EFX: Frequency Shifter implementation

Add frequency shifter effect using discrete Hilbert transform. Only mono signal processing by now (LEFT_DIRECTION).

Alc/ALc.c

@@ -550,8 +550,8 @@ static const struct {
     DECL(AL_EFFECT_ECHO),
     DECL(AL_EFFECT_FLANGER),
     DECL(AL_EFFECT_PITCH_SHIFTER),
-#if 0
     DECL(AL_EFFECT_FREQUENCY_SHIFTER),
+#if 0
     DECL(AL_EFFECT_VOCAL_MORPHER),
 #endif
     DECL(AL_EFFECT_RING_MODULATOR),
@@ -632,6 +632,10 @@ static const struct {
     DECL(AL_FLANGER_FEEDBACK),
     DECL(AL_FLANGER_DELAY),
 
+    DECL(AL_FREQUENCY_SHIFTER_FREQUENCY),
+    DECL(AL_FREQUENCY_SHIFTER_LEFT_DIRECTION),
+    DECL(AL_FREQUENCY_SHIFTER_RIGHT_DIRECTION),
+
     DECL(AL_RING_MODULATOR_FREQUENCY),
     DECL(AL_RING_MODULATOR_HIGHPASS_CUTOFF),
     DECL(AL_RING_MODULATOR_WAVEFORM),

