Re: Adding filters

by Daniel PEACOCK :: Rate this Message:

Hi Robert,

I just built an application using this code and the filter is working
correctly for me (the sound becomes filtered and much quieter).

In the initialization code ...

DeviceName=alcGetString(0,ALC_DEFAULT_DEVICE_SPECIFIER);

//ALC_DEFAULT_ALL_DEVICES_SPECIFIER this was here in henrys code

printf("\n\nDevice is %s\n",DeviceName);

That code will display the name of the *default* device on the system -
which should be the one you opened - but I think the purpose of the log is
to display the device that is being used. In which case you need to use
the following ...

DeviceName=alcGetString(Device,ALC_DEVICE_SPECIFIER);

printf("\n\nDevice Used is %s\n",DeviceName);

i.e. pass in the device handle and use the ALC_DEVICE_SPECIFIER enum.

What device name is returned? What versions of the openal32.dll and
wrap_oal.dll files do you have?

Thanks,

Dan
Creative Labs (UK) Ltd.

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Robert Smyth
<macgabhr@...>
Sent by: To
openal-bounces@op openal@...
ensource.creative cc
.com
Subject
[Openal] Adding filters
05/26/2009 10:43
AM

Hi,

I am trying to add filters to a raw source using openal. THe code I am
using can be seen below. I have read the sdk ext manual and seem to be
doing everything correctly. The program compiles and I get a correct sound
device to be found and no erros when creating my filter but instead of
playing the filtered source it just repeats what has already been played,
i.e the filter doesnt seem to work. I am using microsoft visual studio 9.0
on a dell precision through windows.

// Basic.cpp : Defines the entry point for the console application.

//

// Basic

// Just makes a basic sound for a few seconds then applies a low pass
filter

// Then some effects

#include

<alut.h>

#include

<efx.h>

#include

<conio.h>

#include

<stdlib.h>

#include

<stdio.h>

#include

<al.h>

#include

<alc.h>

#include

<EFX-Util.h>

#include

<efx-creative.h>

#define

NULL 0

LPALGENFILTERS alGenFilters;

LPALFILTERI alFilteri;

LPALFILTERF alFilterf;

LPALGENEFFECTS alGenEffects;

LPALEFFECTI alEffecti;

LPALEFFECTF alEffectf;

LPALGENAUXILIARYEFFECTSLOTS alGenAuxiliaryEffectSlots;

LPALAUXILIARYEFFECTSLOTI alAuxiliaryEffectSloti;

LPALISFILTER alIsFilter;

int

main(int argc, char **argv)

{

ALuint helloBuffer, source;

ALuint filter,filtera;

ALuint EffectSlot,ReverbEffect;

ALCcontext *Context;

ALCdevice *Device;

ALCint iSends;

const

ALCchar *DeviceName;

// Setting up openal

alutInit (&argc, argv);

Context=alcGetCurrentContext();

Device=alcGetContextsDevice(Context);

DeviceName=alcGetString(0,ALC_DEFAULT_DEVICE_SPECIFIER);

//ALC_DEFAULT_ALL_DEVICES_SPECIFIER this was here in henrys code

printf(

"\n\nDevice is %s\n",DeviceName);

// And effects definitions

alGenFilters = (LPALGENFILTERS)alGetProcAddress(

"alGenFilters");

alFilteri=(LPALFILTERI)alGetProcAddress(

"alFilteri");

alFilterf=(LPALFILTERF)alGetProcAddress(

"alFilterf");

alGenEffects=(LPALGENEFFECTS)alGetProcAddress(

"alGenEffects");

alEffecti=(LPALEFFECTI)alGetProcAddress(

"alEffecti");

alEffectf=(LPALEFFECTF)alGetProcAddress(

"alEffectf");

alGenAuxiliaryEffectSlots=(LPALGENAUXILIARYEFFECTSLOTS)alGetProcAddress(

"alGenAuxiliaryEffectSlots");

alAuxiliaryEffectSloti=(LPALAUXILIARYEFFECTSLOTI)alGetProcAddress(

"alAuxiliaryEffectSloti");

alIsFilter= (LPALISFILTER)alGetProcAddress(

"alIsFilter");

// Setup Buffer from input file or helloworld

if(argc==2)

helloBuffer= alutCreateBufferFromFile(argv[1]);

else

helloBuffer = alutCreateBufferHelloWorld ();

// Generate Source and attach buffer

alGenSources(1,&source);

alSourcei(source,AL_BUFFER,helloBuffer);

// Set up some soruce parameters

alSourcei(source, AL_LOOPING, AL_TRUE);

printf(

"\nRaw Source\n");

alSourcePlay (source);

alutSleep(3);

alSourceStop(source);

// Now with a filter

alGetError();

alGenFilters(1,&filter);

if

(alGetError() == AL_NO_ERROR)

printf(

"Generated Filter %i\n",filter);

alFilteri(filter,AL_FILTER_TYPE,AL_FILTER_LOWPASS);

if

(alGetError() != AL_NO_ERROR)

printf(

"Low Pass Filter not supported\n");

else

{

alFilterf(filter,AL_LOWPASS_GAIN,0.5);

alFilterf(filter,AL_LOWPASS_GAINHF,0.01);

}

alSourcei(source,AL_DIRECT_FILTER,filter);

if

(alGetError() == AL_NO_ERROR)

{

printf(

"\nFiltered Source\n");

}

alSourcePlay (source);

alutSleep(3);

alSourceStop(source);

--
Robert Smyth_______________________________________________
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