mirror of https://git.ffmpeg.org/ffmpeg.git
425 lines
11 KiB
C
425 lines
11 KiB
C
/*
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* imdct.c
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* Copyright (C) 2000-2002 Michel Lespinasse <walken@zoy.org>
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* Copyright (C) 1999-2000 Aaron Holtzman <aholtzma@ess.engr.uvic.ca>
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*
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* The ifft algorithms in this file have been largely inspired by Dan
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* Bernstein's work, djbfft, available at http://cr.yp.to/djbfft.html
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*
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* This file is part of a52dec, a free ATSC A-52 stream decoder.
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* See http://liba52.sourceforge.net/ for updates.
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*
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* a52dec is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* a52dec is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include "a52.h"
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#include "a52_internal.h"
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#include "mm_accel.h"
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typedef struct complex_s {
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sample_t real;
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sample_t imag;
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} complex_t;
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static complex_t buf[128];
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static uint8_t fftorder[] = {
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0,128, 64,192, 32,160,224, 96, 16,144, 80,208,240,112, 48,176,
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8,136, 72,200, 40,168,232,104,248,120, 56,184, 24,152,216, 88,
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4,132, 68,196, 36,164,228,100, 20,148, 84,212,244,116, 52,180,
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252,124, 60,188, 28,156,220, 92, 12,140, 76,204,236,108, 44,172,
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2,130, 66,194, 34,162,226, 98, 18,146, 82,210,242,114, 50,178,
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10,138, 74,202, 42,170,234,106,250,122, 58,186, 26,154,218, 90,
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254,126, 62,190, 30,158,222, 94, 14,142, 78,206,238,110, 46,174,
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6,134, 70,198, 38,166,230,102,246,118, 54,182, 22,150,214, 86
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};
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/* Root values for IFFT */
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static sample_t roots16[3];
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static sample_t roots32[7];
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static sample_t roots64[15];
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static sample_t roots128[31];
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/* Twiddle factors for IMDCT */
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static complex_t pre1[128];
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static complex_t post1[64];
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static complex_t pre2[64];
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static complex_t post2[32];
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static sample_t a52_imdct_window[256];
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static void (* ifft128) (complex_t * buf);
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static void (* ifft64) (complex_t * buf);
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static inline void ifft2 (complex_t * buf)
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{
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double r, i;
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r = buf[0].real;
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i = buf[0].imag;
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buf[0].real += buf[1].real;
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buf[0].imag += buf[1].imag;
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buf[1].real = r - buf[1].real;
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buf[1].imag = i - buf[1].imag;
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}
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static inline void ifft4 (complex_t * buf)
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{
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double tmp1, tmp2, tmp3, tmp4, tmp5, tmp6, tmp7, tmp8;
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tmp1 = buf[0].real + buf[1].real;
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tmp2 = buf[3].real + buf[2].real;
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tmp3 = buf[0].imag + buf[1].imag;
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tmp4 = buf[2].imag + buf[3].imag;
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tmp5 = buf[0].real - buf[1].real;
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tmp6 = buf[0].imag - buf[1].imag;
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tmp7 = buf[2].imag - buf[3].imag;
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tmp8 = buf[3].real - buf[2].real;
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buf[0].real = tmp1 + tmp2;
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buf[0].imag = tmp3 + tmp4;
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buf[2].real = tmp1 - tmp2;
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buf[2].imag = tmp3 - tmp4;
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buf[1].real = tmp5 + tmp7;
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buf[1].imag = tmp6 + tmp8;
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buf[3].real = tmp5 - tmp7;
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buf[3].imag = tmp6 - tmp8;
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}
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/* the basic split-radix ifft butterfly */
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#define BUTTERFLY(a0,a1,a2,a3,wr,wi) do { \
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tmp5 = a2.real * wr + a2.imag * wi; \
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tmp6 = a2.imag * wr - a2.real * wi; \
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tmp7 = a3.real * wr - a3.imag * wi; \
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tmp8 = a3.imag * wr + a3.real * wi; \
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tmp1 = tmp5 + tmp7; \
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tmp2 = tmp6 + tmp8; \
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tmp3 = tmp6 - tmp8; \
