compressed. It converts uncompressed video to a compressed format or vice versa.
Anyone who's looking for most convenient and robust way of writing MP4 files with OpenCV or FFmpeg, can see my state-of-the-art VidGear Video-Processing Python library's WriteGear API that works with both OpenCV backend and FFmpeg backend and even supports GPU encoders. Here's an example to encode with H264 encoder in WriteGear with FFmpeg backend:
This worked for me.
self._name = name + '.mp4' self._cap = VideoCapture(0) self._fourcc = VideoWriter_fourcc(*'MP4V') self._out = VideoWriter(self._name, self._fourcc, 20.0, (640,480)) What worked for me was to make sure the input 'frame' size is equal to output video's size (in this case, (680, 480) ).
http://answers.opencv.org/question/27902/how-to-record-video-using-opencv-and-python/
Here is my working code (Mac OSX Sierra 10.12.6):
cap = cv2.VideoCapture(0) cap.set(3,640) cap.set(4,480) fourcc = cv2.VideoWriter_fourcc(*'MP4V') out = cv2.VideoWriter('output.mp4', fourcc, 20.0, (640,480)) while(True): ret, frame = cap.read() out.write(frame) cv2.imshow('frame', frame) c = cv2.waitKey(1) if c & 0xFF == ord('q'): break cap.release() out.release() cv2.destroyAllWindows() Note: I installed openh264 as suggested by @10SecTom but I'm not sure if that was relevant to the problem.
Just in case:
brew install openh264 If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
