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/*-
* 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.
*/
#ifndef BS2B_H
#define BS2B_H
/* Number of crossfeed levels */
#define BS2B_CLEVELS 3
/* Normal crossfeed levels */
#define BS2B_HIGH_CLEVEL 3
#define BS2B_MIDDLE_CLEVEL 2
#define BS2B_LOW_CLEVEL 1
/* Easy crossfeed levels */
#define BS2B_HIGH_ECLEVEL BS2B_HIGH_CLEVEL + BS2B_CLEVELS
#define BS2B_MIDDLE_ECLEVEL BS2B_MIDDLE_CLEVEL + BS2B_CLEVELS
#define BS2B_LOW_ECLEVEL BS2B_LOW_CLEVEL + BS2B_CLEVELS
/* Default crossfeed levels */
#define BS2B_DEFAULT_CLEVEL BS2B_HIGH_ECLEVEL
/* Default sample rate (Hz) */
#define BS2B_DEFAULT_SRATE 44100
#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */
struct bs2b {
int level; /* Crossfeed level */
int srate; /* Sample rate (Hz) */
/* Lowpass IIR filter coefficients */
float a0_lo;
float b1_lo;
/* Highboost IIR filter coefficients */
float a0_hi;
float a1_hi;
float b1_hi;
/* Buffer of last filtered sample.
* [0] - first channel, [1] - second channel
*/
struct t_last_sample {
float asis[2];
float lo[2];
float hi[2];
} last_sample;
};
/* Clear buffers and set new coefficients with new crossfeed level and sample
* rate values.
* level - crossfeed level of *LEVEL values.
* srate - sample rate by Hz.
*/
void bs2b_set_params(struct bs2b *bs2b, int level, int srate);
/* Return current crossfeed level value */
int bs2b_get_level(struct bs2b *bs2b);
/* Return current sample rate value */
int bs2b_get_srate(struct bs2b *bs2b);
/* Clear buffer */
void bs2b_clear(struct bs2b *bs2b);
/* Crossfeeds one stereo sample that are pointed by sample.
* [0] - first channel, [1] - second channel.
* Returns crossfided sample by sample pointer.
*/
inline void bs2b_cross_feed(struct bs2b *bs2b, float *restrict sample)
{
/* 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))
/* 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];
#undef hi_filter
#undef lo_filter
} /* bs2b_cross_feed */
#ifdef __cplusplus
} /* extern "C" */
#endif /* __cplusplus */
#endif /* BS2B_H */
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