[emms-help] play audio only when playing media

[Alex Vong]

Hi emms,

I want to ask is there a way to play audio only when playing a video
file, like a mkv file? So far I have tried 2 method, and both failed:

Method 1:
  (setq-default emms-player-vlc-parameters (cons "--no-video"
                                                 emms-player-vlc-parameters))
Problem:
  I cannot play video anymore. What I want is I can disable video at
  will.

Method2:
  (defun music-play-directory (dir)
    (interactive
     (let ((promt "Play directory: ")
           (mustmatch t))
       (list (emms-read-directory-name promt
                                       emms-source-file-default-directory
                                       emms-source-file-default-directory
                                       mustmatch))))
    (emms-play-directory dir))
Problem:
  The function return immediately. Only the 1st video is played without
  video, the rest are played with video.

How should I fix my function?

Thanks,
Alex