xenia-project/FFmpeg
1
0
Fork 0
mirror of https://github.com/xenia-project/FFmpeg.git synced 2024-11-24 12:09:55 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

aacenc: use the decoder's lcg PRNG

Browse Source 
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
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

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__); \