diff options
| -rw-r--r-- | utils/makehrtf.c | 1479 |
1 files changed, 740 insertions, 739 deletions
diff --git a/utils/makehrtf.c b/utils/makehrtf.c index a2638121..53ee46dd 100644 --- a/utils/makehrtf.c +++ b/utils/makehrtf.c @@ -1,739 +1,740 @@ -/**
- * HRTF utility for producing and demonstrating the process of creating an
- * OpenAL Soft compatible HRIR data set.
- *
- * It can currently make use of the 44.1 KHz diffuse and compact KEMAR HRIRs
- * provided by MIT at:
- *
- * http://sound.media.mit.edu/resources/KEMAR.html
- */
-
-#include <stdint.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <math.h>
-#include <string.h>
-
-// The sample rate of the MIT HRIR data sets.
-#define MIT_IR_RATE (44100)
-
-// The total number of used impulse responses from the MIT HRIR data sets.
-#define MIT_IR_COUNT (828)
-
-// The size (in samples) of each HRIR in the MIT data sets.
-#define MIT_IR_SIZE (128)
-
-// The total number of elevations given a step of 10 degrees.
-#define MIT_EV_COUNT (19)
-
-// The first elevation that the MIT data sets have HRIRs for.
-#define MIT_EV_START (5)
-
-// The head radius (in meters) used by the MIT data sets.
-#define MIT_RADIUS (0.09f)
-
-// The source to listener distance (in meters) used by the MIT data sets.
-#define MIT_DISTANCE (1.4f)
-
-// The resulting size (in samples) of a mininum-phase reconstructed HRIR.
-#define MIN_IR_SIZE (32)
-
-// The size (in samples) of the real cepstrum used in reconstruction. This
-// needs to be large enough to reduce inaccuracy.
-#define CEP_SIZE (8192)
-
-// The OpenAL Soft HRTF format marker. It stands for minimum-phase head
-// response protocol 00.
-#define MHR_FORMAT ("MinPHR00")
-
-typedef struct ComplexT ComplexT;
-typedef struct HrirDataT HrirDataT;
-
-// A complex number type.
-struct ComplexT {
- float mVec [2];
-};
-
-// The HRIR data definition. This can be used to add support for new HRIR
-// sources in the future.
-struct HrirDataT {
- int mIrRate,
- mIrCount,
- mIrSize,
- mEvCount,
- mEvStart;
- const int * mEvOffset,
- * mAzCount;
- float mRadius,
- mDistance,
- * mHrirs,
- * mHrtds,
- mMaxHrtd;
-};
-
-// The linear index of the first HRIR for each elevation of the MIT data set.
-static const int MIT_EV_OFFSET [MIT_EV_COUNT] = {
- 0, 1, 13, 37, 73, 118, 174, 234, 306, 378, 450, 522, 594, 654, 710, 755, 791, 815, 827
-},
-
-// The count of distinct azimuth steps for each elevation in the MIT data
-// set.
- MIT_AZ_COUNT [MIT_EV_COUNT] = {
- 1, 12, 24, 36, 45, 56, 60, 72, 72, 72, 72, 72, 60, 56, 45, 36, 24, 12, 1
-};
-
-// Performs a forward Fast Fourier Transform.
-static void FftProc (int n, const ComplexT * fftIn, ComplexT * fftOut) {
- int m2, rk, k, m;
- float a, b;
- int i;
- float wx, wy;
- int j, km2;
- float tx, ty, wyd;
-
- // Data copy and bit-reversal ordering.
- m2 = (n >> 1);
- rk = 0;
- for (k = 0; k < n; k ++) {
- fftOut [rk] . mVec [0] = fftIn [k] . mVec [0];
- fftOut [rk] . mVec [1] = fftIn [k] . mVec [1];
- if (k < (n - 1)) {
- m = m2;
- while (rk >= m) {
- rk -= m;
- m >>= 1;
- }
- rk += m;
- }
- }
- // Perform the FFT.
- m2 = 1;
- for (m = 2; m <= n; m <<= 1) {
- a = sin (M_PI / m);
- a = 2.0f * a * a;
- b = sin (2.0f * M_PI / m);
- for (i = 0; i < n; i += m) {
- wx = 1.0f;
- wy = 0.0f;
- for (k = i, j = 0; j < m2; k ++, j ++) {
- km2 = k + m2;
- tx = (wx * fftOut [km2] . mVec [0]) - (wy * fftOut [km2] . mVec [1]);
- ty = (wx * fftOut [km2] . mVec [1]) + (wy * fftOut [km2] . mVec [0]);
- fftOut [km2] . mVec [0] = fftOut [k] . mVec [0] - tx;
- fftOut [km2] . mVec [1] = fftOut [k] . mVec [1] - ty;
- fftOut [k] . mVec [0] += tx;
- fftOut [k] . mVec [1] += ty;
- wyd = (a * wy) - (b * wx);
- wx -= (a * wx) + (b * wy);
- wy -= wyd;
- }
- }
- m2 = m;
- }
-}
-
-// Performs an inverse Fast Fourier Transform.
-static void FftInvProc (int n, const ComplexT * fftIn, ComplexT * fftOut) {
- int m2, rk, k, m;
- float a, b;
- int i;
- float wx, wy;
- int j, km2;
- float tx, ty, wyd, invn;
-
- // Data copy and bit-reversal ordering.
- m2 = (n >> 1);
- rk = 0;
- for (k = 0; k < n; k ++) {
- fftOut [rk] . mVec [0] = fftIn [k] . mVec [0];
- fftOut [rk] . mVec [1] = fftIn [k] . mVec [1];
- if (k < (n - 1)) {
- m = m2;
- while (rk >= m) {
- rk -= m;
- m >>= 1;
- }
- rk += m;
- }
- }
- // Perform the IFFT.
- m2 = 1;
- for (m = 2; m <= n; m <<= 1) {
- a = sin (M_PI / m);
- a = 2.0f * a * a;
- b = -sin (2.0f * M_PI / m);
- for (i = 0; i < n; i += m) {
- wx = 1.0f;
- wy = 0.0f;
- for (k = i, j = 0; j < m2; k ++, j ++) {
- km2 = k + m2;
- tx = (wx * fftOut [km2] . mVec [0]) - (wy * fftOut [km2] . mVec [1]);
- ty = (wx * fftOut [km2] . mVec [1]) + (wy * fftOut [km2] . mVec [0]);
- fftOut [km2] . mVec [0] = fftOut [k] . mVec [0] - tx;
- fftOut [km2] . mVec [1] = fftOut [k] . mVec [1] - ty;
- fftOut [k] . mVec [0] += tx;
- fftOut [k] . mVec [1] += ty;
- wyd = (a * wy) - (b * wx);
- wx -= (a * wx) + (b * wy);
- wy -= wyd;
- }
- }
- m2 = m;
- }
- // Normalize the samples.
- invn = 1.0f / n;
- for (i = 0; i < n; i ++) {
- fftOut [i] . mVec [0] *= invn;
- fftOut [i] . mVec [1] *= invn;
- }
-}
-
-// Complex absolute value.
-static void ComplexAbs (const ComplexT * in, ComplexT * out) {
- out -> mVec [0] = sqrt ((in -> mVec [0] * in -> mVec [0]) + (in -> mVec [1] * in -> mVec [1]));
- out -> mVec [1] = 0.0f;
-}
-
-// Complex logarithm.
