OpenCV VideoWriter不写入Output.avi [英] OpenCV VideoWriter Not Writing to Output.avi
问题描述
我正在尝试编写一段简单的代码来拍摄视频,裁剪并写入输出文件.
I'm attempting to write a simple bit of code that takes a video, crops it, and writes to an output file.
OS: Windows 10
Conda Environment Python Version: 3.7
OpenCV Version: 3.4.2
ffmpeg Version: 2.7.0
文件输入规范:
Codec: H264 - MPEG-4 AVC (part 10)(avc1)
Type: Video
Video resolution: 640x360
Frame rate: 5.056860
代码无法产生输出(它创建了文件但未写入文件):
import numpy as np
import cv2
cap = cv2.VideoCapture('croptest1.mp4')
# Define the codec and create VideoWriter object
fourcc = cv2.VideoWriter_fourcc('F', 'M', 'P', '4')
out = cv2.VideoWriter('output.avi', fourcc, 20.0,
(int(cap.get(3)), int(cap.get(4))))
# Verify input shape
width = cap.get(3)
height = cap.get(4)
fps = cap.get(5)
print(width, height, fps)
while(cap.isOpened()):
ret, frame = cap.read()
if ret == True:
# from top left =frame[y0:y1, x0:x1]
cropped_frame = frame[20:360, 0:640]
# write the clipped frames
out.write(cropped_frame)
# show the clipped video
cv2.imshow('cropped_frame', cropped_frame)
if cv2.waitKey(1) & 0xFF == ord('q'):
break
else:
break
# Release everything if job is finished
cap.release()
out.release()
cv2.destroyAllWindows()
对fourcc和out变量的变种试图使编解码器正常工作:
fourcc = cv2.cv.CV_FOURCC(*'DIVX')
fourcc = cv2.VideoWriter_fourcc(*'DIVX')
out = cv2.VideoWriter('ditch_effort.avi', -1, 20.0, (640, 360))
基于此链接我应该可以引用此Fourcc参考列表,以确定要使用的适当Fourcc压缩代码.我尝试了很多变体,但无法获取要写入的输出文件.当我运行代码时,#verify输入形状变量会打印相应的640、360和正确的帧频.
Based on this link I should be able to refer to this fourcc reference list to determine the appropriate fourcc compression code to use. I have tried a bunch of variations, but cannot get the output file to be written. When I run the code, the #verify input shape variables print the corresponding 640, 360 and correct Frame Rate.
任何人都可以告诉我我的问题是什么...将不胜感激.
Can any one tell me what my issue is...would be much appreciated.
推荐答案
发生错误的原因是cropped_frame
的尺寸(640,340)与writer
中声明的尺寸(640,360)之间的差异.
The reason of error is the differences between the dimension of the cropped_frame
(640,340) and the dimension declared in the writer
(640,360).
所以作者应该是:
out = cv2.VideoWriter('output.avi', fourcc, 20.0,(640,340))
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