[Openal] choppy sound :(

[Carlo VOGELSANG]

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>                                               
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                                                                   Subject 
                                       Re: [Openal] choppy sound :(        
             07/28/2007 08:45                                              
             PM                                                            
                                                                           
                                                                           
                                                                           
                                                                           




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> 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"
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>
>                         *"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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