Alc/effects/fshifter.c

@@ -0,0 +1,323 @@
+/**
+ * OpenAL cross platform audio library
+ * Copyright (C) 2018 by Raul Herraiz.
+ * This library is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU Library General Public
+ *  License as published by the Free Software Foundation; either
+ *  version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ *  Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ *  License along with this library; if not, write to the
+ *  Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ * Or go to http://www.gnu.org/copyleft/lgpl.html
+ */
+
+#include "config.h"
+
+#include <math.h>
+#include <stdlib.h>
+
+#include "alMain.h"
+#include "alAuxEffectSlot.h"
+#include "alError.h"
+#include "alu.h"
+#include "filters/defs.h"
+
+#include "alcomplex.h"
+
+#define HIL_SIZE 1024
+#define OVERSAMP       (1<<2)
+
+#define HIL_STEP    (HIL_SIZE / OVERSAMP)
+#define FIFO_LATENCY (HIL_STEP * (OVERSAMP-1))
+
+
+typedef struct ALfshifterState {
+    DERIVE_FROM_TYPE(ALeffectState);
+
+    /* Effect parameters */
+    ALsizei  count;
+    ALdouble frac_freq;
+    ALdouble inc;
+    ALdouble ld_sign;
+
+    /*Effects buffers*/ 
+    ALfloat   InFIFO[HIL_SIZE];
+    ALcomplex OutFIFO[HIL_SIZE];
+    ALcomplex OutputAccum[2*HIL_SIZE];
+    ALcomplex Analytic[HIL_SIZE];
+    ALcomplex Outdata[BUFFERSIZE];
+
+    alignas(16) ALfloat BufferOut[BUFFERSIZE];
+
+    /* Effect gains for each output channel */
+    ALfloat CurrentGains[MAX_OUTPUT_CHANNELS];
+    ALfloat TargetGains[MAX_OUTPUT_CHANNELS];
+
+} ALfshifterState;
+
+static ALvoid ALfshifterState_Destruct(ALfshifterState *state);
+static ALboolean ALfshifterState_deviceUpdate(ALfshifterState *state, ALCdevice *device);
+static ALvoid ALfshifterState_update(ALfshifterState *state, const ALCcontext *context, const ALeffectslot *slot, const ALeffectProps *props);
+static ALvoid ALfshifterState_process(ALfshifterState *state, ALsizei SamplesToDo, const ALfloat (*restrict SamplesIn)[BUFFERSIZE], ALfloat (*restrict SamplesOut)[BUFFERSIZE], ALsizei NumChannels);
+DECLARE_DEFAULT_ALLOCATORS(ALfshifterState)
+
+DEFINE_ALEFFECTSTATE_VTABLE(ALfshifterState);
+
+/* Define a Hann window, used to filter the HIL input and output. */
+alignas(16) static ALdouble HannWindow[HIL_SIZE];
+
+static void InitHannWindow(void)
+{
+    ALsizei i;
+
+    /* Create lookup table of the Hann window for the desired size, i.e. HIL_SIZE */
+    for(i = 0;i < HIL_SIZE>>1;i++)
+    {
+        ALdouble val = sin(M_PI * (ALdouble)i / (ALdouble)(HIL_SIZE-1));
+        HannWindow[i] = HannWindow[HIL_SIZE-1-i] = val * val;
+    }
+}
+
+static alonce_flag HannInitOnce = AL_ONCE_FLAG_INIT;
+
+static void ALfshifterState_Construct(ALfshifterState *state)
+{
+    ALeffectState_Construct(STATIC_CAST(ALeffectState, state));
+    SET_VTABLE2(ALfshifterState, ALeffectState, state);
+
+    alcall_once(&HannInitOnce, InitHannWindow);
+}
+
+static ALvoid ALfshifterState_Destruct(ALfshifterState *state)
+{
+    ALeffectState_Destruct(STATIC_CAST(ALeffectState,state));
+}
+
+static ALboolean ALfshifterState_deviceUpdate(ALfshifterState *state, ALCdevice *device)
+{
+    /* (Re-)initializing parameters and clear the buffers. */
+    state->count       =  FIFO_LATENCY;
+    state->frac_freq   =  0.0;
+    state->inc         =  0.0;
+    state->ld_sign     = -1.0;
+
+    memset(state->InFIFO     , 0, HIL_SIZE*sizeof(ALfloat));
+    memset(state->OutFIFO    , 0, HIL_SIZE*sizeof(ALcomplex));
+    memset(state->OutputAccum, 0, 2*HIL_SIZE*sizeof(ALcomplex));
+    memset(state->Analytic   , 0, HIL_SIZE*sizeof(ALcomplex));
+
+    memset(state->CurrentGains, 0, sizeof(state->CurrentGains));
+    memset(state->TargetGains,  0, sizeof(state->TargetGains));
