python调用摄像头录制视频,如何在Python中使用OpenCV存储网络摄像头视频

最新推荐文章于 2023-12-12 20:28:15 发布

洛克t

最新推荐文章于 2023-12-12 20:28:15 发布

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文章标签： python调用摄像头录制视频

I've got a script in Python which reads out my webcam and shows it in a window. I now want to store the results, so following this tutorial I wrote the following code:

import cv2

import imutils

camera = cv2.VideoCapture(0)

# Define the codec and create VideoWriter object to save the video

fourcc = cv2.VideoWriter_fourcc(*'XVID')

video_writer = cv2.VideoWriter('output.avi', fourcc, 20.0, (640, 480))

while True:

try:

(grabbed, frame) = camera.read() # grab the current frame

frame = imutils.resize(frame, width=640, height=480)

cv2.imshow("Frame", frame) # show the frame to our screen

key = cv2.waitKey(1) & 0xFF # I don't really have an idea what this does, but it works..

video_writer.write(frame) # Write the video to the file system

except KeyboardInterrupt:

break

# cleanup the camera and close any open windows

camera.release()

video_writer.release()

cv2.destroyAllWindows()

print "\n\nBye bye\n"

This perfectly shows the real time video footage from my webcam in a new window. But writing the video file seems to fail. It does create a file called output.avi, but the file is empty (zero bytes) and on the command line I see the following errors:

OpenCV: Frame size does not match video size.

etc.

I clearly resize the frame to the size in which I want to save the video (640x480) so I'm not sure why it wouldn't match.

When I run the script again (so in this case the empty output.avi already exists), it shows these errors:

2017-04-17 10:57:14.147 Python[86358:5848730] AVF: AVAssetWriter status: Cannot Save

2017-04-17 10:57:14.332 Python[86358:5848730] mMovieWriter.status: 3. Error: Cannot Save

2017-04-17 10:57:14.366 Python[86358:5848730] mMovieWriter.status: 3. Error: Cannot Save

2017-04-17 10:57:14.394 Python[86358:5848730] mMovieWriter.status: 3. Error: Cannot Save

etc.

In the tutorial it says that the Four digit FourCC code is used to specify the video codec which is platform dependent and that the list of available codes can be found in fourcc.org. I'm on OSX so I tried a bunch of different codec-codes: DIVX, XVID, MJPG, X264, WMV1, WMV2. But unfortunately none of them work for me. They all give the same errors, except for MJPG, which gives me the following error:

OpenCV Error: Assertion failed (img.cols == width && img.rows == height && channels == 3) in write, file /tmp/opencv3-20170216-77040-y1hrk1/opencv-3.2.0/modules/videoio/src/cap_mjpeg_encoder.cpp, line 829

Traceback (most recent call last):

File "store_video.py", line 15, in

video_writer.write(frame) # Write the video to the file system

cv2.error: /tmp/opencv3-20170216-77040-y1hrk1/opencv-3.2.0/modules/videoio/src/cap_mjpeg_encoder.cpp:829: error: (-215) img.cols == width && img.rows == height && channels == 3 in function write

Does anybody know what could be wrong here? All tips are welcome!

解决方案

It's probably because you built OpenCV with AVFoundation and it doesn't support XVID or other codec. You can try mp4v and m4v extension.

import cv2

camera = cv2.VideoCapture(0)

# Define the codec and create VideoWriter object to save the video

fourcc = cv2.VideoWriter_fourcc('m','p','4','v')

video_writer = cv2.VideoWriter('output.m4v', fourcc, 30.0, (640, 480))

while True:

(grabbed, frame) = camera.read() # grab the current frame

frame = cv2.resize(frame, (640,480))

cv2.imshow("Frame", frame) # show the frame to our screen