-static void ComplexLog (const ComplexT * in, ComplexT * out) {
- float r, t;
-
- r = sqrt ((in -> mVec [0] * in -> mVec [0]) + (in -> mVec [1] * in -> mVec [1]));
- t = atan2 (in -> mVec [1], in -> mVec [0]);
- if (t < 0.0f)
- t += 2.0f * M_PI;
- out -> mVec [0] = log (r);
- out -> mVec [1] = t;
-}
-
-// Complex exponent.
-static void ComplexExp (const ComplexT * in, ComplexT * out) {
- float e;
-
- e = exp (in -> mVec [0]);
- out -> mVec [0] = e * cos (in -> mVec [1]);
- out -> mVec [1] = e * sin (in -> mVec [1]);
-}
-
-// Calculates the real cepstrum of a given impulse response. It currently
-// uses a fixed cepstrum size. To make this more robust, it should be
-// rewritten to handle a variable size cepstrum.
-static void RealCepstrum (int irSize, const float * ir, float cep [CEP_SIZE]) {
- ComplexT in [CEP_SIZE], out [CEP_SIZE];
- int index;
-
- for (index = 0; index < irSize; index ++) {
- in [index] . mVec [0] = ir [index];
- in [index] . mVec [1] = 0.0f;
- }
- for (; index < CEP_SIZE; index ++) {
- in [index] . mVec [0] = 0.0f;
- in [index] . mVec [1] = 0.0f;
- }
- FftProc (CEP_SIZE, in, out);
- for (index = 0; index < CEP_SIZE; index ++) {
- ComplexAbs (& out [index], & out [index]);
- if (out [index] . mVec [0] < 0.000001f)
- out [index] . mVec [0] = 0.000001f;
- ComplexLog (& out [index], & in [index]);
- }
- FftInvProc (CEP_SIZE, in, out);
- for (index = 0; index < CEP_SIZE; index ++)
- cep [index] = out [index] . mVec [0];
-}
-
-// Reconstructs the minimum-phase impulse response for a given real cepstrum.
-// Like the above function, this should eventually be modified to handle a
-// variable size cepstrum.
-static void MinimumPhase (const float cep [CEP_SIZE], int irSize, float * mpIr) {
- ComplexT in [CEP_SIZE], out [CEP_SIZE];
- int index;
-
- in [0] . mVec [0] = cep [0];
- for (index = 1; index < (CEP_SIZE / 2); index ++)
- in [index] . mVec [0] = 2.0f * cep [index];
- if ((CEP_SIZE % 2) != 1) {
- in [index] . mVec [0] = cep [index];
- index ++;
- }
- for (; index < CEP_SIZE; index ++)
- in [index] . mVec [0] = 0.0f;
- for (index = 0; index < CEP_SIZE; index ++)
- in [index] . mVec [1] = 0.0f;
- FftProc (CEP_SIZE, in, out);
- for (index = 0; index < CEP_SIZE; index ++)
- ComplexExp (& out [index], & in [index]);
- FftInvProc (CEP_SIZE, in, out);
- for (index = 0; index < irSize; index ++)
- mpIr [index] = out [index] . mVec [0];
-}
-
-// Calculate the left-ear time delay using a spherical head model.
-static float CalcLTD (float ev, float az, float rad, float dist) {
- float azp, dlp, l, al;
-
- azp = asin (cos (ev) * sin (az));
- dlp = sqrt ((dist * dist) + (rad * rad) + (2.0f * dist * rad * sin (azp)));
- l = sqrt ((dist * dist) - (rad * rad));
- al = (0.5f * M_PI) + azp;
- if (dlp > l)
- dlp = l + (rad * (al - acos (rad / dist)));
- return (dlp / 343.3f);
-}
-
-// Read a 16-bit little-endian integer from a file and convert it to a 32-bit
-// floating-point value in the range of -1.0 to 1.0.
-static int ReadInt16LeAsFloat32 (const char * fileName, FILE * fp, float * val) {
- uint8_t vb [2];
- uint16_t vw;
-
- if (fread (vb, 1, sizeof (vb), fp) != sizeof (vb)) {
- fclose (fp);
- fprintf (stderr, "Error reading from file, '%s'.\n", fileName);
- return (0);
- }
- vw = (((uint16_t) vb [1]) << 8) | vb [0];
- (* val) = ((int16_t) vw) / 32768.0f;
- return (1);
-}
-
-// Write a string to a file.
-static int WriteString (const char * val, const char * fileName, FILE * fp) {
- size_t len;
-
- len = strlen (val);
- if (fwrite (val, 1, len, fp) != len) {
- fclose (fp);
- fprintf (stderr, "Error writing to file, '%s'.\n", fileName);
- return (0);
- }
- return (1);
-}
-
-// Write a 32-bit floating-point value in the range of -1.0 to 1.0 to a file
-// as a 16-bit little-endian integer.
-static int WriteFloat32AsInt16Le (float val, const char * fileName, FILE * fp) {
- int16_t vw;
- uint8_t vb [2];
-
- vw = (short) round (32767.0f * val);
- vb [0] = vw & 0x00FF;
- vb [1] = (vw >> 8) & 0x00FF;
- if (fwrite (vb, 1, sizeof (vb), fp) != sizeof (vb)) {
- fclose (fp);
- fprintf (stderr, "Error writing to file, '%s'.\n", fileName);
- return (0);
- }
- return (1);
-}
-
-// Write a 32-bit little-endian unsigned integer to a file.
-static int WriteUInt32Le (uint32_t val, const char * fileName, FILE * fp) {
- uint8_t vb [4];
-
- vb [0] = val & 0x000000FF;
- vb [1] = (val >> 8) & 0x000000FF;
- vb [2] = (val >> 16) & 0x000000FF;
- vb [3] = (val >> 24) & 0x000000FF;
- if (fwrite (vb, 1, sizeof (vb), fp) != sizeof (vb)) {
- fclose (fp);
- fprintf (stderr, "Error writing to file, '%s'.\n", fileName);
- return (0);
- }
- return (1);
-}
-
-// Write a 16-bit little-endian unsigned integer to a file.
-static int WriteUInt16Le (uint16_t val, const char * fileName, FILE * fp) {
- uint8_t vb [2];
-
- vb [0] = val & 0x00FF;
- vb [1] = (val >> 8) & 0x00FF;
- if (fwrite (vb, 1, sizeof (vb), fp) != sizeof (vb)) {
- fclose (fp);
- fprintf (stderr, "Error writing to file, '%s'.\n", fileName);
- return (0);
- }
- return (1);
-}
-
-// Write an 8-bit unsigned integer to a file.
-static int WriteUInt8 (uint8_t val, const char * fileName, FILE * fp) {
- if (fwrite (& val, 1, sizeof (val), fp) != sizeof (val)) {
- fclose (fp);
- fprintf (stderr, "Error writing to file, '%s'.\n", fileName);
- return (0);
- }
- return (1);
-}
-
-// Load the MIT HRIRs. This loads the entire diffuse or compact set starting
-// counter-clockwise up at the bottom elevation and clockwise at the forward
-// azimuth.
