生成运动的2D正弦波图案

Question

我正在尝试生成如下所示模式的视频，该视频使用python中的OpenCV水平移动。

我以以下方式编写。视频文件已生成，没有任何错误，但是在任何视频播放器中均未打开

        import cv2
        import numpy as np
        from cv2 import VideoWriter, VideoWriter_fourcc

        video = VideoWriter('_sine_pattern_gen_'+str(60)+'_fps.avi', VideoWriter_fourcc(*'MP42'), 60, (346, 260))

        x = np.arange(346)  # generate 1-D sine wave of required period 
        y = np.sin(2 * np.pi * x / 20) 

        y += max(y) # offset sine wave by the max value to go out of negative range of sine 

        frame = np.array([[y[j] for j in range(346)] for i in range(260)], dtype='uint8') # create 2-D array of sine-wave

        for _ in range(0, 346):
            video.write(frame)
            shifted_frame =  np.roll(frame, 2, axis=1) # roll the columns of the sine wave to get moving effect
            frame = shifted_frame 

        cv2.destroyAllWindows()
        video.release()

Answer 1

当VideoWriter需要彩色图像时，使用单通道灰度图像是一个问题。可以使用标志isColor=False来解决此问题。

此外，由于图像的类型为uint8，而y最多只能显示2，因此看起来像是黑色视频，而不是您显示的图像。您可以将y乘以y[j]*127以达到0-255的整个范围。以下应该起作用：

import cv2
import numpy as np
from cv2 import VideoWriter, VideoWriter_fourcc

fname = '_sine_pattern_gen_'+str(60)+'_fps.avi'
video = VideoWriter(fname, VideoWriter_fourcc(*'MP42'), 60, (346, 260), isColor=False)

x = np.arange(346)  # generate 1-D sine wave of required period 
y = np.sin(2 * np.pi * x / 20)

y += max(y) # offset sine wave by the max value to go out of negative range of sine 

frame = np.array([[y[j]*127 for j in range(346)] for i in range(260)], dtype=np.uint8) # create 2-D array of sine-wave

for _ in range(0, 346):
    video.write(frame)
    shifted_frame =  np.roll(frame, 2, axis=1) # roll the columns of the sine wave to get moving effect
    frame = shifted_frame 

video.release()