131 lines
3.6 KiB
C++
131 lines
3.6 KiB
C++
/* Simple resampler based on bsnes's ruby audio library */
|
|
|
|
#ifndef __HERMITE_RESAMPLER_H
|
|
#define __HERMITE_RESAMPLER_H
|
|
|
|
#include "resampler.h"
|
|
|
|
#undef CLAMP
|
|
#undef SHORT_CLAMP
|
|
#define CLAMP(x, low, high) (((x) > (high)) ? (high) : (((x) < (low)) ? (low) : (x)))
|
|
#define SHORT_CLAMP(n) ((short) CLAMP((n), -32768, 32767))
|
|
|
|
class HermiteResampler : public Resampler
|
|
{
|
|
protected:
|
|
|
|
uint32 r_step;
|
|
uint32 r_frac;
|
|
int r_left[4], r_right[4];
|
|
|
|
static inline int32
|
|
hermite (int32 mu1, int32 a, int32 b, int32 c, int32 d)
|
|
{
|
|
int32 mu2, mu3, m0, m1, a0, a1, a2, a3;
|
|
|
|
mu2 = (mu1 * mu1) >> 15;
|
|
mu3 = (mu2 * mu1) >> 15;
|
|
|
|
m0 = (c - a) << 14;
|
|
m1 = (d - b) << 14;
|
|
|
|
a0 = (mu3 << 1) - (3 * mu2) + (1 << 15);
|
|
a1 = mu3 - (mu2 << 1) + mu1;
|
|
a2 = mu3 - mu2;
|
|
a3 = 3 * mu2 - (mu3 << 1);
|
|
|
|
return ((a0 * b) +
|
|
((a1 * m0) >> 15) +
|
|
((a2 * m1) >> 15) +
|
|
(a3 * c)) >> 15;
|
|
}
|
|
|
|
public:
|
|
HermiteResampler (int num_samples) : Resampler (num_samples)
|
|
{
|
|
clear ();
|
|
}
|
|
|
|
~HermiteResampler ()
|
|
{
|
|
}
|
|
|
|
void
|
|
time_ratio (double ratio)
|
|
{
|
|
r_step = (1 << 16) * ratio;
|
|
clear ();
|
|
}
|
|
|
|
void
|
|
clear (void)
|
|
{
|
|
ring_buffer::clear ();
|
|
r_frac = (1 << 16);
|
|
r_left [0] = r_left [1] = r_left [2] = r_left [3] = 0;
|
|
r_right[0] = r_right[1] = r_right[2] = r_right[3] = 0;
|
|
}
|
|
|
|
void
|
|
read (short *data, int num_samples)
|
|
{
|
|
int i_position = start >> 1;
|
|
int max_samples = buffer_size >> 1;
|
|
short *internal_buffer = (short *) buffer;
|
|
int o_position = 0;
|
|
int consumed = 0;
|
|
|
|
while (o_position < num_samples && consumed < buffer_size)
|
|
{
|
|
int s_left = internal_buffer[i_position];
|
|
int s_right = internal_buffer[i_position + 1];
|
|
int hermite_val;
|
|
|
|
while (r_frac <= (1 << 16) && o_position < num_samples)
|
|
{
|
|
hermite_val = hermite (r_frac >> 1, r_left [0], r_left [1], r_left [2], r_left [3]);
|
|
data[o_position] = SHORT_CLAMP (hermite_val);
|
|
hermite_val = hermite (r_frac >> 1, r_right[0], r_right[1], r_right[2], r_right[3]);
|
|
data[o_position + 1] = SHORT_CLAMP (hermite_val);
|
|
|
|
o_position += 2;
|
|
|
|
r_frac += r_step;
|
|
}
|
|
|
|
if (r_frac > (1 << 16))
|
|
{
|
|
r_left [0] = r_left [1];
|
|
r_left [1] = r_left [2];
|
|
r_left [2] = r_left [3];
|
|
r_left [3] = s_left;
|
|
|
|
r_right[0] = r_right[1];
|
|
r_right[1] = r_right[2];
|
|
r_right[2] = r_right[3];
|
|
r_right[3] = s_right;
|
|
|
|
r_frac -= (1 << 16);
|
|
|
|
i_position += 2;
|
|
if (i_position >= max_samples)
|
|
i_position -= max_samples;
|
|
consumed += 2;
|
|
}
|
|
}
|
|
|
|
size -= consumed << 1;
|
|
start += consumed << 1;
|
|
if (start >= buffer_size)
|
|
start -= buffer_size;
|
|
}
|
|
|
|
inline int
|
|
avail (void)
|
|
{
|
|
return ((((uint32) size) << 14) - r_frac) / r_step * 2;
|
|
}
|
|
};
|
|
|
|
#endif /* __HERMITE_RESAMPLER_H */
|