Mercurial > spc_convert

     1 // Simple low-pass and high-pass filter to better match sound output of a SNES

     2 

     3 // snes_spc 0.9.0

     4 #ifndef SPC_FILTER_H

     5 #define SPC_FILTER_H

     6 

     7 #include "blargg_common.h"

     8 

     9 struct SPC_Filter {

    10 public:

    11 	

    12 	// Filters count samples of stereo sound in place. Count must be a multiple of 2.

    13 	typedef short sample_t;

    14 	void run( sample_t* io, int count );

    15 	

    16 // Optional features

    17 

    18 	// Clears filter to silence

    19 	void clear();

    20 

    21 	// Sets gain (volume), where gain_unit is normal. Gains greater than gain_unit

    22 	// are fine, since output is clamped to 16-bit sample range.

    23 	enum { gain_unit = 0x100 };

    24 	void set_gain( int gain );

    25 

    26 	// Sets amount of bass (logarithmic scale)

    27 	enum { bass_none =  0 };

    28 	enum { bass_norm =  8 }; // normal amount

    29 	enum { bass_max  = 31 };

    30 	void set_bass( int bass );

    31 	

    32 public:

    33 	SPC_Filter();

    34 	BLARGG_DISABLE_NOTHROW

    35 private:

    36 	enum { gain_bits = 8 };

    37 	int gain;

    38 	int bass;

    39 	struct chan_t { int p1, pp1, sum; };

    40 	chan_t ch [2];

    41 };

    42 

    43 inline void SPC_Filter::set_gain( int g ) { gain = g; }

    44 

    45 inline void SPC_Filter::set_bass( int b ) { bass = b; }

    46 

    47 #endif
author	Robert McIntyre <rlm@mit.edu>
date	Fri, 21 Oct 2011 05:53:11 -0700
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