diff options
| -rw-r--r-- | libavcodec/ac3dec.c | 72 |
1 files changed, 5 insertions, 67 deletions
diff --git a/libavcodec/ac3dec.c b/libavcodec/ac3dec.c index a0bb35803d..48a7becfa7 100644 --- a/libavcodec/ac3dec.c +++ b/libavcodec/ac3dec.c @@ -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; } |