+
+    return AL_TRUE;
+}
+
+static ALvoid ALfshifterState_update(ALfshifterState *state, const ALCcontext *context, const ALeffectslot *slot, const ALeffectProps *props)
+{
+    const ALCdevice *device = context->Device;
+    ALfloat coeffs[MAX_AMBI_COEFFS];
+
+    state->frac_freq = props->Fshifter.Frequency/device->Frequency;
+
+    switch (props->Fshifter.Left_direction)
+    {
+      case AL_FREQUENCY_SHIFTER_DIRECTION_DOWN:
+           state->ld_sign   = -1.0;
+      break;
+
+      case AL_FREQUENCY_SHIFTER_DIRECTION_UP:
+           state->ld_sign   =  1.0;
+      break;
+
+      case AL_FREQUENCY_SHIFTER_DIRECTION_OFF:
+           state->frac_freq =  0.0;
+      break;
+    }
+
+    CalcAngleCoeffs(0.0f, 0.0f, 0.0f, coeffs);
+    ComputeDryPanGains(&device->Dry, coeffs, slot->Params.Gain, state->TargetGains);
+}
+
+static ALvoid ALfshifterState_process(ALfshifterState *state, ALsizei SamplesToDo, const ALfloat (*restrict SamplesIn)[BUFFERSIZE], ALfloat (*restrict SamplesOut)[BUFFERSIZE], ALsizei NumChannels)
+{
+    ALsizei i,k;
+    ALfloat *restrict BufferOut  = state->BufferOut;
+
+    for (i = 0; i < SamplesToDo; i++){
+
+        /* Fill FIFO buffer with samples data */
+        state->InFIFO[state->count] = SamplesIn[0][i];
+        state->Outdata[i]  = state->OutFIFO[state->count-FIFO_LATENCY];
+
+        state->count++;
+
+        /* Check whether FIFO buffer is filled */
+        if (state->count >= HIL_SIZE ) 
+        {
+            state->count = FIFO_LATENCY;
+
+            /* Real signal windowing and store in Analytic buffer */
+            for (k = 0; k < HIL_SIZE;k++) 
+            {
+                state->Analytic[k].Real = state->InFIFO[k] * HannWindow[k];
+                state->Analytic[k].Imag = 0.0f;
+            }
+            /*Processing signal by Discrete Hilbert Transform (analytical signal)*/
+            hilbert(HIL_SIZE, state->Analytic);
+
+            /* Windowing and add to output accumulator */ 
+            for(k=0; k < HIL_SIZE; k++) 
+            {
+                state->OutputAccum[k].Real  +=  2.0f*HannWindow[k]*state->Analytic[k].Real / OVERSAMP;
+                state->OutputAccum[k].Imag  +=  2.0f*HannWindow[k]*state->Analytic[k].Imag / OVERSAMP;
+            }
+            for (k = 0; k < HIL_STEP; k++) 
+            {
+                state->OutFIFO[k] = state->OutputAccum[k];
+            }
+
+            /* shift accumulator */
+            memmove(state->OutputAccum, state->OutputAccum + HIL_STEP, HIL_SIZE*sizeof(ALcomplex));
+
+            /* move input FIFO */
+            for (k = 0; k < FIFO_LATENCY; k++) state->InFIFO[k] = state->InFIFO[k + HIL_STEP];
+            }
+    }
+    /*Process frequency shifter using the analytic signal obtained*/
+    for ( k = 0; k < SamplesToDo; k++, state->inc += state->frac_freq ) 
+    {
+        ALdouble phase;
+
+        if( state->inc >= 1.0 )  state->inc -= 1.0;
+
+        phase = (2.0*M_PI*state->inc);
+
+        BufferOut[k] = (ALfloat)(state->Outdata[k].Real*cos(phase) + 
+                                 state->ld_sign*state->Outdata[k].Imag*sin(phase));
+    }
+
+    /* Now, mix the processed sound data to the output. */
+    MixSamples(BufferOut, NumChannels, SamplesOut, state->CurrentGains, state->TargetGains,
+               maxi(SamplesToDo, 512), 0, SamplesToDo);
+
+}
+
+typedef struct FshifterStateFactory {
+    DERIVE_FROM_TYPE(EffectStateFactory);
+} FshifterStateFactory;
+
+static ALeffectState *FshifterStateFactory_create(FshifterStateFactory *UNUSED(factory))
+{
+    ALfshifterState *state;
+
+    NEW_OBJ0(state, ALfshifterState)();
+    if(!state) return NULL;
+
+    return STATIC_CAST(ALeffectState, state);
