Virtual Master Control API

snd_ctl_make_virtual_master — Create a virtual master control
snd_ctl_add_vmaster_hook — Add a hook to a vmaster control
snd_ctl_sync_vmaster — Sync the vmaster slaves and hook
snd_ctl_add_slave — Add a virtual slave control
snd_ctl_add_slave_uncached — Add a virtual slave control