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• subprocess.py returns a File Not Found error

  7 avril 2021, par wasneeplus

  As part of a video analysis script I wanted to find the duration of a video file. For this I found the script offered in the first answer to this question : How to get the duration of a video in Python ?

  


  import subprocess

def get_length(filename):
    result = subprocess.run(["ffprobe", "-v", "error", "-show_entries",
                             "format=duration", "-of",
                             "default=noprint_wrappers=1:nokey=1", filename],
        stdout=subprocess.PIPE,
        stderr=subprocess.STDOUT)
    return float(result.stdout)


  


  This code works fine when my friend runs it in a Jupyter server environment, but when I try it on my laptop the trouble starts.

  


  When I imput the following filename into the function :

  


  filename = "C:\\Users\\benja\\OneDrive - De Haagse Hogeschool\\Onderzoeken 3\\8V.mp4"


  


  I get the following error :

  


      Traceback (most recent call last):&#xA;  File "c:/Users/benja/OneDrive - De Haagse Hogeschool/Onderzoeken 3/python_script.py", line 9, in <module>&#xA;    num_of_frames = math.floor((pf.get_length(filename) - 1)) * 30&#xA;  File "c:\Users\benja\OneDrive - De Haagse Hogeschool\Onderzoeken 3\python_funcs.py", line 21, in get_length&#xA;    stderr=subprocess.STDOUT)&#xA;  File "C:\Users\benja\Anaconda3\lib\subprocess.py", line 466, in run&#xA;    with Popen(*popenargs, **kwargs) as process:&#xA;  File "C:\Users\benja\Anaconda3\lib\subprocess.py", line 769, in __init__&#xA;    restore_signals, start_new_session)&#xA;  File "C:\Users\benja\Anaconda3\lib\subprocess.py", line 1172, in _execute_child&#xA;    startupinfo)&#xA;FileNotFoundError: [WinError 2] Het systeem kan het opgegeven bestand niet vinden&#xA;</module>

  


  I do realise that my problem is almost identical to that of several other questions on here. However, their solutions don't seem to work for me. I have tried to :

  


  

  • Add the location of ffmpeg-win64-4.2.2.exe to the Path system variable.

  


  • Add the location of python.exe to the ComSpec system variable.

  


  • Put the videofile in the same directory as the script.

  


  


  I would be most grateful if someone could point me in the right direction. Thank you in advance.

  


• Why process output reader returns null data ? When same code in other process works correct

  26 août 2019, par Владимир Водов

  I try to get output from ffmpeg process but cant get output.
  In another processes and commands it works correctly but output returns immideately when start !

          using (var process = new Process())
  
          {
  
              process.StartInfo = new ProcessStartInfo()
  
              {
  
                  FileName = LinkHelper.IPFS_PATH,
  
                  Arguments = cmd,
  
                  UseShellExecute = false,
  
                  CreateNoWindow = true,
  
                  RedirectStandardOutput = true
  
              };
  
  
  
              process.ErrorDataReceived += FfmpegErrorRecieved;
  
              process.Start();
  
  
  
              using (StreamReader reader = process.StandardOutput)
  
              {
  
                  string output = await reader.ReadToEndAsync();
  
                  Console.WriteLine(output);
  
              }               
  
              process.WaitForExit();
  
          }

  Before output handle !

  Update :
  As szatmary said ffmpeg use output error instead standard output, so when you initialize process.StandartInfo don’t forget initialize property "RedirectStandardError" to TRUE !

  Here is correct code :

  private async Task DetectFFmpegCamerasAsync()
  
      {
  
          var cmd = "-list_devices true -f dshow -i dummy";
  
          using (var process = new Process())
  
          {
  
              process.StartInfo = new ProcessStartInfo()
  
              {
  
                  FileName = LinkHelper.FFMPEG_PATH,
  
                  Arguments = cmd,
  
                  UseShellExecute = false,
  
                  CreateNoWindow = true,
  
                  RedirectStandardError = true
  
              };
  
  
  
              process.Start();
  
  
  
              using (StreamReader reader = process.StandardError)
  
              {
  
                  string output = await reader.ReadToEndAsync();
  
                  Console.WriteLine($"Camera detection output: \n {output}");
  
              }               
  
              process.WaitForExit();
  
          }
  
      }

• FFMPEG or moviepy : easiest way to remove segments using list of timestamps ?

  26 août 2020, par I Z

  I have a bunch of videos that I need to trim by removing segments that contain silence, noise, and other fluff. I don't have a GUI-based video editing tool available to me (not even Movie Maker) but I do have moviepy and ffmpeg. So if I have a list of segments I want to remove as pairs of from-to timestamps, which tool is easier to set up (either a Python script or a shell script in cygwin under Win10) to process those videos ? TIA !