我会这样做:

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');
       //...

   }
});

只需确保已安装ffmpeg并且它是系统路径的一部分，还请确保所有必需的代码均已存在.

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

更新:

对于没有音频的视频，只需执行.noAudio().videoCodec('copy'):

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();
}

更新2:

用于将视频和音频合并为单个:

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();
}