I have lao installed on OS X 10.8.5 and on a Linux Mint 14 Virtualbox VM, both via luarocks. I'm running the example Lua script.

On OS X, ao.openLive() causes a segmentation fault. On Mint, at least it just errs: Lua prints the default error "something went wrong", returned from l_open_live.

Not sure if this is the cause, but when trying to compile I get complaints that the ao_option *opt inside table2option can return uninitialized. As noted here, that means it points to jibberish:
http://stackoverflow.com/a/7150353

Either way, passing an option table to ao.openLive() doesn't help -- segfault persists.

i'm using the example ao_live.lua but show this error, my operating system is GNU/Linux:

$ luajit ao_live.lua

=================================================
=> type:	live
=> priority:	50
=> options:
	 - server
	 - sink
	 - dev
	 - id
	 - verbose
	 - quiet
	 - matrix
	 - debug
	 - client_namebuffer_time
=> shortName:	pulse
=> preferredByteFormat:	native
=> comment:	Outputs to the PulseAudio Sound Server
=> name:	PulseAudio Output
=================================================
=> type:	live
=> priority:	20
=> options:
	 - dsp
	 - dev
	 - id
	 - buffer_time
	 - verbose
	 - quiet
	 - matrix
	 - debug
=> shortName:	oss
=> preferredByteFormat:	native
=> comment:	Outputs audio to the Open Sound System driver.
=> name:	OSS audio driver output 
=================================================
=> type:	live
=> priority:	0
=> options:
	 - debug
	 - verbose
	 - matrix
	 - quiet
=> shortName:	null
=> preferredByteFormat:	native
=> comment:	This driver does nothing.
=> name:	Null output
=================================================
=> type:	file
=> priority:	0
=> options:
	 - matrix
	 - verbose
	 - quiet
	 - debug
=> shortName:	wav
=> preferredByteFormat:	little
=> comment:	Sends output to a .wav file
=> name:	WAV file output
=================================================
=> type:	file
=> priority:	0
=> options:
	 - byteorder
	 - matrix
	 - verbose
	 - quiet
	 - debug
=> shortName:	raw
=> preferredByteFormat:	native
=> comment:	Writes raw audio samples to a file
=> name:	RAW sample output
=================================================
=> type:	file
=> priority:	0
=> options:
	 - matrix
	 - verbose
	 - quiet
	 - debug
=> shortName:	au
=> preferredByteFormat:	big
=> comment:	Sends output to a .au file
=> name:	AU file output
=================================================
=> Device ID: 0
=================================================
luajit: ao_live.lua:32: cannot open the device
stack traceback:
	[C]: in function 'openLive'
	ao_live.lua:32: in main chunk
	[C]: at 0x5564d7c0cf40

I've just installed a new debian, and I'm getting that
  lua: error loading module 'ao' from file '/usr/local/lib/lua/5.3/ao.so':
    /usr/local/lib/lua/5.3/ao.so: undefined symbol: ao_file_extension
error. This means that lots of people probably get it. Seeing that ao_file_extension only occurs in the l_file_extension routine, which is undocumented in lao and always has been, I'd like to suggest that we comment out that routine . . .

I'm trying to run examples/ao_live.lua which crashes with the message

lua: error loading module 'ao' from file '/usr/local/lib/lua/5.1/ao.so':
  Error relocating /usr/local/lib/lua/5.1/ao.so: ao_file_extension: symbol not found
stack traceback:
  [C]: ?
  [C]: in function 'require'
  examples/ao_live.lua:1: in main chunk
  [C]: ?

I'm using Alpine Linux with libao-1.2.0-r1. Any idea what could be wrong since the version is the most recent one (1.2)?

Greetings again; in lao.c, l_play(lua_State *L) tries to duplicate the samples::
char *buffer = strndup(samples, num_bytes);
but http://linux.die.net/man/3/strndup says:
The strndup() function is similar, but ONLY COPIES AT MOST n bytes.
If s is longer than n, only n bytes are copied, and a terminating null byte ('\0') is added.
and I found ao_example.lua just played random noise and garbage :-(

But if I play the samples directly:
int result = ao_play(dev, samples, num_bytes);
then gcc warns me that I'm discarding a const qualifier, but ao_example.lua plays me a nice sine wave :-)

It's hard to believe that this has ever worked; so if the user base is small, it might be OK to change the API from require("ao") to local ao = require("ao"), see previous issue...

Regards, Peter

l___gc (which is used to ao_shutdown) is never called.

Hi. I get:
/usr/local/lib/lua/5.2/ao.so: undefined symbol: luaL_register
which reminds me of a change I had to make in my midialsa.lua

if LUA_VERSION_NUM >= 502

luaL_setfuncs(L, prv, 0);    /* 5.2 */
return 0;

else

luaL_register(L, NULL, prv); /* 5.1 */
return 0;

endif

YMMV ...
Regards, Peter

To allow setting quiet=yes in time to stop the debug messages emitted by ao_initialize(),
I suggest we add a append_global_option(k,v) function, and delay calling ao_initialize() until the next function is called.

If that function is append_global_option then we call that first and ao_initialize second (assuming it works that way round), whereas if it's some other function like open() then we call ao_initialize first and the function second.

There was previously ineffective code (removed in a5a9b7b) trying to automatically call ao_shutdown if lao was unloaded.

This could be done by e.g. making this userdata an upvalue for all functions

	/* Create object with __gc metamethod so that ao gets shut down on exit */
	lua_newuserdata(L, 0);
	lua_createtable(L, 0, 1);
	lua_pushcfunction(L, l_shutdown);
	lua_setfield(L, -2, "__gc");
	lua_setmetatable(L, -2);