AerialX/openal-soft-android
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Apply the dry filter to multi-channel sources

Browse Source 
Unlike mono sources, they use 2 chained one-pole filters instead of 4
This commit is contained in:
Chris Robinson 2008-12-10 11:54:13 -08:00
parent ed03570e1a
commit 3056f91ec5
2 changed files with 50 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

63
Alc/ALu.c
View File

@ -178,6 +178,20 @@ static __inline ALfloat lpFilter(FILTER *iir, ALfloat input)
return output;
}
static __inline ALfloat lpFilterMC(FILTER *iir, ALuint chan, ALfloat input)
{
ALfloat *history = &iir->history[chan*2];
ALfloat a = iir->coeff;
ALfloat output = input;
output = output + (history[0]-output)*a;
history[0] = output;
output = output + (history[1]-output)*a;
history[1] = output;
return output;
}
static __inline ALshort aluF2S(ALfloat Value)
{
@ -594,16 +608,33 @@ static ALvoid CalcSourceParams(ALCcontext *ALContext, ALsource *ALSource,
//1. Multi-channel buffers always play "normal"
pitch[0] = ALSource->flPitch;
drysend[FRONT_LEFT] = SourceVolume * ListenerGain;
drysend[FRONT_RIGHT] = SourceVolume * ListenerGain;
drysend[SIDE_LEFT] = SourceVolume * ListenerGain;
drysend[SIDE_RIGHT] = SourceVolume * ListenerGain;
drysend[BACK_LEFT] = SourceVolume * ListenerGain;
drysend[BACK_RIGHT] = SourceVolume * ListenerGain;
drysend[CENTER] = SourceVolume * ListenerGain;
drysend[LFE] = SourceVolume * ListenerGain;
DryMix = SourceVolume;
switch(ALSource->DirectFilter.type)
{
case AL_FILTER_LOWPASS:
DryMix *= ALSource->DirectFilter.Gain;
DryGainHF *= ALSource->DirectFilter.GainHF;
break;
}
drysend[FRONT_LEFT] = DryMix * ListenerGain;
drysend[FRONT_RIGHT] = DryMix * ListenerGain;
drysend[SIDE_LEFT] = DryMix * ListenerGain;
drysend[SIDE_RIGHT] = DryMix * ListenerGain;
drysend[BACK_LEFT] = DryMix * ListenerGain;
drysend[BACK_RIGHT] = DryMix * ListenerGain;
drysend[CENTER] = DryMix * ListenerGain;
drysend[LFE] = DryMix * ListenerGain;
*wetsend = 0.0f;
WetGainHF = 1.0f;
cw = cos(2.0f*3.141592654f * LOWPASSFREQCUTOFF / ALContext->Frequency);
g = __max(DryGainHF, 0.01f);
a = 0.0f;
if(g < 0.9999f) // 1-epsilon
a = (1 - g*cw - aluSqrt(2*g*(1-cw) - g*g*(1 - cw*cw))) / (1 - g);
ALSource->iirFilter.coeff = a;
ALSource->Send[0].iirFilter.coeff = 0.0f;
*drygainhf = DryGainHF;
*wetgainhf = WetGainHF;
@ -825,9 +856,11 @@ ALvoid aluMixData(ALCcontext *ALContext,ALvoid *buffer,ALsizei size,ALenum forma
ALfloat samp1, samp2;
//First order interpolator (front left)
samp1 = lerp(Data[k*Channels], Data[(k+1)*Channels], DataPosFrac);
samp1 = lpFilterMC(DryFilter, FRONT_LEFT, samp1);
DryBuffer[j][FRONT_LEFT] += samp1*DrySend[FRONT_LEFT];
//First order interpolator (front right)
samp2 = lerp(Data[k*Channels+1], Data[(k+1)*Channels+1], DataPosFrac);
samp2 = lpFilterMC(DryFilter, FRONT_RIGHT, samp2);
DryBuffer[j][FRONT_RIGHT] += samp2*DrySend[FRONT_RIGHT];
if(Channels >= 4)
{
@ -838,31 +871,31 @@ ALvoid aluMixData(ALCcontext *ALContext,ALvoid *buffer,ALsizei size,ALenum forma
{
//First order interpolator (center)
value = lerp(Data[k*Channels+i], Data[(k+1)*Channels+i], DataPosFrac);
DryBuffer[j][CENTER] += value*DrySend[CENTER];
DryBuffer[j][CENTER] += lpFilterMC(DryFilter, CENTER, value)*DrySend[CENTER];
i++;
}
//First order interpolator (lfe)
value = lerp(Data[k*Channels+i], Data[(k+1)*Channels+i], DataPosFrac);
DryBuffer[j][LFE] += value*DrySend[LFE];
DryBuffer[j][LFE] += lpFilterMC(DryFilter, LFE, value)*DrySend[LFE];
i++;
}
//First order interpolator (back left)
value = lerp(Data[k*Channels+i], Data[(k+1)*Channels+i], DataPosFrac);
DryBuffer[j][BACK_LEFT] += value*DrySend[BACK_LEFT];
DryBuffer[j][BACK_LEFT] += lpFilterMC(DryFilter, BACK_LEFT, value)*DrySend[BACK_LEFT];
i++;
//First order interpolator (back right)
value = lerp(Data[k*Channels+i], Data[(k+1)*Channels+i], DataPosFrac);
DryBuffer[j][BACK_RIGHT] += value*DrySend[BACK_RIGHT];
DryBuffer[j][BACK_RIGHT] += lpFilterMC(DryFilter, BACK_RIGHT, value)*DrySend[BACK_RIGHT];
i++;
if(Channels >= 7)
{
//First order interpolator (side left)
value = lerp(Data[k*Channels+i], Data[(k+1)*Channels+i], DataPosFrac);
DryBuffer[j][SIDE_LEFT] += value*DrySend[SIDE_LEFT];
DryBuffer[j][SIDE_LEFT] += lpFilterMC(DryFilter, SIDE_LEFT, value)*DrySend[SIDE_LEFT];
i++;
//First order interpolator (side right)
value = lerp(Data[k*Channels+i], Data[(k+1)*Channels+i], DataPosFrac);
DryBuffer[j][SIDE_RIGHT] += value*DrySend[SIDE_RIGHT];
DryBuffer[j][SIDE_RIGHT] += lpFilterMC(DryFilter, SIDE_RIGHT, value)*DrySend[SIDE_RIGHT];
i++;
}
}

3
OpenAL32/Include/alFilter.h
View File

@ -2,13 +2,14 @@
#define _AL_FILTER_H_
#include "AL/al.h"
#include "alu.h"
#ifdef __cplusplus
extern "C" {
#endif
typedef struct {
ALfloat history[4];
ALfloat history[OUTPUTCHANNELS*2];
ALfloat coeff;
} FILTER;