diff options
| -rw-r--r-- | libavcodec/ac3enc.c | 47 | ||||
| -rw-r--r-- | libavcodec/ac3tab.h | 41 |
2 files changed, 50 insertions, 38 deletions
diff --git a/libavcodec/ac3enc.c b/libavcodec/ac3enc.c index 5ec8b4f5ac..a587c647b5 100644 --- a/libavcodec/ac3enc.c +++ b/libavcodec/ac3enc.c @@ -81,6 +81,51 @@ 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) { @@ -882,6 +927,8 @@ 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; diff --git a/libavcodec/ac3tab.h b/libavcodec/ac3tab.h index d8771fbeee..3621b87a71 100644 --- a/libavcodec/ac3tab.h +++ b/libavcodec/ac3tab.h @@ -12,44 +12,6 @@ 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]= { @@ -176,6 +138,9 @@ 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]; |