diff options
Diffstat (limited to 'faad2/src/libfaad/mdct.c')
| -rw-r--r-- | faad2/src/libfaad/mdct.c | 301 |
1 files changed, 301 insertions, 0 deletions
diff --git a/faad2/src/libfaad/mdct.c b/faad2/src/libfaad/mdct.c new file mode 100644 index 0000000..6c4f584 --- /dev/null +++ b/faad2/src/libfaad/mdct.c @@ -0,0 +1,301 @@ +/*
+** FAAD2 - Freeware Advanced Audio (AAC) Decoder including SBR decoding
+** Copyright (C) 2003-2005 M. Bakker, Nero 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.
+**
+** The "appropriate copyright message" mentioned in section 2c of the GPLv2
+** must read: "Code from FAAD2 is copyright (c) Nero AG, www.nero.com"
+**
+** Commercial non-GPL licensing of this software is possible.
+** For more info contact Nero AG through Mpeg4AAClicense@nero.com.
+**
+** $Id: mdct.c,v 1.47 2007/11/01 12:33:31 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 <stdlib.h>
+#ifdef _WIN32_WCE
+#define assert(x)
+#else
+#include <assert.h>
+#endif
+
+#include "cfft.h"
+#include "mdct.h"
+#include "mdct_tab.h"
+
+
+mdct_info *faad_mdct_init(uint16_t N)
+{
+ mdct_info *mdct = (mdct_info*)faad_malloc(sizeof(mdct_info));
+
+ assert(N % 8 == 0);
+
+ mdct->N = N;
+
+ /* NOTE: For "small framelengths" in FIXED_POINT the coefficients need to be
+ * scaled by sqrt("(nearest power of 2) > N" / N) */
+
+ /* RE(mdct->sincos[k]) = scale*(real_t)(cos(2.0*M_PI*(k+1./8.) / (real_t)N));
+ * IM(mdct->sincos[k]) = scale*(real_t)(sin(2.0*M_PI*(k+1./8.) / (real_t)N)); */
+ /* scale is 1 for fixed point, sqrt(N) for floating point */
+ switch (N)
+ {
+ case 2048: mdct->sincos = (complex_t*)mdct_tab_2048; break;
+ case 256: mdct->sincos = (complex_t*)mdct_tab_256; break;
+#ifdef LD_DEC
+ case 1024: mdct->sincos = (complex_t*)mdct_tab_1024; break;
+#endif
+#ifdef ALLOW_SMALL_FRAMELENGTH
+ case 1920: mdct->sincos = (complex_t*)mdct_tab_1920; break;
+ case 240: mdct->sincos = (complex_t*)mdct_tab_240; break;
+#ifdef LD_DEC
+ case 960: mdct->sincos = (complex_t*)mdct_tab_960; break;
+#endif
+#endif
+#ifdef SSR_DEC
+ case 512: mdct->sincos = (complex_t*)mdct_tab_512; break;
+ case 64: mdct->sincos = (complex_t*)mdct_tab_64; break;
+#endif
+ }
+
+ /* initialise fft */
+ mdct->cfft = cffti(N/4);
+
+#ifdef PROFILE
+ mdct->cycles = 0;
+ mdct->fft_cycles = 0;
+#endif
+
+ return mdct;
+}
+
+void faad_mdct_end(mdct_info *mdct)
+{
+ if (mdct != NULL)
+ {
+#ifdef PROFILE
