Use custom map

[pedromsilvapt]

The custom method does not allow to specify multiple parameters with the same name, such as map, for example '-map 0:v:0 -map 0:a:0' to transcode only the first video stream and the first audio-stream. I think a third option, custom( 'map', '0:v:0', true ) to specify wether to replace an existing command or to concatenate if it already existed would be very useful. Or, at least, a raw() method that appends it's content to the command.

[sscssc]

Hello,
I had the same problem, for fix
Go to ligne 405 and change :

this.args[key] = args;

to :

this.args[Object.keys(this.args).length] = args;