javascript - video to audio file convert & save through FFMPEG in node js -

i working on ffmpeg on node js. i'd retrieve audio track video file using node js. save such file can't figure out how.

i though line of code me :

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

i have got in npm package. don't quite understand how work , how save audio file.

some other line of code 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 retrieve audio ffmpeg video ? how save ?

i 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 installed , part of system path, make sure necessary codes present.

update:

for video without audio, .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 , audio 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(); }