OpenCV MP4创建

Question

我一直在尝试用OpenCV在python中写MP4视频文件。

当我同时使用linux和windows时，AVI创建工作得很好：

out = cv2.VideoWriter('x.avi', 0, 30, (640, 480))

和

fourcc = cv2.VideoWriter_fourcc(*"XVID")
out = cv2.VideoWriter('x.avi', fourcc, 30, (640, 480))

甚至

fourcc = cv2.VideoWriter_fourcc(*"XVID")
out = cv2.VideoWriter('x', fourcc, 30, (640, 480))

。

但是，当我尝试保存一个MP4时，任何东西都不会保存--使用：

fourcc = cv2.VideoWriter_fourcc(*"H264")
out = cv2.VideoWriter('x.mp4', fourcc, 30, (640, 480))

和

fourcc = cv2.VideoWriter_fourcc(*"AVC1")
out = cv2.VideoWriter('x.mp4', fourcc, 30, (640, 480))

没有发生错误，只是没有保存任何内容。

在过去的几天里，我尝试了所有的方法，尽一切努力避免创建AVI，然后使用ffmpeg将其转换为MP4，因为我发现这是一种可怕的做法。

Answer 1

给出框架的高度和宽度的右值：

import cv2

print ('Press [ESC] to quit demo')
# Read from the input video file
# input_file = 'Your path to input video file'
# camera = cv2.VideoCapture(input_file)

# Or read from your computer camera
camera = cv2.VideoCapture(0)

# Output video file may be with another extension, but I didn't try
# output_file = 'Your path to output video file' + '.avi'
output_file = "out.avi"

# 4-byte code of the video codec may be another, but I did not try
fourcc = cv2.VideoWriter_fourcc(*'DIVX')

is_begin = True
while camera.isOpened():
    _, frame = camera.read()
    if frame is None:
        break

    # Your code
    processed = frame

    if is_begin:
        # Right values of high and width
        h, w, _ = processed.shape
        out = cv2.VideoWriter(output_file, fourcc, 30, (w, h), True)
        print(out.isOpened()) # To check that you opened VideoWriter
        is_begin = False

    out.write(processed)
    cv2.imshow('', processed)
    choice = cv2.waitKey(1)
    if choice == 27:
        break

camera.release()
out.release()
cv2.destroyAllWindows()

这段代码适用于我。