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lavc/aacsbr: sbr_dequant optimization

Browse Source 
This uses ff_exp2fi to get a speedup (~ 6x).

sample benchmark (Haswell, GNU/Linux):
old:
  19102 decicycles in sbr_dequant,    1023 runs,      1 skips
  19002 decicycles in sbr_dequant,    2045 runs,      3 skips
  17638 decicycles in sbr_dequant,    4093 runs,      3 skips
  15825 decicycles in sbr_dequant,    8189 runs,      3 skips
  16404 decicycles in sbr_dequant,   16379 runs,      5 skips

new:
   3063 decicycles in sbr_dequant,    1024 runs,      0 skips
   3049 decicycles in sbr_dequant,    2048 runs,      0 skips
   2968 decicycles in sbr_dequant,    4096 runs,      0 skips
   2818 decicycles in sbr_dequant,    8191 runs,      1 skips
   2853 decicycles in sbr_dequant,   16383 runs,      1 skips

Reviewed-by: Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com>
Signed-off-by: Ganesh Ajjanagadde <gajjanagadde@gmail.com>
pull/167/head
Ganesh Ajjanagadde 9 years ago
parent ce10f572c1
commit def3c83e1b
2 changed files with 23 additions and 13 deletions
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  1. 34
      libavcodec/aacsbr.c
  2. 2
      libavcodec/aacsbr.h

34
libavcodec/aacsbr.c
Unescape View File

@ -33,6 +33,7 @@
#include "aacsbrdata.h"
#include "aacsbr_tablegen.h"
#include "fft.h"
#include "internal.h"
#include "aacps.h"
#include "sbrdsp.h"
#include "libavutil/internal.h"
@ -73,15 +74,22 @@ static void sbr_dequant(SpectralBandReplication *sbr, int id_aac)
{
int k, e;
int ch;
static const double exp2_tab[2] = {1, M_SQRT2};
if (id_aac == TYPE_CPE && sbr->bs_coupling) {
float alpha = sbr->data[0].bs_amp_res ? 1.0f : 0.5f;
float pan_offset = sbr->data[0].bs_amp_res ? 12.0f : 24.0f;
int pan_offset = sbr->data[0].bs_amp_res ? 12 : 24;
for (e = 1; e <= sbr->data[0].bs_num_env; e++) {
for (k = 0; k < sbr->n[sbr->data[0].bs_freq_res[e]]; k++) {
float temp1 = exp2f(sbr->data[0].env_facs_q[e][k] * alpha + 7.0f);
float temp2 = exp2f((pan_offset - sbr->data[1].env_facs_q[e][k]) * alpha);
float fac;
float temp1, temp2, fac;
if (sbr->data[0].bs_amp_res) {
temp1 = ff_exp2fi(sbr->data[0].env_facs_q[e][k] + 7);
temp2 = ff_exp2fi(pan_offset - sbr->data[1].env_facs_q[e][k]);
}
else {
temp1 = ff_exp2fi((sbr->data[0].env_facs_q[e][k]>>1) + 7) *
exp2_tab[sbr->data[0].env_facs_q[e][k] & 1];
temp2 = ff_exp2fi((pan_offset - sbr->data[1].env_facs_q[e][k])>>1) *
exp2_tab[(pan_offset - sbr->data[1].env_facs_q[e][k]) & 1];
}
if (temp1 > 1E20) {
av_log(NULL, AV_LOG_ERROR, "envelope scalefactor overflow in dequant\n");
temp1 = 1;
@ -93,8 +101,8 @@ static void sbr_dequant(SpectralBandReplication *sbr, int id_aac)
}
for (e = 1; e <= sbr->data[0].bs_num_noise; e++) {
for (k = 0; k < sbr->n_q; k++) {
float temp1 = exp2f(NOISE_FLOOR_OFFSET - sbr->data[0].noise_facs_q[e][k] + 1);
float temp2 = exp2f(12 - sbr->data[1].noise_facs_q[e][k]);
float temp1 = ff_exp2fi(NOISE_FLOOR_OFFSET - sbr->data[0].noise_facs_q[e][k] + 1);
float temp2 = ff_exp2fi(12 - sbr->data[1].noise_facs_q[e][k]);
float fac;
av_assert0(temp1 <= 1E20);
fac = temp1 / (1.0f + temp2);
@ -104,11 +112,13 @@ static void sbr_dequant(SpectralBandReplication *sbr, int id_aac)
}
} else { // SCE or one non-coupled CPE
for (ch = 0; ch < (id_aac == TYPE_CPE) + 1; ch++) {
float alpha = sbr->data[ch].bs_amp_res ? 1.0f : 0.5f;
for (e = 1; e <= sbr->data[ch].bs_num_env; e++)
for (k = 0; k < sbr->n[sbr->data[ch].bs_freq_res[e]]; k++){
sbr->data[ch].env_facs[e][k] =
exp2f(alpha * sbr->data[ch].env_facs_q[e][k] + 6.0f);
if (sbr->data[ch].bs_amp_res)
sbr->data[ch].env_facs[e][k] = ff_exp2fi(sbr->data[ch].env_facs_q[e][k] + 6);
else
sbr->data[ch].env_facs[e][k] = ff_exp2fi((sbr->data[ch].env_facs_q[e][k]>>1) + 6)
* exp2_tab[sbr->data[ch].env_facs_q[e][k] & 1];
if (sbr->data[ch].env_facs[e][k] > 1E20) {
av_log(NULL, AV_LOG_ERROR, "envelope scalefactor overflow in dequant\n");
sbr->data[ch].env_facs[e][k] = 1;
@ -118,7 +128,7 @@ static void sbr_dequant(SpectralBandReplication *sbr, int id_aac)
for (e = 1; e <= sbr->data[ch].bs_num_noise; e++)
for (k = 0; k < sbr->n_q; k++)
sbr->data[ch].noise_facs[e][k] =
exp2f(NOISE_FLOOR_OFFSET - sbr->data[ch].noise_facs_q[e][k]);
ff_exp2fi(NOISE_FLOOR_OFFSET - sbr->data[ch].noise_facs_q[e][k]);
}
}
}

2
libavcodec/aacsbr.h
Unescape View File

@ -34,7 +34,7 @@
#include "sbr.h"
#define ENVELOPE_ADJUSTMENT_OFFSET 2
#define NOISE_FLOOR_OFFSET FIXR(6.0f)
#define NOISE_FLOOR_OFFSET 6
/**
* SBR VLC tables

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