Node.js Fluent-FFMPEG Example to Extract Audio (MP3) From Video MP4 File in Command Line

Welcome folks today in this blog post we will be using the fluent-ffmpeg library to extract mp3 audio file from video mp4 video in command line using node.js. All the full source code of the application is shown below.

Get Started

In order to get started you need to make a new node.js project using the below command as shown below

npm init -y

npm i fluent-ffmpeg

And now we need to create the index.js file and copy paste the following code

index.js

(function () {
  var ffmpeg = require("fluent-ffmpeg");

  var args = process.argv.slice(2);

  function baseName(str) {
    var base = new String(str).substring(str.lastIndexOf("/") + 1);
    if (base.lastIndexOf(".") != -1) {
      base = base.substring(0, base.lastIndexOf("."));
    }

    return base;
  }

  args.forEach(function (val, index, array) {
    var filename = val;

    console.log(val);

    var basename = baseName(filename);

    console.log(basename);

    ffmpeg(filename)
      .toFormat("mp3")
      .saveToFile("audio.mp3", (stdout, stderr) => {})

      .on("error", function (err) {
        console.log(err);
      })
      .on("progress", function (progress) {
        console.log("... frmaes " + progress.frames);
      })
      .on("end", function () {
        console.log("Finished processing");
      })
      .run();
  });
})();

(function () {

var ffmpeg = require("fluent-ffmpeg");

var args = process.argv.slice(2);

function baseName(str) {

var base = new String(str).substring(str.lastIndexOf("/") + 1);

if (base.lastIndexOf(".") != -1) {

base = base.substring(0, base.lastIndexOf("."));

}

return base;

}

args.forEach(function (val, index, array) {

var filename = val;

console.log(val);

var basename = baseName(filename);

console.log(basename);

ffmpeg(filename)

.toFormat("mp3")

.saveToFile("audio.mp3", (stdout, stderr) => {})

.on("error", function (err) {

console.log(err);

})

.on("progress", function (progress) {

console.log("... frmaes " + progress.frames);

})

.on("end", function () {

console.log("Finished processing");

})

.run();

});

})();

As you can see we are importing the fluent-ffmpeg library and then we are using the toFormat() method to extract the audio from the video file. And then we are using the saveToFile() method to save the audio.mp3 file inside the root directory. And then we are listening on various events for error and progress events. And then we are calling the run() method to execute the ffmpeg command

Now in order to run this node.js app you need to pass the path of the video.mp4 file in the command line

nodemon index.js video.mp4

Now this will create the audio.mp3 output file inside the root directory as shown below