-static int LoadMitHrirs (const char * baseName, HrirDataT * hData) {
- const int EV_ANGLE [MIT_EV_COUNT] = {
- -90, -80, -70, -60, -50, -40, -30, -20, -10, 0, 10, 20, 30, 40, 50, 60, 70, 80, 90
- };
- int e, a;
- char fileName [1024];
- FILE * fp = NULL;
- int j0, j1, i;
- float s;
-
- for (e = MIT_EV_START; e < MIT_EV_COUNT; e ++) {
- for (a = 0; a < MIT_AZ_COUNT [e]; a ++) {
- // The data packs the first 180 degrees in the left channel, and
- // the last 180 degrees in the right channel.
- if (round ((360.0f / MIT_AZ_COUNT [e]) * a) > 180.0f)
- break;
- // Determine which file to open.
- snprintf (fileName, 1023, "%s%d/H%de%03da.wav", baseName, EV_ANGLE [e], EV_ANGLE [e], (int) round ((360.0f / MIT_AZ_COUNT [e]) * a));
- if ((fp = fopen (fileName, "rb")) == NULL) {
- fprintf (stderr, "Could not open file, '%s'.\n", fileName);
- return (0);
- }
- // Assuming they have not changed format, skip the .WAV header.
- fseek (fp, 44, SEEK_SET);
- // Map the left and right channels to their appropriate azimuth
- // offsets.
- j0 = (MIT_EV_OFFSET [e] + a) * MIT_IR_SIZE;
- j1 = (MIT_EV_OFFSET [e] + ((MIT_AZ_COUNT [e] - a) % MIT_AZ_COUNT [e])) * MIT_IR_SIZE;
- // Read in the data, converting it to floating-point.
- for (i = 0; i < MIT_IR_SIZE; i ++) {
- if (! ReadInt16LeAsFloat32 (fileName, fp, & s))
- return (0);
- hData -> mHrirs [j0 + i] = s;
- if (! ReadInt16LeAsFloat32 (fileName, fp, & s))
- return (0);
- hData -> mHrirs [j1 + i] = s;
- }
- fclose (fp);
- }
- }
- return (1);
-}
-
-// Performs the minimum phase reconstruction for a given HRIR data set. The
-// cepstrum size should be made configureable at some point in the future.
-static void ReconstructHrirs (int minIrSize, HrirDataT * hData) {
- int start, end, step, j;
- float cep [CEP_SIZE];
-
- start = hData -> mEvOffset [hData -> mEvStart];
- end = hData -> mIrCount;
- step = hData -> mIrSize;
- for (j = start; j < end; j ++) {
- RealCepstrum (step, & hData -> mHrirs [j * step], cep);
- MinimumPhase (cep, minIrSize, & hData -> mHrirs [j * minIrSize]);
- }
- hData -> mIrSize = minIrSize;
-}
-
-// Renormalize the entire HRIR data set, and attenutate it slightly.
-static void RenormalizeHrirs (const HrirDataT * hData) {
- int step, start, end;
- float norm;
- int j, i;
-
- step = hData -> mIrSize;
- start = hData -> mEvOffset [hData -> mEvStart] * step;
- end = hData -> mIrCount * step;
- norm = 0.0f;
- for (j = start; j < end; j += step) {
- for (i = 0; i < step; i ++) {
- if (fabs (hData -> mHrirs [j + i]) > norm)
- norm = fabs (hData -> mHrirs [j + i]);
- }
- }
- if (norm > 0.000001f)
- norm = 1.0f / norm;
- norm *= 0.95f;
- for (j = start; j < end; j += step) {
- for (i = 0; i < step; i ++)
- hData -> mHrirs [j + i] *= norm;
- }
-}
-
-// Given an elevation offset and azimuth, calculates two offsets for
-// addressing the HRIRs buffer and their interpolation factor.
-static void CalcAzIndices (const HrirDataT * hData, int oi, float az, int * j0, int * j1, float * jf) {
- int ai;
-
- az = fmod ((2.0f * M_PI) + az, 2.0f * M_PI) * hData -> mAzCount [oi] / (2.0f * M_PI);
- ai = (int) az;
- az -= ai;
- (* j0) = hData -> mEvOffset [oi] + ai;
- (* j1) = hData -> mEvOffset [oi] + ((ai + 1) % hData -> mAzCount [oi]);
- (* jf) = az;
-}
-
-// Perform a linear interpolation.
-static float Lerp (float a, float b, float f) {
- return (a + (f * (b - a)));
-}
-
-// Attempt to synthesize any missing HRIRs at the bottom elevations. Right
-// now this just blends the lowest elevation HRIRs together and applies some
-// attenuates and high frequency damping. It's not a realistic model to use,
-// but it is simple.
-static void SynthesizeHrirs (HrirDataT * hData) {
- int step, oi, i, a, j, e;
- float of;
- int j0, j1;
- float jf;
- float lp [4], s0, s1;
-
- if (hData -> mEvStart <= 0)
- return;
- step = hData -> mIrSize;
- oi = hData -> mEvStart;
- for (i = 0; i < step; i ++)
- hData -> mHrirs [i] = 0.0f;
- for (a = 0; a < hData -> mAzCount [oi]; a ++) {
- j = (hData -> mEvOffset [oi] + a) * step;
- for (i = 0; i < step; i ++)
- hData -> mHrirs [i] += hData -> mHrirs [j + i] / hData -> mAzCount [oi];
- }
- for (e = 1; e < hData -> mEvStart; e ++) {
- of = ((float) e) / hData -> mEvStart;
- for (a = 0; a < hData -> mAzCount [e]; a ++) {
- j = (hData -> mEvOffset [e] + a) * step;
- CalcAzIndices (hData, oi, a * 2.0f * M_PI / hData -> mAzCount [e], & j0, & j1, & jf);
- j0 *= step;
- j1 *= step;
- lp [0] = 0.0f;
- lp [1] = 0.0f;
- lp [2] = 0.0f;
- lp [3] = 0.0f;
- for (i = 0; i < step; i ++) {
- s0 = hData -> mHrirs [i];
- s1 = Lerp (hData -> mHrirs [j0 + i], hData -> mHrirs [j1 + i], jf);
- s0 = Lerp (s0, s1, of);
- lp [0] = Lerp (s0, lp [0], 0.15f - (0.15f * of));
- lp [1] = Lerp (lp [0], lp [1], 0.15f - (0.15f * of));
- lp [2] = Lerp (lp [1], lp [2], 0.15f - (0.15f * of));
- lp [3] = Lerp (lp [2], lp [3], 0.15f - (0.15f * of));
- hData -> mHrirs [j + i] = lp [3];
- }
- }
- }
- lp [0] = 0.0f;
- lp [1] = 0.0f;
- lp [2] = 0.0f;
- lp [3] = 0.0f;
- for (i = 0; i < step; i ++) {
- s0 = hData -> mHrirs [i];
- lp [0] = Lerp (s0, lp [0], 0.15f);
- lp [1] = Lerp (lp [0], lp [1], 0.15f);
- lp [2] = Lerp (lp [1], lp [2], 0.15f);
- lp [3] = Lerp (lp [2], lp [3], 0.15f);
- hData -> mHrirs [i] = lp [3];
- }
- hData -> mEvStart = 0;
-}
-
-// Calculate the effective head-related time delays for the each HRIR, now
-// that they are minimum-phase.
