[Bf-committers] Experiences with the engine and sound on linux

[Kester Maddock]

Hi,

Most OpenAL docs are at www.openal.org, and creative labs & nvidia have sdks 
for it.

The advantage of OpenAL is that it provides cross platform hardware 
acceleration of 3d mixing.  Only nvidia & creative labs hardware afaik 
supports this.

UT2k3 also uses OpenAL so it can't be that broken.

Apart from that, SDL is the way to go. :-)

Separate out the file format bits, so that it's easy to add support for eg Ogg 
Vorbis, and open/close /dev/dsp with the main blender.  That used to confuse 
OpenAL a lot.  On Linux, it might be nice to release /dev/dsp so that other 
applications can use the sound card when blender is not using it.

Split off the CD audio driver would be a good idea as well.

Good luck!

Kester

On Friday 24 December 2004 01:16, Alexander Ewering wrote:
> On Thu, 23 Dec 2004, Ton Roosendaal wrote:
> > Hi,
> >
> > I think a lot of people, including me, will agree on this. :)
> >
> > Kent Mein mentioned (on irc) a while ago he liked to look into this for a
> > next release, fixing up the Soundsystem module to have it run without
> > openAL (optional or default). This is very welcome work for a developer
> > to do, we really need to cleanup the two mixed audio systems in Blender.
>
> Yes. And I like SDL, too. It's much cleaner, not that bloated, it
> actually works, has nice documentation, AND I have experience with it ;)
>
> > From my humble ignorant perspective, a recode can just do this;
> >
> > - kick out openAL completely and only use SDL; but first check if there's
> > issues with supported audio formats
> > - remove all weird dependencies with audio we have in blender/src and
> > blender/blenkernel. There's highly confusing code that mixes up loading
> > sound (.wav) files with initializing the audio system. Initializing sound
> > should not be related to loading files.
> > - make sure audio is only initialized and closed once, and can be omitted
> > with "-noaudio" commandline option.
> > - code a simple SDL version for the "listener" to fade out sound on
> > certain distances
>
> I completely agree.
>
> Considering the supported audio formats.. I haven't looked into that ever,
> because I hardly use anything else than simple raw WAVs... but for game
> development, I agree it should be possible to include at least MP3s for
> size's sake.
>
> The SDL version of the listener would look like this:
>
> The same loop (or a copy of it) that currently gets run while in ALT-A
> would be running in the game engine, keeping the mixing buffer filled.
>
> Then, simple panning (based on direction of sound actuators relative to
> the listener) and attenuation (based on the "loudness" value of an
> object and the distance) could be done. The code for this is already
> there and used for the sequencer.
>
> Basically, the "loudness" of a sound decides how quickly it attenuates
> with distance. The louder the sound, the less it attenuates.
>
> One thing that someone else would have to do/prepare for this is inclusion
> of SDL and the mixing loop inside the game engine and exported runtimes.
>
> If I should be able to do anything for this, it would of course have to
> be in C :)
>
> > -Ton-
> >
> > On 23 Dec, 2004, at 12:30, Alexander Ewering wrote:
> >> Hello,
> >>
> >> I've recently tried to get sound working in the game engine on linux
> >> (from a user perspective), and it was a total failure.
> >>
> >> The only occasion when I could get sound to be heard AT ALL was when
> >> I set it to one of the Looping modes, non-looped sounds just don't
> >> work. This is the same behaviour as in 2.25, btw (it got introduced
> >> in 2.25, too).
> >>
> >> I thought I had seen a commit that fixed this, but appearently I've
> >> been wrong.
> >>
> >> Even then, the looped sound (which is unusable because it's an
> >> event sound) came with about half a second latency. I guess that
> >> can be fixed with a smaller mixing buffer size, though.
> >>
> >> On the whole, I would like to say the following about OpenAL:
> >>
> >> In my opinion, it's a library of questionable quality. It has terrible
> >> docs (try
> >> to google for any of the functions, you won't find a lot of useful
> >> hits), there is no command reference anywhere (anywhere = what I
> >> could find in 5 minutes (5 minutes is a lot for me)), the packages
> >> that come with various distributions are unstable or strangely
> >> linked.
> >>
> >> On the whole, wouldn't it be an option to move to SDL and SDL_mixer?
> >>
> >> I'm not sure if we can get all the funky spacial doppler effects
> >> then, but at least we can get it *basically* working :) For me,
> >> directional panning and attenuation with an adjustable rolloff
> >> factor would be far enough. And that's even possible without SDL_mixer
> >> by simple reusage of, for example, the sequencer audio code...
> >>
> >> Of course, I wouldn't know how to deal with all this if it should
> >> work in exported runtimes, etc., nor in the plugin...
> >>
> >> Well, maybe some people can give opinions or flame me :)
> >>
> >> Oh, and is it possible to switch to the old (pre-2.25) audio system? (I
> >> think it was FMOD)
> >>
> >> | alexander ewering              instinctive mediaworks
> >> | ae[@]instinctive[.]de   http://www[.]instinctive[.]de
> >>
> >> _______________________________________________
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> >> http://projects.blender.org/mailman/listinfo/bf-committers
> >
> > -------------------------------------------------------------------------
> >- Ton Roosendaal  Blender Foundation ton at blender.org
> > http://www.blender.org
> >
> > _______________________________________________
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> > http://projects.blender.org/mailman/listinfo/bf-committers
> >
> | alexander ewering              instinctive mediaworks
> | ae[@]instinctive[.]de   http://www[.]instinctive[.]de
>
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