So, here's what I'm trying to do right now, and probably nobody knows the answer but here goes. What I'm trying to set up is an entity that emits a constant sound, but is also toggleable. So when you turn it off, the sound goes silent, and when you turn it on, the sound starts up again.

Problem 1: if you are out of hearing range when it turns on, the object will be silent when you get close.

Problem 2: if you save and reload the savegame, the object will be silent.

The basic cause is that sound() calls are fire-and-forget and quake assumes the sounds are short-lived so the above situations won't be much of a problem.

I've tried various solutions, the latest is various versions of "restart the sound every 1 second or so." The problems with that are first, when you approach the object its sound starts up suddenly instead of fading in, and second, you can hear obvious repetition when standing next to the object.

Increasing the frequency of sound() calls reduces the sudden start, but worsens the repetition. I'm going to try and improve this hack by having 3 or four different sounds, and playing them at random, so that you don't hear any obvious repetition of sounds. 

it is possible, but it's slightly hacky.

unfortunaly, i don't remember who told me about this method... it may have been lordhavoc, but i'm not sure.

anyway, the engine can only load ambient sounds (true ambient sounds that the engine keeps track of regardless of player position) properly when the map is loading up.

you can trick it by using an unused SVC (29). unfortunatly, you can't specify a filename for this, you need to actually feed in the # of the sound in the order as it was loaded into cache. �_�

the best way to do this is to precache your ambient sounds first, this way you don't have to worry about anything being precached before it and mucking up your ambient sounds.

the first sound precaches are located in weapons.qc (W_Precache). load any new ambient sounds in there at the top of the function.


float SVC_SPAWNSTATICSOUND = 29;

Define the constant for convenience, and write a little function to use it:
void(float soundnum, vector org, float ambvolume, float atten) spawnambient =
{
WriteByte(MSG_ALL, SVC_SPAWNSTATICSOUND);
WriteCoord(MSG_ALL, org_x);
WriteCoord(MSG_ALL, org_y);
WriteCoord(MSG_ALL, org_z);
WriteByte(MSG_ALL, soundnum);
WriteByte(MSG_ALL, ambvolume * 255); //translate this into a value between 0 and 255...
WriteByte(MSG_ALL, atten * 64);
};

now just call your new function with whatever sound # you want.

this will spawn a true ambient sound into the map after it was loaded, and won't stop playing when you move out of range.

you'll notice the lack of any channel specification... i'm not sure if it's possible to turn it off again after it's been turned on. i can't check right now, but i'd guess using a non-looping sound will give you that 'non-looping sound for ambient sound' error, since it's not just a normal sound call.
but you will at least be able to turn it on. :x

maybe someone else can build on this? 

Interesting, it would only work if the it could be turned off again somehow. Hmm....