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aacpsy: use exp2(f) instead of pow(f)(2,...)

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Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
This commit is contained in:
Michael Niedermayer 2012-09-09 12:59:55 +02:00
parent b027156b19
commit 4819d43d7f
1 changed files with 6 additions and 4 deletions
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10
libavcodec/aacpsy.c
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@ -24,6 +24,8 @@
* AAC encoder psychoacoustic model
*/
#include "libavutil/libm.h"
#include "avcodec.h"
#include "aactab.h"
#include "psymodel.h"
@ -333,7 +335,7 @@ static av_cold int psy_3gpp_init(FFPsyContext *ctx) {
coeff->spread_low[1] = pow(10.0, -bark_width * en_spread_low);
coeff->spread_hi [1] = pow(10.0, -bark_width * en_spread_hi);
pe_min = bark_pe * bark_width;
minsnr = pow(2.0f, pe_min / band_sizes[g]) - 1.5f;
minsnr = exp2(pe_min / band_sizes[g]) - 1.5f;
coeff->min_snr = av_clipf(1.0f / minsnr, PSY_SNR_25DB, PSY_SNR_1DB);
}
start = 0;
@ -524,8 +526,8 @@ static float calc_reduction_3gpp(float a, float desired_pe, float pe,
{
float thr_avg, reduction;
thr_avg = powf(2.0f, (a - pe) / (4.0f * active_lines));
reduction = powf(2.0f, (a - desired_pe) / (4.0f * active_lines)) - thr_avg;
thr_avg = exp2f((a - pe) / (4.0f * active_lines));
reduction = exp2f((a - desired_pe) / (4.0f * active_lines)) - thr_avg;
return FFMAX(reduction, 0.0f);
}
@ -703,7 +705,7 @@ static void psy_3gpp_analyze_channel(FFPsyContext *ctx, int channel,
float delta_sfb_pe = band->norm_fac * norm_fac * delta_pe;
float thr = band->thr;
thr *= powf(2.0f, delta_sfb_pe / band->active_lines);
thr *= exp2f(delta_sfb_pe / band->active_lines);
if (thr > coeffs[g].min_snr * band->energy && band->avoid_holes == PSY_3GPP_AH_INACTIVE)
thr = FFMAX(band->thr, coeffs[g].min_snr * band->energy);
band->thr = thr;