Hi, I get the following error when trying to build this package:
 
gcc -DHAVE_CONFIG_H -I. -DDEFAULT_OSS_ALT_AUDIO_DEVICE=\"\" -D_REENTRANT -I/opt/pkg.obj/audio/xmms-crossfade/work.ultra10/.buildlink/include -I/opt/pkg.obj/audio/xmms-crossfade/work.ultra10/.buildlink/include/glib/glib-1.2 -I/opt/pkg.obj/audio/xmms-crossfade/work.ultra10/.buildlink/include/gtk-1.2 -I/opt/pkg.obj/audio/xmms-crossfade/work.ultra10/.buildlink/include/xmms -I/opt/pkg.obj/audio/xmms-crossfade/work.ultra10/.buildlink/lib/glib/include -I/opt/pkg.obj/audio/xmms-crossfade/work.ultra10/.x11-buildlink/include -O -DGLX_GLXEXT_LEGACY -Wall -c 
oss.c  -fPIC -DPIC -o .libs/oss.o
oss.c: In function 'oss_get_volume':
oss.c:150: error: 'SOUND_MIXER_READ_DEVMASK' undeclared (first use in this 
function)
oss.c:150: error: (Each undeclared identifier is reported only once
oss.c:150: error: for each function it appears in.)
oss.c:151: error: 'SOUND_MASK_PCM' undeclared (first use in this function)
oss.c:152: error: 'SOUND_MIXER_READ_PCM' undeclared (first use in this 
function)
oss.c:153: error: 'SOUND_MASK_VOLUME' undeclared (first use in this function)
oss.c:154: error: 'SOUND_MIXER_READ_VOLUME' undeclared (first use in this 
function)
... and so on

So I put the following line in audio/xmms-crossfade/Makefile

CONFIGURE_ARGS+=        --disable-oss

This is probably not correct for most platforms. Maybe the Makefile should 
have some logic that tests for OSS and then disables it if the OS does not 
support it.