-static void CalculateHrtds (HrirDataT * hData) {
- float minHrtd, maxHrtd;
- int e, a, j;
- float t;
-
- minHrtd = 1000.0f;
- maxHrtd = -1000.0f;
- for (e = 0; e < hData -> mEvCount; e ++) {
- for (a = 0; a < hData -> mAzCount [e]; a ++) {
- j = hData -> mEvOffset [e] + a;
- t = CalcLTD ((-90.0f + (e * 180.0f / (hData -> mEvCount - 1))) * M_PI / 180.0f,
- (a * 360.0f / hData -> mAzCount [e]) * M_PI / 180.0f,
- hData -> mRadius, hData -> mDistance);
- hData -> mHrtds [j] = t;
- if (t > maxHrtd)
- maxHrtd = t;
- if (t < minHrtd)
- minHrtd = t;
- }
- }
- maxHrtd -= minHrtd;
- for (j = 0; j < hData -> mIrCount; j ++)
- hData -> mHrtds [j] -= minHrtd;
- hData -> mMaxHrtd = maxHrtd;
-}
-
-// Save the OpenAL Soft HRTF data set.
-static int SaveMhr (const HrirDataT * hData, const char * fileName) {
- FILE * fp = NULL;
- int e, step, end, j, i;
-
- if ((fp = fopen (fileName, "wb")) == NULL) {
- fprintf (stderr, "Could not create file, '%s'.\n", fileName);
- return (0);
- }
- if (! WriteString (MHR_FORMAT, fileName, fp))
- return (0);
- if (! WriteUInt32Le ((uint32_t) hData -> mIrRate, fileName, fp))
- return (0);
- if (! WriteUInt16Le ((uint16_t) hData -> mIrCount, fileName, fp))
- return (0);
- if (! WriteUInt16Le ((uint16_t) hData -> mIrSize, fileName, fp))
- return (0);
- if (! WriteUInt8 ((uint8_t) hData -> mEvCount, fileName, fp))
- return (0);
- for (e = 0; e < hData -> mEvCount; e ++) {
- if (! WriteUInt16Le ((uint16_t) hData -> mEvOffset [e], fileName, fp))
- return (0);
- }
- step = hData -> mIrSize;
- end = hData -> mIrCount * step;
- for (j = 0; j < end; j += step) {
- for (i = 0; i < step; i ++) {
- if (! WriteFloat32AsInt16Le (hData -> mHrirs [j + i], fileName, fp))
- return (0);
- }
- }
- for (j = 0; j < hData -> mIrCount; j ++) {
- i = (int) round (44100.0f * hData -> mHrtds [j]);
- if (i > 127)
- i = 127;
- if (! WriteUInt8 ((uint8_t) i, fileName, fp))
- return (0);
- }
- fclose (fp);
- return (1);
-}
-
-// Save the OpenAL Soft built-in table.
-static int SaveTab (const HrirDataT * hData, const char * fileName) {
- FILE * fp = NULL;
- int step, end, j, i;
- char text [16];
-
- if ((fp = fopen (fileName, "wb")) == NULL) {
- fprintf (stderr, "Could not create file, '%s'.\n", fileName);
- return (0);
- }
- if (! WriteString ("/* This data is Copyright 1994 by the MIT Media Laboratory. It is provided free\n"
- " * with no restrictions on use, provided the authors are cited when the data is\n"
- " * used in any research or commercial application. */\n"
- "/* Bill Gardner <[email protected]> and Keith Martin <[email protected]> */\n"
- "\n"
- " /* HRIR Coefficients */\n"
- " {\n", fileName, fp))
- return (0);
- step = hData -> mIrSize;
- end = hData -> mIrCount * step;
- for (j = 0; j < end; j += step) {
- if (! WriteString (" { ", fileName, fp))
- return (0);
- for (i = 0; i < step; i ++) {
- snprintf (text, 15, "%+d, ", (int) round (32767.0f * hData -> mHrirs [j + i]));
- if (! WriteString (text, fileName, fp))
- return (0);
- }
- if (! WriteString ("},\n", fileName, fp))
- return (0);
- }
- if (! WriteString (" },\n"
- "\n"
- " /* HRIR Delays */\n"
- " { ", fileName, fp))
- return (0);
- for (j = 0; j < hData -> mIrCount; j ++) {
- snprintf (text, 15, "%d, ", (int) round (44100.0f * hData -> mHrtds [j]));
- if (! WriteString (text, fileName, fp))
- return (0);
- }
- if (! WriteString ("}\n", fileName, fp))
- return (0);
- fclose (fp);
- return (1);
-}
-
-// Loads and processes an MIT data set. At present, the HRIR and HRTD data
-// is loaded and processed in a static buffer. That should change to using
-// heap allocated memory in the future. A cleanup function will then be
-// required.
-static int MakeMit(const char *baseInName, HrirDataT *hData)
-{
- static float hrirs[MIT_IR_COUNT * MIT_IR_SIZE];
- static float hrtds[MIT_IR_COUNT];
-
- hData->mIrRate = MIT_IR_RATE;
- hData->mIrCount = MIT_IR_COUNT;
- hData->mIrSize = MIT_IR_SIZE;
- hData->mEvCount = MIT_EV_COUNT;
- hData->mEvStart = MIT_EV_START;
- hData->mEvOffset = MIT_EV_OFFSET;
- hData->mAzCount = MIT_AZ_COUNT;
- hData->mRadius = MIT_RADIUS;
- hData->mDistance = MIT_DISTANCE;
- hData->mHrirs = hrirs;
- hData->mHrtds = hrtds;
- fprintf(stderr, "Loading base HRIR data...\n");
- if(!LoadMitHrirs(baseInName, hData))
- return 0;
- fprintf(stderr, "Performing minimum phase reconstruction and truncation...\n");
- ReconstructHrirs(MIN_IR_SIZE, hData);
- fprintf(stderr, "Renormalizing minimum phase HRIR data...\n");
- RenormalizeHrirs(hData);
- fprintf(stderr, "Synthesizing missing elevations...\n");
- SynthesizeHrirs(hData);
- fprintf(stderr, "Calculating impulse delays...\n");
- CalculateHrtds(hData);
- return 1;
-}
-
-// Simple dispatch. Provided a command, the path to the MIT set of choice,
-// and an optional output filename, this will produce an OpenAL Soft
-// compatible HRTF set in the chosen format.
