head related transfer function

git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@13997 b3059339-0415-0410-9bf9-f77b7e298cf2

4 files changed, 898 insertions, 1 deletions

diff --git a/libaf/Makefile b/libaf/Makefile
index abeb2b015f..3dff12ced2 100644
--- a/libaf/Makefile
+++ b/libaf/Makefile
@@ -2,7 +2,10 @@ include ../config.mak
 
 LIBNAME = libaf.a
 
-SRCS=af.c af_mp.c af_dummy.c af_delay.c af_channels.c af_format.c af_resample.c window.c filter.c af_volume.c af_equalizer.c af_tools.c af_comp.c af_gate.c af_pan.c af_surround.c af_sub.c af_export.c af_volnorm.c af_extrastereo.c af_lavcresample.c af_sweep.c
+SRCS=af.c af_mp.c af_dummy.c af_delay.c af_channels.c af_format.c af_resample.c \
+window.c filter.c af_volume.c af_equalizer.c af_tools.c af_comp.c af_gate.c \
+af_pan.c af_surround.c af_sub.c af_export.c af_volnorm.c af_extrastereo.c \
+af_lavcresample.c af_sweep.c af_hrtf.c
 
 OBJS=$(SRCS:.c=.o)
 
diff --git a/libaf/af.c b/libaf/af.c
index ed9affd37b..98ac1169ff 100644
--- a/libaf/af.c
+++ b/libaf/af.c
@@ -27,6 +27,7 @@ extern af_info_t af_info_volnorm;
 extern af_info_t af_info_extrastereo;
 extern af_info_t af_info_lavcresample;
 extern af_info_t af_info_sweep;
+extern af_info_t af_info_hrtf;
 
 static af_info_t* filter_list[]={ 
    &af_info_dummy,
@@ -50,6 +51,7 @@ static af_info_t* filter_list[]={
    &af_info_lavcresample,
 #endif
    &af_info_sweep,
+   &af_info_hrtf,
    NULL 
 };
 
diff --git a/libaf/af_hrtf.c b/libaf/af_hrtf.c
new file mode 100644
index 0000000000..afb3bf0991
--- /dev/null
+++ b/libaf/af_hrtf.c
@@ -0,0 +1,416 @@
+/* Experimental audio filter that mixes 5.1 and 5.1 with matrix
+   encoded rear channels into headphone signal using FIR filtering
+   with HRTF.
+*/
+//#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <inttypes.h>
+
+#include <math.h>
+
+#include "af.h"
+#include "dsp.h"
+
+/* HRTF filter coefficients and adjustable parameters */
+#include "af_hrtf.h"
+
+typedef struct af_hrtf_s {
+    /* Lengths */
+    int dlbuflen, hrflen, basslen;
+    /* L, C, R, Ls, Rs channels */
+    float *lf, *rf, *lr, *rr, *cf, *cr;
+    float *cf_ir, *af_ir, *of_ir, *ar_ir, *or_ir, *cr_ir;
+    int cf_o, af_o, of_o, ar_o, or_o, cr_o;
+    /* Bass */
+    float *ba_l, *ba_r;
+    float *ba_ir;
+    /* Whether to matrix decode the rear center channel */
+    int matrix_mode;
+    /* Full wave rectified amplitude used to steer the active matrix
+       decoding of center rear channel */
+    float lr_fwr, rr_fwr;
+    /* Cyclic position on the ring buffer */
+    int cyc_pos;
+} af_hrtf_t;
+
+/* Convolution on a ring buffer
+ *    nx:	length of the ring buffer
+ *    nk:	length of the convolution kernel
+ *    sx:	ring buffer
+ *    sk:	convolution kernel
+ *    offset:	offset on the ring buffer, can be 
+ */
+static float conv(const int nx, const int nk, float *sx, float *sk,
+		  const int offset)
+{
+    /* k = reminder of offset / nx */
+    int k = offset >= 0 ? offset % nx : nx + (offset % nx);
+
+    if(nk + k <= nx)
+	return fir(nk, sx + k, sk);
+    else
+	return fir(nk + k - nx, sx, sk + nx - k) +
+	    fir(nx - k, sx + k, sk);
+}
+
+/* Detect when the impulse response starts (significantly) */
+int pulse_detect(float *sx)
+{
+    /* nmax must be the reference impulse response length (128) minus
+       s->hrflen */
+    const int nmax = 128 - HRTFFILTLEN;
+    const float thresh = IRTHRESH;
+    int i;
+
+    for(i = 0; i < nmax; i++)
+	if(fabs(sx[i]) > thresh)
+	    return i;
+    return 0;
+}
+
+inline void update_ch(af_hrtf_t *s, short *in, const int k)
+{
+    /* Update the full wave rectified total amplutude */
+    s->lr_fwr += abs(in[2]) - fabs(s->lr[k]);
+    s->rr_fwr += abs(in[3]) - fabs(s->rr[k]);
+
+    s->lf[k] = in[0];
+    s->cf[k] = in[4];
+    s->rf[k] = in[1];
+    s->lr[k] = in[2];
+    s->rr[k] = in[3];
+
+    s->ba_l[k] = in[0] + in[4] + in[2];
+    s->ba_r[k] = in[4] + in[1] + in[3];
+}
+
+inline void matrix_decode_cr(af_hrtf_t *s, short *in, const int k)
+{
+    /* Active matrix decoding of the center rear channel, 1 in the
+       denominator is to prevent singularity */
+    float lr_agc = in[2] * (s->lr_fwr + s->rr_fwr) /
+	(1 + s->lr_fwr + s->lr_fwr);
+    float rr_agc = in[3] * (s->lr_fwr + s->rr_fwr) /
+	(1 + s->rr_fwr + s->rr_fwr);
+
+    s->cr[k] = (lr_agc + rr_agc) * M_SQRT1_2;
+}
+
+/* Initialization and runtime control */
+static int control(struct af_instance_s *af, int cmd, void* arg)
+{
+    af_hrtf_t *s = af->setup;
+    char mode;
+
+    switch(cmd) {
+    case AF_CONTROL_REINIT:
+	af->data->rate   = ((af_data_t*)arg)->rate;
+	if(af->data->rate != 48000) {
+	    af_msg(AF_MSG_ERROR,
+		   "[hrtf] ERROR: Sampling rate is not 48000 Hz (%d)!\n",
+		   af->data->rate);
+	    return AF_ERROR;
+	}
+	af->data->nch    = ((af_data_t*)arg)->nch;
