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openal-soft/OpenAL32/alFilter.c
Chris Robinson 48aa1e10d6 Use the high-shelf filter in place of low-pass 
They effectively both work to lower (or raise) high frequencies. However, the
high-shelf performs better when gain=1.
2013-05-28 10:57:38 -07:00

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/**
* OpenAL cross platform audio library
* Copyright (C) 1999-2007 by authors.
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
* Or go to http://www.gnu.org/copyleft/lgpl.html
*/
#include "config.h"
#include <stdlib.h>
#include "alMain.h"
#include "alu.h"
#include "alFilter.h"
#include "alThunk.h"
#include "alError.h"
static void InitFilterParams(ALfilter *filter, ALenum type);
AL_API ALvoid AL_APIENTRY alGenFilters(ALsizei n, ALuint *filters)
{
ALCcontext *Context;
ALsizei cur = 0;
Context = GetContextRef();
if(!Context) return;
al_try
{
ALCdevice *device = Context->Device;
ALenum err;
CHECK_VALUE(Context, n >= 0);
for(cur = 0;cur < n;cur++)
{
ALfilter *filter = calloc(1, sizeof(ALfilter));
if(!filter)
{
alDeleteFilters(cur, filters);
al_throwerr(Context, AL_OUT_OF_MEMORY);
}
InitFilterParams(filter, AL_FILTER_NULL);
err = NewThunkEntry(&filter->id);
if(err == AL_NO_ERROR)
err = InsertUIntMapEntry(&device->FilterMap, filter->id, filter);
if(err != AL_NO_ERROR)
{
FreeThunkEntry(filter->id);
memset(filter, 0, sizeof(ALfilter));
free(filter);
alDeleteFilters(cur, filters);
al_throwerr(Context, err);
}
filters[cur] = filter->id;
}
}
al_endtry;
ALCcontext_DecRef(Context);
}
AL_API ALvoid AL_APIENTRY alDeleteFilters(ALsizei n, const ALuint *filters)
{
ALCcontext *Context;
ALfilter *Filter;
ALsizei i;
Context = GetContextRef();
if(!Context) return;
al_try
{
ALCdevice *device = Context->Device;
CHECK_VALUE(Context, n >= 0);
for(i = 0;i < n;i++)
{
if(filters[i] && LookupFilter(device, filters[i]) == NULL)
al_throwerr(Context, AL_INVALID_NAME);
}
for(i = 0;i < n;i++)
{
if((Filter=RemoveFilter(device, filters[i])) == NULL)
continue;
FreeThunkEntry(Filter->id);
memset(Filter, 0, sizeof(*Filter));
free(Filter);
}
}
al_endtry;
ALCcontext_DecRef(Context);
}
AL_API ALboolean AL_APIENTRY alIsFilter(ALuint filter)
{
ALCcontext *Context;
ALboolean result;
Context = GetContextRef();
if(!Context) return AL_FALSE;
result = ((!filter || LookupFilter(Context->Device, filter)) ?
AL_TRUE : AL_FALSE);
ALCcontext_DecRef(Context);
return result;
}
AL_API ALvoid AL_APIENTRY alFilteri(ALuint filter, ALenum param, ALint value)
{
ALCcontext *Context;
ALCdevice *Device;
ALfilter *ALFilter;
Context = GetContextRef();
if(!Context) return;
Device = Context->Device;
if((ALFilter=LookupFilter(Device, filter)) == NULL)
alSetError(Context, AL_INVALID_NAME);
else
{
if(param == AL_FILTER_TYPE)
{
if(value == AL_FILTER_NULL || value == AL_FILTER_LOWPASS)
InitFilterParams(ALFilter, value);
else
alSetError(Context, AL_INVALID_VALUE);
}
else
{
/* Call the appropriate handler */
ALfilter_SetParami(ALFilter, Context, param, value);
}
}
ALCcontext_DecRef(Context);
}
AL_API ALvoid AL_APIENTRY alFilteriv(ALuint filter, ALenum param, const ALint *values)
{
ALCcontext *Context;
ALCdevice *Device;
ALfilter *ALFilter;
switch(param)
{
case AL_FILTER_TYPE:
alFilteri(filter, param, values[0]);
return;
}
Context = GetContextRef();