-int main(int argc, char *argv[])
-{
- char baseName[1024];
- const char *outName = NULL;
- HrirDataT hData;
-
- if(argc < 3 || strcmp(argv [1], "-h") == 0 || strcmp (argv [1], "--help") == 0)
- {
- fprintf(stderr, "Usage: %s <command> <path of MIT set> [ <output file> ]\n\n", argv[0]);
- fprintf(stderr, "Commands:\n");
- fprintf(stderr, " -m, --make-mhr Makes an OpenAL Soft compatible HRTF data set.\n");
- fprintf(stderr, " Defaults output to: ./oal_soft_hrtf_44100.mhr\n");
- fprintf(stderr, " -t, --make-tab Makes the built-in table used when compiling OpenAL Soft.\n");
- fprintf(stderr, " Defaults output to: ./hrtf_tables.inc\n");
- fprintf(stderr, " -h, --help Displays this help information.\n");
- return 0;
- }
-
- snprintf(baseName, sizeof(baseName), "%s/elev", argv[2]);
- if(strcmp(argv[1], "-m") == 0 || strcmp(argv[1], "--make-mhr") == 0)
- {
- if(argc > 3)
- outName = argv[3];
- else
- outName = "./oal_soft_hrtf_44100.mhr";
- if(!MakeMit(baseName, &hData))
- return -1;
- fprintf(stderr, "Creating data set file...\n");
- if(!SaveMhr(&hData, outName))
- return -1;
- }
- else if(strcmp(argv[1], "-t") == 0 || strcmp(argv[1], "--make-tab") == 0)
- {
- if(argc > 3)
- outName = argv[3];
- else
- outName = "./hrtf_tables.inc";
- if(!MakeMit(baseName, &hData))
- return -1;
- fprintf(stderr, "Creating table file...\n");
- if(!SaveTab(&hData, outName))
- return -1;
- }
- else
- {
- fprintf(stderr, "Invalid command '%s'\n", argv[1]);
- return -1;
- }
- fprintf(stderr, "Done.\n");
- return 0;
-}
+/** + * HRTF utility for producing and demonstrating the process of creating an + * OpenAL Soft compatible HRIR data set. + * + * It can currently make use of the 44.1 KHz diffuse and compact KEMAR HRIRs + * provided by MIT at: + * + * http://sound.media.mit.edu/resources/KEMAR.html + */ + +#include <stdio.h> +#include <stdlib.h> +#include <math.h> +#include <string.h> + +#include "AL/al.h" + +// The sample rate of the MIT HRIR data sets. +#define MIT_IR_RATE (44100) + +// The total number of used impulse responses from the MIT HRIR data sets. +#define MIT_IR_COUNT (828) + +// The size (in samples) of each HRIR in the MIT data sets. +#define MIT_IR_SIZE (128) + +// The total number of elevations given a step of 10 degrees. +#define MIT_EV_COUNT (19) + +// The first elevation that the MIT data sets have HRIRs for. +#define MIT_EV_START (5) + +// The head radius (in meters) used by the MIT data sets. +#define MIT_RADIUS (0.09f) + +// The source to listener distance (in meters) used by the MIT data sets. +#define MIT_DISTANCE (1.4f) + +// The resulting size (in samples) of a mininum-phase reconstructed HRIR. +#define MIN_IR_SIZE (32) + +// The size (in samples) of the real cepstrum used in reconstruction. This +// needs to be large enough to reduce inaccuracy. +#define CEP_SIZE (8192) + +// The OpenAL Soft HRTF format marker. It stands for minimum-phase head +// response protocol 00. +#define MHR_FORMAT ("MinPHR00") + +typedef struct ComplexT ComplexT; +typedef struct HrirDataT HrirDataT; + +// A complex number type. +struct ComplexT { + float mVec [2]; +}; + +// The HRIR data definition. This can be used to add support for new HRIR +// sources in the future. +struct HrirDataT { + int mIrRate, + mIrCount, + mIrSize, + mEvCount, + mEvStart; + const int * mEvOffset, + * mAzCount; + float mRadius, + mDistance, + * mHrirs, + * mHrtds, + mMaxHrtd; +}; + +// The linear index of the first HRIR for each elevation of the MIT data set. +static const int MIT_EV_OFFSET [MIT_EV_COUNT] = { + 0, 1, 13, 37, 73, 118, 174, 234, 306, 378, 450, 522, 594, 654, 710, 755, 791, 815, 827 +}, + +// The count of distinct azimuth steps for each elevation in the MIT data +// set. + MIT_AZ_COUNT [MIT_EV_COUNT] = { + 1, 12, 24, 36, 45, 56, 60, 72, 72, 72, 72, 72, 60, 56, 45, 36, 24, 12, 1 +}; + +// Performs a forward Fast Fourier Transform. +static void FftProc (int n, const ComplexT * fftIn, ComplexT * fftOut) { + int m2, rk, k, m; + float a, b; + int i; + float wx, wy; + int j, km2; + float tx, ty, wyd; + + // Data copy and bit-reversal ordering. + m2 = (n >> 1); + rk = 0; + for (k = 0; k < n; k ++) { + fftOut [rk] . mVec [0] = fftIn [k] . mVec [0]; + fftOut [rk] . mVec [1] = fftIn [k] . mVec [1]; + if (k < (n - 1)) { + m = m2; + while (rk >= m) { + rk -= m; + m >>= 1; + } + rk += m; + } + } + // Perform the FFT. + m2 = 1; + for (m = 2; m <= n; m <<= 1) { + a = sin (M_PI / m); + a = 2.0f * a * a; + b = sin (2.0f * M_PI / m); + for (i = 0; i < n; i += m) { + wx = 1.0f; + wy = 0.0f; + for (k = i, j = 0; j < m2; k ++, j ++) { + km2 = k + m2; + tx = (wx * fftOut [km2] . mVec [0]) - (wy * fftOut [km2] . mVec [1]); + ty = (wx * fftOut [km2] . mVec [1]) + (wy * fftOut [km2] . mVec [0]); + fftOut [km2] . mVec [0] = fftOut [k] . mVec [0] - tx; + fftOut [km2] . mVec [1] = fftOut [k] . mVec [1] - ty; + fftOut [k] . mVec [0] += tx; + fftOut [k] . mVec [1] += ty; + wyd = (a * wy) - (b * wx); + wx -= (a * wx) + (b * wy); + wy -= wyd; + } + } + m2 = m; + } +} + +// Performs an inverse Fast Fourier Transform. +static void FftInvProc (int n, const ComplexT * fftIn, ComplexT * fftOut) { + int m2, rk, k, m; + float a, b; + int i; + float wx, wy; + int j, km2; + float tx, ty, wyd, invn; + + // Data copy and bit-reversal ordering. + m2 = (n >> 1); + rk = 0; + for (k = 0; k < n; k ++) { + fftOut [rk] . mVec [0] = fftIn [k] . mVec [0]; + fftOut [rk] . mVec [1] = fftIn [k] . mVec [1]; + if (k < (n - 1)) { + m = m2; + while (rk >= m) { + rk -= m; + m >>= 1; + } + rk += m; + } + } + // Perform the IFFT. + m2 = 1; + for (m = 2; m <= n; m <<= 1) { + a = sin (M_PI / m); + a = 2.0f * a * a; + b = -sin (2.0f * M_PI / m); + for (i = 0; i < n; i += m) { + wx = 1.0f; + wy = 0.0f; + for (k = i, j = 0; j < m2; k ++, j ++) { + km2 = k + m2; + tx = (wx * fftOut [km2] . mVec [0]) - (wy * fftOut [km2] . mVec [1]); + ty = (wx * fftOut [km2] . mVec [1]) + (wy * fftOut [km2] . mVec [0]); + fftOut [km2] . mVec [0] = fftOut [k] . mVec [0] - tx; + fftOut [km2] . mVec [1] = fftOut [k] . mVec [1] - ty; + fftOut [k] . mVec [0] += tx; + fftOut [k] . mVec [1] += ty; + wyd = (a * wy) - (b * wx); + wx -= (a * wx) + (b * wy); + wy -= wyd; + } + } + m2 = m; + } + // Normalize the samples. + invn = 1.0f / n; + for (i = 0; i < n; i ++) { + fftOut [i] . mVec [0] *= invn; + fftOut [i] . mVec [1] *= invn; + } +} + +// Complex absolute value. +static void ComplexAbs (const ComplexT * in, ComplexT * out) { + out -> mVec [0] = sqrt ((in -> mVec [0] * in -> mVec [0]) + (in -> mVec [1] * in -> mVec [1])); + out -> mVec [1] = 0.0f; +} + +// Complex logarithm. +static void ComplexLog (const ComplexT * in, ComplexT * out) { + float r, t; + + r = sqrt ((in -> mVec [0] * in -> mVec [0]) + (in -> mVec [1] * in -> mVec [1])); + t = atan2 (in -> mVec [1], in -> mVec [0]); + if (t < 0.0f) + t += 2.0f * M_PI; + out -> mVec [0] = log (r); + out -> mVec [1] = t; +} + +// Complex exponent. +static void ComplexExp (const ComplexT * in, ComplexT * out) { + float e; + + e = exp (in -> mVec [0]); + out -> mVec [0] = e * cos (in -> mVec [1]); + out -> mVec [1] = e * sin (in -> mVec [1]); +} + +// Calculates the real cepstrum of a given impulse response. It currently +// uses a fixed cepstrum size. To make this more robust, it should be +// rewritten to handle a variable size cepstrum. +static void RealCepstrum (int irSize, const float * ir, float cep [CEP_SIZE]) { + ComplexT in [CEP_SIZE], out [CEP_SIZE]; + int index; + + for (index = 0; index < irSize; index ++) { + in [index] . mVec [0] = ir [index]; + in [index] . mVec [1] = 0.0f; + } + for (; index < CEP_SIZE; index ++) { + in [index] . mVec [0] = 0.0f; + in [index] . mVec [1] = 0.0f; + } + FftProc (CEP_SIZE, in, out); + for (index = 0; index < CEP_SIZE; index ++) { + ComplexAbs (& out [index], & out [index]); + if (out [index] . mVec [0] < 0.000001f) + out [index] . mVec [0] = 0.000001f; + ComplexLog (& out [index], & in [index]); + } + FftInvProc (CEP_SIZE, in, out); + for (index = 0; index < CEP_SIZE; index ++) + cep [index] = out [index] . mVec [0]; +} + +// Reconstructs the minimum-phase impulse response for a given real cepstrum. +// Like the above function, this should eventually be modified to handle a +// variable size cepstrum. +static void MinimumPhase (const float cep [CEP_SIZE], int irSize, float * mpIr) { + ComplexT in [CEP_SIZE], out [CEP_SIZE]; + int index; + + in [0] . mVec [0] = cep [0]; + for (index = 1; index < (CEP_SIZE / 2); index ++) + in [index] . mVec [0] = 2.0f * cep [index]; + if ((CEP_SIZE % 2) != 1) { + in [index] . mVec [0] = cep [index]; + index ++; + } + for (; index < CEP_SIZE; index ++) + in [index] . mVec [0] = 0.0f; + for (index = 0; index < CEP_SIZE; index ++) + in [index] . mVec [1] = 0.0f; + FftProc (CEP_SIZE, in, out); + for (index = 0; index < CEP_SIZE; index ++) + ComplexExp (& out [index], & in [index]); + FftInvProc (CEP_SIZE, in, out); + for (index = 0; index < irSize; index ++) + mpIr [index] = out [index] . mVec [0]; +} + +// Calculate the left-ear time delay using a spherical head model. +static float CalcLTD (float ev, float az, float rad, float dist) { + float azp, dlp, l, al; + + azp = asin (cos (ev) * sin (az)); + dlp = sqrt ((dist * dist) + (rad * rad) + (2.0f * dist * rad * sin (azp))); + l = sqrt ((dist * dist) - (rad * rad)); + al = (0.5f * M_PI) + azp; + if (dlp > l) + dlp = l + (rad * (al - acos (rad / dist))); + return (dlp / 343.3f); +} + +// Read a 16-bit little-endian integer from a file and convert it to a 32-bit +// floating-point value in the range of -1.0 to 1.0. +static int ReadInt16LeAsFloat32 (const char * fileName, FILE * fp, float * val) { + ALubyte vb [2]; + ALushort vw; + + if (fread (vb, 1, sizeof (vb), fp) != sizeof (vb)) { + fclose (fp); + fprintf (stderr, "Error reading from file, '%s'.\n", fileName); + return (0); + } + vw = (((unsigned short) vb [1]) << 8) | vb [0]; + (* val) = ((short) vw) / 32768.0f; + return (1); +} + +// Write a string to a file. +static int WriteString (const char * val, const char * fileName, FILE * fp) { + size_t len; + + len = strlen (val); + if (fwrite (val, 1, len, fp) != len) { + fclose (fp); + fprintf (stderr, "Error writing to file, '%s'.\n", fileName); + return (0); + } + return (1); +} + +// Write a 32-bit floating-point value in the range of -1.0 to 1.0 to a file +// as a 16-bit little-endian integer. +static int WriteFloat32AsInt16Le (float val, const char * fileName, FILE * fp) { + ALshort vw; + ALubyte vb [2]; + + vw = (short) round (32767.0f * val); + vb [0] = vw & 0x00FF; + vb [1] = (vw >> 8) & 0x00FF; + if (fwrite (vb, 1, sizeof (vb), fp) != sizeof (vb)) { + fclose (fp); + fprintf (stderr, "Error writing to file, '%s'.\n", fileName); + return (0); + } + return (1); +} + +// Write a 32-bit little-endian unsigned integer to a file. +static int WriteUInt32Le (ALuint val, const char * fileName, FILE * fp) { + ALubyte vb [4]; + + vb [0] = val & 0x000000FF; + vb [1] = (val >> 8) & 0x000000FF; + vb [2] = (val >> 16) & 0x000000FF; + vb [3] = (val >> 24) & 0x000000FF; + if (fwrite (vb, 1, sizeof (vb), fp) != sizeof (vb)) { + fclose (fp); + fprintf (stderr, "Error writing to file, '%s'.\n", fileName); + return (0); + } + return (1); +} + +// Write a 16-bit little-endian unsigned integer to a file. +static int WriteUInt16Le (ALushort val, const char * fileName, FILE * fp) { + ALubyte vb [2]; + + vb [0] = val & 0x00FF; + vb [1] = (val >> 8) & 0x00FF; + if (fwrite (vb, 1, sizeof (vb), fp) != sizeof (vb)) { + fclose (fp); + fprintf (stderr, "Error writing to file, '%s'.\n", fileName); + return (0); + } + return (1); +} + +// Write an 8-bit unsigned integer to a file. +static int WriteUInt8 (ALubyte val, const char * fileName, FILE * fp) { + if (fwrite (& val, 1, sizeof (val), fp) != sizeof (val)) { + fclose (fp); + fprintf (stderr, "Error writing to file, '%s'.