+	if(af->data->nch < 5) {
+	    af_msg(AF_MSG_ERROR,
+		   "[hrtf] ERROR: Insufficient channels (%d < 5).\n",
+		   af->data->nch);
+	    return AF_ERROR;
+	}
+	af->data->format = AF_FORMAT_SI | AF_FORMAT_NE;
+	af->data->bps    = 2;
+	return AF_OK;
+    case AF_CONTROL_COMMAND_LINE:
+	sscanf((char*)arg, "%c", &mode);
+	switch(mode) {
+	case 'm':
+	    s->matrix_mode = 1;
+	    break;
+	case '0':
+	    s->matrix_mode = 0;
+	    break;
+	default:
+	    af_msg(AF_MSG_ERROR,
+		   "[hrtf] Mode is neither 'm', nor '0' (%c).\n",
+		   mode);
+	    return AF_ERROR;
+	}
+	return AF_OK;
+    }    
+
+    af_msg(AF_MSG_INFO,
+	   "[hrtf] Using HRTF to mix %s discrete surround into "
+	   "L, R channels\n", s->matrix_mode ? "5" : "5+1");
+    if(s->matrix_mode)
+	af_msg(AF_MSG_INFO,
+	       "[hrtf] Using active matrix to decode rear center "
+	       "channel\n");
+
+    return AF_UNKNOWN;
+}
+
+/* Deallocate memory */
+static void uninit(struct af_instance_s *af)
+{
+    if(af->setup) {
+	af_hrtf_t *s = af->setup;
+
+	if(s->lf)
+	    free(s->lf);
+	if(s->rf)
+	    free(s->rf);
+	if(s->lr)
+	    free(s->lr);
+	if(s->rr)
+	    free(s->rr);
+	if(s->cf)
+	    free(s->cf);
+	if(s->cr)
+	    free(s->cr);
+	if(s->ba_l)
+	    free(s->ba_l);
+	if(s->ba_r)
+	    free(s->ba_r);
+	if(s->ba_ir)
+	    free(s->ba_ir);
+	free(af->setup);
+    }
+    if(af->data)
+	free(af->data);
+}
+
+/* Filter data through filter
+
+Two "tricks" are used to compensate the "color" of the KEMAR data:
+
+1. The KEMAR data is refiltered to ensure that the front L, R channels
+on the same side of the ear are equalized (especially in the high
+frequencies).
+
+2. A bass compensation is introduced to ensure that 0-200 Hz are not
+damped (without any real 3D acoustical image, however).
+*/
+static af_data_t* play(struct af_instance_s *af, af_data_t *data)
+{
+    af_hrtf_t *s = af->setup;
+    short *in = data->audio; // Input audio data
+    short *out = NULL; // Output audio data
+    short *end = in + data->len / sizeof(short); // Loop end
+    float common, left, right, diff, left_b, right_b;
+    const int dblen = s->dlbuflen, hlen = s->hrflen, blen = s->basslen;
+
+    if(AF_OK != RESIZE_LOCAL_BUFFER(af, data))
+	return NULL;
+
+    out = af->data->audio;
+
+    /* MPlayer's 5 channel layout (notation for the variable):
+     * 
+     * 0: L (LF), 1: R (RF), 2: Ls (LR), 3: Rs (RR), 4: C (CF), matrix
+     * encoded: Cs (CR)
+     * 
+     * or: L = left, C = center, R = right, F = front, R = rear
+     * 
+     * Filter notation:
+     * 
+     *      CF
+     * OF        AF
+     *      Ear->
+     * OR        AR
+     *      CR
+     * 
+     * or: C = center, A = same side, O = opposite, F = front, R = rear
+     */
+
+    while(in < end) {
+	const int k = s->cyc_pos;
+
+	update_ch(s, in, k);
+
+	/* Simulate a 7.5 ms -20 dB echo of the center channel in the
+	   front channels (like reflection from a room wall) - a kind of
+	   psycho-acoustically "cheating" to focus the center front
+	   channel, which is normally hard to be perceived as front */
+	s->lf[k] += CFECHOAMPL * s->cf[(k + CFECHODELAY) % s->dlbuflen];
+	s->rf[k] += CFECHOAMPL * s->cf[(k + CFECHODELAY) % s->dlbuflen];
+
+	/* Mixer filter matrix */
+	common = conv(dblen, hlen, s->cf, s->cf_ir, k + s->cf_o);
+	if(s->matrix_mode) {
+	    /* In matrix decoding mode, the rear channel gain must be
+	       renormalized, as there is an additional channel. */
+	    matrix_decode_cr(s, in, k);
+	    common +=
+		conv(dblen, hlen, s->cr, s->cr_ir, k + s->cr_o) *
+		M1_76DB;
+	    left    =
+		( conv(dblen, hlen, s->lf, s->af_ir, k + s->af_o) +
+		  conv(dblen, hlen, s->rf, s->of_ir, k + s->of_o) +
+		  (conv(dblen, hlen, s->lr, s->ar_ir, k + s->ar_o) +
+		   conv(dblen, hlen, s->rr, s->or_ir, k + s->or_o)) *
+		  M1_76DB + common);
+	    right   =
+		( conv(dblen, hlen, s->rf, s->af_ir, k + s->af_o) +
+		  conv(dblen, hlen, s->lf, s->of_ir, k + s->of_o) +
+		  (conv(dblen, hlen, s->rr, s->ar_ir, k + s->ar_o) +
+		   conv(dblen, hlen, s->lr, s->or_ir, k + s->or_o)) *
+		  M1_76DB + common);
+	}
+	else {
+	    left    =
+		( conv(dblen, hlen, s->lf, s->af_ir, k + s->af_o) +
+		  conv(dblen, hlen, s->rf, s->of_ir, k + s->of_o) +
+		  conv(dblen, hlen, s->lr, s->ar_ir, k + s->ar_o) +
+		  conv(dblen, hlen, s->rr, s->or_ir, k + s->or_o) +
+		  common);
+	    right   =
+		( conv(dblen, hlen, s->rf, s->af_ir, k + s->af_o) +
+		  conv(dblen, hlen, s->lf, s->of_ir, k + s->of_o) +
+		  conv(dblen, hlen, s->rr, s->ar_ir, k + s->ar_o) +
+		  conv(dblen, hlen, s->lr, s->or_ir, k + s->or_o) +
+		  common);
+	}
+
+	/* Bass compensation for the lower frequency cut of the HRTF.  A
+	   cross talk of the left and right channel is introduced to
+	   match the directional characteristics of higher frequencies.
