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• Can I create a proccess to kill blocked processes in a queue with Python ?

  15 mars 2017, par user3182473

  I would like to create a process, which kills blocked processes in a queue. These processes are actually ’ffmpeg’ command in my work, which are unstable and blocked occasionally.

  For simplicity I use ’echo’ instead of ’ffmpeg’ as example here. I found that the alive process become ’finished’ from the queue, and the subprocess returncode is 0. Why ?

  And can anyone tell how I can modify my code with python2.7 to fit this requirement ? Any suggestion would be appreciated.

  import subprocess
  
  import os
  
  import multiprocessing
  
  import time
  
  
  
  cmds = ['echo "a" &sleep 10','echo "b"']
  
  queue = multiprocessing.Queue(maxsize=3)
  
  
  
  class ProcessKiller(multiprocessing.Process):
  
      def __init__(self,queue):
  
          multiprocessing.Process.__init__(self)
  
          self.queue = queue
  
  
  
      def run(self):
  
          while True:
  
              try:
  
                  proc = self.queue.get(block=False)
  
                  print 'bbbbb',proc.poll(),proc.pid #WHY HERE THE RETURNCODE=0?
  
                  if proc.poll() is None:
  
                      print 'tokill'
  
                      time.sleep(5)
  
                      if proc.poll() is None:
  
                          os.killpg(os.getpgid(proc.pid),signal,SIGTERM)
  
                          print 'killed'
  
              except Exception as e:
  
                  time.sleep(0.5)
  
  
  
  pk = ProcessKiller(queue)
  
  pk.start()
  
  
  
  for item in cmds:
  
      cmd = subprocess.Popen(item,preexec_fn=os.setsid,shell=True)
  
      print 'aaaaa',cmd.poll(), cmd.pid
  
      queue.put(cmd,block=False)
  
  
  
      time.sleep(3)        
  
      print 'cccc',cmd.poll()
  
  
  
      time.sleep(10)
  
      print 'dddd', cmd.poll()
  
      cmd.communicate()
  
  
  
      print 'finished'

  The result from this script :

  aaaaa None 120748
  
  a
  
  bbbbb 0 120748
  
  cccc None
  
  dddd 0
  
  finished
  
  aaaaa None 120755
  
  b
  
  bbbbb 0 120755
  
  cccc 0
  
  dddd 0
  
  finished

  UPDATE : Now I use a while loop to monitor the status of the subprocess. It works. However, I am still curious why the status of the process changes from the queue.

• Realtime recording in multiple encodings python

  3 janvier 2015, par erip

  I am working on a project that requires audio recording and am using python. I would like to use a start button to begin recording and a stop button to stop it. Additionally, I’d like to support multiple filetypes like .wav, .mp3, .aiff.

  As far as I know, there doesn’t exist something that can do this "in one go", meaning I could record something as a .wav and then post-process the file to encode it in different formats using ffmpeg or a similar library.

  This presents a small problem because my project is web-based, so I would have to save the .wav and then save the .*.

  Does anyone know of another solution to my problem ?

  Thanks, erip

• Live streaming doesnt work

  13 février 2013, par John Smith

  Im using FFmpeg to capture my screen :

  ffmpeg -f dshow -i video="UScreenCapture" -r 5 -s 640x480 -acodec libmp3lame -ac 1 -vcodec mpeg 4 -vtag divx -q 10 -f mpegts tcp://127.0.0.1:1234

  so let it stream to somewhere. The accepter script :

   error_reporting(E_ALL); /* Allow the script to hang around waiting for connections. */
  
   set_time_limit(30); /* Turn on implicit output flushing so we see what we're getting as it comes in. */
  
   ob_implicit_flush();
  
  
  
  
  
  $address = '127.0.0.1';
  
  $port = 1234;
  
  $outfile = dirname(__FILE__)."/output.flv";
  
  $ofp = fopen($outfile, 'wb');
  
  
  
   if (($sock = socket_create(AF_INET, SOCK_STREAM, SOL_TCP)) === false) { echo "socket_create() failed: reason: " . socket_strerror(socket_last_error()) . "\n"; sleep (5); die; }
  
   if (socket_bind($sock, $address, $port) === false) { echo "socket_bind() failed: reason: " . socket_strerror(socket_last_error($sock)) . "\n"; sleep (5); die; }
  
   if (socket_listen($sock, 5) === false) { echo "socket_listen() failed: reason: " . socket_strerror(socket_last_error($sock)) . "\n"; sleep (5); die; }
  
   if (($msgsock = socket_accept($sock)) === false) { echo "socket_accept() failed: reason: " . socket_strerror(socket_last_error($sock)) . "\n"; sleep (5); break; }
  
   do {
  
      $a = '';
  
      socket_recv ($msgsock, $a, 65536, MSG_WAITALL);
  
      fwrite ($ofp, $a);
  
      //echo strlen($a)."\r\n";
  
   } while (true);

  it seems to save the stuff to the disk OK. Now here comes the html :

  I dont really know how to do this, but based on an example :

  <video src="/output.flv"></video>

  but it doesnt do anything. And if I want to stream the live incoming stuff, then whats the matter ?