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• How to record sound/audio via FFmpeg, Alsa, PulseAudio or Sox without a soundcard (using the commandline)

  13 avril 2019, par Heart Of A Lion

  I’m trying to record audio on an Ubuntu server that has no soundcard or any other audio device. When I use the following Alsa command to list any audio devices, then it can’t find any devices.

  arecord -l

  I’ve tried recording/capturing audio using the following packages, but because there is no soundcard they all fail to record any audio :

  ffmpeg, alsa, pulseaudio, sox

  Now it should be possible to record sound on a server that has no soundcard, as some people have managed to do it. The question is how.

  Can someone give a step by step commandline walk-through of how to do this on an Ubuntu server, so that audio can be recorded on the server using any of the above-mentioned packages ?

• Merge mp4 files in order based on number from filenames in Python

  7 juillet 2019, par ahbon

  I try to merge lots of mp4 files from a directory test into one output.mp4 using ffmpeg in Python.

  path = '/Users/x/Documents/test'
  
  
  
  import os
  
  
  
  for filename in os.listdir(path):
  
      if filename.endswith(".mp4"):
  
          print(filename)

  Output :

  4. 04-unix,minix,Linux.mp4
  
  6. 05-Linux.mp4
  
  7. 06-ls.mp4
  
  5. 04-unix.mp4
  
  9. 08-command.mp4
  
  1. 01-intro.mp4
  
  3. 03-os.mp4
  
  8. 07-minux.mp4
  
  2. 02-os.mp4
  
  10. 09-help.mp4

  I have tried with the solution below from the reference here : ffmpy concatenate multiple files with a file list

  import os
  
  import subprocess
  
  import time
  
  
  
  
  
  base_dir = "/path/to/the/files"
  
  video_files = "video_list.txt"
  
  output_file = "output.avi"
  
  
  
  # where to seek the files
  
  file_list = open(video_files, "w")
  
  
  
  # remove prior output
  
  try:
  
      os.remove(output_file)
  
  except OSError:
  
      pass
  
  
  
  # scan for the video files
  
  start = time.time()
  
  for root, dirs, files in os.walk(base_dir):
  
      for video in files:
  
          if video.endswith(".avi"):
  
              file_list.write("file './%s'\n" % video)
  
  file_list.close()
  
  
  
  # merge the video files
  
  cmd = ["ffmpeg",
  
         "-f",
  
         "concat",
  
         "-safe",
  
         "0",
  
         "-loglevel",
  
         "quiet",
  
         "-i",
  
         "%s" % video_files,
  
         "-c",
  
         "copy",
  
         "%s" % output_file
  
         ]
  
  
  
  p = subprocess.Popen(cmd, stdin=subprocess.PIPE)
  
  
  
  fout = p.stdin
  
  fout.close()
  
  p.wait()
  
  
  
  print(p.returncode)
  
  if p.returncode != 0:
  
      raise subprocess.CalledProcessError(p.returncode, cmd)
  
  
  
  end = time.time()
  
  print("Merging the files took", end - start, "seconds.")

  I have merged them and get an output.mp4 but the files are not merged in order with the first number split by point (1, 2, 3, ...) : which I can get by filename.split(".")[0] :

  1. 01-intro.mp4
  
  2. 02-os.mp4
  
  3. 03-os.mp4
  
  4. 04-unix,minix,Linux.mp4
  
  5. 04-unix.mp4
  
  6. 05-Linux.mp4
  
  7. 06-ls.mp4
  
  8. 07-minux.mp4
  
  9. 08-command.mp4
  
  10. 09-help.mp4

  How can I merge them correctly and concisely in Python ? Thanks.

• 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
  )