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Ramp channel gains to remove pops and clicks from abrupt changes

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Thanks to Christopher Fitzgerald for helping me work on it
This commit is contained in:
Chris Robinson 2008-08-14 05:43:52 -07:00
parent f8ef66954c
commit 22557070ec
3 changed files with 72 additions and 20 deletions
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72
Alc/ALu.c
View File

@ -31,6 +31,7 @@
#include "alThunk.h"
#include "alListener.h"
#include "alAuxEffectSlot.h"
#include "alu.h"
#include "bs2b.h"
#if defined(HAVE_STDINT_H)
@ -69,18 +70,9 @@ typedef long long ALint64;
#define FRACTIONMASK ((1L<<FRACTIONBITS)-1)
#define MAX_PITCH 4
enum {
FRONT_LEFT = 0,
FRONT_RIGHT,
SIDE_LEFT,
SIDE_RIGHT,
BACK_LEFT,
BACK_RIGHT,
CENTER,
LFE,
OUTPUTCHANNELS
};
/* Minimum ramp length in milliseconds. The value below was chosen to
* adequately reduce clicks and pops from harsh gain changes. */
#define MIN_RAMP_LENGTH 16
ALboolean DuplicateStereo = AL_FALSE;
@ -628,10 +620,17 @@ ALvoid aluMixData(ALCcontext *ALContext,ALvoid *buffer,ALsizei size,ALenum forma
{
static float DryBuffer[BUFFERSIZE][OUTPUTCHANNELS];
static float WetBuffer[BUFFERSIZE][OUTPUTCHANNELS];
ALfloat DrySend[OUTPUTCHANNELS] = { 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f };
ALfloat WetSend[OUTPUTCHANNELS] = { 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f };
ALfloat newDrySend[OUTPUTCHANNELS] = { 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f };
ALfloat newWetSend[OUTPUTCHANNELS] = { 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f };
ALfloat DryGainHF = 0.0f;
ALfloat WetGainHF = 0.0f;
ALfloat *DrySend;
ALfloat *WetSend;
ALuint rampLength;
ALfloat dryGainStep[OUTPUTCHANNELS];
ALfloat wetGainStep[OUTPUTCHANNELS];
ALfloat dryGainHFStep;
ALfloat wetGainHFStep;
ALuint BlockAlign,BufferSize;
ALuint DataSize=0,DataPosInt=0,DataPosFrac=0;
ALuint Channels,Frequency,ulExtraSamples;
@ -672,9 +671,20 @@ ALvoid aluMixData(ALCcontext *ALContext,ALvoid *buffer,ALsizei size,ALenum forma
while(size > 0)
{
//Setup variables
ALEffectSlot = (ALContext ? ALContext->AuxiliaryEffectSlot : NULL);
ALSource = (ALContext ? ALContext->Source : NULL);
SamplesToDo = min(size, BUFFERSIZE);
if(ALContext)
{
ALEffectSlot = ALContext->AuxiliaryEffectSlot;
ALSource = ALContext->Source;
rampLength = ALContext->Frequency * MIN_RAMP_LENGTH / 1000;
}
else
{
ALEffectSlot = NULL;
ALSource = NULL;
rampLength = 0;
}
rampLength = max(rampLength, SamplesToDo);
//Clear mixing buffer
memset(DryBuffer, 0, SamplesToDo*OUTPUTCHANNELS*sizeof(ALfloat));
@ -703,10 +713,9 @@ ALvoid aluMixData(ALCcontext *ALContext,ALvoid *buffer,ALsizei size,ALenum forma
Frequency = ALBuffer->frequency;
CalcSourceParams(ALContext, ALSource,
(Channels==1) ? AL_TRUE : AL_FALSE,
format, DrySend, WetSend, &Pitch,
&DryGainHF, &WetGainHF);
(Channels==1) ? AL_TRUE : AL_FALSE,
format, newDrySend, newWetSend, &Pitch,
&DryGainHF, &WetGainHF);
Pitch = (Pitch*Frequency) / ALContext->Frequency;
DataSize /= Channels * aluBytesFromFormat(ALBuffer->format);
@ -715,6 +724,19 @@ ALvoid aluMixData(ALCcontext *ALContext,ALvoid *buffer,ALsizei size,ALenum forma
DataPosInt = ALSource->position;
DataPosFrac = ALSource->position_fraction;
Filter = &ALSource->iirFilter;
DrySend = ALSource->DryGains;
WetSend = ALSource->WetGains;
//Compute the gain steps for each output channel
for(i = 0;i < OUTPUTCHANNELS;i++)
{
dryGainStep[i] = (newDrySend[i]-DrySend[i]) / rampLength;
wetGainStep[i] = (newWetSend[i]-WetSend[i]) / rampLength;
}
dryGainHFStep = (DryGainHF-ALSource->DryGainHF) / rampLength;
wetGainHFStep = (WetGainHF-ALSource->WetGainHF) / rampLength;
DryGainHF = ALSource->DryGainHF;
WetGainHF = ALSource->WetGainHF;
//Compute 18.14 fixed point step
increment = (ALint)(Pitch*(ALfloat)(1L<<FRACTIONBITS));
@ -767,6 +789,14 @@ ALvoid aluMixData(ALCcontext *ALContext,ALvoid *buffer,ALsizei size,ALenum forma
k = DataPosFrac>>FRACTIONBITS;
fraction = DataPosFrac&FRACTIONMASK;
for(i = 0;i < OUTPUTCHANNELS;i++)
{
DrySend[i] += dryGainStep[i];
WetSend[i] += wetGainStep[i];
}
DryGainHF += dryGainHFStep;
WetGainHF += wetGainHFStep;
if(Channels==1)
{
ALfloat sample, lowsamp, outsamp;
@ -872,6 +902,8 @@ ALvoid aluMixData(ALCcontext *ALContext,ALvoid *buffer,ALsizei size,ALenum forma
//Update source info
ALSource->position = DataPosInt;
ALSource->position_fraction = DataPosFrac;
ALSource->DryGainHF = DryGainHF;
ALSource->WetGainHF = WetGainHF;
}
//Handle looping sources

7
OpenAL32/Include/alSource.h
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@ -7,6 +7,7 @@
#define MAX_SENDS 1
#include "alFilter.h"
#include "alu.h"
#include "AL/al.h"
#define AL_DIRECT_FILTER 0x20005
@ -94,6 +95,12 @@ typedef struct ALsource
// Source Type (Static, Streaming, or Undetermined)
ALint lSourceType;
// Current gains, which are ramped while mixed
ALfloat DryGains[OUTPUTCHANNELS];
ALfloat WetGains[OUTPUTCHANNELS];
ALfloat DryGainHF;
ALfloat WetGainHF;
struct ALsource *next;
} ALsource;

13
OpenAL32/Include/alu.h
View File

@ -8,6 +8,19 @@
extern "C" {
#endif
enum {
FRONT_LEFT = 0,
FRONT_RIGHT,
SIDE_LEFT,
SIDE_RIGHT,
BACK_LEFT,
BACK_RIGHT,
CENTER,
LFE,
OUTPUTCHANNELS
};
extern ALboolean DuplicateStereo;
__inline ALuint aluBytesFromFormat(ALenum format);