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• Meteor Spawn_Child_Process for FFMpeg [duplicate]

  2 mars 2013, par user2009114

  Hi I am trying to use Meteor and javascript (Node) to spawn an ffmpeg transcoding event and then stream it live through HTML5 video tags. However, though I can get it working with node.js it seems to hang on the Meteor server and not stream anything though it does seem to be transcoding okay. It appears that the transcoding thread hangs up the server, or is not even a different thread at all ? I am pasting the relevant server side code followed by the client code calling it. One JQuery function calls the transcoding process and the PollForPlaylist is called from the video tags by the hls/. Any help would be much appreciated in solving this. I am wondering if there is a meteor function which I can call to spawn a thread for the ffmpeg function ? Or maybe there is another way to push data to the video tag through jQuery ?

  var spawnNewProcess = function(file, playlistPath) {
  
      var outputUrlPrefix = '/segment/';
  
      var args = ['-i', file, '-async', '1', '-acodec', 'libmp3lame', '-b:a', 128 + 'k', '-vf', 'scale=min(' + targetWidth + '\\, iw):-1', '-b:v', videoBitrate + 'k', '-ar', '44100', '-ac', '2', '-vcodec', 'libx264', '-x264opts', 'level=3.0', '-profile:v', 'baseline', '-preset:v' ,'superfast', '-threads', '0', '-flags', '-global_header', '-map', '0', '-f', 'segment', '-segment_time', '10', '-segment_list', 'stream.m3u8', '-segment_format', 'mpegts', '-segment_list_flags', 'live', 'stream%05d.ts'];
  
  
  
      var encoderChild = childProcess.spawn(transcoderPath, args, {cwd: outputPath});
  
  
  
      console.log(transcoderPath + args);
  
  
  
      encoderProcesses[file] = encoderChild;
  
      currentFile = file;
  
  
  
      console.log('Spawned transcoder instance');
  
  
  
      if (debug) {
  
          encoderChild.stderr.on('data', function(data) {
  
              console.log(data.toString());
  
          });
  
      }
  
  
  
      encoderChild.on('exit', function(code) {
  
          console.log('Transcoder exited with code ' + code);
  
  
  
          delete encoderProcesses[file];
  
      });
  
  
  
      // Kill any "zombie" processes
  
      setTimeout(function() {
  
          if (encoderProcesses[file]) {
  
              console.log('Killing long running process');
  
  
  
              killProcess(encoderProcesses[file]);
  
          }
  
      }, processCleanupTimeout);
  
  };
  
  
  
  var pollForPlaylist = function(file, response) {
  
      var numTries = 0;
  
      console.log("IN POLL FOR PLAYLIST");
  
  
  
      var tryOpenFile = function() {
  
          if (numTries > 20) {
  
              console.log('Gave up trying to open m3u8 file');
  
              response.writeHead(500);
  
              response.end();
  
          }
  
          else {
  
              console.log("IN ELSE");
  
              fs.readFile(playlistPath, function (err, data) {
  
                  console.log("Trying to read file");
  
                  if (err || data.length === 0) {
  
                      numTries++;
  
                      setTimeout(tryOpenFile, 200);
  
                      console.log("ERROR, number of tries", numTries);
  
                  }
  
                  else {
  
                      if (!debug) {
  
                          response.setHeader('Content-Type', 'application/x-mpegURL');
  
                      }
  
                      console.log('response: ' + data);
  
                      response.write(data);
  
                      response.end();
  
                  }
  
              });
  
          }
  
      };
  
          console.log("Try open");
  
          tryOpenFile();
  
  };
  
  
  
  var killProcess = function(processToKill, callback) {
  
      processToKill.kill();
  
  
  
      setTimeout(function() {
  
          processToKill.kill('SIGKILL');
  
      }, 5000);
  
  
  
      processToKill.on('exit', function(code) {
  
          if (callback) callback();
  
      });
  
  }
  
  
  
  var handlePlaylistRequest = function(file, request, response) {
  
      if (!file) {
  
          request.writeHead(400);
  
          request.end();
  
      }
  
  
  
      if (lock) {
  
          console.log('Ongoing spawn process not finished, denying request');
  
          response.writeHead(503);
  
          response.end();
  
          return;
  
      }
  
  
  
      file = path.join('/', file); // Remove ".." etc
  
      file = path.join(rootPath, file);
  
  
  
      console.log("PLAYLIST PATH", playlistPath);
  
      if (currentFile != file) {
  
          lock = true;
  
  
  
          console.log('New file to encode chosen');
  
  
  
          // Make sure old one gets killed
  
          if (encoderProcesses[currentFile]) {
  
              killProcess(encoderProcesses[currentFile], function() {
  
                  fs.unlink(playlistPath, function (err) {
  
                      spawnNewProcess(file, playlistPath, outputPath);
  
                      lock = false;
  
                  });
  
              });
  
          }
  
          else {
  
              fs.unlink(playlistPath, function (err) {
  
                  spawnNewProcess(file, playlistPath, outputPath);
  
                  lock = false;
  
              });
  
          }
  
          currentFile = file;
  
      }
  
  };

  The Client side code which calls this is :

  var videoNode = document.querySelector('video');
  
  $.get('hls/?file='+file);
  
  videoNode.src = "hls/" + file;