FAQ

Frequently asked questions

Please read those before filing an issue, your question may be answered there.

How do I do X with fluent-ffmpeg?

Please ensure first that you know how to achieve what you want on command line. If you don't, have a look at the ffmpeg documentation and ask the ffmpeg community first, as you're far more likely to get an appropriate answer there.

When you know how to achieve your goal on command line and don't know how to translate it to fluent-ffmpeg calls, please ensure that you've read the documentation first. If you find some command line switch that has no matching fluent-ffmpeg method, you can use the inputOptions() and outputOptions() method instead.

My command is not executed.

Please ensure that you added handlers for both the end and error handlers. One of those should be called and give you more information about what happened.

How can I add filters/options when taking screenshots or using mergeToFile?

Short answer: you can't. Screenshots and merge facilities are just helper "recipes" to help achieve common actions.

Error messages

Error: ffmpeg exited with code 1

Fluent-ffmpeg tries to extract error messages from ffmpeg output, but sometimes it fails. In that case, you can look at additional arguments passed to the error event handler: they hold the raw output from ffmpeg:

ffmpeg(...)
  .on('error', function(err, stdout, stderr) {
    console.log('Error: ' + err.message);
    console.log('ffmpeg output:\n' + stdout);
    console.log('ffmpeg stderr:\n' + stderr);
  });

Most of the time you can get a clearer explanation this way. If you still don't get what's wrong, please include stdout and stderr contents in your bug report.