No sound

[haloboydeath]

I got the sound to work just by changing a few options... but I had to reinstall ubuntu... and it no longer has sound...

[Froste]

But shouldn't openal just redirect the sound to whatever output you've chosen, why would it do its own software mixing? Does the current (the regular/old/SI) openal avoid doing software mixing? And what does it mean by deprecating vorbis extensions?

[Mikan]

Originally Posted by Froste

But shouldn't openal just redirect the sound to whatever output you've chosen, why would it do its own software mixing? Does the current (the regular/old/SI) openal avoid doing software mixing? And what does it mean by deprecating vorbis extensions?

Most sound cards, especially those embedded in motherboards, do not have 3D audio.

When you play sound with OpenAL from a 3D game, the game doesn't actually perform any operations such as spatialization. It simply says "the listener is at X,Y,Z and the sound source is at X,Y,Z" and relies on OpenAL to not only transform that into a 2-dimensional space, but also to localize it depending on the user's speaker setup. For example, on stereo speakers, the sound can only come from the left or the right, but on surround sound speakers, it can come from any number of directions.

Applications that are written to use OpenAL know absolutely nothing about this, and most sound cards don't support it either. In fact, most sound cards these days don't even support multiple applications (basically only accepting 1 sound stream at any given time), and require a software mixer to perform the work even for normal desktop use. Such a mixer is usually implemented in the drivers on Windows, or ALSA or alternate sound systems such as aRts or ESD on Linux.

The only sound cards which tend to have OpenAL accelerated in hardware are those which use chipsets which have largely manufactured by Creative, and with the regression of the Sound Blaster as a staple in computers over the last decade, they tend to be few and far between.

DirectX's DirectSound3D has been widely supported in hardware up until a few years ago, but even that is going to fade out completely, as Vista dropped support for hardware-accelerated DirectSound3D, meaning manufacturers no longer have any reason to include 3D audio in sound cards whatsoever.

So these days the only way to get reliable 3D audio support without implementing it directly in the application (which is the approach games like Half Life 2 have taken), is to use a library such as OpenAL, and an implementation that falls back upon software mixing whenever a hardware interface is not available (which will be in most cases), or alternatively, due to the low prevailance of 3D audio support in sound cards, just use software mixing all of the time and avoid the extra maintenance overhead.

Regards,

[Froste]

But that's what I don't get, artsd, esd, dmix jack and now pulse are the software mixers in linux, does openal incorporate its own software mixer before that? Or is it only the new openal-soft that does this?

As you prolly know I've got an sblive which does its own hardware mixing, and I'd rather use the option that offloads as much as it can onto the hardware so I don't have to use cpu resources for handling the sound mixing, would openal-soft interfere with this and still insist on doing software mixing?

[Mikan]

Originally Posted by Froste

But that's what I don't get, artsd, esd, dmix jack and now pulse are the software mixers in linux, does openal incorporate its own software mixer before that? Or is it only the new openal-soft that does this?

As you prolly know I've got an sblive which does its own hardware mixing, and I'd rather use the option that offloads as much as it can onto the hardware so I don't have to use cpu resources for handling the sound mixing, would openal-soft interfere with this and still insist on doing software mixing?

Sound servers on Linux are only for 2D audio, to handle the problem of multiple applications needing to play sound simultaneously. This is normally handled directly in the drivers on Windows, giving a sort of transparency (but it's still very much there).

OpenAL has to account for alot more than just sending sound to one or two speakers or more, it has to account for real-world effects like the speed of sound, occluding objects between the listener and the source, and the doppler effect. That's why you need OpenAL to compliment to OpenGL.

As for the mixing problem, the truth is OpenAL has never been accelerated on Linux. That is why the original goals of OpenAL Soft were to port the Windows version and make it accelerated under ALSA, so that it would use your existing 3D sound hardware (such as an SB Live). For whatever reasons, this proved to be impossible, and the author changed goals.

So unless you use Windows, you've never had and never will have 3D sound acceleration, and the only features being used from your sound card are it's 2D output capabilities, possibly with surround sound support (which is still 2D, as you can't have speakers below or above you).

And even on Windows, you only have it if you're using Windows XP or older.

Regards,

[Panda_Bear]

i got my sound on linux running by doing the openalrc override stuff works a treat