2.3.2. Audio output devices

MPlayer's audio interface is called libao2. It currently contains these drivers :

The fact is, Linux soundcard drivers are usually bad, and always as incompatible as they can be. It MAY take a while to find your optimal settings.

• if you have OSS as driver, first try with -ao oss (this is the default). If you experience glitches, halts or anything out of the ordinary, have a look at -ao sdl (NOTE: of course you'll have to have a new SDL library and its devel pair installed). It helps in a lot of cases (it also supports ESD, ARTS, and up/downsampling. /esd is GNOME's, arts is KDE's sound daemon/).
• if you have ALSA version 0.5, then you ALMOST always have to use -ao alsa5 , since 0.5 has buggy OSS emulation code, and will crash MPlayer with a message like this:
  
  DEMUXER: Too many (945 in 8390980 bytes) video packets in the buffer!
• if you have ALSA version 0.9, use -ao oss or -ao sdl as you wish. You can also use -ao alsa9 as it works now, however it has many problems (losing sync, disappearing audio, etc).

On Solaris/FreeBSD systems, use the SUN audio driver with the -ao sun option, otherwise you'll have no video, nor audio playing.

2.3.2.1. Soundcard experiences, recommendations

VIA onboard chipset (via82cxxx) 48Khz only
	Driver:	from here
Aureal Vortex 2
	OSS:	no driver
	OSS/Pro:	OK
	ALSA:	no driver
	Max kHz:	48
	Driver:	aureal.sourceforge.net
	Driver2:	from here (buffer size increased to 32k)
GUS PnP
	OSS:	no driver
	OSS/Pro:	OK
	ALSA:	OK
	Max kHz:	48
SB Live!
	OSS:	OK
	ALSA:	(?)
	Max kHz:	48
SB AWE 64
	OSS:	max 44kHz
	ALSA:	48kHz sounds shit
	Max kHz:	48
Gravis UltraSound ACE
	OSS:	max 44Khz. not OK
	ALSA:	OK
	Max kHz:	48
Gravis UltraSound MAX
	OSS:	OK
	ALSA:	OK (?)
	Max kHz:	48
ESS 688
	OSS:	OK
	ALSA:	OK (?)
	Max kHz:	48
C-Media cards (which ones?)
	OSS:	not OK (hissing) (?)
	ALSA:	OK (?)
	Max kHz:	?
Yamaha cards (*ymf*)
	OSS:	not OK (?) (maybe -ao sdl)
	ALSA:	OK only with ALSA 0.5 with OSS emulation AND -ao sdl (!) (?)
	Max kHz:	?
Cards with envy24 chips (like Terratec EWS88MT)
	OSS:	?
	OSS/Pro:	OK
	ALSA:	?
	Max kHz:	?
PC Speaker or DAC
	OSS:	OK (use the SDL driver : -ao sdl)
	ALSA:	no driver
	Max kHz:	the driver emulates 44.1 maybe more
	Driver:	ftp://ftp.infradead.org/pub/pcsp

• on Linux, use at least kernel 2.4 if possible, 2.2 isn't tested
• if sound clicks when playing from CD-ROM, turn on IRQ unmasking ! for example "hdparm -u1 /dev/cdrom" (see "man hdparm" !!!) This is recommended anyways... (for XMMS, etc...) Read section 4.1.
• don't use your soundcard by other application ( for ex. XMMS ) ! if you use ESD, start MPlayer with the '-vo sdl:esd' option !
• Please tell us how MPlayer and your soundcard(s) worked together!

2.3.2.2. Audio plugins

2.3.2.2.1. Up/Downsampling

2.3.2.2.2. Surround Sound decoding