diff options
| author | Chris Robinson <[email protected]> | 2008-01-03 05:36:51 -0800 |
|---|---|---|
| committer | Chris Robinson <[email protected]> | 2008-01-03 05:36:51 -0800 |
| commit | 8fe39042da3369acb4aa8e5a8837709c4338d0f0 (patch) | |
| tree | 8bcd0d73000fa4082e2e62cf13d8f660cffd72d9 /Alc/bs2b.c | |
| parent | 7ef623c71d092f696f5bd7f7170ba475728ecccf (diff) | |
Add the Bauer stereophonic-to-binaural DSP (bs2b) code and hooks
Diffstat (limited to 'Alc/bs2b.c')
| -rw-r--r-- | Alc/bs2b.c | 201 |
1 files changed, 201 insertions, 0 deletions
diff --git a/Alc/bs2b.c b/Alc/bs2b.c new file mode 100644 index 00000000..069ed614 --- /dev/null +++ b/Alc/bs2b.c @@ -0,0 +1,201 @@ +/*-
+ * 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 <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 */
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