\n", fileName); + return (0); + } + return (1); +} + +// Load the MIT HRIRs. This loads the entire diffuse or compact set starting +// counter-clockwise up at the bottom elevation and clockwise at the forward +// azimuth. +static int LoadMitHrirs (const char * baseName, HrirDataT * hData) { + const int EV_ANGLE [MIT_EV_COUNT] = { + -90, -80, -70, -60, -50, -40, -30, -20, -10, 0, 10, 20, 30, 40, 50, 60, 70, 80, 90 + }; + int e, a; + char fileName [1024]; + FILE * fp = NULL; + int j0, j1, i; + float s; + + for (e = MIT_EV_START; e < MIT_EV_COUNT; e ++) { + for (a = 0; a < MIT_AZ_COUNT [e]; a ++) { + // The data packs the first 180 degrees in the left channel, and + // the last 180 degrees in the right channel. + if (round ((360.0f / MIT_AZ_COUNT [e]) * a) > 180.0f) + break; + // Determine which file to open. + snprintf (fileName, 1023, "%s%d/H%de%03da.wav", baseName, EV_ANGLE [e], EV_ANGLE [e], (int) round ((360.0f / MIT_AZ_COUNT [e]) * a)); + if ((fp = fopen (fileName, "rb")) == NULL) { + fprintf (stderr, "Could not open file, '%s'.\n", fileName); + return (0); + } + // Assuming they have not changed format, skip the .WAV header. + fseek (fp, 44, SEEK_SET); + // Map the left and right channels to their appropriate azimuth + // offsets. + j0 = (MIT_EV_OFFSET [e] + a) * MIT_IR_SIZE; + j1 = (MIT_EV_OFFSET [e] + ((MIT_AZ_COUNT [e] - a) % MIT_AZ_COUNT [e])) * MIT_IR_SIZE; + // Read in the data, converting it to floating-point. + for (i = 0; i < MIT_IR_SIZE; i ++) { + if (! ReadInt16LeAsFloat32 (fileName, fp, & s)) + return (0); + hData -> mHrirs [j0 + i] = s; + if (! ReadInt16LeAsFloat32 (fileName, fp, & s)) + return (0); + hData -> mHrirs [j1 + i] = s; + } + fclose (fp); + } + } + return (1); +} + +// Performs the minimum phase reconstruction for a given HRIR data set. The +// cepstrum size should be made configureable at some point in the future. +static void ReconstructHrirs (int minIrSize, HrirDataT * hData) { + int start, end, step, j; + float cep [CEP_SIZE]; + + start = hData -> mEvOffset [hData -> mEvStart]; + end = hData -> mIrCount; + step = hData -> mIrSize; + for (j = start; j < end; j ++) { + RealCepstrum (step, & hData -> mHrirs [j * step], cep); + MinimumPhase (cep, minIrSize, & hData -> mHrirs [j * minIrSize]); + } + hData -> mIrSize = minIrSize; +} + +// Renormalize the entire HRIR data set, and attenutate it slightly. +static void RenormalizeHrirs (const HrirDataT * hData) { + int step, start, end; + float norm; + int j, i; + + step = hData -> mIrSize; + start = hData -> mEvOffset [hData -> mEvStart] * step; + end = hData -> mIrCount * step; + norm = 0.0f; + for (j = start; j < end; j += step) { + for (i = 0; i < step; i ++) { + if (fabs (hData -> mHrirs [j + i]) > norm) + norm = fabs (hData -> mHrirs [j + i]); + } + } + if (norm > 0.000001f) + norm = 1.0f / norm; + norm *= 0.95f; + for (j = start; j < end; j += step) { + for (i = 0; i < step; i ++) + hData -> mHrirs [j + i] *= norm; + } +} + +// Given an elevation offset and azimuth, calculates two offsets for +// addressing the HRIRs buffer and their interpolation factor. +static void CalcAzIndices (const HrirDataT * hData, int oi, float az, int * j0, int * j1, float * jf) { + int ai; + + az = fmod ((2.0f * M_PI) + az, 2.0f * M_PI) * hData -> mAzCount [oi] / (2.0f * M_PI); + ai = (int) az; + az -= ai; + (* j0) = hData -> mEvOffset [oi] + ai; + (* j1) = hData -> mEvOffset [oi] + ((ai + 1) % hData -> mAzCount [oi]); + (* jf) = az; +} + +// Perform a linear interpolation. +static float Lerp (float a, float b, float f) { + return (a + (f * (b - a))); +} + +// Attempt to synthesize any missing HRIRs at the bottom elevations. Right +// now this just blends the lowest elevation HRIRs together and applies some +// attenuates and high frequency damping. It's not a realistic model to use, +// but it is simple. +static void SynthesizeHrirs (HrirDataT * hData) { + int step, oi, i, a, j, e; + float of; + int j0, j1; + float jf; + float lp [4], s0, s1; + + if (hData -> mEvStart <= 0) + return; + step = hData -> mIrSize; + oi = hData -> mEvStart; + for (i = 0; i < step; i ++) + hData -> mHrirs [i] = 0.0f; + for (a = 0; a < hData -> mAzCount [oi]; a ++) { + j = (hData -> mEvOffset [oi] + a) * step; + for (i = 0; i < step; i ++) + hData -> mHrirs [i] += hData -> mHrirs [j + i] / hData -> mAzCount [oi]; + } + for (e = 1; e < hData -> mEvStart; e ++) { + of = ((float) e) / hData -> mEvStart; + for (a = 0; a < hData -> mAzCount [e]; a ++) { + j = (hData -> mEvOffset [e] + a) * step; + CalcAzIndices (hData, oi, a * 2.0f * M_PI / hData -> mAzCount [e], & j0, & j1, & jf); + j0 *= step; + j1 *= step; + lp [0] = 0.0f; + lp [1] = 0.0f; + lp [2] = 0.0f; + lp [3] = 0.0f; + for (i = 0; i < step; i ++) { + s0 = hData -> mHrirs [i]; + s1 = Lerp (hData -> mHrirs [j0 + i], hData -> mHrirs [j1 + i], jf); + s0 = Lerp (s0, s1, of); + lp [0] = Lerp (s0, lp [0], 0.15f - (0.15f * of)); + lp [1] = Lerp (lp [0], lp [1], 0.15f - (0.15f * of)); + lp [2] = Lerp (lp [1], lp [2], 0.15f - (0.15f * of)); + lp [3] = Lerp (lp [2], lp [3], 0.15f - (0.15f * of)); + hData -> mHrirs [j + i] = lp [3]; + } + } + } + lp [0] = 0.0f; + lp [1] = 0.0f; + lp [2] = 0.0f; + lp [3] = 0.0f; + for (i = 0; i < step; i ++) { + s0 = hData -> mHrirs [i]; + lp [0] = Lerp (s0, lp [0], 0.15f); + lp [1] = Lerp (lp [0], lp [1], 0.15f); + lp [2] = Lerp (lp [1], lp [2], 0.15f); + lp [3] = Lerp (lp [2], lp [3], 0.15f); + hData -> mHrirs [i] = lp [3]; + } + hData -> mEvStart = 0; +} + +// Calculate the effective head-related time delays for the each HRIR, now +// that they are minimum-phase. +static void CalculateHrtds (HrirDataT * hData) { + float minHrtd, maxHrtd; + int e, a, j; + float t; + + minHrtd = 1000.0f; + maxHrtd = -1000.0f; + for (e = 0; e < hData -> mEvCount; e ++) { + for (a = 0; a < hData -> mAzCount [e]; a ++) { + j = hData -> mEvOffset [e] + a; + t = CalcLTD ((-90.0f + (e * 180.0f / (hData -> mEvCount - 1))) * M_PI / 180.0f, + (a * 360.0f / hData -> mAzCount [e]) * M_PI / 180.0f, + hData -> mRadius, hData -> mDistance); + hData -> mHrtds [j] = t; + if (t > maxHrtd) + maxHrtd = t; + if (t < minHrtd) + minHrtd = t; + } + } + maxHrtd -= minHrtd; + for (j = 0; j < hData -> mIrCount; j ++) + hData -> mHrtds [j] -= minHrtd; + hData -> mMaxHrtd = maxHrtd; +} + +// Save the OpenAL Soft HRTF data set. +static int SaveMhr (const HrirDataT * hData, const char * fileName) { + FILE * fp = NULL; + int e, step, end, j, i; + + if ((fp = fopen (fileName, "wb")) == NULL) { + fprintf (stderr, "Could not create file, '%s'.