[Openal] choppy sound :(

M. Kalthoff m.kalt at web.de
Tue Jul 31 11:49:14 PDT 2007


Hi again,

yeah, Carlo, i guess you are right there.
when counting the steps over time(in a wave editor of course ;)
one can clearly estimate about ~40 steps per second, which leads
to an update interval of ~25msecs.

i'll test it on a machine with a better soundcard soon. but for
now i'll just think that that is the cause.

thanks.

matze




Carlo VOGELSANG schrieb:
> Hi Matze;
> 
> This is probably caused because the Generic Software device (i.e. the 
> software mixer) does not ramp volumes between the beginning
> and end of each mixing block. (i.e. the volume levels used for each 
> speaker are constant for the whole block, even when the application
> calls setposition frequently).
> 
> If the changes are too big between mixing blocks, you can get artifacts. 
> A rapid moving sound (position changes close to the listener) can cause
> artifacts. Even though you might be updating pretty quickly, it's the 
> size of the mixing blocks that determine the 'real' update rate (in this 
> case 25msec)
> 
> -Carlo
> 
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> 
>                         *"M. Kalthoff" <m.kalt at web.de>*
>                         Sent by: openal-bounces at opensource.creative.com
> 
>                         07/28/2007 08:45 PM
> 
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> Re: [Openal] choppy sound :(
> 
> 	
> 
> 
> Hi,
> 
> Sadly, installing the new OpenAL run-times didn't solve the problem.
> 
> Maybe you get a better idea if you listen to a short sample i recorded
> [~84kB]
> 
> http://www.hotlinkfiles.com/files/161131_cmfmy/artifacts.mp3
> 
> You can hear there a rotating sine wave sample with outerCone = 60° and
> innerCone = 40°, while listener and source aren't moving.
> 
> The artifacts are noticeable especially during the interpolation between
> inner and outer cone. Even at update rates >100 times/second(but it
> gets less intense/often).
> 
> Same occurs with "fast" moving sources or listeners.
> 
> If anyone has an idea, let me know.
> 
> Thx,
> 
> matze
> 
> 
> 
> Daniel PEACOCK schrieb:
>  > Hi,
>  >
>  > Can you please try installing the new OpenAL run-times available from
>  > http://developer.creative.com/landing.asp?cat=1&sbcat=31&top=38 
> <http://developer.creative.com/landing.asp?cat=1&sbcat=31&top=38> 
>  > <http://developer.creative.com/landing.asp?cat=1&sbcat=31&top=38 
> <http://developer.creative.com/landing.asp?cat=1&sbcat=31&top=38>> and
>  > seeing if this improves the situation?
>  >
>  > Thanks,
>  >
>  > Dan
>  > Creative Labs, Inc.
>  >
>  > ------------------------------------------------------------------------
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>  > Inactive hide details for "M. Kalthoff" <m.kalt at web.de>"M. Kalthoff"
>  > <m.kalt at web.de>
>  >
>  >
>  >                         *"M. Kalthoff" <m.kalt at web.de>*
>  >                         Sent by: openal-bounces at opensource.creative.com
>  >
>  >                         07/17/2007 05:14 AM
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>  > Subject
>  >
>  > [Openal] choppy sound :(
>  >
>  >
>  >
>  >
>  > oooops,
>  > i forgot to change the mails-subject.
>  > sorry.
>  > and sorry for this mail, explaining the obvious.
>  >
>  > matze
>  >
>  >
>  >
>  > M. Kalthoff schrieb:
>  >  > Hi everyone,
>  >  >
>  >  > i've got a little problem, and hope someone can help.
>  >  > the sound is kind of chopped if i quickly move the listener or source.
>  >  > i'm updating as suggested in the effects extension guide.pdf[p. 45]
>  >  > at approximately 30 times per second.
>  >  > (the problem is the same but a little less noticeable if i remove the
>  >  > brake and update at >100 times per second)
>  >  >
>  >  > current hardware setup is:
>  >  >     Pentium 4 2,4GHz
>  >  >     512MB
>  >  >
>  >  >     [0] "Generic Software" (default)
>  >  >         Effect Extension Supported: YES
>  >  >         Supported Specification Version: 1.1
>  >  >    
>  >  >         Max Sources: 256
>  >  >         Max Effect Slots: 128
>  >  >         Max Aux Effect Slots: 1
>  >  >         Max Aux Effect Slot Sends: 1
>  >  >         [...]
>  >  >
>  >  >
>  >  > current test-scene setup is:
>  >  >     - 1 sound source (a looping sine wave sample)
>  >  >       at [0, 0, 0]
>  >  >       slowly rotating (10s per 360°)
>  >  >       inner cone = 45°
>  >  >       outer cone = 180°
>  >  >
>  >  > everything sounds fine, is directional and calculated correctly,
>  >  > i guess.
>  >  > if i now quickly move the listener(which is attached to the camera),
>  >  > the sound gets choppy as if i wouldn't update the listeners position
>  >  > as often as needed.
>  >  >
>  >  > would be nice if someone could give me a hint for fixing this.
>  >  > thanks.
>  >  >
>  >  > m. kalthoff
>  >
>  >
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