spc_convert: snes_spc/SPC_Filter.h annotate

added old scripts for historical interest.

rev	line source
rlm@0	1 // Simple low-pass and high-pass filter to better match sound output of a SNES
rlm@0	2
rlm@0	3 // snes_spc 0.9.0
rlm@0	4 #ifndef SPC_FILTER_H
rlm@0	5 #define SPC_FILTER_H
rlm@0	6
rlm@0	7 #include "blargg_common.h"
rlm@0	8
rlm@0	9 struct SPC_Filter {
rlm@0	10 public:
rlm@0	11
rlm@0	12 // Filters count samples of stereo sound in place. Count must be a multiple of 2.
rlm@0	13 typedef short sample_t;
rlm@0	14 void run( sample_t* io, int count );
rlm@0	15
rlm@0	16 // Optional features
rlm@0	17
rlm@0	18 // Clears filter to silence
rlm@0	19 void clear();
rlm@0	20
rlm@0	21 // Sets gain (volume), where gain_unit is normal. Gains greater than gain_unit
rlm@0	22 // are fine, since output is clamped to 16-bit sample range.
rlm@0	23 enum { gain_unit = 0x100 };
rlm@0	24 void set_gain( int gain );
rlm@0	25
rlm@0	26 // Sets amount of bass (logarithmic scale)
rlm@0	27 enum { bass_none = 0 };
rlm@0	28 enum { bass_norm = 8 }; // normal amount
rlm@0	29 enum { bass_max = 31 };
rlm@0	30 void set_bass( int bass );
rlm@0	31
rlm@0	32 public:
rlm@0	33 SPC_Filter();
rlm@0	34 BLARGG_DISABLE_NOTHROW
rlm@0	35 private:
rlm@0	36 enum { gain_bits = 8 };
rlm@0	37 int gain;
rlm@0	38 int bass;
rlm@0	39 struct chan_t { int p1, pp1, sum; };
rlm@0	40 chan_t ch [2];
rlm@0	41 };
rlm@0	42
rlm@0	43 inline void SPC_Filter::set_gain( int g ) { gain = g; }
rlm@0	44
rlm@0	45 inline void SPC_Filter::set_bass( int b ) { bass = b; }
rlm@0	46
rlm@0	47 #endif

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