+}
+
+DEFINE_EFFECTSTATEFACTORY_VTABLE(FshifterStateFactory);
+
+EffectStateFactory *FshifterStateFactory_getFactory(void)
+{
+    static FshifterStateFactory FshifterFactory = { { GET_VTABLE2(FshifterStateFactory, EffectStateFactory) } };
+
+    return STATIC_CAST(EffectStateFactory, &FshifterFactory);
+}
+
+void ALfshifter_setParamf(ALeffect *effect, ALCcontext *context, ALenum param, ALfloat val)
+{
+    ALeffectProps *props = &effect->Props;
+    switch(param)
+    {
+        case AL_FREQUENCY_SHIFTER_FREQUENCY:
+            if(!(val >= AL_FREQUENCY_SHIFTER_MIN_FREQUENCY && val <= AL_FREQUENCY_SHIFTER_MAX_FREQUENCY))
+                SETERR_RETURN(context, AL_INVALID_VALUE,,"Frequency shifter frequency out of range");
+            props->Fshifter.Frequency = (ALfloat) val;
+            break;
+
+        default:
+            alSetError(context, AL_INVALID_ENUM, "Invalid frequency shifter float property 0x%04x", param);
+    }
+}
+
+void ALfshifter_setParamfv(ALeffect *effect, ALCcontext *context, ALenum param, const ALfloat *vals)
+{
+    ALfshifter_setParamf(effect, context, param, vals[0]);
+}
+
+void ALfshifter_setParami(ALeffect *effect, ALCcontext *context, ALenum param, ALint val)
+{
+    ALeffectProps *props = &effect->Props;
+    switch(param)
+    {
+        case AL_FREQUENCY_SHIFTER_LEFT_DIRECTION:
+            if(!(val >= AL_FREQUENCY_SHIFTER_MIN_LEFT_DIRECTION && val <= AL_FREQUENCY_SHIFTER_MAX_LEFT_DIRECTION))
+                SETERR_RETURN(context, AL_INVALID_VALUE,,"Frequency shifter left direction out of range");
+            props->Fshifter.Left_direction = val;
+            break;
+
+        case AL_FREQUENCY_SHIFTER_RIGHT_DIRECTION:
+            if(!(val >= AL_FREQUENCY_SHIFTER_MIN_RIGHT_DIRECTION && val <= AL_FREQUENCY_SHIFTER_MAX_RIGHT_DIRECTION))
+                SETERR_RETURN(context, AL_INVALID_VALUE,,"Frequency shifter right direction out of range");
+            props->Fshifter.Right_direction = val;
+            break;
+
+        default:
+            alSetError(context, AL_INVALID_ENUM, "Invalid frequency shifter integer property 0x%04x", param);
+    }
+}
+void ALfshifter_setParamiv(ALeffect *effect, ALCcontext *context, ALenum param, const ALint *vals)
+{
+    ALfshifter_setParami(effect, context, param, vals[0]);
+}
+
+void ALfshifter_getParami(const ALeffect *effect, ALCcontext *context, ALenum param, ALint *val)
+{
+    const ALeffectProps *props = &effect->Props;
+    switch(param)
+    {
+        case AL_FREQUENCY_SHIFTER_LEFT_DIRECTION:
+            *val = (ALint)props->Fshifter.Left_direction;
+            break;
+        case AL_FREQUENCY_SHIFTER_RIGHT_DIRECTION:
+            *val = (ALint)props->Fshifter.Right_direction;
+            break;
+        default:
+            alSetError(context, AL_INVALID_ENUM, "Invalid frequency shifter integer property 0x%04x", param);
+    }
+}
+void ALfshifter_getParamiv(const ALeffect *effect, ALCcontext *context, ALenum param, ALint *vals)
+{
+    ALfshifter_getParami(effect, context, param, vals);
+}
+
+void ALfshifter_getParamf(const ALeffect *effect, ALCcontext *context, ALenum param, ALfloat *val)
+{
+
+    const ALeffectProps *props = &effect->Props;
+    switch(param)
+    {
+        case AL_FREQUENCY_SHIFTER_FREQUENCY:
+            *val = (ALfloat)props->Fshifter.Frequency;
+            break;
+
+        default:
+            alSetError(context, AL_INVALID_ENUM, "Invalid frequency shifter float property 0x%04x", param);
+    }
+
+}
+
+void ALfshifter_getParamfv(const ALeffect *effect, ALCcontext *context, ALenum param, ALfloat *vals)
+{
+    ALfshifter_getParamf(effect, context, param, vals);
+}
+
+DEFINE_ALEFFECT_VTABLE(ALfshifter);

