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use random number generator from libavutil

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Originally committed as revision 9678 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Justin Ruggles 2007-07-14 23:57:05 +00:00
parent 9d10960194
commit cb503702ee
1 changed files with 5 additions and 67 deletions
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72
libavcodec/ac3dec.c
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@ -8,9 +8,6 @@
* Michel Lespinasse and Aaron Holtzman.
* http://liba52.sourceforge.net
*
* The Mersenne Twister is based on code written by Makoto Matsumoto and
* Takuji Nishimura.
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
@ -39,6 +36,7 @@
#include "ac3tab.h"
#include "bitstream.h"
#include "dsputil.h"
#include "random.h"
static const int nfchans_tbl[8] = { 2, 1, 2, 3, 3, 4, 4, 5 };
@ -117,20 +115,6 @@ static const float slevs[4] = { LEVEL_MINUS_3DB, LEVEL_MINUS_6DB, LEVEL_ZERO, LE
#define AC3_INPUT_2F_2R 0x06
#define AC3_INPUT_3F_2R 0x07
/* Mersenne Twister */
#define NMT 624
#define MMT 397
#define MATRIX_A 0x9908b0df
#define UPPER_MASK 0x80000000
#define LOWER_MASK 0x7fffffff
typedef struct {
uint32_t mt[NMT];
int mti;
} dither_state;
/* Mersenne Twister */
typedef struct {
uint16_t crc1;
uint8_t fscod;
@ -221,55 +205,9 @@ typedef struct {
/* Miscellaneous. */
GetBitContext gb;
dither_state dith_state; //for dither generation
AVRandomState dith_state; //for dither generation
} AC3DecodeContext;
/* BEGIN Mersenne Twister Code. */
static void dither_seed(dither_state *state, uint32_t seed)
{
static const uint32_t mag01[2] = { 0x00, MATRIX_A };
uint32_t y;
int kk;
if (seed == 0)
seed = 0x7ba05e; //default seed to my birthday!
state->mt[0] = seed;
for (state->mti = 1; state->mti < NMT; state->mti++)
state->mt[state->mti] = ((69069 * state->mt[state->mti - 1]) + 1);
for (kk = 0; kk < NMT - MMT; kk++) {
y = (state->mt[kk] & UPPER_MASK) | (state->mt[kk + 1] & LOWER_MASK);
state->mt[kk] = state->mt[kk + MMT] ^ (y >> 1) ^ mag01[y & 0x01];
}
for (;kk < NMT - 1; kk++) {
y = (state->mt[kk] & UPPER_MASK) | (state->mt[kk + 1] & LOWER_MASK);
state->mt[kk] = state->mt[kk + (MMT - NMT)] ^ (y >> 1) ^ mag01[y & 0x01];
}
y = (state->mt[NMT - 1] & UPPER_MASK) | (state->mt[0] & LOWER_MASK);
state->mt[NMT - 1] = state->mt[MMT - 1] ^ (y >> 1) ^ mag01[y & 0x01];
state->mti = 0;
}
static int16_t dither_int16(dither_state *state)
{
uint32_t y;
if (state->mti >= NMT)
state->mti = 0;
y = state->mt[state->mti++];
y ^= (y >> 11);
y ^= ((y << 7) & 0x9d2c5680);
y ^= ((y << 15) & 0xefc60000);
y ^= (y >> 18);
return ((y << 16) >> 16);
}
/* END Mersenne Twister */
/*********** BEGIN INIT HELPER FUNCTIONS ***********/
/**
* Generate a Kaiser-Bessel Derived Window.
@ -431,7 +369,7 @@ static int ac3_decode_init(AVCodecContext *avctx)
ff_mdct_init(&ctx->imdct_512, 9, 1);
ac3_window_init(ctx->window);
dsputil_init(&ctx->dsp, avctx);
dither_seed(&ctx->dith_state, 0);
av_init_random(0, &ctx->dith_state);
return 0;
}
@ -898,7 +836,7 @@ static int get_transform_coeffs_cpling(AC3DecodeContext *ctx, mant_groups *m)
for (ch = 0; ch < ctx->nfchans; ch++)
if (((ctx->chincpl) >> ch) & 1) {
if ((ctx->dithflag >> ch) & 1) {
TRANSFORM_COEFF(cplcoeff, dither_int16(&ctx->dith_state), exps[start], scale_factors);
TRANSFORM_COEFF(cplcoeff, av_random(&ctx->dith_state) & 0xFFFF, exps[start], scale_factors);
ctx->transform_coeffs[ch + 1][start] = cplcoeff * cplcos[ch] * LEVEL_MINUS_3DB;
} else
ctx->transform_coeffs[ch + 1][start] = 0;
@ -996,7 +934,7 @@ static int get_transform_coeffs_ch(AC3DecodeContext *ctx, int ch_index, mant_gro
continue;
}
else {
TRANSFORM_COEFF(coeffs[i], dither_int16(&ctx->dith_state), exps[i], factors);
TRANSFORM_COEFF(coeffs[i], av_random(&ctx->dith_state) & 0xFFFF, exps[i], factors);
coeffs[i] *= LEVEL_MINUS_3DB;
continue;
}