Hello, i need to give to my clients the possibility to change crossfading, how can i do?

Is only server side function?

I also request this.

You should be able to enable this using the centovacast.conf file.

Find:
CLIENT_ENCODER_SETTINGS=false

Change to:
CLIENT_ENCODER_SETTINGS=true

Restart centovacast:
/etc/init.d/centovacast restart

This will give the clients the ability to change sample rate, channels, crossfade, etc.  (It's all tied into 1)