video to audio file convert & save through FFMPEG

Question

I am working on an FFMPEG on node js. I'd like to retrieve the audio track from a video file using node js. I would also like to save such file but I can't figure out how.

I though this line of code would help me :

ffmpeg('/path/to/file.avi').noVideo();

I have got this in npm package. I don't quite understand how to work with this and how to actually save the audio file.

Some other line of code that come in play :

try {
    var process = new ffmpeg('/path/to/your_movie.avi');
    process.then(function (video) {
        // Callback mode
        video.fnExtractSoundToMP3('/path/to/your_audio_file.mp3', function (error, file) {
            if (!error)
                console.log('Audio file: ' + file);
        });
    }, function (err) {
        console.log('Error: ' + err);
    });
} catch (e) {
    console.log(e.code);
    console.log(e.msg);
}

My question is:

How do I retrieve the audio from a FFMPEG video ? How do I save it ?

Answer 1

I would do it like:

var ffmpeg = require('fluent-ffmpeg');
/**
 *    input - string, path of input file
 *    output - string, path of output file
 *    callback - function, node-style callback fn (error, result)        
 */
function convert(input, output, callback) {
    ffmpeg(input)
        .output(output)
        .on('end', function() {                    
            console.log('conversion ended');
            callback(null);
        }).on('error', function(err){
            console.log('error: ', e.code, e.msg);
            callback(err);
        }).run();
}

convert('./df.mp4', './output.mp3', function(err){
   if(!err) {
       console.log('conversion complete');
       //...

   }
});

just make sure ffmpeg is installed and is part of system path, also make sure all the necessary codes are present.

Update:

for video without audio, simply do .noAudio().videoCodec('copy'):

function copyWitoutAudio(input, output, callback) {
    ffmpeg(input)
        .output(output)
        .noAudio().videoCodec('copy')
        .on('end', function() {                    
            console.log('conversion ended');
            callback(null);
        }).on('error', function(err){
            console.log('error: ', err);
            callback(err);
        }).run();
}

---

Update 2:

for merging video and audio into single:

function mergeMedia(aud, vid, output, callback) {
    ffmpeg()
        .input(aud)
        .input(vid)
        .output(output)
        .outputOptions(
          '-strict', '-2',
          '-map', '0:0',
          '-map', '1:0'
        ).on('end', function() {                    
            console.log('conversion ended');
            callback(null);
        }).on('error', function(err){
            console.log('error: ', err);
            callback(err);
        }).run();
}