/* ** FAAD2 - Freeware Advanced Audio (AAC) Decoder including SBR decoding ** Copyright (C) 2003 M. Bakker, Ahead Software AG, http://www.nero.com ** ** This program is free software; you can redistribute it and/or modify ** it under the terms of the GNU General Public License as published by ** the Free Software Foundation; either version 2 of the License, or ** (at your option) any later version. ** ** This program is distributed in the hope that it will be useful, ** but WITHOUT ANY WARRANTY; without even the implied warranty of ** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the ** GNU General Public License for more details. ** ** You should have received a copy of the GNU General Public License ** along with this program; if not, write to the Free Software ** Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. ** ** Any non-GPL usage of this software or parts of this software is strictly ** forbidden. ** ** Commercial non-GPL licensing of this software is possible. ** For more info contact Ahead Software through Mpeg4AAClicense@nero.com. ** ** $Id: mdct.c,v 1.28 2003/09/30 12:43:05 menno Exp $ **/ /* * Fast (I)MDCT Implementation using (I)FFT ((Inverse) Fast Fourier Transform) * and consists of three steps: pre-(I)FFT complex multiplication, complex * (I)FFT, post-(I)FFT complex multiplication, * * As described in: * P. Duhamel, Y. Mahieux, and J.P. Petit, "A Fast Algorithm for the * Implementation of Filter Banks Based on 'Time Domain Aliasing * Cancellation’," IEEE Proc. on ICASSP‘91, 1991, pp. 2209-2212. * * * As of April 6th 2002 completely rewritten. * This (I)MDCT can now be used for any data size n, where n is divisible by 8. * */ #include "common.h" #include "structs.h" #include #ifdef _WIN32_WCE #define assert(x) #else #include #endif #include "cfft.h" #include "mdct.h" /* const_tab[]: 0: sqrt(2 / N) 1: cos(2 * PI / N) 2: sin(2 * PI / N) 3: cos(2 * PI * (1/8) / N) 4: sin(2 * PI * (1/8) / N) */ #ifndef FIXED_POINT #ifdef _MSC_VER #pragma warning(disable:4305) #pragma warning(disable:4244) #endif real_t const_tab[][5] = { { COEF_CONST(0.0312500000), COEF_CONST(0.9999952938), COEF_CONST(0.0030679568), COEF_CONST(0.9999999265), COEF_CONST(0.0003834952) }, /* 2048 */ { COEF_CONST(0.0322748612), COEF_CONST(0.9999946356), COEF_CONST(0.0032724866), COEF_CONST(0.9999999404), COEF_CONST(0.0004090615) }, /* 1920 */ { COEF_CONST(0.0441941738), COEF_CONST(0.9999811649), COEF_CONST(0.0061358847), COEF_CONST(0.9999997020), COEF_CONST(0.0007669903) }, /* 1024 */ { COEF_CONST(0.0456435465), COEF_CONST(0.9999786019), COEF_CONST(0.0065449383), COEF_CONST(0.9999996424), COEF_CONST(0.0008181230) }, /* 960 */ { COEF_CONST(0.0883883476), COEF_CONST(0.9996988177), COEF_CONST(0.0245412290), COEF_CONST(0.9999952912), COEF_CONST(0.0030679568) }, /* 256 */ { COEF_CONST(0.0912870929), COEF_CONST(0.9996573329), COEF_CONST(0.0261769500), COEF_CONST(0.9999946356), COEF_CONST(0.0032724866) } /* 240 */ #ifdef SSR_DEC ,{ COEF_CONST(0.062500000), COEF_CONST(0.999924702), COEF_CONST(0.012271538), COEF_CONST(0.999998823), COEF_CONST(0.00153398) }, /* 512 */ { COEF_CONST(0.176776695), COEF_CONST(0.995184727), COEF_CONST(0.09801714), COEF_CONST(0.999924702), COEF_CONST(0.012271538) } /* 64 */ #endif }; #else real_t const_tab[][5] = { { COEF_CONST(1), COEF_CONST(0.9999952938), COEF_CONST(0.0030679568), COEF_CONST(0.9999999265), COEF_CONST(0.0003834952) }, /* 2048 */ { COEF_CONST(/* sqrt(1024/960) */ 1.03279556), COEF_CONST(0.9999946356), COEF_CONST(0.0032724866), COEF_CONST(0), COEF_CONST(0.0004090615) }, /* 1920 */ { COEF_CONST(1), COEF_CONST(0.9999811649), COEF_CONST(0.0061358847), COEF_CONST(0.9999997020), COEF_CONST(0.0007669903) }, /* 1024 */ { COEF_CONST(/* sqrt(512/480) */ 1.03279556), COEF_CONST(0.9999786019), COEF_CONST(0.0065449383), COEF_CONST(0.9999996424), COEF_CONST(0.0008181230) }, /* 960 */ { COEF_CONST(1), COEF_CONST(0.9996988177), COEF_CONST(0.0245412290), COEF_CONST(0.9999952912), COEF_CONST(0.0030679568) }, /* 256 */ { COEF_CONST(/* sqrt(256/240) */ 1.03279556), COEF_CONST(0.9996573329), COEF_CONST(0.0261769500), COEF_CONST(0.9999946356), COEF_CONST(0.0032724866) } /* 240 */ #ifdef SSR_DEC ,{ COEF_CONST(0), COEF_CONST(0.999924702), COEF_CONST(0.012271538), COEF_CONST(0.999998823), COEF_CONST(0.00153398) }, /* 512 */ { COEF_CONST(0), COEF_CONST(0.995184727), COEF_CONST(0.09801714), COEF_CONST(0.999924702), COEF_CONST(0.012271538) } /* 64 */ #endif }; #endif uint8_t map_N_to_idx(uint16_t N) { /* gives an index into const_tab above */ /* for normal AAC deocding (eg. no scalable profile) only */ /* index 0 and 4 will be used */ switch(N) { case 2048: return 0; case 1920: return 1; case 1024: return 2; case 960: return 3; case 256: return 4; case 240: return 5; #ifdef SSR_DEC case 512: return 6; case 64: return 7; #endif } return 0; } mdct_info *faad_mdct_init(uint16_t N) { uint16_t k, N_idx; real_t cangle, sangle, c, s, cold; real_t scale; mdct_info *mdct = (mdct_info*)malloc(sizeof(mdct_info)); assert(N % 8 == 0); mdct->N = N; mdct->sincos = (complex_t*)malloc(N/4*sizeof(complex_t)); mdct->Z1 = (complex_t*)malloc(N/4*sizeof(complex_t)); N_idx = map_N_to_idx(N); scale = const_tab[N_idx][0]; cangle = const_tab[N_idx][1]; sangle = const_tab[N_idx][2]; c = const_tab[N_idx][3]; s = const_tab[N_idx][4]; /* (co)sine table build using recurrence relations */ /* this can also be done using static table lookup or */ /* some form of interpolation */ for (k = 0; k < N/4; k++) { #if 1 RE(mdct->sincos[k]) = -1*MUL_C_C(c,scale); IM(mdct->sincos[k]) = -1*MUL_C_C(s,scale); cold = c; c = MUL_C_C(c,cangle) - MUL_C_C(s,sangle); s = MUL_C_C(s,cangle) + MUL_C_C(cold,sangle); #else /* no recurrence, just sines */ RE(mdct->sincos[k]) = -scale*cos(2.0*M_PI*(k+1./8.) / (float)N); IM(mdct->sincos[k]) = -scale*sin(2.0*M_PI*(k+1./8.) / (float)N); #endif } /* initialise fft */ mdct->cfft = cffti(N/4); return mdct; } void faad_mdct_end(mdct_info *mdct) { if (mdct != NULL) { cfftu(mdct->cfft); if (mdct->Z1) free(mdct->Z1); if (mdct->sincos) free(mdct->sincos); free(mdct); } } void faad_imdct(mdct_info *mdct, real_t *X_in, real_t *X_out) { uint16_t k; complex_t x; complex_t *Z1 = mdct->Z1; complex_t *sincos = mdct->sincos; uint16_t N = mdct->N; uint16_t N2 = N >> 1; uint16_t N4 = N >> 2; uint16_t N8 = N >> 3; /* pre-IFFT complex multiplication */ for (k = 0; k < N4; k++) { RE(Z1[k]) = MUL_R_C(X_in[N2 - 1 - 2*k], RE(sincos[k])) - MUL_R_C(X_in[2*k], IM(sincos[k])); IM(Z1[k]) = MUL_R_C(X_in[2*k], RE(sincos[k])) + MUL_R_C(X_in[N2 - 1 - 2*k], IM(sincos[k])); } /* complex IFFT, any non-scaling FFT can be used here */ cfftb(mdct->cfft, Z1); /* post-IFFT complex multiplication */ for (k = 0; k < N4; k++) { RE(x) = RE(Z1[k]); IM(x) = IM(Z1[k]); RE(Z1[k]) = MUL_R_C(RE(x), RE(sincos[k])) - MUL_R_C(IM(x), IM(sincos[k])); IM(Z1[k]) = MUL_R_C(IM(x), RE(sincos[k])) + MUL_R_C(RE(x), IM(sincos[k])); } /* reordering */ for (k = 0; k < N8; k++) { X_out[ 2*k] = IM(Z1[N8 + k]); X_out[ 1 + 2*k] = -RE(Z1[N8 - 1 - k]); X_out[N4 + 2*k] = RE(Z1[ k]); X_out[N4 + 1 + 2*k] = -IM(Z1[N4 - 1 - k]); X_out[N2 + 2*k] = RE(Z1[N8 + k]); X_out[N2 + 1 + 2*k] = -IM(Z1[N8 - 1 - k]); X_out[N2 + N4 + 2*k] = -IM(Z1[ k]); X_out[N2 + N4 + 1 + 2*k] = RE(Z1[N4 - 1 - k]); } } #ifdef LTP_DEC void faad_mdct(mdct_info *mdct, real_t *X_in, real_t *X_out) { uint16_t k; complex_t x; complex_t *Z1 = mdct->Z1; complex_t *sincos = mdct->sincos; uint16_t N = mdct->N; uint16_t N2 = N >> 1; uint16_t N4 = N >> 2; uint16_t N8 = N >> 3; real_t scale = REAL_CONST(N); /* pre-FFT complex multiplication */ for (k = 0; k < N8; k++) { uint16_t n = k << 1; RE(x) = X_in[N - N4 - 1 - n] + X_in[N - N4 + n]; IM(x) = X_in[ N4 + n] - X_in[ N4 - 1 - n]; RE(Z1[k]) = -MUL_R_C(RE(x), RE(sincos[k])) - MUL_R_C(IM(x), IM(sincos[k])); IM(Z1[k]) = -MUL_R_C(IM(x), RE(sincos[k])) + MUL_R_C(RE(x), IM(sincos[k])); RE(x) = X_in[N2 - 1 - n] - X_in[ n]; IM(x) = X_in[N2 + n] + X_in[N - 1 - n]; RE(Z1[k + N8]) = -MUL_R_C(RE(x), RE(sincos[k + N8])) - MUL_R_C(IM(x), IM(sincos[k + N8])); IM(Z1[k + N8]) = -MUL_R_C(IM(x), RE(sincos[k + N8])) + MUL_R_C(RE(x), IM(sincos[k + N8])); } /* complex FFT, any non-scaling FFT can be used here */ cfftf(mdct->cfft, Z1); /* post-FFT complex multiplication */ for (k = 0; k < N4; k++) { uint16_t n = k << 1; RE(x) = MUL(MUL_R_C(RE(Z1[k]), RE(sincos[k])) + MUL_R_C(IM(Z1[k]), IM(sincos[k])), scale); IM(x) = MUL(MUL_R_C(IM(Z1[k]), RE(sincos[k])) - MUL_R_C(RE(Z1[k]), IM(sincos[k])), scale); X_out[ n] = RE(x); X_out[N2 - 1 - n] = -IM(x); X_out[N2 + n] = IM(x); X_out[N - 1 - n] = -RE(x); } } #endif