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Use a 2-pole filter for the wet path low-pass filter

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This should help keep CPU use from increasing a lot when the number of sends
increases. Also changes the function names to reflect the difference
This commit is contained in:
Chris Robinson 2009-04-14 22:04:18 -07:00
parent f245f0ef87
commit e9a6a1d6f5
1 changed files with 10 additions and 8 deletions
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18
Alc/ALu.c
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@ -181,7 +181,7 @@ __inline ALuint aluChannelsFromFormat(ALenum format)
}
static __inline ALfloat lpFilter(FILTER *iir, ALfloat input)
static __inline ALfloat lpFilter4P(FILTER *iir, ALfloat input)
{
ALfloat *history = iir->history;
ALfloat a = iir->coeff;
@ -199,7 +199,7 @@ static __inline ALfloat lpFilter(FILTER *iir, ALfloat input)
return output;
}
static __inline ALfloat lpFilterMC(FILTER *iir, ALuint chan, ALfloat input)
static __inline ALfloat lpFilter2P(FILTER *iir, ALuint chan, ALfloat input)
{
ALfloat *history = &iir->history[chan*2];
ALfloat a = iir->coeff;
@ -1052,7 +1052,10 @@ ALvoid aluMixData(ALCcontext *ALContext,ALvoid *buffer,ALsizei size,ALenum forma
for(i = 0;i < MAX_SENDS;i++)
{
g = aluSqrt(__max(WetGainHF[i], 0.0001f));
// The wet path uses two chained one-pole filters,
// so take the base gain (square root of the
// squared gain)
g = __max(WetGainHF[i], 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);
@ -1062,8 +1065,7 @@ ALvoid aluMixData(ALCcontext *ALContext,ALvoid *buffer,ALsizei size,ALenum forma
else
{
// Multi-channel sources use two chained one-pole
// filters, so take the base gain (square root of the
// squared gain)
// filters
cw = cos(2.0*M_PI * LOWPASSFREQCUTOFF / ALContext->Frequency);
g = __max(DryGainHF, 0.01f);
a = 0.0f;
@ -1177,7 +1179,7 @@ ALvoid aluMixData(ALCcontext *ALContext,ALvoid *buffer,ALsizei size,ALenum forma
value = lerp(Data[k], Data[k+1], DataPosFrac);
//Direct path final mix buffer and panning
outsamp = lpFilter(DryFilter, value);
outsamp = lpFilter4P(DryFilter, value);
DryBuffer[j][FRONT_LEFT] += outsamp*DrySend[FRONT_LEFT];
DryBuffer[j][FRONT_RIGHT] += outsamp*DrySend[FRONT_RIGHT];
DryBuffer[j][SIDE_LEFT] += outsamp*DrySend[SIDE_LEFT];
@ -1190,7 +1192,7 @@ ALvoid aluMixData(ALCcontext *ALContext,ALvoid *buffer,ALsizei size,ALenum forma
//Room path final mix buffer and panning
for(i = 0;i < MAX_SENDS;i++)
{
outsamp = lpFilter(WetFilter[i], value);
outsamp = lpFilter2P(WetFilter[i], 0, value);
WetBuffer[i][j] += outsamp*WetSend[i];
}
@ -1217,7 +1219,7 @@ ALvoid aluMixData(ALCcontext *ALContext,ALvoid *buffer,ALsizei size,ALenum forma
for(i = 0;i < Channels;i++) \
{ \
value = lerp(Data[k*Channels + i], Data[(k+1)*Channels + i], DataPosFrac); \
values[i] = lpFilterMC(DryFilter, chans[i], value)*DrySend[chans[i]]; \
values[i] = lpFilter2P(DryFilter, chans[i], value)*DrySend[chans[i]]; \
} \
for(out = 0;out < OUTPUTCHANNELS;out++) \
{ \