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aacenc: use the decoder's lcg PRNG

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Using lfg was an overkill in this case where the random numbers
were only used for encoder descisions. Should increase result
uniformity between different FPUs and gives a slight speedup.

Signed-off-by: Rostislav Pehlivanov <atomnuker@gmail.com>
This commit is contained in:
Rostislav Pehlivanov 2016-10-08 01:47:04 +01:00
parent cfa3c2655a
commit 230178dfe2
4 changed files with 17 additions and 8 deletions
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8
libavcodec/aaccoder.c
View File

@ -643,11 +643,9 @@ static void search_for_pns(AACEncContext *s, AVCodecContext *avctx, SingleChanne
float band_energy, scale, pns_senergy;
const int start_c = (w+w2)*128+sce->ics.swb_offset[g];
band = &s->psy.ch[s->cur_channel].psy_bands[(w+w2)*16+g];
for (i = 0; i < sce->ics.swb_sizes[g]; i+=2) {
double rnd[2];
av_bmg_get(&s->lfg, rnd);
PNS[i+0] = (float)rnd[0];
PNS[i+1] = (float)rnd[1];
for (i = 0; i < sce->ics.swb_sizes[g]; i++) {
s->random_state = lcg_random(s->random_state);
PNS[i] = s->random_state;
}
band_energy = s->fdsp->scalarproduct_float(PNS, PNS, sce->ics.swb_sizes[g]);
scale = noise_amp/sqrtf(band_energy);

2
libavcodec/aacenc.c
View File

@ -1031,7 +1031,7 @@ static av_cold int aac_encode_init(AVCodecContext *avctx)
goto fail;
s->psypp = ff_psy_preprocess_init(avctx);
ff_lpc_init(&s->lpc, 2*avctx->frame_size, TNS_MAX_ORDER, FF_LPC_TYPE_LEVINSON);
av_lfg_init(&s->lfg, 0x72adca55);
s->random_state = 0x1f2e3d4c;
if (HAVE_MIPSDSP)
ff_aac_coder_init_mips(s);

2
libavcodec/aacenc.h
View File

@ -23,7 +23,6 @@
#define AVCODEC_AACENC_H
#include "libavutil/float_dsp.h"
#include "libavutil/lfg.h"
#include "avcodec.h"
#include "put_bits.h"
@ -100,7 +99,6 @@ typedef struct AACEncContext {
FFTContext mdct1024; ///< long (1024 samples) frame transform context
FFTContext mdct128; ///< short (128 samples) frame transform context
AVFloatDSPContext *fdsp;
AVLFG lfg; ///< PRNG needed for PNS
float *planar_samples[8]; ///< saved preprocessed input
int profile; ///< copied from avctx

13
libavcodec/aacenc_utils.h
View File

@ -252,6 +252,19 @@ static inline int ff_sfdelta_can_replace(const SingleChannelElement *sce,
&& sce->sf_idx[nextband[band]] <= (new_sf + SCALE_MAX_DIFF);
}
/**
* linear congruential pseudorandom number generator
*
* @param previous_val pointer to the current state of the generator
*
* @return Returns a 32-bit pseudorandom integer
*/
static av_always_inline int lcg_random(unsigned previous_val)
{
union { unsigned u; int s; } v = { previous_val * 1664525u + 1013904223 };
return v.s;
}
#define ERROR_IF(cond, ...) \
if (cond) { \
av_log(avctx, AV_LOG_ERROR, __VA_ARGS__); \