+	   The bass will not have any real 3D perception, but that is
+	   OK. */
+	left_b  = conv(dblen, blen, s->ba_l, s->ba_ir, k);
+	right_b = conv(dblen, blen, s->ba_r, s->ba_ir, k);
+	left  += (1 - BASSCROSS) * left_b  + BASSCROSS * right_b;
+	right += (1 - BASSCROSS) * right_b + BASSCROSS * left_b;
+	/* Also mix the LFE channel (if available) */
+	if(af->data->nch >= 6) {
+	    left  += out[5] * M3_01DB;
+	    right += out[5] * M3_01DB;
+	}
+
+	/* Amplitude renormalization. */
+	left  *= AMPLNORM;
+	right *= AMPLNORM;
+
+	/* "Cheating": linear stereo expansion to amplify the 3D
+	   perception.  Note: Too much will destroy the acoustic space
+	   and may even result in headaches. */
+	diff = STEXPAND2 * (left - right);
+	out[0] = (int16_t)(left  + diff);
+	out[1] = (int16_t)(right - diff);
+
+	/* The remaining channels are not needed any more */
+	out[2] = out[3] = out[4] = 0;
+	if(af->data->nch >= 6)
+	    out[5] = 0;
+
+	/* Next sample... */
+	in = &in[data->nch];
+	out = &out[af->data->nch];
+	(s->cyc_pos)--;
+	if(s->cyc_pos < 0)
+	    s->cyc_pos += dblen;
+    }
+
+    /* Set output data */
+    data->audio = af->data->audio;
+    data->len   = (data->len * af->mul.n) / af->mul.d;
+    data->nch   = af->data->nch;
+
+    return data;
+}
+
+static int allocate(af_hrtf_t *s)
+{
+    if ((s->lf = malloc(s->dlbuflen * sizeof(float))) == NULL) return -1;
+    if ((s->rf = malloc(s->dlbuflen * sizeof(float))) == NULL) return -1;
+    if ((s->lr = malloc(s->dlbuflen * sizeof(float))) == NULL) return -1;
+    if ((s->rr = malloc(s->dlbuflen * sizeof(float))) == NULL) return -1;
+    if ((s->cf = malloc(s->dlbuflen * sizeof(float))) == NULL) return -1;
+    if ((s->cr = malloc(s->dlbuflen * sizeof(float))) == NULL) return -1;
+    if ((s->ba_l = malloc(s->dlbuflen * sizeof(float))) == NULL) return -1;
+    if ((s->ba_r = malloc(s->dlbuflen * sizeof(float))) == NULL) return -1;
+    return 0;
+}
+
+/* Allocate memory and set function pointers */
+static int open(af_instance_t* af)
+{
+    int i;
+    af_hrtf_t *s;
+    float fc;
+
+    af_msg(AF_MSG_INFO,
+	   "[hrtf] Head related impulse response (HRIR) derived from KEMAR measurement\n"
+	   "[hrtf] data by Bill Gardner <billg@media.mit.edu>\n"
+	   "[hrtf] and Keith Martin <kdm@media.mit.edu>.\n"
+	   "[hrtf] This data is Copyright 1994 by the MIT Media Laboratory.  It is\n"
+	   "[hrtf] provided free with no restrictions on use, provided the authors are\n"
+	   "[hrtf] cited when the data is used in any research or commercial application.\n"
+	   "[hrtf] URL: http://sound.media.mit.edu/KEMAR.html\n");
+
+    af->control = control;
+    af->uninit = uninit;
+    af->play = play;
+    af->mul.n = 1;
+    af->mul.d = 1;
+    af->data = calloc(1, sizeof(af_data_t));
+    af->setup = calloc(1, sizeof(af_hrtf_t));
+    if((af->data == NULL) || (af->setup == NULL))
+	return AF_ERROR;
+
+    s = af->setup;
+
+    s->dlbuflen = DELAYBUFLEN;
+    s->hrflen = HRTFFILTLEN;
+    s->basslen = BASSFILTLEN;
+
+    s->cyc_pos = s->dlbuflen - 1;
+    s->matrix_mode = 1;
+
+    if (allocate(s) != 0) {
+ 	af_msg(AF_MSG_ERROR, "[hrtf] Memory allocation error.\n");
+	return AF_ERROR;
+    }
+
+    for(i = 0; i < s->dlbuflen; i++)
+	s->lf[i] = s->rf[i] = s->lr[i] = s->rr[i] = s->cf[i] =
+	    s->cr[i] = 0;
+
+    s->lr_fwr =
+	s->rr_fwr = 0;
+
+    s->cf_ir = cf_filt + (s->cf_o = pulse_detect(cf_filt));
+    s->af_ir = af_filt + (s->af_o = pulse_detect(af_filt));
+    s->of_ir = of_filt + (s->of_o = pulse_detect(of_filt));
+    s->ar_ir = ar_filt + (s->ar_o = pulse_detect(ar_filt));
+    s->or_ir = or_filt + (s->or_o = pulse_detect(or_filt));
+    s->cr_ir = cr_filt + (s->cr_o = pulse_detect(cr_filt));
