Killing a FFmpeg process triggered by spawn in NodeJs

Question

I am facing an issue wanting to kill a FFmpeg process triggered by spawn from the child_process native NodeJs package.

Here is the script i use to trigger the ffmpeg process.

Assume that the conversion takes a long time, like about 2 hours.

/**
 * Execute a command line cmd
 * with the arguments in options given as an array of string
 * processStore is an array that will store the process during its execution
 * and remove it at the end of the command or when error occurs
 */
function execCommandLine({
   cmd,
   options = [],
   processStore = [],
}) {
  return new Promise((resolve, reject) => {
    const spwaned_process = childProcess.spawn(cmd, options);

    // Append the process to a buffer to keep track on it
    processStore.push(spwaned_process);

    // Do nothing about stdout
    spwaned_process.stdout.on('data', () => true);

    // Do nothing about stderr
    spwaned_process.stderr.on('data', () => true);

    spwaned_process.on('close', () => {
      const index = processStore.indexOf(spwaned_process);

      if (index !== -1) {
        processStore.splice(index, 1);
      }

      resolve();
    });

    spwaned_process.on('error', () => {
      const index = processStore.indexOf(spwaned_process);

      if (index !== -1) {
        processStore.splice(index, 1);
      }

      reject();
    });
  });
}

const processStore = [];

await execCommandLine({
  cmd: 'ffmpeg',

  options: [
    '-i',
    '/path/to/input',
    '-c:v',
    'libvpx-vp9',
    '-strict',
    '-2',
    '-crf',
    '30',
    '-b:v',
    '0',
    '-vf',
    'scale=1920:1080',
    '/path/to/output',
  ],

  processStore,
});

During the conversion, the following code is called to kill all process into the processStore, including the FFmpeg process that is triggered.

// getProcessStore() returns the const processStore array of the above script
getProcessStore().forEach(x => x.kill());

process.exit();

After the program exit, when i run ps -ef | grep ffmpeg, there is still some FFmpeg process running.

root 198 1 0 09:26 ? 00:00:00 ffmpeg -i /path/to/input -ss 00:01:47 -vframes 1 /path/to/output

root 217 1 0 09:26 ? 00:00:00 ps -ef

Do you have an idea about the way to kill a ffmpeg process properly ?

score 3 · Answer 1 · answered Nov 22 '18 at 10:05

As stated in the node.js documentation of subprocess.kill([signal]), the default sent signal is SIGTERM.

Ffmpeg do not terminature receiving SIGTERM as explained by @sashoalm in here.

Newer versions of ffmpeg don't use 'q' anymore, at least on Ubuntu Oneiric, instead they say to press Ctrl+C to stop them. So with a newer version you can simply use 'killall -INT' to send them SIGINT instead of SIGTERM, and they should exit cleanly.

So call x.kill('SIGINT');

Killing a FFmpeg process triggered by spawn in NodeJs

1 Answers1