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tmp4 = tmp7 - tmp5; \
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a2.real = a0.real - tmp1; \
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a2.imag = a0.imag - tmp2; \
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a3.real = a1.real - tmp3; \
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a3.imag = a1.imag - tmp4; \
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a0.real += tmp1; \
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a0.imag += tmp2; \
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a1.real += tmp3; \
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a1.imag += tmp4; \
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} while (0)
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/* split-radix ifft butterfly, specialized for wr=1 wi=0 */
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#define BUTTERFLY_ZERO(a0,a1,a2,a3) do { \
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tmp1 = a2.real + a3.real; \
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tmp2 = a2.imag + a3.imag; \
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tmp3 = a2.imag - a3.imag; \
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tmp4 = a3.real - a2.real; \
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a2.real = a0.real - tmp1; \
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a2.imag = a0.imag - tmp2; \
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a3.real = a1.real - tmp3; \
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a3.imag = a1.imag - tmp4; \
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a0.real += tmp1; \
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a0.imag += tmp2; \
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a1.real += tmp3; \
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a1.imag += tmp4; \
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} while (0)
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/* split-radix ifft butterfly, specialized for wr=wi */
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#define BUTTERFLY_HALF(a0,a1,a2,a3,w) do { \
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tmp5 = (a2.real + a2.imag) * w; \
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tmp6 = (a2.imag - a2.real) * w; \
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tmp7 = (a3.real - a3.imag) * w; \
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tmp8 = (a3.imag + a3.real) * w; \
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tmp1 = tmp5 + tmp7; \
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tmp2 = tmp6 + tmp8; \
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tmp3 = tmp6 - tmp8; \
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tmp4 = tmp7 - tmp5; \
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a2.real = a0.real - tmp1; \
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a2.imag = a0.imag - tmp2; \
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a3.real = a1.real - tmp3; \
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a3.imag = a1.imag - tmp4; \
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a0.real += tmp1; \
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a0.imag += tmp2; \
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a1.real += tmp3; \
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a1.imag += tmp4; \
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} while (0)
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static inline void ifft8 (complex_t * buf)
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{
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double tmp1, tmp2, tmp3, tmp4, tmp5, tmp6, tmp7, tmp8;
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ifft4 (buf);
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ifft2 (buf + 4);
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ifft2 (buf + 6);
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BUTTERFLY_ZERO (buf[0], buf[2], buf[4], buf[6]);
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BUTTERFLY_HALF (buf[1], buf[3], buf[5], buf[7], roots16[1]);
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}
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static void ifft_pass (complex_t * buf, sample_t * weight, int n)
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{
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complex_t * buf1;
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complex_t * buf2;
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complex_t * buf3;
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double tmp1, tmp2, tmp3, tmp4, tmp5, tmp6, tmp7, tmp8;
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int i;
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buf++;
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buf1 = buf + n;
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buf2 = buf + 2 * n;
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buf3 = buf + 3 * n;
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BUTTERFLY_ZERO (buf[-1], buf1[-1], buf2[-1], buf3[-1]);
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i = n - 1;
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do {
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BUTTERFLY (buf[0], buf1[0], buf2[0], buf3[0], weight[n], weight[2*i]);
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buf++;
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buf1++;
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buf2++;
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buf3++;
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weight++;
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} while (--i);
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}
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static void ifft16 (complex_t * buf)
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{
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ifft8 (buf);
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ifft4 (buf + 8);
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ifft4 (buf + 12);
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ifft_pass (buf, roots16 - 4, 4);
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}
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static void ifft32 (complex_t * buf)
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{
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ifft16 (buf);
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ifft8 (buf + 16);
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ifft8 (buf + 24);
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ifft_pass (buf, roots32 - 8, 8);
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}
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static void ifft64_c (complex_t * buf)
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{
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ifft32 (buf);
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ifft16 (buf + 32);