if(!Context) return;
Device = Context->Device;
if((ALFilter=LookupFilter(Device, filter)) == NULL)
alSetError(Context, AL_INVALID_NAME);
else
{
/* Call the appropriate handler */
ALfilter_SetParamiv(ALFilter, Context, param, values);
}
ALCcontext_DecRef(Context);
}
AL_API ALvoid AL_APIENTRY alFilterf(ALuint filter, ALenum param, ALfloat value)
{
ALCcontext *Context;
ALCdevice *Device;
ALfilter *ALFilter;
Context = GetContextRef();
if(!Context) return;
Device = Context->Device;
if((ALFilter=LookupFilter(Device, filter)) == NULL)
alSetError(Context, AL_INVALID_NAME);
else
{
/* Call the appropriate handler */
ALfilter_SetParamf(ALFilter, Context, param, value);
}
ALCcontext_DecRef(Context);
}
AL_API ALvoid AL_APIENTRY alFilterfv(ALuint filter, ALenum param, const ALfloat *values)
{
ALCcontext *Context;
ALCdevice *Device;
ALfilter *ALFilter;
Context = GetContextRef();
if(!Context) return;
Device = Context->Device;
if((ALFilter=LookupFilter(Device, filter)) == NULL)
alSetError(Context, AL_INVALID_NAME);
else
{
/* Call the appropriate handler */
ALfilter_SetParamfv(ALFilter, Context, param, values);
}
ALCcontext_DecRef(Context);
}
AL_API ALvoid AL_APIENTRY alGetFilteri(ALuint filter, ALenum param, ALint *value)
{
ALCcontext *Context;
ALCdevice *Device;
ALfilter *ALFilter;
Context = GetContextRef();
if(!Context) return;
Device = Context->Device;
if((ALFilter=LookupFilter(Device, filter)) == NULL)
alSetError(Context, AL_INVALID_NAME);
else
{
if(param == AL_FILTER_TYPE)
*value = ALFilter->type;
else
{
/* Call the appropriate handler */
ALfilter_GetParami(ALFilter, Context, param, value);
}
}
ALCcontext_DecRef(Context);
}
AL_API ALvoid AL_APIENTRY alGetFilteriv(ALuint filter, ALenum param, ALint *values)
{
ALCcontext *Context;
ALCdevice *Device;
ALfilter *ALFilter;
switch(param)
{
case AL_FILTER_TYPE:
alGetFilteri(filter, param, values);
return;
}
Context = GetContextRef();
if(!Context) return;
Device = Context->Device;
if((ALFilter=LookupFilter(Device, filter)) == NULL)
alSetError(Context, AL_INVALID_NAME);
else
{
/* Call the appropriate handler */
ALfilter_GetParamiv(ALFilter, Context, param, values);
}
ALCcontext_DecRef(Context);
}
AL_API ALvoid AL_APIENTRY alGetFilterf(ALuint filter, ALenum param, ALfloat *value)
{
ALCcontext *Context;
ALCdevice *Device;
ALfilter *ALFilter;
Context = GetContextRef();
if(!Context) return;
Device = Context->Device;
if((ALFilter=LookupFilter(Device, filter)) == NULL)
alSetError(Context, AL_INVALID_NAME);
else
{
/* Call the appropriate handler */
ALfilter_GetParamf(ALFilter, Context, param, value);
}
ALCcontext_DecRef(Context);
}
AL_API ALvoid AL_APIENTRY alGetFilterfv(ALuint filter, ALenum param, ALfloat *values)
{
ALCcontext *Context;
ALCdevice *Device;
ALfilter *ALFilter;
Context = GetContextRef();
if(!Context) return;
Device = Context->Device;
if((ALFilter=LookupFilter(Device, filter)) == NULL)
alSetError(Context, AL_INVALID_NAME);
else
{
/* Call the appropriate handler */
ALfilter_GetParamfv(ALFilter, Context, param, values);
}
ALCcontext_DecRef(Context);
}
void ALfilterState_clear(ALfilterState *filter)
{
filter->x[0] = 0.0f;
filter->x[1] = 0.0f;
filter->y[0] = 0.0f;
filter->y[1] = 0.0f;
}
void ALfilterState_setParams(ALfilterState *filter, ALfilterType type, ALfloat gain, ALfloat freq_scale, ALfloat bandwidth)
