I'm currently developing a video player software which intended to be an embeedded player. I'm using Java with VLCJ library for the video player. What i'm looking is a way, something to transform the audio output to make the output sound as oldman or a kid (pitch shifting, i guess is the name). VLC have this when enabling time stretch, but the video play speed is affected (slower to get oldman sound, but fast-forward-alike to get kid voice effect. Is there any solutions for this? I don't find this feature on VLC(J), so i think what i need is the audio output of the ubuntu itself (Ubuntu 12.04) to do this job. something like filtering audio output system wide. Any software or setting to do this? it also need to be controllable via command line to provide realtime effect changing. Thanks in advance.