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• How do I use ffmpeg with Python by passing File Objects (instead of locations to files on disk)

  1er mai 2012, par Lyle Pratt

  I'm trying to use ffmpeg with Python's subprocess module to convert some audio files. I grab the audio files from a URL and would like to just be able to pass the Python File Objects to ffmpeg, instead of first saving them to disk. It would also be very nice if I could just get back a file stream instead of having ffmpeg save the output to a file.

  For reference, this is what I'm doing now :

  tmp = "/dev/shm"
  
  audio_wav_file = requests.get(audio_url)
  
  ##              ##                         ##
  
  ## This is what I don't want to have to do ##
  
  wavfile = open(tmp+filename, 'wrb')   
  
  wavfile.write(audio_wav_file.content)
  
  wavfile.close()
  
  ##              ##                         ##
  
  conversion = subprocess.Popen('ffmpeg -i "'+tmp+filename+'" -y "'+tmp+filename_noext+'.flac" 2>&1', shell = True, stdout = subprocess.PIPE).stdout.read()

  Does anyone know how to do this ?

  Thanks !

• lavc/avcodec.h : fix prolems -> problems typo

  2 juillet 2013, par Stefano Sabatini

  lavc/avcodec.h : fix prolems -> problems typo
  

  • [DH] libavcodec/avcodec.h

• Killing python ffmpeg subprocess breaks cli output

  17 mars 2016, par JayLev

  I’m trying to execute a system command with subprocess and reading the output.

  But if the command takes more than 10 seconds I want to kill the subprocess.

  I’ve tried doing this in several ways.

  My last try was inspired by this post : http://stackoverflow.com/a/3326559/969208

  Example :

  import os
  
  import signal
  
  from subprocess import Popen, PIPE
  
  
  
  class Alarm(Exception):
  
      pass
  
  
  
  def alarm_handler(signum, frame):
  
      raise Alarm
  
  
  
  def pexec(args):
  
  
  
      p = Popen(args, stdout=PIPE, stderr=PIPE)
  
  
  
      signal.signal(signal.SIGALRM, alarm_handler)
  
      signal.alarm(10)
  
  
  
      stdout = stderr = ''
  
      try:
  
          stdout, stderr = p.communicate()
  
          signal.alarm(0)
  
      except Alarm:
  
          try:
  
              os.kill(p.pid, signal.SIGKILL)
  
          except:
  
              pass
  
  
  
      return (stdout, stderr)

  The problem is : After the program exits no chars are shown in the cli until I hit return. And hitting return will not give me a new line.

  I suppose this has something to do with the stdout and stderr pipe.

  I’ve tried flushing and reading from the pipe (p.stdout.flush())

  I’ve also tried with different Popen args, but might’ve missed something. Just thought I’d keep it simple here.

  I’m running this on a Debian server.

  Am I missing something here ?

  EDIT :

  It seems this is only the case when killing an ongoing ffmpeg process. If the ffmpeg process exits normally before 10 seconds, there is no problem at all.

  I’ve tried executing a couple of different command that take longer than 10 seconds, one who prints output, one who doesn’t and a ffmpeg command to check the integrity of a file.

  args = ['sleep', '12s'] # Works fine
  
  args = ['ls', '-R', '/var'] # Works fine, prints lots for a long time
  
  args = ['ffmpeg', '-v', '1', '-i', 'large_file.mov','-f', 'null', '-'] # Breaks cli output

  I believe ffmpeg prints using \r and prints everything on the strerr pipe. Can this be the cause ? Any ideas how to fix it ?