Revert bad ac3enc commit, the commited code was bigger and slower.

Originally committed as revision 5327 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/ac3enc.c

@@ -81,51 +81,6 @@ static inline int16_t fix15(float a)
     return v;
 }
 
-
-/**
- * Generate a Kaiser Window.
- */
-static void k_window_init(int alpha, double *window, int n, int iter)
-{
-    int j, k;
-    double a, x;
-    a = alpha * M_PI / n;
-    a = a*a;
-    for(k=0; k<n; k++) {
-        x = k * (n - k) * a;
-        window[k] = 1.0;
-        for(j=iter; j>0; j--) {
-            window[k] = (window[k] * x / (j*j)) + 1.0;
-        }
-    }
-}
-
-/**
- * Generate a Kaiser-Bessel Derived Window.
- * @param alpha  determines window shape
- * @param window array to fill with window values
- * @param iter   number of iterations to use in BesselI0
- */
-
-static void kbd_window_init(int alpha, int16_t *out_window, int iter)
-{
-    int k, n2;
-    double kwindow[256];
-    double window[256];
-
-    n2 = 256;
-    k_window_init(alpha, kwindow, n2, iter);
-    window[0] = kwindow[0];
-    for(k=1; k<n2; k++) {
-        window[k] = window[k-1] + kwindow[k];
-    }
-    for(k=0; k<n2; k++) {
-        window[k] = sqrt(window[k] / (window[n2-1]+1));
-        //out_window[k] = round(window[k]*((1<<15)-1)); //enable this for a rounded window
-        out_window[k] = fix15(window[k]);
-    }
-}
-
 static inline int calc_lowcomp1(int a, int b0, int b1)
 {
     if ((b0 + 256) == b1) {
@@ -927,8 +882,6 @@ static int AC3_encode_init(AVCodecContext *avctx)
     ac3_common_init();
 
     /* mdct init */
-    kbd_window_init(5.0, ac3_window, 50);
-
     fft_init(MDCT_NBITS - 2);
     for(i=0;i<N/4;i++) {
         alpha = 2 * M_PI * (i + 1.0 / 8.0) / (float)N;

libavcodec/ac3tab.h

@@ -12,6 +12,44 @@ static const uint16_t ac3_bitratetab[19] = {
     160, 192, 224, 256, 320, 384, 448, 512, 576, 640
 };
 
+/* AC3 MDCT window */
+
+/* MDCT window */
+static const int16_t ac3_window[256] = {
+    4,    7,   12,   16,   21,   28,   34,   42,
+   51,   61,   72,   84,   97,  111,  127,  145,
+  164,  184,  207,  231,  257,  285,  315,  347,
+  382,  419,  458,  500,  544,  591,  641,  694,
+  750,  810,  872,  937, 1007, 1079, 1155, 1235,
+ 1318, 1406, 1497, 1593, 1692, 1796, 1903, 2016,
+ 2132, 2253, 2379, 2509, 2644, 2783, 2927, 3076,
+ 3230, 3389, 3552, 3721, 3894, 4072, 4255, 4444,
+ 4637, 4835, 5038, 5246, 5459, 5677, 5899, 6127,
+ 6359, 6596, 6837, 7083, 7334, 7589, 7848, 8112,
+ 8380, 8652, 8927, 9207, 9491, 9778,10069,10363,
+10660,10960,11264,11570,11879,12190,12504,12820,
+13138,13458,13780,14103,14427,14753,15079,15407,
+15735,16063,16392,16720,17049,17377,17705,18032,
+18358,18683,19007,19330,19651,19970,20287,20602,
+20914,21225,21532,21837,22139,22438,22733,23025,
+23314,23599,23880,24157,24430,24699,24964,25225,
+25481,25732,25979,26221,26459,26691,26919,27142,
+27359,27572,27780,27983,28180,28373,28560,28742,
+28919,29091,29258,29420,29577,29729,29876,30018,
+30155,30288,30415,30538,30657,30771,30880,30985,
+31086,31182,31274,31363,31447,31528,31605,31678,
+31747,31814,31877,31936,31993,32046,32097,32145,
+32190,32232,32272,32310,32345,32378,32409,32438,
+32465,32490,32513,32535,32556,32574,32592,32608,
+32623,32636,32649,32661,32671,32681,32690,32698,
+32705,32712,32718,32724,32729,32733,32737,32741,
+32744,32747,32750,32752,32754,32756,32757,32759,
+32760,32761,32762,32763,32764,32764,32765,32765,
+32766,32766,32766,32766,32767,32767,32767,32767,
+32767,32767,32767,32767,32767,32767,32767,32767,
+32767,32767,32767,32767,32767,32767,32767,32767,
+};
+
 static uint8_t masktab[253];
 
 static const uint8_t latab[260]= {
@@ -138,9 +176,6 @@ static const uint8_t bndsz[50]={
 
 static uint8_t bndtab[51];
 
-/* AC3 MDCT window */
-static int16_t ac3_window[256];
-
 /* fft & mdct sin cos tables */
 static int16_t costab[64];
 static int16_t sintab[64];