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libavcodec: changed mathematical functions in aacpsy.c

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This patch changes existing mathematical functions with faster
ones. Speeds up encoding more than 10%. Tested on x86 and
MIPS platforms.

Signed-off-by: Bojan Zivkovic <bojan@mips.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
This commit is contained in:
Bojan Zivkovic 2013-03-06 14:55:03 +01:00 committed by Michael Niedermayer
parent d95143ec82
commit 1f5b5b8062
1 changed files with 7 additions and 3 deletions
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10
libavcodec/aacpsy.c
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@ -541,8 +541,10 @@ static float calc_reduced_thr_3gpp(AacPsyBand *band, float min_snr,
float thr = band->thr;
if (band->energy > thr) {
thr = powf(thr, 0.25f) + reduction;
thr = powf(thr, 4.0f);
thr = sqrtf(thr);
thr = sqrtf(thr) + reduction;
thr *= thr;
thr *= thr;
/* This deviates from the 3GPP spec to match the reference encoder.
* It performs min(thr_reduced, max(thr, energy/min_snr)) only for bands
@ -582,13 +584,15 @@ static void psy_3gpp_analyze_channel(FFPsyContext *ctx, int channel,
AacPsyBand *band = &pch->band[w+g];
float form_factor = 0.0f;
float Temp;
band->energy = 0.0f;
for (i = 0; i < band_sizes[g]; i++) {
band->energy += coefs[start+i] * coefs[start+i];
form_factor += sqrtf(fabs(coefs[start+i]));
}
Temp = band->energy > 0 ? sqrtf((float)band_sizes[g] / band->energy) : 0;
band->thr = band->energy * 0.001258925f;
band->nz_lines = band->energy>0 ? form_factor / powf(band->energy / band_sizes[g], 0.25f) : 0;
band->nz_lines = form_factor * sqrtf(Temp);
start += band_sizes[g];
}