[FFmpeg-soc] [soc]: r218 - in aac: aac.c aac.h

[banan]

Author: banan
Date: Sat Jun  2 15:47:09 2007
New Revision: 218

Log:
Use av_random.


Modified:
   aac/aac.c
   aac/aac.h

Modified: aac/aac.c
==============================================================================
--- aac/aac.c	(original)
+++ aac/aac.c	Sat Jun  2 15:47:09 2007
@@ -28,6 +28,7 @@
 #include "avcodec.h"
 #include "bitstream.h"
 #include "dsputil.h"
+#include "random.h"
 
 #include "aac.h"
 #include "aactab.h"
@@ -163,55 +164,6 @@ static void ssr_context_init(ssr_context
     }
 }
 
-/* BEGIN Mersenne Twister Code. */
-static void dither_seed(dither_state *state, uint32_t seed) {
-    if (seed == 0)
-        seed = 0x1f2e3d4c;
-
-    state->mt[0] = seed;
-    for (state->mti = 1; state->mti < N; state->mti++)
-        state->mt[state->mti] = ((69069 * state->mt[state->mti - 1]) + 1);
-}
-
-static uint32_t dither_uint32(dither_state *state) {
-    uint32_t y;
-    static const uint32_t mag01[2] = { 0x00, MATRIX_A };
-    int kk;
-
-    if (state->mti >= N) {
-        for (kk = 0; kk < N - M; kk++) {
-            y = (state->mt[kk] & UPPER_MASK) | (state->mt[kk + 1] & LOWER_MASK);
-            state->mt[kk] = state->mt[kk + M] ^ (y >> 1) ^ mag01[y & 0x01];
-        }
-        for (;kk < N - 1; kk++) {
-            y = (state->mt[kk] & UPPER_MASK) | (state->mt[kk + 1] & LOWER_MASK);
-            state->mt[kk] = state->mt[kk + (M - N)] ^ (y >> 1) ^ mag01[y & 0x01];
-        }
-        y = (state->mt[N - 1] & UPPER_MASK) | (state->mt[0] & LOWER_MASK);
-        state->mt[N - 1] = state->mt[M - 1] ^ (y >> 1) ^ mag01[y & 0x01];
-
-        state->mti = 0;
-    }
-
-    y = state->mt[state->mti++];
-    y ^= (y >> 11);
-    y ^= ((y << 7) & 0x9d2c5680);
-    y ^= ((y << 15) & 0xefc60000);
-    y ^= (y >> 18);
-
-    return y;
-}
-
-static inline int16_t dither_int16(dither_state *state) {
-    return ((dither_uint32(state) << 16) >> 16);
-}
-
-//static inline int32_t dither_int32(dither_state *state) {
-//    return (int32_t)dither_uint32(state);
-//}
-
-/* END Mersenne Twister */
-
 // General functions
 #define TAG_MASK 0x00f
 #define FLAG_SCE 0x100
@@ -561,8 +513,9 @@ static int aac_decode_init(AVCodecContex
             }
         }
     }
-    // dither init
-    dither_seed(&ac->dither, 0);
+
+    /* Initialize RNG dither */
+    av_init_random(0x1f2e3d4c, &ac->random_state);
 
     // 1024  - compensate wrong imdct method
     // 32768 - values in AAC build for ready float->int 16 bit audio, using
@@ -866,7 +819,7 @@ static void spectral_data(aac_context_t 
             if (cur_cb == NOISE_HCB) {
                 for (group = 0; group < ics->group_len[g]; group++) {
                     for (k = offsets[i]; k < offsets[i+1]; k++)
-                        icoef[group*128+k] = dither_int16(&ac->dither);
+                        icoef[group*128+k] = av_random(&ac->random_state) & 0x0000FFFF;
                 }
                 continue;
             }

Modified: aac/aac.h
==============================================================================
--- aac/aac.h	(original)
+++ aac/aac.h	Sat Jun  2 15:47:09 2007
@@ -77,18 +77,6 @@ enum {
 //ltp
 #define MAX_LTP_LONG_SFB 40
 
-// dithering
-#define N 624
-#define M 397
-#define MATRIX_A    0x9908b0df
-#define UPPER_MASK  0x80000000
-#define LOWER_MASK  0x7fffffff
-
-typedef struct {
-    uint32_t mt[N];
-    int      mti;
-} dither_state;
-
 typedef struct {
     int present;
     int generated;
@@ -256,7 +244,6 @@ typedef struct {
     GetBitContext gb;
     VLC mainvlc;
     VLC books[11];
-    dither_state dither;
 
     // main config
     int audioObjectType;
@@ -303,6 +290,7 @@ typedef struct {
     DSPContext dsp;
     int * vq[11];
     ssr_context * ssrctx;
+    AVRandomState random_state;
 
     // statistics
     int num_frame;