From a75e75aef5f62ca282db8c0a0aa9d1c25551eae7 Mon Sep 17 00:00:00 2001 From: Chris Robinson Date: Wed, 23 Jul 2008 22:29:53 -0700 Subject: [PATCH] Implement an alternative low-pass filter This method samples from the buffer so that it gets a time-correct 5khz stream, which is subtracted from the original sample and has the high-frequency gain applied, then added back. A better method may be to average all the samples from the current one to the one freq/5000 away, instead of bilinear filtering the two nearest freq/5000 apart. Processing cost will need to determine its viability --- Alc/ALu.c | 68 +++++++++++++++++++++------------------------ OpenAL32/Include/alSource.h | 3 -- 2 files changed, 32 insertions(+), 39 deletions(-) diff --git a/Alc/ALu.c b/Alc/ALu.c index fcb156a0..0895842f 100644 --- a/Alc/ALu.c +++ b/Alc/ALu.c @@ -210,20 +210,9 @@ static __inline ALvoid aluMatrixVector(ALfloat *vector,ALfloat matrix[3][3]) memcpy(vector, result, sizeof(result)); } -static __inline ALfloat aluComputeSample(ALfloat GainHF, ALfloat sample, ALfloat LastSample) +static __inline ALfloat aluComputeSample(ALfloat GainHF, ALfloat sample, ALfloat LowSample) { - if(GainHF < 1.0f) - { - if(GainHF > 0.0f) - { - sample *= GainHF; - sample += LastSample * (1.0f-GainHF); - } - else - sample = 0.0f; - } - - return sample; + return LowSample + ((sample - LowSample) * GainHF); } static ALvoid CalcSourceParams(ALCcontext *ALContext, ALsource *ALSource, @@ -603,11 +592,13 @@ ALvoid aluMixData(ALCcontext *ALContext,ALvoid *buffer,ALsizei size,ALenum forma ALuint BlockAlign,BufferSize; ALuint DataSize=0,DataPosInt=0,DataPosFrac=0; ALuint Channels,Frequency,ulExtraSamples; - ALfloat DrySample, WetSample; ALboolean doReverb; ALfloat Pitch; - ALint Looping,increment,State; - ALuint Buffer,fraction; + ALint Looping,State; + ALint fraction,increment; + ALint LowFrac; + ALuint LowStep; + ALuint Buffer; ALuint SamplesToDo; ALsource *ALSource; ALbuffer *ALBuffer; @@ -676,8 +667,6 @@ ALvoid aluMixData(ALCcontext *ALContext,ALvoid *buffer,ALsizei size,ALenum forma //Get source info DataPosInt = ALSource->position; DataPosFrac = ALSource->position_fraction; - DrySample = ALSource->LastDrySample; - WetSample = ALSource->LastWetSample; //Compute 18.14 fixed point step increment = (ALint)(Pitch*(ALfloat)(1L< 8) LowStep = 8; Data += DataPosInt*Channels; while(BufferSize--) { k = DataPosFrac>>FRACTIONBITS; fraction = DataPosFrac&FRACTIONMASK; + LowFrac = ((DataPosFrac+(DataPosInt<>FRACTIONBITS)); + sample = (Data[k]*((1<> FRACTIONBITS; + lowsamp = (Data[((k+DataPosInt)/LowStep )*LowStep - DataPosInt]*((1<> + FRACTIONBITS; //Direct path final mix buffer and panning - DrySample = aluComputeSample(DryGainHF, sample, DrySample); - DryBuffer[j][FRONT_LEFT] += DrySample*DrySend[FRONT_LEFT]; - DryBuffer[j][FRONT_RIGHT] += DrySample*DrySend[FRONT_RIGHT]; - DryBuffer[j][SIDE_LEFT] += DrySample*DrySend[SIDE_LEFT]; - DryBuffer[j][SIDE_RIGHT] += DrySample*DrySend[SIDE_RIGHT]; - DryBuffer[j][BACK_LEFT] += DrySample*DrySend[BACK_LEFT]; - DryBuffer[j][BACK_RIGHT] += DrySample*DrySend[BACK_RIGHT]; + outsamp = aluComputeSample(DryGainHF, sample, lowsamp); + DryBuffer[j][FRONT_LEFT] += outsamp*DrySend[FRONT_LEFT]; + DryBuffer[j][FRONT_RIGHT] += outsamp*DrySend[FRONT_RIGHT]; + DryBuffer[j][SIDE_LEFT] += outsamp*DrySend[SIDE_LEFT]; + DryBuffer[j][SIDE_RIGHT] += outsamp*DrySend[SIDE_RIGHT]; + DryBuffer[j][BACK_LEFT] += outsamp*DrySend[BACK_LEFT]; + DryBuffer[j][BACK_RIGHT] += outsamp*DrySend[BACK_RIGHT]; //Room path final mix buffer and panning - WetSample = aluComputeSample(WetGainHF, sample, WetSample); + outsamp = aluComputeSample(WetGainHF, sample, lowsamp); if(doReverb) - ReverbBuffer[j] += WetSample; + ReverbBuffer[j] += outsamp; else { - WetBuffer[j][FRONT_LEFT] += WetSample*WetSend[FRONT_LEFT]; - WetBuffer[j][FRONT_RIGHT] += WetSample*WetSend[FRONT_RIGHT]; - WetBuffer[j][SIDE_LEFT] += WetSample*WetSend[SIDE_LEFT]; - WetBuffer[j][SIDE_RIGHT] += WetSample*WetSend[SIDE_RIGHT]; - WetBuffer[j][BACK_LEFT] += WetSample*WetSend[BACK_LEFT]; - WetBuffer[j][BACK_RIGHT] += WetSample*WetSend[BACK_RIGHT]; + WetBuffer[j][FRONT_LEFT] += outsamp*WetSend[FRONT_LEFT]; + WetBuffer[j][FRONT_RIGHT] += outsamp*WetSend[FRONT_RIGHT]; + WetBuffer[j][SIDE_LEFT] += outsamp*WetSend[SIDE_LEFT]; + WetBuffer[j][SIDE_RIGHT] += outsamp*WetSend[SIDE_RIGHT]; + WetBuffer[j][BACK_LEFT] += outsamp*WetSend[BACK_LEFT]; + WetBuffer[j][BACK_RIGHT] += outsamp*WetSend[BACK_RIGHT]; } } else @@ -826,8 +824,6 @@ ALvoid aluMixData(ALCcontext *ALContext,ALvoid *buffer,ALsizei size,ALenum forma //Update source info ALSource->position = DataPosInt; ALSource->position_fraction = DataPosFrac; - ALSource->LastDrySample = DrySample; - ALSource->LastWetSample = WetSample; } //Handle looping sources diff --git a/OpenAL32/Include/alSource.h b/OpenAL32/Include/alSource.h index 558894ed..1d3fc57c 100644 --- a/OpenAL32/Include/alSource.h +++ b/OpenAL32/Include/alSource.h @@ -70,9 +70,6 @@ typedef struct ALsource ALfilter WetFilter; } Send[MAX_SENDS]; - ALfloat LastDrySample; - ALfloat LastWetSample; - ALboolean DryGainHFAuto; ALboolean WetGainAuto; ALboolean WetGainHFAuto; -- 2.11.4.GIT