126 lines
3.9 KiB
C
126 lines
3.9 KiB
C
/*-
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* Copyright (c) 2005 Boris Mikhaylov
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*
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* Permission is hereby granted, free of charge, to any person obtaining
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* a copy of this software and associated documentation files (the
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* "Software"), to deal in the Software without restriction, including
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* without limitation the rights to use, copy, modify, merge, publish,
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* distribute, sublicense, and/or sell copies of the Software, and to
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* permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice shall be
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* included in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
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* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
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* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
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* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
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* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*/
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#ifndef BS2B_H
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#define BS2B_H
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/* Number of crossfeed levels */
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#define BS2B_CLEVELS 3
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/* Normal crossfeed levels */
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#define BS2B_HIGH_CLEVEL 3
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#define BS2B_MIDDLE_CLEVEL 2
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#define BS2B_LOW_CLEVEL 1
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/* Easy crossfeed levels */
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#define BS2B_HIGH_ECLEVEL BS2B_HIGH_CLEVEL + BS2B_CLEVELS
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#define BS2B_MIDDLE_ECLEVEL BS2B_MIDDLE_CLEVEL + BS2B_CLEVELS
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#define BS2B_LOW_ECLEVEL BS2B_LOW_CLEVEL + BS2B_CLEVELS
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/* Default crossfeed levels */
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#define BS2B_DEFAULT_CLEVEL BS2B_HIGH_ECLEVEL
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/* Default sample rate (Hz) */
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#define BS2B_DEFAULT_SRATE 44100
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#ifdef __cplusplus
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extern "C" {
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#endif /* __cplusplus */
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struct bs2b {
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int level; /* Crossfeed level */
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int srate; /* Sample rate (Hz) */
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/* Lowpass IIR filter coefficients */
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float a0_lo;
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float b1_lo;
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/* Highboost IIR filter coefficients */
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float a0_hi;
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float a1_hi;
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float b1_hi;
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/* Buffer of last filtered sample.
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* [0] - first channel, [1] - second channel
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*/
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struct t_last_sample {
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float asis[2];
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float lo[2];
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float hi[2];
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} last_sample;
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};
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/* Clear buffers and set new coefficients with new crossfeed level and sample
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* rate values.
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* level - crossfeed level of *LEVEL values.
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* srate - sample rate by Hz.
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*/
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void bs2b_set_params(struct bs2b *bs2b, int level, int srate);
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/* Return current crossfeed level value */
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int bs2b_get_level(struct bs2b *bs2b);
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/* Return current sample rate value */
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int bs2b_get_srate(struct bs2b *bs2b);
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/* Clear buffer */
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void bs2b_clear(struct bs2b *bs2b);
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/* Crossfeeds one stereo sample that are pointed by sample.
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* [0] - first channel, [1] - second channel.
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* Returns crossfided sample by sample pointer.
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*/
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inline void bs2b_cross_feed(struct bs2b *bs2b, float *restrict sample)
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{
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/* Single pole IIR filter.
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* O[n] = a0*I[n] + a1*I[n-1] + b1*O[n-1]
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*/
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/* Lowpass filter */
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#define lo_filter(in, out_1) (bs2b->a0_lo*(in) + bs2b->b1_lo*(out_1))
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/* Highboost filter */
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#define hi_filter(in, in_1, out_1) (bs2b->a0_hi*(in) + bs2b->a1_hi*(in_1) + bs2b->b1_hi*(out_1))
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/* Lowpass filter */
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bs2b->last_sample.lo[0] = lo_filter(sample[0], bs2b->last_sample.lo[0]);
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bs2b->last_sample.lo[1] = lo_filter(sample[1], bs2b->last_sample.lo[1]);
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/* Highboost filter */
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bs2b->last_sample.hi[0] = hi_filter(sample[0], bs2b->last_sample.asis[0], bs2b->last_sample.hi[0]);
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bs2b->last_sample.hi[1] = hi_filter(sample[1], bs2b->last_sample.asis[1], bs2b->last_sample.hi[1]);
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bs2b->last_sample.asis[0] = sample[0];
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bs2b->last_sample.asis[1] = sample[1];
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/* Crossfeed */
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sample[0] = bs2b->last_sample.hi[0] + bs2b->last_sample.lo[1];
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sample[1] = bs2b->last_sample.hi[1] + bs2b->last_sample.lo[0];
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#undef hi_filter
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#undef lo_filter
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} /* bs2b_cross_feed */
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#ifdef __cplusplus
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} /* extern "C" */
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#endif /* __cplusplus */
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#endif /* BS2B_H */
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