{
ALfloat alpha;
ALfloat w0;
w0 = 2.0f*F_PI * freq_scale;
/* Calculate filter coefficients depending on filter type */
switch(type)
{
case ALfilterType_HighShelf:
alpha = sinf(w0) / 2.0f * sqrtf((gain + 1.0f/gain) *
(1.0f/0.75f - 1.0f) + 2.0f);
filter->b[0] = gain * ((gain + 1.0f) +
(gain - 1.0f) * cosf(w0) +
2.0f * sqrtf(gain) * alpha);
filter->b[1] = -2.0f * gain * ((gain - 1.0f) +
(gain + 1.0f) * cosf(w0));
filter->b[2] = gain * ((gain + 1.0f) +
(gain - 1.0f) * cosf(w0) -
2.0f * sqrtf(gain) * alpha);
filter->a[0] = (gain + 1.0f) -
(gain - 1.0f) * cosf(w0) +
2.0f * sqrtf(gain) * alpha;
filter->a[1] = 2.0f * ((gain - 1.0f) -
(gain + 1.0f) * cosf(w0));
filter->a[2] = (gain + 1.0f) -
(gain - 1.0f) * cosf(w0) -
2.0f * sqrtf(gain) * alpha;
break;
case ALfilterType_LowShelf:
alpha = sinf(w0) / 2.0f * sqrtf((gain + 1.0f / gain) *
(1.0f / 0.75f - 1.0f) + 2.0f);
filter->b[0] = gain * ((gain + 1.0f) -
(gain - 1.0f) * cosf(w0) +
2.0f * sqrtf(gain) * alpha);
filter->b[1] = 2.0f * gain * ((gain - 1.0f) -
(gain + 1.0f) * cosf(w0));
filter->b[2] = gain * ((gain + 1.0f) -
(gain - 1.0f) * cosf(w0) -
2.0f * sqrtf(gain) * alpha);
filter->a[0] = (gain + 1.0f) +
(gain - 1.0f) * cosf(w0) +
2.0f * sqrtf(gain) * alpha;
filter->a[1] = -2.0f * ((gain - 1.0f) +
(gain + 1.0f) * cosf(w0));
filter->a[2] = (gain + 1.0f) +
(gain - 1.0f) * cosf(w0) -
2.0f * sqrtf(gain) * alpha;
break;
case ALfilterType_Peaking:
alpha = sinf(w0) * sinhf(logf(2.0f) / 2.0f * bandwidth * w0 / sinf(w0));
filter->b[0] = 1.0f + alpha * gain;
filter->b[1] = -2.0f * cosf(w0);
filter->b[2] = 1.0f - alpha * gain;
filter->a[0] = 1.0f + alpha / gain;
filter->a[1] = -2.0f * cosf(w0);
filter->a[2] = 1.0f - alpha / gain;
break;
}
filter->b[2] /= filter->a[0];
filter->b[1] /= filter->a[0];
filter->b[0] /= filter->a[0];
filter->a[2] /= filter->a[0];
filter->a[1] /= filter->a[0];
filter->a[0] /= filter->a[0];
}
ALfloat lpCoeffCalc(ALfloat g, ALfloat cw)
{
ALfloat a = 0.0f;
if(g < 0.9999f) /* 1-epsilon */
{
/* Be careful with gains < 0.001, as that causes the coefficient head
* towards 1, which will flatten the signal */
g = maxf(g, 0.001f);
a = (1 - g*cw - sqrtf(2*g*(1-cw) - g*g*(1 - cw*cw))) /
(1 - g);
}
return a;
}
static void lp_SetParami(ALfilter *filter, ALCcontext *context, ALenum param, ALint val)
{ SET_ERROR_AND_RETURN(context, AL_INVALID_ENUM); (void)filter;(void)param;(void)val; }
static void lp_SetParamiv(ALfilter *filter, ALCcontext *context, ALenum param, const ALint *vals)
{ SET_ERROR_AND_RETURN(context, AL_INVALID_ENUM); (void)filter;(void)param;(void)vals; }
static void lp_SetParamf(ALfilter *filter, ALCcontext *context, ALenum param, ALfloat val)
{
switch(param)
{
case AL_LOWPASS_GAIN:
if(!(val >= AL_LOWPASS_MIN_GAIN && val <= AL_LOWPASS_MAX_GAIN))
SET_ERROR_AND_RETURN(context, AL_INVALID_VALUE);
filter->Gain = val;
break;
case AL_LOWPASS_GAINHF:
if(!(val >= AL_LOWPASS_MIN_GAINHF && val <= AL_LOWPASS_MAX_GAINHF))
SET_ERROR_AND_RETURN(context, AL_INVALID_VALUE);
filter->GainHF = val;
break;
default:
SET_ERROR_AND_RETURN(context, AL_INVALID_ENUM);
}
}
static void lp_SetParamfv(ALfilter *filter, ALCcontext *context, ALenum param, const ALfloat *vals)
{
lp_SetParamf(filter, context, param, vals[0]);
}
static void lp_GetParami(ALfilter *filter, ALCcontext *context, ALenum param, ALint *val)
