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Do per phase normalization to avoid dc fluctuations.

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git-svn-id: https://gambatte.svn.sourceforge.net/svnroot/gambatte@168 9dfb2916-2d38-0410-aef4-c5fe6c9ffc24
This commit is contained in:
sinamas 2008-10-14 23:52:24 +00:00
parent 160b2786fa
commit f46b46d915
1 changed files with 87 additions and 39 deletions
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126
common/resample/makesinckernel.h
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@ -39,18 +39,34 @@ void makeSincKernel(short *const kernel, const unsigned phases, const unsigned p
dkernel[(i % phases) * phaseLen + i / phases] = win(i, M) * sinc;
}
{
double maxabsgain = 0;
for (unsigned ph = 0; ph < phases; ++ph) {
double gain = 0;
double absgain = 0;
for (long i = 0; i < M + 1; ++i)
gain += std::abs(dkernel[i]);
for (unsigned i = 0; i < phaseLen; ++i) {
gain += dkernel[ph * phaseLen + i];
absgain += std::abs(dkernel[ph * phaseLen + i]);
}
gain = phases * 0x10000 / gain;
gain = 1.0 / gain;
for (long i = 0; i < M + 1; ++i)
kernel[i] = std::floor(dkernel[i] * gain + 0.5);
// Per phase normalization to avoid DC fluctuations.
for (unsigned i = 0; i < phaseLen; ++i)
dkernel[ph * phaseLen + i] *= gain;
absgain *= gain;
if (absgain > maxabsgain)
maxabsgain = absgain;
}
const double gain = 0x10000 / maxabsgain;
for (long i = 0; i < M + 1; ++i)
kernel[i] = std::floor(dkernel[i] * gain + 0.5);
delete[] dkernel;
}*/
@ -58,47 +74,79 @@ void makeSincKernel(short *const kernel, const unsigned phases, const unsigned p
const long M = static_cast<long>(phaseLen) * phases - 1;
double *const dkernel = new double[M / 2 + 1];
{
double *const dkernel = new double[M / 2 + 1];
double *dk = dkernel;
for (long i = 0; i < M / 2 + 1; ++i) {
const double sinc = i * 2 == M ?
PI * fc :
std::sin(PI * fc * (i * 2 - M)) / (i * 2 - M);
dkernel[i] = win(i, M) * sinc;
}
double gain = 0;
for (long i = 0; i < M / 2; ++i)
gain += std::abs(dkernel[i]);
gain *= 2;
gain += std::abs((M & 1) ? dkernel[M / 2] * 2 : dkernel[M / 2]);
gain = phases * 0x10000 / gain;
{
long kpos = 0;
for (long i = 0; i < M / 2 + 1; ++i) {
kernel[kpos] = std::floor(dkernel[i] * gain + 0.5);
for (unsigned ph = 0; ph < phases; ++ph) {
for (long i = ph; i < M / 2 + 1; i += phases) {
const double sinc = i * 2 == M ?
PI * fc :
std::sin(PI * fc * (i * 2 - M)) / (i * 2 - M);
if ((kpos += phaseLen) > M)
kpos -= M;
*dk++ = win(i, M) * sinc;
}
}
delete[] dkernel;
}
double maxabsgain = 0.0;
{
double *dkp1 = dkernel;
double *dkp2 = dkernel + M / 2;
for (unsigned phase = 0; phase < phases; ++phase) {
short *k = kernel + phase * phaseLen;
short *km = kernel + M - phase * phaseLen;
for (long i = phase; i < M / 2 + 1; i += phases)
*km-- = *k++;
for (unsigned ph = 0; ph < (phases + 1) / 2; ++ph) {
double gain = 0.0;
double absgain = 0.0;
{
const double *kp1 = dkp1;
const double *kp2 = dkp2;
long i = ph;
for (; i < M / 2 + 1; i += phases) {
gain += *kp1;
absgain += std::abs(*kp1++);
}
for (; i < M + 1; i += phases) {
gain += *kp2;
absgain += std::abs(*kp2--);
}
}
gain = 1.0 / gain;
long i = ph;
for (; i < M / 2 + 1; i += phases)
*dkp1++ *= gain;
if (dkp1 < dkp2) {
for (; i < M + 1; i += phases)
*dkp2-- *= gain;
}
absgain *= gain;
if (absgain > maxabsgain)
maxabsgain = absgain;
}
}
const double gain = 0x10000 / maxabsgain;
const double *dk = dkernel;
for (unsigned ph = 0; ph < phases; ++ph) {
short *k = kernel + ph * phaseLen;
short *km = kernel + M - ph * phaseLen;
for (long i = ph; i < M / 2 + 1; i += phases)
*km-- = *k++ = std::floor(*dk++ * gain + 0.5);
}
delete[] dkernel;
}
#endif