+
+    if((s->ba_ir = malloc(s->basslen * sizeof(float))) == NULL) {
+ 	af_msg(AF_MSG_ERROR, "[hrtf] Memory allocation error.\n");
+	return AF_ERROR;
+    }
+    fc = 2.0 * BASSFILTFREQ / (float)af->data->rate;
+    if(design_fir(s->basslen, s->ba_ir, &fc, LP | KAISER, 4 * M_PI) ==
+       -1) {
+	af_msg(AF_MSG_ERROR, "[hrtf] Unable to design low-pass "
+	       "filter.\n");
+	return AF_ERROR;
+    }
+    for(i = 0; i < s->basslen; i++)
+	s->ba_ir[i] *= BASSGAIN;
+    
+    return AF_OK;
+}
+
+/* Description of this filter */
+af_info_t af_info_hrtf = {
+    "HRTF Headphone",
+    "hrtf",
+    "ylai",
+    "",
+    AF_FLAGS_REENTRANT,
+    open
+};
diff --git a/libaf/af_hrtf.h b/libaf/af_hrtf.h
new file mode 100644
index 0000000000..a607622225
--- /dev/null
+++ b/libaf/af_hrtf.h
@@ -0,0 +1,476 @@
+/* Amplitude scaling factors */
+#define M17_0DB		0.1414213562
+#define M6_99DB		0.4472135955
+#define M4_77DB		0.5773502692
+#define M3_01DB		0.7071067812
+#define M1_76DB		0.8164965809
+
+#define DELAYBUFLEN	1024	/* Length of the delay buffer */
+#define HRTFFILTLEN	64	/* HRTF filter length */
+#define IRTHRESH	0.001	/* Impulse response pruning thresh. */
+
+#define AMPLNORM	M6_99DB	/* Overall amplitude renormalization */
+
+#define BASSFILTFREQ	180	/* Bass compensation filter cut (Hz) */
+#define BASSFILTLEN	193	/* Bass compensation filter length */
+#define BASSGAIN	M4_77DB	/* Bass compensation gain */
+#define BASSCROSS	0.35	/* Bass cross talk */
+
+#define CFECHODELAY	360	/* Center front echo delay (samples) */
+#define CFECHOAMPL	M17_0DB	/* Center front echo amplitude */
+
+#define STEXPAND2	0.07	/* Stereo expansion / 2 */
+
+/* Head related impulse response (HRIR) derived from KEMAR measurement
+   data by Bill Gardner <billg@media.mit.edu> and Keith Martin
+   <kdm@media.mit.edu>:
+
+   "This data is Copyright 1994 by the MIT Media Laboratory.  It is
+   provided free with no restrictions on use, provided the authors are
+   cited when the data is used in any research or commercial
+   application."
+
+   URL: http://sound.media.mit.edu/KEMAR.html
+*/
+
+/* EQUALIZED KEMAR HRIR
+
+How to generate these data:
+
+1. You need the MIT Media Lab's KEMAR data, read it into an software
+   capable of signal/time series analysis (like Mathematica, Matlab,
+   ...)
+
+2. Construct an equalizing FIR inverse filter by calculating the
+   transfer function of the front, same side impulse response, then
+   take 1 over the absolute magnitude.
+
+3. Cut the poles in the inverse filter's transfer function
+   specification by limiting the amplification to 2.5 (note, this
+   number assumes that you have correct signal processing
+   normalization of the Fourier transform).
+
+4. Design the FIR inverse filter by calculating the inverse Fourier
+   transform, then chopping the coefficients down to a reasonable
+   number (N = 15 is used here), apply the Kaiser-Bessel window (alpha
+   = 2 is used here).  Note the objective is remove the color bias
+   only (as if you are using an equalizer), _not_ to do a full inverse
+   filtering. (Note: beta = pi*alpha in other notation.)
+
+   For N = 15, alpha = 2, you should get the following impulse
+   response:
+
+    0.001001558668605168,  0.00698457265741865,  0.040453643039829436,
+    0.012230541722147855, -0.11939760844854072,  0.16468099899755967,
+   -0.30297563073747436,   1.3140211791355982,  -0.30297563073747436,
+    0.16468099899755967,  -0.11939760844854072,  0.012230541722147855,
+    0.040453643039829436,  0.00698457265741865,  0.001001558668605168
+
+5. Linearly convolve all KEMAR HRIR with this inverse filter.
+
+6. Resample from 44.1 kHz sampling frequency to 48 kHz.
