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Calculate filter coefficients in aluMixData

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This commit is contained in:
Chris Robinson 2009-03-13 22:58:54 -07:00
parent 89ddd7d8e5
commit 8a857c35ee
1 changed files with 44 additions and 38 deletions
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82
Alc/ALu.c
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@ -575,7 +575,6 @@ static ALvoid CalcSourceParams(ALCcontext *ALContext, ALsource *ALSource,
ALfloat DirGain, AmbientGain;
const ALfloat *SpeakerGain;
ALint pos, s;
ALfloat cw, a, g;
//Get context properties
DopplerFactor = ALContext->DopplerFactor * ALSource->DopplerFactor;
@ -850,25 +849,6 @@ static ALvoid CalcSourceParams(ALCcontext *ALContext, ALsource *ALSource,
}
*wetsend = WetMix;
// Update filter coefficients. Calculations based on the I3DL2 spec.
cw = cos(2.0*M_PI * LOWPASSFREQCUTOFF / ALContext->Frequency);
// We use four chained one-pole filters, so we need to take the fourth
// root of the squared gain, which is the same as the square root of
// the base gain.
// Be careful with gains < 0.0001, as that causes the coefficient to
// head towards 1, which will flatten the signal
g = aluSqrt(__max(DryGainHF, 0.0001f));
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;
g = aluSqrt(__max(WetGainHF, 0.0001f));
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->Send[0].iirFilter.coeff = a;
*drygainhf = DryGainHF;
*wetgainhf = WetGainHF;
}
@ -900,14 +880,6 @@ static ALvoid CalcSourceParams(ALCcontext *ALContext, ALsource *ALSource,
drysend[LFE] = DryMix * ListenerGain;
*wetsend = 0.0f;
cw = cos(2.0*M_PI * 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;
}
@ -947,6 +919,7 @@ ALvoid aluMixData(ALCcontext *ALContext,ALvoid *buffer,ALsizei size,ALenum forma
ALfloat value;
ALshort *Data;
ALuint i,j,k,out;
ALfloat cw, a, g;
ALbufferlistitem *BufferListItem;
ALuint loop;
ALint64 DataSize64,DataPos64;
@ -1020,23 +993,62 @@ ALvoid aluMixData(ALCcontext *ALContext,ALvoid *buffer,ALsizei size,ALenum forma
if(DataPosInt >= DataSize)
goto skipmix;
//Get source info
DryFilter = &ALSource->iirFilter;
WetFilter = &ALSource->Send[0].iirFilter;
DrySend = ALSource->DryGains;
WetSend = &ALSource->WetGain;
CalcSourceParams(ALContext, ALSource,
(Channels==1) ? AL_TRUE : AL_FALSE,
newDrySend, &newWetSend, &Pitch,
&DryGainHF, &WetGainHF);
Pitch = (Pitch*Frequency) / ALContext->Frequency;
if(DuplicateStereo && Channels > 1)
if(Channels == 1)
{
if(Channels == 2)
// Update filter coefficients. Calculations based on
// the I3DL2 spec.
cw = cos(2.0*M_PI * LOWPASSFREQCUTOFF / ALContext->Frequency);
// We use four chained one-pole filters, so we need to
// take the fourth root of the squared gain, which is
// the same as the square root of the base gain.
// Be careful with gains < 0.0001, as that causes the
// coefficient to head towards 1, which will flatten
// the signal
g = aluSqrt(__max(DryGainHF, 0.0001f));
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);
DryFilter->coeff = a;
g = aluSqrt(__max(WetGainHF, 0.0001f));
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);
WetFilter->coeff = a;
}
else
{
// Multi-channel sources use two chained one-pole
// filters, so take the base gain (square root of the
// squared gain)
cw = cos(2.0*M_PI * 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);
DryFilter->coeff = a;
WetFilter->coeff = 0.0f;
if(DuplicateStereo && Channels == 2)
{
Matrix[FRONT_LEFT][SIDE_LEFT] = 1.0f;
Matrix[FRONT_RIGHT][SIDE_RIGHT] = 1.0f;
Matrix[FRONT_LEFT][BACK_LEFT] = 1.0f;
Matrix[FRONT_RIGHT][BACK_RIGHT] = 1.0f;
}
else
else if(DuplicateStereo)
{
Matrix[FRONT_LEFT][SIDE_LEFT] = 0.0f;
Matrix[FRONT_RIGHT][SIDE_RIGHT] = 0.0f;
@ -1045,12 +1057,6 @@ ALvoid aluMixData(ALCcontext *ALContext,ALvoid *buffer,ALsizei size,ALenum forma
}
}
//Get source info
DryFilter = &ALSource->iirFilter;
WetFilter = &ALSource->Send[0].iirFilter;
DrySend = ALSource->DryGains;
WetSend = &ALSource->WetGain;
//Compute the gain steps for each output channel
if(ALSource->FirstStart && DataPosInt == 0 && DataPosFrac == 0)
{