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• Python script fails execution on subprocess.run() call only when called from context menu

  10 mars 2019, par Jesse McDonald

  I have a python script that I want to call from the windows file browser context menu (https://www.howtogeek.com/107965/how-to-add-any-application-shortcut-to-windows-explorers-context-menu/)

  I am currently debugging calling it from the non-specific context (HKEY_CLASSES_ROOT\Directory\Background\shell) with the command "python "D :\toolbox\mineAudio.py" 0"
  (note python3 is on the path as python and the script is at D :\toolbox\mineAudio.py)

  When I call the script from cmd it works as expected with that command, and when I make debug modifications to the script (adding os.system("pause") to random lines) I can verify it is running correctly up to the point it hits the line meta=cmd(['ffmpeg','-i',target]) (line 46) where it instantly and silently fails (note ffmpeg is also on the path)

  EDIT : it actually gets as far as line 15

  result = subprocess.run(command, stdout=subprocess.PIPE,stderr=subprocess.PIPE,startupinfo=startupinfo)

  I cant figure out why the program is failing there as that line works fine everywhere else I have tested the script from other than the context menu.

  Here is the full script if you want to brows through it

  import subprocess
  
  import os
  
  import sys
  
  from sys import argv
  
  from tree import tree
  
  #for command line use:
  
  #mineAudo.py [prompt=1] [dir=cwd]
  
  #first arg prompt will prompt user for dir if 1, otherwise it wont
  
  #second arg is the directory to use, if specified this will override prompt, if not and prompt=0, current working dir is used
  
  def cmd(command):
  
      startupinfo = subprocess.STARTUPINFO()
  
      startupinfo.dwFlags |= subprocess.STARTF_USESHOWWINDOW
  
      startupinfo.wShowWindow = subprocess.SW_HIDE
  
      result = subprocess.run(command, stdout=subprocess.PIPE,stderr=subprocess.PIPE,startupinfo=startupinfo)
  
      return result.stderr.decode("utf-8")
  
  def stripStreams(meta):
  
      i=1;
  
      lines=[]
  
      while i>0 :
  
          i=meta.find("Stream",i+1)
  
          lineEnd=meta.find("\n",i)
  
          lines.append(meta[i:lineEnd])
  
  
  
      return lines
  
  def mineAudio(streams):
  
      ret=[]
  
      for stream in streams:
  
          if "Audio:" in stream:
  
              start =stream.find("#")+1
  
              end=stream.find("(",start)
  
              ret.append(stream[start:end])
  
      return ret
  
  def convDir(dirTarget):
  
      targets=tree(dirTarget)
  
      convList(targets,dirTarget)
  
  
  
  def convList(targets,dirTarget):
  
          print(targets)
  
          #target="2018-05-31 06-16-39.mp4"
  
          i=0
  
          for target in targets:
  
              i+=1
  
  
  
              if(target[target.rfind("."):]==".mp4"):
  
                  print("("+str(i)+"/"+str(len(targets))+") starting file "+target)
  
                  meta=cmd(['ffmpeg','-i',target])
  
                  streams=stripStreams(meta)
  
                  streams=mineAudio(streams)
  
                  count=0
  
                  output=target[target.rfind("/")+1:target.rfind(".")]
  
                  file=target[target.rfind("/")+1:]
  
                  #print (output)
  
                  try:
  
                      os.mkdir(dirTarget+"\\"+output)
  
                  except:
  
                      pass
  
                  for s in streams:
  
                      print("converting track "+str(count+1)+" of "+str(len(streams)));
  
                      count+=1
  
                      cmd("ffmpeg -i \""+target+"\" -vn -sn -c:a mp3 -ab 192k -map "+s+" \""+dirTarget+"\\"+output+"\\"+output+" Track "+str(count)+".mp3\"")
  
                  print("moving "+target+" to "+dirTarget+"\\"+output+"\\"+file)
  
                  os.rename(target,dirTarget+"\\"+output+"\\"+file)
  
                  print("Finished file "+target)
  
              else:
  
                  print("("+str(i)+"/"+str(len(targets))+") skiping non mp4 file "+target)
  
