从python生成电影，而不将单个帧保存到文件

问题描述

我想在matplotlib中的python脚本中生成的框架中创建一个h264或divx电影。这部电影中有大约100k帧。

I would like to create an h264 or divx movie from frames that I generate in a python script in matplotlib. There are about 100k frames in this movie.

在网络上的例子中1]，我只看到了将每个框架保存为png，然后在这些文件上运行mencoder或ffmpeg的方法。在我的情况下，保存每个框架是不切实际的。有没有办法从matplotlib生成的图，并将其直接导入ffmpeg，不生成中间文件？

In examples on the web [eg. 1], I have only seen the method of saving each frame as a png and then running mencoder or ffmpeg on these files. In my case, saving each frame is impractical. Is there a way to take a plot generated from matplotlib and pipe it directly to ffmpeg, generating no intermediate files?

使用ffmpeg的C-api编程对我来说太难了[例如2]。此外，我需要一个具有良好压缩率的编码，如x264，因为影片文件将不适用于后续步骤。所以这将是伟大的坚持mencoder / ffmpeg / x264。

Programming with ffmpeg's C-api is too difficult for me [eg. 2]. Also, I need an encoding that has good compression such as x264 as the movie file will otherwise be too large for a subsequent step. So it would be great to stick with mencoder/ffmpeg/x264.

有什么可以做的管道[3]？

Is there something that can be done with pipes [3]?

[1]

[2]

[3]

推荐答案

此功能现在（至少从1.2.0，可能是1.1）通过 MovieWriter 类烘焙成matplotlib，它的子 - 动画模块中的类。

This functionality is now (at least as of 1.2.0, maybe 1.1) baked into matplotlib via the MovieWriter class and it's sub-classes in the animation module.

import matplotlib.animation as animation
import numpy as np
from pylab import *


dpi = 100

def ani_frame():
    fig = plt.figure()
    ax = fig.add_subplot(111)
    ax.set_aspect('equal')
    ax.get_xaxis().set_visible(False)
    ax.get_yaxis().set_visible(False)

    im = ax.imshow(rand(300,300),cmap='gray',interpolation='nearest')
    im.set_clim([0,1])
    fig.set_size_inches([5,5])


    tight_layout()


    def update_img(n):
        tmp = rand(300,300)
        im.set_data(tmp)
        return im

    #legend(loc=0)
    ani = animation.FuncAnimation(fig,update_img,300,interval=30)
    writer = animation.writers['ffmpeg'](fps=30)

    ani.save('demo.mp4',writer=writer,dpi=dpi)
    return ani

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