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ifft16 (buf + 48);
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ifft_pass (buf, roots64 - 16, 16);
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}
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static void ifft128_c (complex_t * buf)
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{
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ifft32 (buf);
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ifft16 (buf + 32);
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ifft16 (buf + 48);
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ifft_pass (buf, roots64 - 16, 16);
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ifft32 (buf + 64);
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ifft32 (buf + 96);
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ifft_pass (buf, roots128 - 32, 32);
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}
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void a52_imdct_512 (sample_t * data, sample_t * delay, sample_t bias)
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{
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int i, k;
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sample_t t_r, t_i, a_r, a_i, b_r, b_i, w_1, w_2;
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const sample_t * window = a52_imdct_window;
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for (i = 0; i < 128; i++) {
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k = fftorder[i];
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t_r = pre1[i].real;
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t_i = pre1[i].imag;
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buf[i].real = t_i * data[255-k] + t_r * data[k];
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buf[i].imag = t_r * data[255-k] - t_i * data[k];
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}
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ifft128 (buf);
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/* Post IFFT complex multiply plus IFFT complex conjugate*/
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/* Window and convert to real valued signal */
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for (i = 0; i < 64; i++) {
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/* y[n] = z[n] * (xcos1[n] + j * xsin1[n]) ; */
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t_r = post1[i].real;
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t_i = post1[i].imag;
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a_r = t_r * buf[i].real + t_i * buf[i].imag;
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a_i = t_i * buf[i].real - t_r * buf[i].imag;
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b_r = t_i * buf[127-i].real + t_r * buf[127-i].imag;
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b_i = t_r * buf[127-i].real - t_i * buf[127-i].imag;
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w_1 = window[2*i];
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w_2 = window[255-2*i];
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data[2*i] = delay[2*i] * w_2 - a_r * w_1 + bias;
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data[255-2*i] = delay[2*i] * w_1 + a_r * w_2 + bias;
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delay[2*i] = a_i;
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w_1 = window[2*i+1];
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w_2 = window[254-2*i];
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data[2*i+1] = delay[2*i+1] * w_2 + b_r * w_1 + bias;
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data[254-2*i] = delay[2*i+1] * w_1 - b_r * w_2 + bias;
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delay[2*i+1] = b_i;
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}
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}
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void a52_imdct_256(sample_t data[],sample_t delay[],sample_t bias)
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{
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int i, k;
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sample_t t_r, t_i, a_r, a_i, b_r, b_i, c_r, c_i, d_r, d_i, w_1, w_2;
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complex_t * buf1, * buf2;
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const sample_t * window = a52_imdct_window;
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buf1 = &buf[0];
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buf2 = &buf[64];
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/* Pre IFFT complex multiply plus IFFT cmplx conjugate */
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for (i = 0; i < 64; i++) {
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k = fftorder[i];
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t_r = pre2[i].real;
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t_i = pre2[i].imag;
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buf1[i].real = t_i * data[254-k] + t_r * data[k];
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buf1[i].imag = t_r * data[254-k] - t_i * data[k];
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buf2[i].real = t_i * data[255-k] + t_r * data[k+1];
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buf2[i].imag = t_r * data[255-k] - t_i * data[k+1];
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}
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ifft64 (buf1);
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ifft64 (buf2);
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/* Post IFFT complex multiply */
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/* Window and convert to real valued signal */
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for (i = 0; i < 32; i++) {
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/* y1[n] = z1[n] * (xcos2[n] + j * xs in2[n]) ; */
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t_r = post2[i].real;
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t_i = post2[i].imag;
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a_r = t_r * buf1[i].real + t_i * buf1[i].imag;
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a_i = t_i * buf1[i].real - t_r * buf1[i].imag;
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b_r = t_i * buf1[63-i].real + t_r * buf1[63-i].imag;
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b_i = t_r * buf1[63-i].real - t_i * buf1[63-i].imag;
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c_r = t_r * buf2[i].real + t_i * buf2[i].imag;
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c_i = t_i * buf2[i].real - t_r * buf2[i].imag;
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d_r = t_i * buf2[63-i].real + t_r * buf2[63-i].imag;
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d_i = t_r * buf2[63-i].real - t_i * buf2[63-i].imag;
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w_1 = window[2*i];
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w_2 = window[255-2*i];
