Built and installed mplayer on Fedora 18 (had working before in F-16, 12).
I had some issues with needed development versions of gtk and zlib to build - apparently the .h files needed are only in the development release, even though the libraries appear to be here by default.
The below fixed the config and make for mplayer for me (64 bit version).
yum install zlib-devel.x86_64 gtk2-devel.x86_64
However my mplayer has NO SOUND AT ALL and it used to work fine. Other system sound tests work fine as does Skype.
The only difference I see is that in Fedora 16 (and 12), the system-settings sound showed both the intenal (on the monitor) speakers AND the external plugged in SONY speakers that I use.
The fedora 18 system-settings sound menu now only shows ONE output device (internal), but when I test THERE, it uses the speakers (as does skype)..
I tried mplayer -ao XXX with each of the 5 below options (well not null).
Most of them just say "No Audio" as there is no device.
"mplayer -ao help" yields:
Available audio output drivers:
oss OSS/ioctl audio output
mpegpes DVB audio output
v4l2 V4L2 MPEG Audio Decoder output
null Null audio output
pcm RAW PCM/WAVE file writer audio output