  
  
  def prompt():
  
      while True:
  
          dirTarget=input("input target dir: ")
  
          convDir(dirTarget)
  
  
  
  
  
  
  
  if __name__ == "__main__":
  
          sys.setrecursionlimit(2000)    
  
          if len(argv)>2:
  
                  if os.path.isdir(argv[2]):
  
                      convDir(argv[2])
  
                  else:
  
                      convList([argv[2]],os.path.dirname(argv[2]))
  
          elif(len(argv)>1):
  
                  if int(argv[1])==1:
  
                      prompt()
  
                  else:
  
                      convDir(os.getcwd())
  
          else:
  
              prompt()
  
  
  
  
  
          os.system("pause")

  Note that I am not married to this particular implementation, any implementation with the same effect (extracting the .mp3 tracks from an .mp4 file automatically) would be fine too

  also, here is the file Tree

  #Returns the paths of all files in a directory and all sub directories relative to start directory
  
  import os
  
  def tree(directory,target="f"):
  
      paths=[]
  
      for currentDir,dirs,files in os.walk(directory):
  
          if target=="f":
  
              for file in files:
  
                  paths.append(currentDir+"/"+file)
  
          if target=="d":
  
              #paths.append(currentDir)
  
              for dir in dirs:
  
                  paths.append(currentDir+"/"+dir)
  
      for i in range(len(paths)):
  
          paths[i]=paths[i].replace("\\","/")
  
      return paths

  Can anyone help me get this working ?

  Edit :
  here is a shorter example code that crashes in the same way (still uses ffmpeg though)

  import subprocess
  
  import os
  
  def cmd(command):
  
      startupinfo = subprocess.STARTUPINFO()
  
      startupinfo.dwFlags |= subprocess.STARTF_USESHOWWINDOW
  
      startupinfo.wShowWindow = subprocess.SW_HIDE
  
  
  
      result = subprocess.run(command,stdin=subprocess.DEVNULL, stdout=subprocess.PIPE,stderr=subprocess.PIPE,startupinfo=startupinfo)
  
  
  
      return result.stderr.decode("utf-8")
  
  
  
  
  
  os.system("pause")
  
  
  
  out=cmd(['ffmpeg','-i','D:\\ffmpeg test\\test\\2018-05-31 06-16-39\\2018-05-31 06-16-39.mp4'])
  
  print(out)
  
  os.system("pause")

  (note the file is hard coded, program output should be
  )

• Limit number of output files in ffmpeg (rorating filenames)

  22 août 2016, par VanDahlen

  I want to convert an MJPEG Stream to JPEG Files by using ffmpeg :

  ffmpeg -i foo.mjpg -vcodec mjpeg -f image2 image%d.jpg

  This works fine, but I want to have "rotating" filenames, that means setting a max. number of output files. When this limit is reached, it shall start with "image1.jpg" again : image1.jpg .. imageN.jpg .. image1.jpg etc.
  I was hoping a specifiger like "%02d" would limit the numbers from 1..99, but this doesn’t seem t o work.

  I have found the "-vframes"-Parameter, but this is the abolsute number of frames to be output.
  Is there any option to make the filenames rotate ?

  Thanks
  VanDahlen

• ffmpeg 3.3.2 and newer native aac encoder maximum number of channels [on hold]

  21 mars 2018, par AndySP

  I’m attempting to convert a MOGG (Multi-channel OGG) audio file with 16 channels into an AAC file using FFMPEG native AAC encoder (tried version 3.3.2 and also version 86344-gb5a0971). I’m using Audacity as the source and Export -> External Application to pipe the output to FFMPEG using the command :

  ffmpeg -i - -c:a aac -b:a 240k "%f" 

  Its returning "Unsupported number of channels : 16" and then failing. If I reduce the number of channels to 6 it works fine but obviously I’m not willing to remove 10 channels before exporting.

  Does anyone have an idea if its possible to get ffmpeg to accept more than 6 channels in AAC ?