+*/
+
+/* Center front (-5 degree) - not 0 degree in order to create a clear
+   front image from a finite distance */
+float cf_filt[128] = {
+   -0.00008638082319075036, 0.0003198059946385229,
+   -0.0005010631339162132, 0.0011424741331126876,
+   -0.001584220794688753, 0.001742715363246275,
+   -0.0011080796626780694, 0.0001651829990860167,
+   0.005235028337314985, 0.0035223828473357776,
+   0.010057681388431303, -0.033469432129545514,
+   0.013391253316233523, 0.004858462839827063,
+   0.08172161220103627, 0.26158596134500023,
+   -0.12420314583323326, -0.14298458356097565,
+   0.14421897280453896, -0.1635792507629016,
+   -0.02187136722480014, 0.2426863044711817,
+   0.07229814207917194, 0.0942742651913879,
+   0.29856830878076834, 0.2944146162057754,
+   -0.12122157003421209, -0.19640092165631157,
+   0.11623836502034968, -0.05794027397995521,
+   -0.34313138341973776, -0.19487516249168105,
+   0.010118993953802401, -0.09460218797710966,
+   -0.16761521117359582, 0.004154461610153861,
+   0.052768641758969316, -0.00041823982226147407,
+   0.021634960445143514, 0.07562793486871108,
+   0.08895407129506479, 0.039857755093416214,
+   0.044257936180422945, 0.061557584906101664,
+   0.015547268541895703, -0.023908191934932484,
+   0.009498030443468223, 0.03816269003221337,
+   -0.009820500607303615, -0.042003975527908084,
+   -0.03335447117311547, -0.029294510859746596,
+   -0.05212623136198511, -0.073427547153205,
+   -0.061190797824958836, -0.04620925059966413,
+   -0.04204619420702159, -0.02331915902615157,
+   0.00211481411477094, 0.00852563995740107,
+   0.008766809731743399, 0.008666632180812078,
+   0.018279202191625352, 0.02924332751289675,
+   0.022293148257836494, 0.012362146008584188,
+   0.008572582458807008, 0.006491370763597344,
+   -0.0019366944997535774, -0.006318669309634434,
+   -0.006457921690218669, -0.015050265524669974,
+   -0.02110660282616213, -0.017027809096377904,
+   -0.01651052305334348, -0.022770064150046673,
+   -0.01999875754219472, -0.012294792027337775,
+   -0.011506057031057188, -0.011448970577312903,
+   -0.004823572302580925, 0.0022451134042777883,
+   0.004145473526859826, 0.005629030064546135,
+   0.008588029213398785, 0.010092048834844231,
+   0.007182013245552008, 0.0014600979508720656,
+   -0.0038314646272511756, -0.003443901997881347,
+   -0.0029483418254804047, -0.007609357112679647,
+   -0.006518368948030822, -0.004495803701497202,
+   -0.007109113004849672, -0.008346237278084265,
+   -0.005560847336252453, -0.002993453167553188,
+   -0.005122897816824269, -0.004389782626604215,
+   -0.0010912633695218108, -0.0019712029474458835,
+   -0.005870162265802235, -0.005626159534954128,
+   -0.00027254977910844407, 0.0013794425431633785,
+   -0.0005919083190430062, -0.0007861203545416682,
+   -0.0007049560240893946, -0.0032720188494468868,
+   -0.004460645567968504, -0.0032018528193571696,
+   -0.0030579229375062105, -0.003593998902656612,
+   -0.0038032977997776445, -0.004613776010454773,
+   -0.0059796549143736845, -0.00420126194319768,
+   -0.0012374419948287222, 0.0008572699213050608,
+   0.0021490971020081094, 0.00047295283198381995,
+   -0.0009670277915884887, -0.001354440866080231,
+   -0.002962902746547851, -0.00533935813338141,
+   -0.005469203016468759, -0.004355784273189485
+};
+/* Front,   same side (30 degree) */
+float af_filt[128] = {
+   -0.004140580614755493, 0.005790934614385445,
+   0.003318916682081112, 0.014257145544366063,
+   0.007328442487127339, -0.06550381777876194,
+   0.03502225818161845, -0.013090579770708259,
+   0.2517776798694195, 0.420770489950659,
+   -0.3418854608834852, -0.24371032493696737,
+   0.04901356150030018, -0.1778083521632833,
+   0.26448004245714163, 0.23245199964546834,
+   0.033053145803936305, 0.46811222821062415,
+   0.5359265986255611, -0.011912195468533787,
+   -0.39763432601411647, -0.034482864386898314,
+   0.029445398240649626, -0.3850940407863262,
+   -0.3272328478175581, -0.14701421403616477,
+   -0.08522137400169517, -0.14936851633336035,
+   -0.09432605283433723, 0.0991200405937827,
+   0.011075012089917331, -0.0051036489980274685,
+   0.0933903289749412, 0.1344189369609565,
+   0.10507466913017807, 0.04240159324684365,
+   0.06559270110638656, 0.026984119875617524,
+   -0.03359846103238096, -0.018000197099174275,
+   0.042031818548178244, 0.03849039666888434,
+   -0.02450829674011345, -0.03407882403088576,
+   -0.029230189282961977, -0.046964865291761734,
+   -0.09458258700116245, -0.1527349330901158,
+   -0.15411577687826097, -0.08761679790956928,
+   -0.033623549089171874, -0.007204768531481949,
+   0.008273425020444852, 0.021368717994908505,
+   0.04366608267875025, 0.05660907333076205,
+   0.06775726495503939, 0.05621881735271431,
+   0.03576231950669927, 0.02500825834889175,
+   0.015423811076054601, 0.007903258334503761,
+   -0.0053873014137761945, -0.006987955469434698,