CMakeLists.txt

@@ -761,6 +761,7 @@ SET(ALC_OBJS
     Alc/effects/distortion.c
     Alc/effects/echo.c
     Alc/effects/equalizer.c
+    Alc/effects/fshifter.c
     Alc/effects/modulator.c
     Alc/effects/null.c
     Alc/effects/pshifter.c

OpenAL32/Include/alAuxEffectSlot.h

@@ -166,6 +166,7 @@ EffectStateFactory *DistortionStateFactory_getFactory(void);
 EffectStateFactory *EchoStateFactory_getFactory(void);
 EffectStateFactory *EqualizerStateFactory_getFactory(void);
 EffectStateFactory *FlangerStateFactory_getFactory(void);
+EffectStateFactory *FshifterStateFactory_getFactory(void);
 EffectStateFactory *ModulatorStateFactory_getFactory(void);
 EffectStateFactory *PshifterStateFactory_getFactory(void);
 

OpenAL32/Include/alEffect.h

@@ -18,6 +18,7 @@ enum {
     ECHO_EFFECT,
     EQUALIZER_EFFECT,
     FLANGER_EFFECT,
+    FSHIFTER_EFFECT,
     MODULATOR_EFFECT,
     PSHIFTER_EFFECT,
     DEDICATED_EFFECT,
@@ -33,7 +34,7 @@ struct EffectList {
     int type;
     ALenum val;
 };
-#define EFFECTLIST_SIZE 12
+#define EFFECTLIST_SIZE 13
 extern const struct EffectList EffectList[EFFECTLIST_SIZE];
 
 
@@ -65,6 +66,7 @@ extern const struct ALeffectVtable ALdistortion_vtable;
 extern const struct ALeffectVtable ALecho_vtable;
 extern const struct ALeffectVtable ALequalizer_vtable;
 extern const struct ALeffectVtable ALflanger_vtable;
+extern const struct ALeffectVtable ALfshifter_vtable;
 extern const struct ALeffectVtable ALmodulator_vtable;
 extern const struct ALeffectVtable ALnull_vtable;
 extern const struct ALeffectVtable ALpshifter_vtable;
@@ -145,6 +147,12 @@ typedef union ALeffectProps {
         ALfloat HighGain;
     } Equalizer;
 
+        struct {
+        ALfloat Frequency;
+        ALint Left_direction;
+        ALint Right_direction;
+    } Fshifter;
+
     struct {
         ALfloat Frequency;
         ALfloat HighPassCutoff;

OpenAL32/alAuxEffectSlot.c

@@ -54,6 +54,7 @@ static const struct {
     { AL_EFFECT_ECHO, EchoStateFactory_getFactory },
     { AL_EFFECT_EQUALIZER, EqualizerStateFactory_getFactory },
     { AL_EFFECT_FLANGER, FlangerStateFactory_getFactory },
+    { AL_EFFECT_FREQUENCY_SHIFTER, FshifterStateFactory_getFactory },
     { AL_EFFECT_RING_MODULATOR, ModulatorStateFactory_getFactory },
     { AL_EFFECT_PITCH_SHIFTER, PshifterStateFactory_getFactory},
     { AL_EFFECT_DEDICATED_DIALOGUE, DedicatedStateFactory_getFactory },

OpenAL32/alEffect.c

@@ -44,6 +44,7 @@ const struct EffectList EffectList[EFFECTLIST_SIZE] = {
     { "echo",       ECHO_EFFECT,       AL_EFFECT_ECHO },
     { "equalizer",  EQUALIZER_EFFECT,  AL_EFFECT_EQUALIZER },
     { "flanger",    FLANGER_EFFECT,    AL_EFFECT_FLANGER },
+    { "fshifter",   FSHIFTER_EFFECT,   AL_EFFECT_FREQUENCY_SHIFTER },
     { "modulator",  MODULATOR_EFFECT,  AL_EFFECT_RING_MODULATOR },
     { "pshifter",   PSHIFTER_EFFECT,   AL_EFFECT_PITCH_SHIFTER },
     { "dedicated",  DEDICATED_EFFECT,  AL_EFFECT_DEDICATED_LOW_FREQUENCY_EFFECT },
@@ -584,6 +585,12 @@ static void InitEffectParams(ALeffect *effect, ALenum type)
         effect->Props.Chorus.Delay = AL_FLANGER_DEFAULT_DELAY;
         effect->vtab = &ALflanger_vtable;
         break;
+        case AL_EFFECT_FREQUENCY_SHIFTER:
+        effect->Props.Fshifter.Frequency       = AL_FREQUENCY_SHIFTER_DEFAULT_FREQUENCY;
+        effect->Props.Fshifter.Left_direction  = AL_FREQUENCY_SHIFTER_DEFAULT_LEFT_DIRECTION;
+        effect->Props.Fshifter.Right_direction = AL_FREQUENCY_SHIFTER_DEFAULT_RIGHT_DIRECTION;
+        effect->vtab = &ALfshifter_vtable;
+        break;
     case AL_EFFECT_RING_MODULATOR:
         effect->Props.Modulator.Frequency      = AL_RING_MODULATOR_DEFAULT_FREQUENCY;
         effect->Props.Modulator.HighPassCutoff = AL_RING_MODULATOR_DEFAULT_HIGHPASS_CUTOFF;