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• Running subprocess.Popen in a compiled script has a significant delay

  6 mai 2022, par thisismy-stackoverflow

  Edit : In this specific example, Python 3.8 is being used on Windows 10.

  


  I need to run FFprobe through subprocess.Popen so I can capture and parse the output. If I do this in a script, it runs almost instantly, but if I compile my script with PyInstaller and do the same thing, it takes over 0.8 seconds to complete. Is there a trick or any way I can execute it faster from the compiled script ? I'm willing to hear FFprobe-specific answers if they exist.

  


  This is what I'm using currently. The extra code is for ensuring FFprobe doesn't flash a console window while running (removing the console window actually made it 0.1 seconds faster on average).

  


  startupinfo = subprocess.STARTUPINFO()
startupinfo.dwFlags |= subprocess.STARTF_USESHOWWINDOW
p = subprocess.Popen(f'ffprobe -show_format -show_streams -of json "{file}"', startupinfo=startupinfo, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
out, err = p.communicate()


  


• Running matplotlib animation on Mac using Spyder : says to install ffmpeg

  28 avril 2017, par Addem

  I installed Anaconda on a new Mac, made a simple animation with matplotlib like

  import numpy as np
  
  from matplotlib import pyplot as plt
  
  from matplotlib import animation
  
  
  
  fig = plt.figure()
  
  ax = plt.axes(xlim=(0, 2), ylim=(-2, 2))
  
  line, = ax.plot([], [], lw=2)
  
  
  
  def init():
  
      line.set_data([], [])
  
      return line,
  
  
  
  def animate(i):
  
      x = np.linspace(0, 2, 1000)
  
      y = np.sin(2 * np.pi * (x - 0.01 * i))
  
      line.set_data(x, y)
  
      return line,
  
  
  
  anim = animation.FuncAnimation(fig, animate, init_func=init,
  
                                 frames=200, interval=20, blit=True)
  
  
  
  
  
  anim.save('basic_animation.mp4', fps=30, extra_args=['-vcodec', 'libx264'])
  
  
  
  plt.show()

  When I run it, it tells me to install ffmpeg. I tried using these instructions : http://stephenjungels.com/jungels.net/articles/ffmpeg-howto.html But the instructions were unclear about what I was supposed to download, especially when it got to the part about a "patch". This also just feels insanely complicated for something that seems like it should be much simpler. I also tried following some instructions for installing ffmpeg using Homebrew but the instructions were again poorly written so that some of the buttons it said should be there weren’t. I tried to figure it out by guessing what I should do, and it seemed to work but with a lot of warning messages. By the end of the process, when I type into a terminal

  which ffmpeg

  it returns /usr/local/bin/ffmpeg. However, even after restarting Spyder and re-running the code, it still tells me to install ffmpeg. I also navigated to /usr/local/bin and it doesn’t have a folder ffmpeg. So my guess is that ffmpeg didn’t install.

  I read in the matplotlib documentation that Anaconda doesn’t give a build for Python that is appropriate, something about a "framework" build (http://matplotlib.org/faq/osx_framework.html). But it says that in Anaconda you can install it easily by running conda install python.app which I did and it worked. It then says to use pythonw rather than python. I’m not really sure what this means, because in Spyder I don’t run scripts from the terminal. I tried navigating to the file anyway and running it with

  pythonw anim.py

  and it mysteriously gave me an I/O error.

  Do I really need to install ffmpeg or is there some simpler fix ?

  If I do need to install ffmpeg, where get I get up-to-date instructions that make the process clear ?

• C# app - running FFMpeg from the command line is not working

  11 avril 2017, par Dan Kahn

  I’m trying to run FFMpeg from the Command Line in C#. Previously I was running it from "CMD.exe" and it was working, but that requires a local installation of ffmpeg with configuring my System environmental variables. So I wanted to run it directly from "ffmpeg.exe". I’m using the following code (all the paths are correct), and nothing happens :

  string programToRun = "C:\\Users\\dkahn\\Documents\\PlaybackTool\\PlaybackTool\\Desktop\\Source\\Player\\Player\\ffmpeg\\ffmpeg.exe";
  
  
  
  string directoryName = "C:\\Users\\dkahn\\Documents\\PlaybackTool\\PlaybackTool\\Desktop\\Source\\Player\\test\\test1-1.mp4";
  
  
  
  string command = "@ffmpeg -i test1-1.mp4 -r 1  -s 180x101 test1-1\\output_%04d.png";
  
  
  
  Process cmd = new Process();
  
  cmd.StartInfo.FileName = programToRun;
  
  cmd.StartInfo.RedirectStandardInput = true;
  
  cmd.StartInfo.RedirectStandardOutput = true;
  
  cmd.StartInfo.CreateNoWindow = true;
  
  cmd.StartInfo.UseShellExecute = false;
  
  cmd.StartInfo.WorkingDirectory = directoryName;
  
  cmd.Start();
  
   cmd.StandardInput.WriteLine(command);
  
  cmd.StandardInput.Flush();
  
  cmd.StandardInput.Close();
  
  cmd.WaitForExit();

  Does anybody have any insight ?