+   -0.012027972007598602, -0.025228281243816594,
+   -0.026225091797257318, -0.023809293997344882,
+   -0.03250172017712295, -0.03195696301067249,
+   -0.01784813952189948, -0.01663267233760342,
+   -0.016184530450468065, -0.011659883749357463,
+   -0.0035378511240219163, -0.0005485800790443406,
+   0.0018432660108168625, 0.011634844139907534,
+   0.018333603402051105, 0.020447379185133056,
+   0.00850783664147828, 0.0004694148911037838,
+   -0.0017047130409786676, -0.0022409152834483997,
+   -0.000860472174892845, -0.004111075059198666,
+   -0.003527843382056666, -0.009640160874903018,
+   -0.01750044574231376, -0.015613389403672443,
+   -0.010790028120953001, -0.0095313499955768,
+   -0.007469721416726809, -0.0019186578145117315,
+   -0.00014977322572890802, -0.0029803838028179728,
+   -0.006520567233727221, 0.000035015132033882596,
+   0.009245098100543752, 0.009896930052308656,
+   0.008316744929565786, 0.004575207140193997,
+   -0.0000647420103997081, -0.004502916832871627,
+   -0.004225962213251224, -0.002886014126381486,
+   -0.006416834142585976, -0.007156609995423569,
+   -0.008840274447579472, -0.01441763751386817,
+   -0.015435817484659574, -0.00924487254924743,
+   -0.0021571721940235205, 0.0028540722992305453,
+   0.00273577475088536, -0.000788412365513805,
+   -0.0032650029728365907, -0.003880217646231338,
+   -0.0035302087299613778, -0.0038531436176586246,
+   -0.0011921632190514074, -0.0020722967099011938,
+   -0.004985351145629344, -0.0042375588844648735,
+   -0.003030360463006021, -0.0014161075428041471,
+   -0.0005083025643192044, 0.00035096963769606926
+};
+/* Front,   opposite (-30 degree) */
+float of_filt[128] = {
+   -0.000013472538374193126, -0.00008048061877079751,
+   0.000043927265781258155, -0.000017931700794858892,
+   -0.000034774602476112886, -0.00009576223008735474,
+   0.0001557797638630691, -0.00018742885883751094,
+   0.00026512448626705716, -0.0001451040203319678,
+   -0.00008263233117758043, 0.0006486245853639179,
+   -0.0010631408451846698, 0.0026571994100746143,
+   0.0014179177997092787, 0.0062326502956616256,
+   -0.008194149324545333, -0.006568029415878379,
+   0.009538759710818582, 0.012309193558632693,
+   0.12336638055838955, 0.046164307101829005,
+   -0.10228706407884815, 0.04047687260345798,
+   -0.00296595313977046, -0.07057949208414134,
+   0.08172114840714612, 0.08736490764127891,
+   0.05105250431333021, 0.11627179512747428,
+   0.20717888490340705, 0.09375052213570291,
+   -0.09784374168330194, -0.010493571845901443,
+   0.053131894303891716, -0.10157443971694806,
+   -0.16264032634244974, -0.05402369511361273,
+   -0.0274403608654217, -0.09860277022495063,
+   -0.06841875821090282, -0.004434574400066223,
+   -0.0005222661652743502, -0.006231881259827263,
+   0.014410397820340159, 0.04885649512730243,
+   0.04361962569042684, 0.03399214029009391,
+   0.04961073933475931, 0.04067325604132289,
+   0.007850647519227257, 0.004564440466905299,
+   0.02257107958021618, 0.008183791928884486,
+   -0.014913479343180557, -0.018685938460856224,
+   -0.01745737397226911, -0.02327177054233603,
+   -0.03723048632685227, -0.044739390162299685,
+   -0.042651220125613766, -0.03730017561004743,
+   -0.029039465434276192, -0.01885087458914294,
+   -0.01207127752277769, -0.006779800724164512,
+   -0.001930416967444157, 0.000029454577995528385,
+   0.0013822760965755472, 0.0014799128583230202,
+   0.0002068200609199832, 0.0022254295286201083,
+   0.005143858159434566, 0.0018580542060917013,
+   -0.0019426046325146259, -0.0014464042108543495,
+   -0.0034430083560735582, -0.009692758426099499,
+   -0.011840035292593485, -0.010716508855893968,
+   -0.012939889036853034, -0.0121846427935653,
+   -0.006198503315630782, -0.0023186723099380305,
+   -0.002679872498314837, -0.003086020446226295,
+   -0.0015709623347698936, -0.0008147490468332398,
+   -0.0012384575726770983, -0.0005212877089109362,
+   0.0017707578744906142, 0.001324932723905786,
+   -0.0017023653780617696, -0.0045108927752919425,
+   -0.005422155613096912, -0.0039489323837623835,
+   -0.005295995750506547, -0.00629706566356189,
+   -0.004685732198036754, -0.0048076735568143,
+   -0.005978864279217503, -0.005928999306332966,
+   -0.004187703549017582, -0.003213999896976475,
+   -0.0028068699816073414, -0.0010889703907593833,
+   0.0003276714243495386, -0.0013015007040186994,
+   -0.003208050402434782, -0.0025115319088208545,
+   -0.0013787553006401076, -0.0018279087370218635,
+   -0.0025904836507747754, -0.002071221947222004,
+   -0.0026424212922485594, -0.0039837031817577,
+   -0.0041635566057380965, -0.004355223489150822,
+   -0.004350395332709937, -0.0036693292471930263,
+   -0.003386384394185026, -0.003972568655001128,
+   -0.004332336840023821, -0.002648767912111827,
+   -0.001384410080218114, -0.0011353792711849466,