{ SET_ERROR_AND_RETURN(context, AL_INVALID_ENUM); (void)filter;(void)param;(void)val; }
static void lp_GetParamiv(ALfilter *filter, ALCcontext *context, ALenum param, ALint *vals)
{ SET_ERROR_AND_RETURN(context, AL_INVALID_ENUM); (void)filter;(void)param;(void)vals; }
static void lp_GetParamf(ALfilter *filter, ALCcontext *context, ALenum param, ALfloat *val)
{
switch(param)
{
case AL_LOWPASS_GAIN:
*val = filter->Gain;
break;
case AL_LOWPASS_GAINHF:
*val = filter->GainHF;
break;
default:
SET_ERROR_AND_RETURN(context, AL_INVALID_ENUM);
}
}
static void lp_GetParamfv(ALfilter *filter, ALCcontext *context, ALenum param, ALfloat *vals)
{
lp_GetParamf(filter, context, param, vals);
}
static void null_SetParami(ALfilter *filter, ALCcontext *context, ALenum param, ALint val)
{ SET_ERROR_AND_RETURN(context, AL_INVALID_ENUM); (void)filter;(void)param;(void)val; }
static void null_SetParamiv(ALfilter *filter, ALCcontext *context, ALenum param, const ALint *vals)
{ SET_ERROR_AND_RETURN(context, AL_INVALID_ENUM); (void)filter;(void)param;(void)vals; }
static void null_SetParamf(ALfilter *filter, ALCcontext *context, ALenum param, ALfloat val)
{ SET_ERROR_AND_RETURN(context, AL_INVALID_ENUM); (void)filter;(void)param;(void)val; }
static void null_SetParamfv(ALfilter *filter, ALCcontext *context, ALenum param, const ALfloat *vals)
{ SET_ERROR_AND_RETURN(context, AL_INVALID_ENUM); (void)filter;(void)param;(void)vals; }
static void null_GetParami(ALfilter *filter, ALCcontext *context, ALenum param, ALint *val)
{ SET_ERROR_AND_RETURN(context, AL_INVALID_ENUM); (void)filter;(void)param;(void)val; }
static void null_GetParamiv(ALfilter *filter, ALCcontext *context, ALenum param, ALint *vals)
{ SET_ERROR_AND_RETURN(context, AL_INVALID_ENUM); (void)filter;(void)param;(void)vals; }
static void null_GetParamf(ALfilter *filter, ALCcontext *context, ALenum param, ALfloat *val)
{ SET_ERROR_AND_RETURN(context, AL_INVALID_ENUM); (void)filter;(void)param;(void)val; }
static void null_GetParamfv(ALfilter *filter, ALCcontext *context, ALenum param, ALfloat *vals)
{ SET_ERROR_AND_RETURN(context, AL_INVALID_ENUM); (void)filter;(void)param;(void)vals; }
ALvoid ReleaseALFilters(ALCdevice *device)
{
ALsizei i;
for(i = 0;i < device->FilterMap.size;i++)
{
ALfilter *temp = device->FilterMap.array[i].value;
device->FilterMap.array[i].value = NULL;
// Release filter structure
FreeThunkEntry(temp->id);
memset(temp, 0, sizeof(ALfilter));
free(temp);
}
}
static void InitFilterParams(ALfilter *filter, ALenum type)
{
if(type == AL_FILTER_LOWPASS)
{
filter->Gain = AL_LOWPASS_DEFAULT_GAIN;
filter->GainHF = AL_LOWPASS_DEFAULT_GAINHF;
filter->SetParami = lp_SetParami;
filter->SetParamiv = lp_SetParamiv;
filter->SetParamf = lp_SetParamf;
filter->SetParamfv = lp_SetParamfv;
filter->GetParami = lp_GetParami;
filter->GetParamiv = lp_GetParamiv;
filter->GetParamf = lp_GetParamf;
filter->GetParamfv = lp_GetParamfv;
}
else
{
filter->SetParami = null_SetParami;
filter->SetParamiv = null_SetParamiv;
filter->SetParamf = null_SetParamf;
filter->SetParamfv = null_SetParamfv;
filter->GetParami = null_GetParami;
filter->GetParamiv = null_GetParamiv;
filter->GetParamf = null_GetParamf;
filter->GetParamfv = null_GetParamfv;
}
filter->type = type;
}
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