如何杀死node.js中的ffmpeg进程

Question

I am using node.js code that convert Axis Ipcamera live stream into mp4 using FFMPEG

 var childProcess=require('child_process');
 var childArguments = [];
var child=[];
var cmd='ffmpeg -i rtsp://172.24.22.117:554/axis-media/media.amp -vcodec libx264 -pix_fmt yuv420p -profile:v baseline -preset slower -crf 18 -vf "scale=trunc(in_w/2)*2:trunc(in_h/2)*2"'+' '+__dirname+'/uploads/ouput.mp4';

  child=childProcess.exec(       
        cmd,
        childArguments,
        {            
            env: process.env,
            silent:true
        },  function (err, stdout, stderr) {
            if (err) {
                throw err;
            }
            console.log(stdout);

        });     

        //    here generate events for listen child process (works properly)
    // Listen for incoming(stdout) data
    child.stdout.on('data', function (data) {
        console.log("Got data from child: " + data);
    });

    // Listen for any errors:
    child.stderr.on('data', function (data) {
        console.log('There was an error: ' + data);
    });

    // Listen for exit event
    child.on('exit', function(code) {
        console.log('Child process exited with exit code ' + code);
        child.stdout.pause();
        child.kill();
    });

my above code works perfectly. It gives the output as I want, but I am not able to kill(stop) the ffmpeg command. I am using the code below for stopping the process, but in background it still continues.

child.kill("SIGTERM"); 

I also used following commands: child.kill('SIGUSR1'); child.kill("SIGHUP"); child.kill("SIGINT");child.kill('SIGUSR2'); for killing this process but it not works.

Currently I forcefully kill the node application to stop ffmpeg command and generate mp4 file. I do not want this. But I want commands that stop ffmpeg process and generate mp4 file, without killing the node application.

Answer 1

var cp = require('child_process');
var cmd = 'ffmpeg...'
var child = cp.exec(cmd, function(err, stdout, stderr) {})
child.stdin.write('q')

Answer 2

This ended up being the solution for me:

child.stdin.end()

It works fine cross-platform. In my specific case, FFmpeg was reading from STDIN for stream data as well. SIGTERM wasn't working. Windows was able to kill with SIGTERM , but only because it doesn't actually use these signals and was forcefully killing the process.

So, you might try just ending STDIN and see if that solves it for your usage as well!

Answer 3

You are calling child.kill() from the child.on('exit') callback, that could be the issue since that callback is not been triggered. child.on('exit') is called actually when the child process finished.

Also if you need to kill the child process explicitly means that the command is not exit by it self. If thats the case maybe you want to set a timeout to call child.kill() after some time of been running.

Answer 4

Sending 'q' in stdin is a good solution but I find it a bit unstable since it doesn't work every time. So here is what I have found.

The processes that are remaining are not spawned directly from your main NodeJS process. In other words they are the childs of your spawned process. I've seen this issue in my case where exec opens up a shell and the shell forks a ffmpeg process.

Currently there is no method in child_process to kill the complete process tree but there is a feature request for it here .

Another solution is to use a module tree-kill . Here's an example I sneaked from their Github page :

Kill all the descendent processes of the process with pid 1, including the process with pid 1 itself:

var kill = require('tree-kill');
kill(1);

So if you want to kill the process tree:

var treekill = require('tree-kill');
treekill(child.pid);