+   -0.0013726264946164232, -0.0020075119315034313
+};
+/* Rear,   same side (135 degree) */
+float ar_filt[128] = {
+   0.004573315040810066, 0.0013592578059426913,
+   0.01553271930902704, -0.0002356117224941317,
+   -0.05746098219774702, 0.03430688963370445,
+   0.00808371687447385, 0.21893535841158596,
+   0.2984357591724814, -0.3302799746504719,
+   -0.3194029149806245, 0.21633225051331056,
+   0.24371260938097083, -0.08843705549751085,
+   0.03939684701343366, 0.45386926431114494,
+   0.07599118140753386, -0.18114706160474578,
+   0.285640624686038, 0.4049515236666218,
+   -0.05347890222071792, -0.31464359045319074,
+   -0.1033502246468194, -0.04553593949283157,
+   -0.1880747731157464, -0.13629090230626037,
+   -0.10435789106123239, -0.19818232801888755,
+   -0.16701805476330397, -0.022793111199284,
+   0.058049696762683685, 0.007048321372693906,
+   -0.002966419183225961, 0.10140569697797763,
+   0.11648999956673124, 0.05218347182779882,
+   0.028427001212735392, 0.04151900310166159,
+   -0.0006960604221423734, -0.05898623212226975,
+   -0.03801934531173312, -0.029306970535287986,
+   -0.04549125782835908, -0.0599222718506552,
+   -0.058299618975430116, -0.03765579129720727,
+   -0.03559302657499581, -0.020647901025903054,
+   -0.005720957338744348, -0.0041915732688915545,
+   -0.0011470880098346143, 0.008737404798553,
+   0.023444168098121512, 0.024204226042172663,
+   0.01894897166475026, 0.020807655257479588,
+   0.021570431128040954, 0.006800556178576289,
+   -0.009000089216921362, -0.010969824547067934,
+   -0.0033653428332822374, -0.012676936164668659,
+   -0.026739938673413587, -0.023427869194287573,
+   -0.023302007105117244, -0.023647155590533712,
+   -0.021289317515613106, -0.009120487305069884,
+   0.0009251551667728967, 0.00004285344125653763,
+   -0.00009042365479456271, 0.00022573242339446494,
+   0.00720168491586098, 0.007111875505402431,
+   0.003186514817683482, 0.00810087718334745,
+   0.012619557025922575, 0.007854726400013397,
+   -0.0024013592881066267, -0.001452457473161119,
+   -0.0025535188366093945, -0.012428911627809337,
+   -0.013729251536694145, -0.0070099675146427344,
+   -0.007165284278706593, -0.01639289295622301,
+   -0.015831795079778305, -0.007305768485523729,
+   -0.003608863157004021, -0.0032640528878698084,
+   0.0030901263998481944, 0.00749497566124848,
+   0.002515185532327241, 0.00004840875738621367,
+   0.0017596043486043966, 0.0046229941553338144,
+   0.0034259167322926096, 0.003707347634186093,
+   0.0035584806528586328, -0.0019078936035275198,
+   -0.006057343815214898, -0.0069262470468817,
+   -0.004345020728618624, -0.004177623355574794,
+   -0.005373506556122508, -0.006624933928893836,
+   -0.008679541408588839, -0.010718719681595322,
+   -0.011392246979594496, -0.007893917064389902,
+   -0.0027572935365832536, -0.00006064707149834412,
+   -0.0012512537319656323, -0.0024501501002409786,
+   -0.0022106788572895998, -0.00234124933370301,
+   -0.0008953445167066823, 0.0005393670625637734,
+   -0.00033175600142209297, -0.004023994309351289,
+   -0.008655472335784443, -0.009899957354849682,
+   -0.008664952919996412, -0.00553483124503576,
+   -0.003735336089277662, -0.002754824348643885,
+   -0.0026884314856593368, -0.004084181815125924
+};
+/* Rear,   opposite (-135 degree) */
+float or_filt[128] = {
+   0.0001220944028243897, -0.000021785381808441314,
+   5.823057988603169e-6, -0.00001217768176447613,
+   -0.00006123604397345513, 5.574117262531134e-6,
+   -0.00004935331914366778, 1.1771577934768211e-6,
+   -0.000059236211621095756, 9.503536190497286e-6,
+   -0.0001494445696103564, 0.00012248858284145305,
+   -0.0000963975321456313, 6.017905197665205e-6,
+   0.00003353395360402643, -0.0001931511015359506,
+   0.0005113536523931485, -0.0005676652619386114,
+   0.0012057159755477467, 0.0009370492250339692,
+   0.004596472288877981, -0.0018831773384237068,
+   -0.008208535225621212, 0.0038178646400751056,
+   0.008726517739105965, 0.06664363898418262,
+   0.06788684221502142, -0.04492315162807267,
+   -0.04019906311255255, 0.026203059677375153,
+   0.013678129114847544, -0.014334962223993527,
+   0.010141709596167392, 0.11559131576945537,
+   0.1586402064538425, 0.059975334707967023,
+   0.004671725963777715, 0.031498678282775874,
+   0.014338626006524587, -0.014749719448472231,
+   -0.02055508237941379, -0.05407690143992048,
+   -0.07767559836886143, -0.05029091786216801,
+   -0.030808335706574427, -0.03401958135442541,
+   -0.030520368430288967, -0.014168302104259355,
+   0.011907621259989802, 0.014286081013069,
+   0.006377467879613449, 0.018546823568277478,
+   0.028297012771618273, 0.025222339408338186,
+   0.021931611353415138, 0.019708894333646355,
+   0.01729258494072014, 0.017468204169564034,
+   0.009729094845051928, -0.002976992018531901,
+   -0.00956986166277019, -0.016125733548332074,
