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• NodeJs : How to pipe two streams into one spawned process stdin (i.e. ffmpeg) resulting in a single output

  20 juin 2018, par Keyne Viana

  In order to convert PCM audio to MP3 I’m using the following :

  function spawnFfmpeg() {
  
      var args = [
  
          '-f', 's16le',
  
          '-ar', '48000',
  
          '-ac', '1',
  
          '-i', 'pipe:0',
  
          '-acodec', 'libmp3lame',
  
          '-f', 'mp3',
  
          'pipe:1'
  
      ];
  
  
  
      var ffmpeg = spawn('ffmpeg', args);
  
  
  
      console.log('Spawning ffmpeg ' + args.join(' '));
  
  
  
      ffmpeg.on('exit', function (code) {
  
          console.log('FFMPEG child process exited with code ' + code);
  
      });
  
  
  
      ffmpeg.stderr.on('data', function (data) {
  
          console.log('Incoming data: ' + data);
  
      });
  
  
  
      return ffmpeg;
  
  }

  Then I pipe everything together :

  writeStream = fs.createWriteStream( "live.mp3" );
  
  var ffmpeg = spawnFfmpeg();
  
  stream.pipe(ffmpeg.stdin);
  
  ffmpeg.stdout.pipe(/* destination */); 

  The thing is... Now I want to merge (overlay) two streams into one. I already found how to do it with ffmpeg : How to overlay two audio files using ffmpeg

  But, the ffmpeg command expects two inputs and so far I’m only able to pipe one input stream into the pipe:0 argument. How do I pipe two streams in the spawned command ? Would something like ffmpeg -i pipe:0 -i pipe:0... work ? How would I pipe the two incoming streams with PCM data (since the command expects two inputs) ?

• Python - check subprocess activity every n seconds

  22 novembre 2017, par hlabor

  I’m trying to make python script (currently on windows) which will open some sub-processes (which will run infinitely) and script should periodically check do all of opened sub-processes still work correctly. So it should be done with while loop, I guess.

  The sub-processes are about FFMPEG livestreaming.

  The problem is when I do time.sleep(n) in my loop, because then every FFMPEG livestream stops, so I suppose time.sleep affect on all of child subprocesses.

  I have no idea how to make it work.

  Here is my python code :

  import os, time, sys, datetime, smtplib, configparser, logging, subprocess, psutil
  
  import subprocess
  
  
  
  def forwardudpstream(channel_number, ip_input, ip_output):
  
      try:
  
          ffmpeg_command = 'ffmpeg -i udp://' + ip_input + ' -vcodec copy -acodec copy -f mpegts "udp://' + ip_output + '?pkt_size=1316"'
  
          ffmpeg_output = subprocess.Popen(ffmpeg_command, stdout=subprocess.PIPE, stderr=subprocess.STDOUT, shell=False)
  
          return str(ffmpeg_output.pid)
  
      except:
  
          print ("Exception!")
  
          return '0'
  
  
  
  while True:
  
      configuration = 'config.ini'
  
      channel_list_file = 'CHANNEL_LIST.conf'
  
      pid_folder = "D:\\Forward_UDP_Stream\\pids\\"
  
      channel_list = [line.rstrip('\n') for line in open(channel_list_file)]
  
      for line in channel_list:
  
          if not line.startswith('#') and ('|' in line):
  
              channel_number, ip_input, ip_output = line.split('|')
  
              print('----------')
  
              print("Channel number = ", channel_number)
  
              print("IP Input = ", ip_input)
  
              print("IP Output = ", ip_output)
  
              pid_file_found = False
  
              print("Checking if pid file exists...")
  
              for pidfile in os.listdir(pid_folder):
  
                  if pidfile.startswith(channel_number + '-'):
  
                      print("Pid file is found for this channel.")
  
                      pid_file_found = True
  
                      pid = int(pidfile.split('-')[1].split('.')[0])
  
                      print("PID = ", str(pid))
  
                      print("Checking if corresponding process is active...")
  
                      if not psutil.pid_exists(pid):
  
                          print("Process is not active.")
  
                          print("Removing old pid file.")
  
                          os.remove(pid_folder + pidfile)
  
                          print("Starting a new process...")
  
                          pid_filename = channel_number + '-' + forwardudpstream(channel_number, ip_input, ip_output) + '.pid'
  
                          pid_file = open(pid_folder + pid_filename, "a")
  
                          pid_file.write("Process is running.")
  
                          pid_file.close()
  
                      else:
  
                          print("Process is active!")
  
                      break
  
              if pid_file_found == False:
  
                  print("Pid file is not found. Starting a new process and creating pid file...")
  
                  pid_filename = channel_number + '-' + forwardudpstream(channel_number, ip_input, ip_output) + '.pid'
  
                  pid_file = open(pid_folder + pid_filename, "a")
  
                  pid_file.write("Process is running.")
  
                  pid_file.close()
  
              time.sleep(10)

  Here is my CHANNEL_LIST.conf file example :

  1|239.1.1.1:10000|239.1.1.2:10000
  
  2|239.1.1.3:10000|239.1.1.4:10000

  Perhaps there is some other solution to put waiting and sub-processes to work together. Does anyone have an idea ?

  UPDATE :
  I finally make it work when I removed stdout=subprocess.PIPE part from the subprocess command.
  Now it looks like this :

  ffmpeg_output = subprocess.Popen(ffmpeg_command, stderr=subprocess.STDOUT, shell=False)

  So now I’m confused why previous command was making a problem...?
  Any explanation ?

• How can I bundle ffmpeg in an Electron application

  14 janvier 2024, par jshbrntt

  I'm building an Electron application starting from the electron-webpack boilerplate.

  



  I found this node module @ffmpeg-installer/ffmpeg which installs a compatible precompiled binary into the /node_modules directory then makes the path of that executable accessible through.

  



  const ffmpegPath = require('@ffmpeg-installer/ffmpeg').path


  



  This works fine during development, but when I build the distributable and run it I get an error when attempting to spawn a child process with that path. Presumably, because the path does not point at the binary.

  



  The path is set to the following when running the distributable.

  



  /Users/me/project/dist/mac/AppName.app/Contents/Resources/app.asar/node_modules/@ffmpeg-installer/darwin-x64/ffmpeg


  



  However, when looking in the AppName.app package contents I find the binary in the following path.

  



  /Users/me/project/dist/mac/AppName.app/Contents/Resources/app.asar.unpacked/node_modules/@ffmpeg-installer/darwin-x64/ffmpeg


  



  How should I include binary dependencies in an Electron application using electron-webpack and electron-builder ?