diff options
Diffstat (limited to 'utils')
| -rw-r--r-- | utils/makehrtf.c | 36 |
1 files changed, 22 insertions, 14 deletions
diff --git a/utils/makehrtf.c b/utils/makehrtf.c index 547c80db..259b717f 100644 --- a/utils/makehrtf.c +++ b/utils/makehrtf.c @@ -64,6 +64,7 @@ #include <stdlib.h> #include <stdarg.h> #include <string.h> +#include <limits.h> #include <ctype.h> #include <math.h> #ifdef HAVE_STRINGS_H @@ -815,18 +816,22 @@ static double Lerp(const double a, const double b, const double f) return a + (f * (b - a)); } -// Performs a high-passed triangular probability density function dither from -// a double to an integer. It assumes the input sample is already scaled. -static int HpTpdfDither(const double in, int *hpHist) +static inline uint dither_rng(uint *seed) { - static const double PRNG_SCALE = 1.0 / (RAND_MAX+1.0); - int prn; - double out; + *seed = (*seed * 96314165) + 907633515; + return *seed; +} + +// Performs a triangular probability density function dither. It assumes the +// input sample is already scaled. +static inline double TpdfDither(const double in, uint *seed) +{ + static const double PRNG_SCALE = 1.0 / UINT_MAX; + uint prn0, prn1; - prn = rand(); - out = round(in + (PRNG_SCALE * (prn - *hpHist))); - *hpHist = prn; - return (int)out; + prn0 = dither_rng(seed); + prn1 = dither_rng(seed); + return round(in + (prn0*PRNG_SCALE - prn1*PRNG_SCALE)); } // Allocates an array of doubles. @@ -1867,8 +1872,9 @@ static int WriteBin4(const ByteOrderT order, const uint bytes, const uint32 in, static int StoreMhr(const HrirDataT *hData, const char *filename) { uint e, step, end, n, j, i; - int hpHist, v; + uint dither_seed; FILE *fp; + int v; if((fp=fopen(filename, "wb")) == NULL) { @@ -1891,13 +1897,15 @@ static int StoreMhr(const HrirDataT *hData, const char *filename) step = hData->mIrSize; end = hData->mIrCount * step; n = hData->mIrPoints; - srand(0x31DF840C); + dither_seed = 22222; for(j = 0;j < end;j += step) { - hpHist = 0; + double out[MAX_TRUNCSIZE]; + for(i = 0;i < n;i++) + out[i] = TpdfDither(32767.0 * hData->mHrirs[j+i], &dither_seed); for(i = 0;i < n;i++) { - v = HpTpdfDither(32767.0 * hData->mHrirs[j+i], &hpHist); + v = (int)Clamp(out[i], -32768.0, 32767.0); if(!WriteBin4(BO_LITTLE, 2, (uint32)v, fp, filename)) return 0; } |