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data[2*i] = delay[2*i] * w_2 - a_r * w_1 + bias;
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data[255-2*i] = delay[2*i] * w_1 + a_r * w_2 + bias;
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delay[2*i] = c_i;
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w_1 = window[128+2*i];
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w_2 = window[127-2*i];
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data[128+2*i] = delay[127-2*i] * w_2 + a_i * w_1 + bias;
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data[127-2*i] = delay[127-2*i] * w_1 - a_i * w_2 + bias;
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delay[127-2*i] = c_r;
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w_1 = window[2*i+1];
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w_2 = window[254-2*i];
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data[2*i+1] = delay[2*i+1] * w_2 - b_i * w_1 + bias;
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data[254-2*i] = delay[2*i+1] * w_1 + b_i * w_2 + bias;
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delay[2*i+1] = d_r;
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w_1 = window[129+2*i];
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w_2 = window[126-2*i];
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data[129+2*i] = delay[126-2*i] * w_2 + b_r * w_1 + bias;
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data[126-2*i] = delay[126-2*i] * w_1 - b_r * w_2 + bias;
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delay[126-2*i] = d_i;
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}
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}
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static double besselI0 (double x)
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{
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double bessel = 1;
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int i = 100;
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do
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bessel = bessel * x / (i * i) + 1;
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while (--i);
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return bessel;
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}
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void a52_imdct_init (uint32_t mm_accel)
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{
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int i, k;
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double sum;
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/* compute imdct window - kaiser-bessel derived window, alpha = 5.0 */
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sum = 0;
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for (i = 0; i < 256; i++) {
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sum += besselI0 (i * (256 - i) * (5 * M_PI / 256) * (5 * M_PI / 256));
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a52_imdct_window[i] = sum;
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}
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sum++;
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for (i = 0; i < 256; i++)
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a52_imdct_window[i] = sqrt (a52_imdct_window[i] / sum);
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for (i = 0; i < 3; i++)
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roots16[i] = cos ((M_PI / 8) * (i + 1));
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for (i = 0; i < 7; i++)
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roots32[i] = cos ((M_PI / 16) * (i + 1));
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for (i = 0; i < 15; i++)
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roots64[i] = cos ((M_PI / 32) * (i + 1));
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for (i = 0; i < 31; i++)
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roots128[i] = cos ((M_PI / 64) * (i + 1));
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for (i = 0; i < 64; i++) {
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k = fftorder[i] / 2 + 64;
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pre1[i].real = cos ((M_PI / 256) * (k - 0.25));
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pre1[i].imag = sin ((M_PI / 256) * (k - 0.25));
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}
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for (i = 64; i < 128; i++) {
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k = fftorder[i] / 2 + 64;
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pre1[i].real = -cos ((M_PI / 256) * (k - 0.25));
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pre1[i].imag = -sin ((M_PI / 256) * (k - 0.25));
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}
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for (i = 0; i < 64; i++) {
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post1[i].real = cos ((M_PI / 256) * (i + 0.5));
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post1[i].imag = sin ((M_PI / 256) * (i + 0.5));
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}
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for (i = 0; i < 64; i++) {
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k = fftorder[i] / 4;
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pre2[i].real = cos ((M_PI / 128) * (k - 0.25));
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pre2[i].imag = sin ((M_PI / 128) * (k - 0.25));
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}
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for (i = 0; i < 32; i++) {
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post2[i].real = cos ((M_PI / 128) * (i + 0.5));
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post2[i].imag = sin ((M_PI / 128) * (i + 0.5));
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}
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#ifdef LIBA52_DJBFFT
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if (mm_accel & MM_ACCEL_DJBFFT) {
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fprintf (stderr, "Using djbfft for IMDCT transform\n");
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ifft128 = (void (*) (complex_t *)) fftc4_un128;
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ifft64 = (void (*) (complex_t *)) fftc4_un64;
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} else
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#endif
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{
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fprintf (stderr, "No accelerated IMDCT transform found\n");
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ifft128 = ifft128_c;
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ifft64 = ifft64_c;
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}
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}
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