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/* aKode Resampler (fast)
Copyright (C) 2004 Allan Sandfeld Jensen <kde@carewolf.com>
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public
License as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public License
along with this library; see the file COPYING.LIB. If not, write to
the Free Software Foundation, Inc., 51 Franklin Steet, Fifth Floor,
Boston, MA 02110-1301, USA.
*/
#include "audioframe.h"
#include "arithmetic.h"
#include "fast_resampler.h"
#define FR_FIDELITY (1<<10)
namespace aKode {
FastResampler* FastResamplerPlugin::openResampler() {
return new FastResampler();
}
extern "C" { FastResamplerPlugin fast_resampler; }
FastResampler::FastResampler() : speed(1.0), sample_rate(44100) {}
// A fast resampling by linear interpolation
// I assume you know binary arithmetics and convertions if you're reading this
// T is the input/output type, Arithm defines the used arithmetic
template<typename T, typename S, template<typename S_Type> class Arithm>
static bool _doBuffer(AudioFrame* in, AudioFrame* out, float speed, unsigned sample_rate)
{
unsigned long vt_pos_start = 0; // virtual positions of new sample
unsigned long vt_pos_end;;
unsigned long real_pos_start, real_pos_end;
long start_fraction, end_fraction;
unsigned long vt_end = in->length * 1024 -1;
int int_speed;
unsigned long out_length;
{
float resample_speed = in->sample_rate/(float)sample_rate;
resample_speed *= speed;
int_speed = (unsigned int)(resample_speed*1024.0+0.5);
out_length = (in->length/int_speed)*1024;
unsigned long out_rem = (in->length%int_speed)*1024 + (int_speed-1);
out_length += out_rem/int_speed;
out->reserveSpace(in, out_length);
out->sample_rate = sample_rate;
}
vt_pos_end = int_speed;
unsigned char channels = in->channels; // take copy to reduce alias-induced reads
unsigned long out_pos = 0;
T** indata = (T**)in->data; // templating ;)
T** outdata = (T**)out->data;
S sspeed = (S)int_speed;
S smax = Arithm<S>::max(in->sample_width);
while(out_pos < out_length && vt_pos_start < vt_end) {
real_pos_start = vt_pos_start / 1024; start_fraction = vt_pos_start % 1024;
real_pos_end = vt_pos_end / 1024; end_fraction = vt_pos_end % 1024;
if (real_pos_start == real_pos_end) {
for(int i=0; i<channels; i++) {
outdata[i][out_pos] = indata[i][real_pos_start];
}
} else {
for(int i=0; i<channels; i++) {
S signal = 0;
S remainder = 0;
S temp;
// add fraction from starting sample
temp = (S)indata[i][real_pos_start];
signal += Arithm<S>::div(temp,sspeed) * (1024L-start_fraction);
remainder += Arithm<S>::rem(temp,sspeed) * (1024L-start_fraction);
// add fraction from end sample
temp= (S)indata[i][real_pos_end];
signal += Arithm<S>::div(temp,sspeed) * (end_fraction);
remainder += Arithm<S>::rem(temp,sspeed) * (end_fraction);
// add all intermediate samples
for(unsigned long j = real_pos_start+1; j<real_pos_end; j++) {
temp= (S)indata[i][j];
signal += Arithm<S>::div(temp,sspeed) * 1024L;
remainder += Arithm<S>::rem(temp,sspeed) * 1024L;
}
// add accummulated remainder
signal += Arithm<S>::div(remainder,sspeed);
// clip to maximum, just to be safe
if (signal > smax) signal = smax;
else
if (signal < -smax) signal = -smax;
outdata[i][out_pos] = (T)signal;
}
}
out_pos++;
vt_pos_start = vt_pos_end;
vt_pos_end += int_speed;
if (vt_pos_end > vt_end) vt_pos_end = vt_end;
}
return true;
}
bool FastResampler::doFrame(AudioFrame* in, AudioFrame* out)
{
if (speed == 1.0 && in->sample_rate == sample_rate) {
swapFrames(out, in);
return true;
}
if (in->sample_width < 0) {
return _doBuffer<float, float, Arithm_FP>(in, out, speed, sample_rate);
} else
if (in->sample_width <= 8) {
return _doBuffer<int8_t, int32_t, Arithm_Int>(in, out, speed, sample_rate);
} else
if (in->sample_width <= 16) {
return _doBuffer<int16_t, int32_t, Arithm_Int>(in, out, speed, sample_rate);
} else
if (in->sample_width <= 24) {
return _doBuffer<int32_t, int32_t, Arithm_Int>(in, out, speed, sample_rate);
} else
return _doBuffer<int32_t, int64_t, Arithm_Int>(in, out, speed, sample_rate);
}
void FastResampler::setSpeed(float _speed)
{
speed = _speed;
}
void FastResampler::setSampleRate(unsigned int rate)
{
sample_rate = rate;
}
} // namespace
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