\n", fileName); + return (0); + } + if (! WriteString (MHR_FORMAT, fileName, fp)) + return (0); + if (! WriteUInt32Le ((ALuint) hData -> mIrRate, fileName, fp)) + return (0); + if (! WriteUInt16Le ((ALushort) hData -> mIrCount, fileName, fp)) + return (0); + if (! WriteUInt16Le ((ALushort) hData -> mIrSize, fileName, fp)) + return (0); + if (! WriteUInt8 ((ALubyte) hData -> mEvCount, fileName, fp)) + return (0); + for (e = 0; e < hData -> mEvCount; e ++) { + if (! WriteUInt16Le ((ALushort) hData -> mEvOffset [e], fileName, fp)) + return (0); + } + step = hData -> mIrSize; + end = hData -> mIrCount * step; + for (j = 0; j < end; j += step) { + for (i = 0; i < step; i ++) { + if (! WriteFloat32AsInt16Le (hData -> mHrirs [j + i], fileName, fp)) + return (0); + } + } + for (j = 0; j < hData -> mIrCount; j ++) { + i = (int) round (44100.0f * hData -> mHrtds [j]); + if (i > 127) + i = 127; + if (! WriteUInt8 ((ALubyte) i, fileName, fp)) + return (0); + } + fclose (fp); + return (1); +} + +// Save the OpenAL Soft built-in table. +static int SaveTab (const HrirDataT * hData, const char * fileName) { + FILE * fp = NULL; + int step, end, j, i; + char text [16]; + + if ((fp = fopen (fileName, "wb")) == NULL) { + fprintf (stderr, "Could not create file, '%s'.\n", fileName); + return (0); + } + if (! WriteString ("/* This data is Copyright 1994 by the MIT Media Laboratory. It is provided free\n" + " * with no restrictions on use, provided the authors are cited when the data is\n" + " * used in any research or commercial application. */\n" + "/* Bill Gardner <[email protected]> and Keith Martin <[email protected]> */\n" + "\n" + " /* HRIR Coefficients */\n" + " {\n", fileName, fp)) + return (0); + step = hData -> mIrSize; + end = hData -> mIrCount * step; + for (j = 0; j < end; j += step) { + if (! WriteString (" { ", fileName, fp)) + return (0); + for (i = 0; i < step; i ++) { + snprintf (text, 15, "%+d, ", (int) round (32767.0f * hData -> mHrirs [j + i])); + if (! WriteString (text, fileName, fp)) + return (0); + } + if (! WriteString ("},\n", fileName, fp)) + return (0); + } + if (! WriteString (" },\n" + "\n" + " /* HRIR Delays */\n" + " { ", fileName, fp)) + return (0); + for (j = 0; j < hData -> mIrCount; j ++) { + snprintf (text, 15, "%d, ", (int) round (44100.0f * hData -> mHrtds [j])); + if (! WriteString (text, fileName, fp)) + return (0); + } + if (! WriteString ("}\n", fileName, fp)) + return (0); + fclose (fp); + return (1); +} + +// Loads and processes an MIT data set. At present, the HRIR and HRTD data +// is loaded and processed in a static buffer. That should change to using +// heap allocated memory in the future. A cleanup function will then be +// required. +static int MakeMit(const char *baseInName, HrirDataT *hData) +{ + static float hrirs[MIT_IR_COUNT * MIT_IR_SIZE]; + static float hrtds[MIT_IR_COUNT]; + + hData->mIrRate = MIT_IR_RATE; + hData->mIrCount = MIT_IR_COUNT; + hData->mIrSize = MIT_IR_SIZE; + hData->mEvCount = MIT_EV_COUNT; + hData->mEvStart = MIT_EV_START; + hData->mEvOffset = MIT_EV_OFFSET; + hData->mAzCount = MIT_AZ_COUNT; + hData->mRadius = MIT_RADIUS; + hData->mDistance = MIT_DISTANCE; + hData->mHrirs = hrirs; + hData->mHrtds = hrtds; + fprintf(stderr, "Loading base HRIR data...\n"); + if(!LoadMitHrirs(baseInName, hData)) + return 0; + fprintf(stderr, "Performing minimum phase reconstruction and truncation...\n"); + ReconstructHrirs(MIN_IR_SIZE, hData); + fprintf(stderr, "Renormalizing minimum phase HRIR data...\n"); + RenormalizeHrirs(hData); + fprintf(stderr, "Synthesizing missing elevations...\n"); + SynthesizeHrirs(hData); + fprintf(stderr, "Calculating impulse delays...\n"); + CalculateHrtds(hData); + return 1; +} + +// Simple dispatch. Provided a command, the path to the MIT set of choice, +// and an optional output filename, this will produce an OpenAL Soft +// compatible HRTF set in the chosen format. +int main(int argc, char *argv[]) +{ + char baseName[1024]; + const char *outName = NULL; + HrirDataT hData; + + if(argc < 3 || strcmp(argv [1], "-h") == 0 || strcmp (argv [1], "--help") == 0) + { + fprintf(stderr, "Usage: %s <command> <path of MIT set> [ <output file> ]\n\n", argv[0]); + fprintf(stderr, "Commands:\n"); + fprintf(stderr, " -m, --make-mhr Makes an OpenAL Soft compatible HRTF data set.\n"); + fprintf(stderr, " Defaults output to: ./oal_soft_hrtf_44100.mhr\n"); + fprintf(stderr, " -t, --make-tab Makes the built-in table used when compiling OpenAL Soft.\n"); + fprintf(stderr, " Defaults output to: ./hrtf_tables.inc\n"); + fprintf(stderr, " -h, --help Displays this help information.\n"); + return 0; + } + + snprintf(baseName, sizeof(baseName), "%s/elev", argv[2]); + if(strcmp(argv[1], "-m") == 0 || strcmp(argv[1], "--make-mhr") == 0) + { + if(argc > 3) + outName = argv[3]; + else + outName = "./oal_soft_hrtf_44100.mhr"; + if(!MakeMit(baseName, &hData)) + return -1; + fprintf(stderr, "Creating data set file...\n"); + if(!SaveMhr(&hData, outName)) + return -1; + } + else if(strcmp(argv[1], "-t") == 0 || strcmp(argv[1], "--make-tab") == 0) + { + if(argc > 3) + outName = argv[3]; + else + outName = "./hrtf_tables.inc"; + if(!MakeMit(baseName, &hData)) + return -1; + fprintf(stderr, "Creating table file...\n"); + if(!SaveTab(&hData, outName)) + return -1; + } + else + { + fprintf(stderr, "Invalid command '%s'\n", argv[1]); + return -1; + } + fprintf(stderr, "Done.\n"); + return 0; +} |