/*- * Copyright (c) 2005 Boris Mikhaylov * * Permission is hereby granted, free of charge, to any person obtaining * a copy of this software and associated documentation files (the * "Software"), to deal in the Software without restriction, including * without limitation the rights to use, copy, modify, merge, publish, * distribute, sublicense, and/or sell copies of the Software, and to * permit persons to whom the Software is furnished to do so, subject to * the following conditions: * * The above copyright notice and this permission notice shall be * included in all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */ #include "config.h" #include <math.h> #include "bs2b.h" #ifndef M_PI #define M_PI 3.14159265358979323846 #endif /* Single pole IIR filter. * O[n] = a0*I[n] + a1*I[n-1] + b1*O[n-1] */ /* Lowpass filter */ #define lo_filter(in, out_1) (bs2b->a0_lo*(in) + bs2b->b1_lo*(out_1)) /* Highboost filter */ #define hi_filter(in, in_1, out_1) (bs2b->a0_hi*(in) + bs2b->a1_hi*(in_1) + bs2b->b1_hi*(out_1)) /* Set up all data. */ static void init(struct bs2b *bs2b) { double Fc_lo, Fc_hi; double G_lo, G_hi; double x; if ((bs2b->srate > 192000) || (bs2b->srate < 2000)) bs2b->srate = BS2B_DEFAULT_SRATE; switch(bs2b->level) { case BS2B_LOW_CLEVEL: /* Low crossfeed level */ Fc_lo = 360.0; Fc_hi = 501.0; G_lo = 0.398107170553497; G_hi = 0.205671765275719; break; case BS2B_MIDDLE_CLEVEL: /* Middle crossfeed level */ Fc_lo = 500.0; Fc_hi = 711.0; G_lo = 0.459726988530872; G_hi = 0.228208484414988; break; case BS2B_HIGH_CLEVEL: /* High crossfeed level (virtual speakers are closer to itself) */ Fc_lo = 700.0; Fc_hi = 1021.0; G_lo = 0.530884444230988; G_hi = 0.250105790667544; break; case BS2B_LOW_ECLEVEL: /* Low easy crossfeed level */ Fc_lo = 360.0; Fc_hi = 494.0; G_lo = 0.316227766016838; G_hi = 0.168236228897329; break; case BS2B_MIDDLE_ECLEVEL: /* Middle easy crossfeed level */ Fc_lo = 500.0; Fc_hi = 689.0; G_lo = 0.354813389233575; G_hi = 0.187169483835901; break; default: /* High easy crossfeed level */ bs2b->level = BS2B_HIGH_ECLEVEL; Fc_lo = 700.0; Fc_hi = 975.0; G_lo = 0.398107170553497; G_hi = 0.205671765275719; break; } /* switch */ /* $fc = $Fc / $s; * $d = 1 / 2 / pi / $fc; * $x = exp(-1 / $d); */ x = exp(-2.0 * M_PI * Fc_lo / bs2b->srate); bs2b->b1_lo = x; bs2b->a0_lo = G_lo * (1.0 - x); x = exp(-2.0 * M_PI * Fc_hi / bs2b->srate); bs2b->b1_hi = x; bs2b->a0_hi = 1.0 - G_hi * (1.0 - x); bs2b->a1_hi = -x; bs2b->gain = 1.0 / (1.0 - G_hi + G_lo); bs2b_clear(bs2b); } /* init */ /* Exported functions. * See descriptions in "bs2b.h" */ void bs2b_set_level(struct bs2b *bs2b, int level) { if(level == bs2b->level) return; bs2b->level = level; init(bs2b); } /* bs2b_set_level */ int bs2b_get_level(struct bs2b *bs2b) { return bs2b->level; } /* bs2b_get_level */ void bs2b_set_srate(struct bs2b *bs2b, int srate) { if (srate == bs2b->srate) return; bs2b->srate = srate; init(bs2b); } /* bs2b_set_srate */ int bs2b_get_srate(struct bs2b *bs2b) { return bs2b->srate; } /* bs2b_get_srate */ void bs2b_clear(struct bs2b *bs2b) { int loopv = sizeof(bs2b->last_sample); while (loopv) { ((char *)&bs2b->last_sample)[--loopv] = 0; } } /* bs2b_clear */ int bs2b_is_clear(struct bs2b *bs2b) { int loopv = sizeof(bs2b->last_sample); while (loopv) { if (((char *)&bs2b->last_sample)[--loopv] != 0) return 0; } return 1; } /* bs2b_is_clear */ void bs2b_cross_feed(struct bs2b *bs2b, float *sample) { /* Lowpass filter */ bs2b->last_sample.lo[0] = lo_filter(sample[0], bs2b->last_sample.lo[0]); bs2b->last_sample.lo[1] = lo_filter(sample[1], bs2b->last_sample.lo[1]); /* Highboost filter */ bs2b->last_sample.hi[0] = hi_filter(sample[0], bs2b->last_sample.asis[0], bs2b->last_sample.hi[0]); bs2b->last_sample.hi[1] = hi_filter(sample[1], bs2b->last_sample.asis[1], bs2b->last_sample.hi[1]); bs2b->last_sample.asis[0] = sample[0]; bs2b->last_sample.asis[1] = sample[1]; /* Crossfeed */ sample[0] = bs2b->last_sample.hi[0] + bs2b->last_sample.lo[1]; sample[1] = bs2b->last_sample.hi[1] + bs2b->last_sample.lo[0]; /* Bass boost cause allpass attenuation */ sample[0] *= bs2b->gain; sample[1] *= bs2b->gain; /* Clipping of overloaded samples */ #if 0 if (sample[0] > 1.0) sample[0] = 1.0; if (sample[0] < -1.0) sample[0] = -1.0; if (sample[1] > 1.0) sample[1] = 1.0; if (sample[1] < -1.0) sample[1] = -1.0; #endif } /* bs2b_cross_feed */