+   -0.02934094241442545, -0.04133767871051455,
+   -0.043536981145416466, -0.0385966307108608,
+   -0.02784453599342459, -0.018995135307247116,
+   -0.012849534096536747, -0.004437491064613308,
+   0.00028385411598204655, 0.003776874988516643,
+   0.008069432041547833, 0.008764754183751848,
+   0.008020908861878062, 0.006830351461360802,
+   0.002218330884267235, -0.0020478725582339444,
+   -0.003997428121462543, -0.007066287373515421,
+   -0.00940847412544698, -0.010938998446237963,
+   -0.011775483016151306, -0.011391103919484287,
+   -0.010586061195163017, -0.009842793078929053,
+   -0.007753202010139829, -0.00569213732353025,
+   -0.006506783349722073, -0.005346134281903736,
+   -0.003913089814898934, -0.0036091443854759727,
+   -0.0020328564301266287, 0.00017932870773467683,
+   0.0032779786679056357, 0.003969695813293966,
+   0.0020339334412434987, -0.00011345940675415259,
+   -0.0018344103399567666, -0.003556764701666365,
+   -0.004263523639408391, -0.002940568582022133,
+   -0.0034341188272627556, -0.006023399920020824,
+   -0.0077456903203677865, -0.007912219312377842,
+   -0.00625202770436523, -0.00530785086116117,
+   -0.005569722659634311, -0.004664448462594344,
+   -0.0037747773914077747, -0.004175649656985592,
+   -0.004659601521384289, -0.005008602967819641,
+   -0.004730625079902729, -0.0034039554356604146,
+   -0.0017110333873406587, -0.0006091938771510242,
+   -0.0016051679050678297, -0.003312864664007262,
+   -0.004505512715977288, -0.004152222189861692,
+   -0.003218596419678823, -0.0027277806209877343,
+   -0.001715005444317267, -0.0012589960071233749,
+   -0.001852908777923165, -0.002540339553144362
+};
+/* Center rear (180 degree) */
+float cr_filt[128] = {
+   -0.00005989110716536726, -0.00022790291829128702,
+   0.0002659166098971966, -0.0003774772716776257,
+   0.0004540309551867803, -0.000420238187386368,
+   0.00025518536450885686, 0.00028285526288953955,
+   -0.001016391007574093, 0.0028634984299063795,
+   0.0021574799687976045, 0.01035121276682072,
+   -0.010481720917298163, -0.013197198495899292,
+   0.0031928225328717195, 0.02903137843618603,
+   0.1632429772511569, 0.1047487989875262,
+   -0.10464685060623742, -0.09260196288035998,
+   -0.007514241993554443, 0.013596249226741712,
+   -0.019876166508450258, 0.1255626123599804,
+   0.3648170359521724, 0.19458249753223478,
+   -0.04434070930031298, 0.046582528121935265,
+   0.09484427347230277, -0.03137795311969644,
+   -0.10297437925363695, -0.09351091015917065,
+   -0.1129521092162064, -0.14925322995658827,
+   -0.1231466295584665, -0.06356719756705227,
+   -0.05442277895126282, -0.07568433015661316,
+   -0.023314932828602003, 0.04260950721318558,
+   0.02249026315598923, 0.02048195669571197,
+   0.05651342117268278, 0.05885038917623213,
+   0.03797102097397795, 0.011767394419953451,
+   0.00560502503429481, 0.005051125343961189,
+   -0.012925933188033823, -0.023918884651306566,
+   -0.013251659441678816, -0.010694772488866284,
+   -0.03080486448617846, -0.03661278237783158,
+   -0.0379227303416262, -0.042189005718490775,
+   -0.026595666344596286, -0.009759025956801257,
+   -0.002064986663513004, -0.002420117028098389,
+   -0.006629991977552491, 0.004619970897631026,
+   0.019450642967537877, 0.0173521119057514,
+   0.017641425439988062, 0.02270029598048491,
+   0.018976431925275348, 0.009299852902290885,
+   -0.001695039371619912, -0.00675162574265618,
+   -0.009380968871003034, -0.011208396125485165,
+   -0.01308640049201482, -0.0165636375633249,
+   -0.022004099870933345, -0.025173458684139286,
+   -0.016918759559175375, -0.00865150653575917,
+   -0.006999929082792643, -0.005454830010518988,
+   -0.0021129521131095317, 0.00018717090054046307,
+   -0.0002864344788569993, 0.0017615225381095569,
+   0.006985907557802283, 0.010577308310476465,
+   0.006466104789306027, -0.0014988738575948326,
+   -0.0039669755229277195, -0.0065156971200080235,
+   -0.009343206924192169, -0.0076430644693577495,
+   -0.004395214976600924, -0.003052735340422483,
+   -0.007019103043066595, -0.00974109267696527,
+   -0.007968015032797376, -0.007801513845528344,
+   -0.007535748903681969, -0.003543341967287925,
+   0.0015083125553729722, 0.0023345972556147025,
+   -0.0010043623069557037, -0.0025295765105203746,
+   -0.0023701840891643634, -0.0005908186035024362,
+   0.0029826252289082847, 0.004829048542117764,
+   0.004488360022902081, 0.00002643748103005408,
+   -0.0042100779212597295, -0.006170600558114495,
+   -0.007267149164680168, -0.006825522903494639,
+   -0.006899834372739123, -0.0073493916110062675,
+   -0.009554351265163382, -0.011790297433830197,
+   -0.010645796603734424, -0.0064661575394022106,
+   -0.002026743466524137, -0.0004337034584909932,
+   -0.0011172647031654614, -0.0017947816283674731,
+   -0.00255615052036616, -0.0017721562881944813,
+   -0.0002379619297227554, 0.0007130120121089036
+};