From ec0350c983c34d008fd10f07366abd80c19d06e0 Mon Sep 17 00:00:00 2001
From: Justin Ruggles <justin.ruggles@gmail.com>
Date: Sun, 17 Aug 2008 17:41:48 +0000
Subject: [PATCH] use LFG instead of Mersenne Twister for AC-3 PRNG
Originally committed as revision 14815 to svn://svn.ffmpeg.org/ffmpeg/trunk
---
libavcodec/ac3dec.c | 5 ++---
libavcodec/ac3dec.h | 4 ++--
libavutil/Makefile | 1 +
3 files changed, 5 insertions(+), 5 deletions(-)
diff --git a/libavcodec/ac3dec.c b/libavcodec/ac3dec.c
index 96296f29228..e8477d7ad3a 100644
--- a/libavcodec/ac3dec.c
+++ b/libavcodec/ac3dec.c
@@ -33,7 +33,6 @@
#include <string.h>
#include "libavutil/crc.h"
-#include "libavutil/random.h"
#include "avcodec.h"
#include "ac3_parser.h"
#include "bitstream.h"
@@ -198,7 +197,7 @@ static av_cold int ac3_decode_init(AVCodecContext *avctx)
ff_mdct_init(&s->imdct_512, 9, 1);
ff_kbd_window_init(s->window, 5.0, 256);
dsputil_init(&s->dsp, avctx);
- av_init_random(0, &s->dith_state);
+ av_lfg_init(&s->dith_state, 0);
/* set bias values for float to int16 conversion */
if(s->dsp.float_to_int16_interleave == ff_float_to_int16_interleave_c) {
@@ -450,7 +449,7 @@ static void get_transform_coeffs_ch(AC3DecodeContext *s, int ch_index, mant_grou
tbap = bap[i];
switch (tbap) {
case 0:
- coeffs[i] = (av_random(&s->dith_state) & 0x7FFFFF) - 0x400000;
+ coeffs[i] = (av_lfg_get(&s->dith_state) & 0x7FFFFF) - 0x400000;
break;
case 1:
diff --git a/libavcodec/ac3dec.h b/libavcodec/ac3dec.h
index de43609f585..4e0eb1d463d 100644
--- a/libavcodec/ac3dec.h
+++ b/libavcodec/ac3dec.h
@@ -27,7 +27,7 @@
#ifndef FFMPEG_AC3DEC_H
#define FFMPEG_AC3DEC_H
-#include "libavutil/random.h"
+#include "libavutil/lfg.h"
#include "ac3tab.h"
#include "ac3.h"
#include "bitstream.h"
@@ -143,7 +143,7 @@ typedef struct {
///@defgroup dithering zero-mantissa dithering
int dither_all; ///< true if all channels are dithered
int dither_flag[AC3_MAX_CHANNELS]; ///< dither flags (dithflg)
- AVRandomState dith_state; ///< for dither generation
+ AVLFG dith_state; ///< for dither generation
///@}
///@defgroup imdct IMDCT
diff --git a/libavutil/Makefile b/libavutil/Makefile
index f21bcda29ac..bd95156760f 100644
--- a/libavutil/Makefile
+++ b/libavutil/Makefile
@@ -9,6 +9,7 @@ OBJS = adler32.o \
des.o \
fifo.o \
intfloat_readwrite.o \
+ lfg.o \
lls.o \
log.o \
lzo.o \
--
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