+ printf("MDCT[%.4d]: %I64d cycles\n", mdct->N, mdct->cycles);
+ printf("CFFT[%.4d]: %I64d cycles\n", mdct->N/4, mdct->fft_cycles);
+#endif
+
+ cfftu(mdct->cfft);
+
+ faad_free(mdct);
+ }
+}
+
+void faad_imdct(mdct_info *mdct, real_t *X_in, real_t *X_out)
+{
+ uint16_t k;
+
+ complex_t x;
+#ifdef ALLOW_SMALL_FRAMELENGTH
+#ifdef FIXED_POINT
+ real_t scale, b_scale = 0;
+#endif
+#endif
+ ALIGN complex_t Z1[512];
+ 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;
+
+#ifdef PROFILE
+ int64_t count1, count2 = faad_get_ts();
+#endif
+
+#ifdef ALLOW_SMALL_FRAMELENGTH
+#ifdef FIXED_POINT
+ /* detect non-power of 2 */
+ if (N & (N-1))
+ {
+ /* adjust scale for non-power of 2 MDCT */
+ /* 2048/1920 */
+ b_scale = 1;
+ scale = COEF_CONST(1.0666666666666667);
+ }
+#endif
+#endif
+
+ /* pre-IFFT complex multiplication */
+ for (k = 0; k < N4; k++)
+ {
+ ComplexMult(&IM(Z1[k]), &RE(Z1[k]),
+ X_in[2*k], X_in[N2 - 1 - 2*k], RE(sincos[k]), IM(sincos[k]));
+ }
+
+#ifdef PROFILE
+ count1 = faad_get_ts();
+#endif
+
+ /* complex IFFT, any non-scaling FFT can be used here */
+ cfftb(mdct->cfft, Z1);
+
+#ifdef PROFILE
+ count1 = faad_get_ts() - count1;
+#endif
+
+ /* post-IFFT complex multiplication */
+ for (k = 0; k < N4; k++)
+ {
+ RE(x) = RE(Z1[k]);
+ IM(x) = IM(Z1[k]);
+ ComplexMult(&IM(Z1[k]), &RE(Z1[k]),
+ IM(x), RE(x), RE(sincos[k]), IM(sincos[k]));
+
+#ifdef ALLOW_SMALL_FRAMELENGTH
+#ifdef FIXED_POINT
+ /* non-power of 2 MDCT scaling */
+ if (b_scale)
+ {
+ RE(Z1[k]) = MUL_C(RE(Z1[k]), scale);
+ IM(Z1[k]) = MUL_C(IM(Z1[k]), scale);
+ }
+#endif
+#endif
+ }
+
+ /* reordering */
+ for (k = 0; k < N8; k+=2)
+ {
+ X_out[ 2*k] = IM(Z1[N8 + k]);
+ X_out[ 2 + 2*k] = IM(Z1[N8 + 1 + k]);
+
+ X_out[ 1 + 2*k] = -RE(Z1[N8 - 1 - k]);
+ X_out[ 3 + 2*k] = -RE(Z1[N8 - 2 - k]);
+
+ X_out[N4 + 2*k] = RE(Z1[ k]);
+ X_out[N4 + + 2 + 2*k] = RE(Z1[ 1 + k]);
+
+ X_out[N4 + 1 + 2*k] = -IM(Z1[N4 - 1 - k]);
+ X_out[N4 + 3 + 2*k] = -IM(Z1[N4 - 2 - k]);
+
+ X_out[N2 + 2*k] = RE(Z1[N8 + k]);
+ X_out[N2 + + 2 + 2*k] = RE(Z1[N8 + 1 + k]);
+
+ X_out[N2 + 1 + 2*k] = -IM(Z1[N8 - 1 - k]);
+ X_out[N2 + 3 + 2*k] = -IM(Z1[N8 - 2 - k]);
+
+ X_out[N2 + N4 + 2*k] = -IM(Z1[ k]);
+ X_out[N2 + N4 + 2 + 2*k] = -IM(Z1[ 1 + k]);
+
+ X_out[N2 + N4 + 1 + 2*k] = RE(Z1[N4 - 1 - k]);
+ X_out[N2 + N4 + 3 + 2*k] = RE(Z1[N4 - 2 - k]);
+ }
+
+#ifdef PROFILE
+ count2 = faad_get_ts() - count2;
+ mdct->fft_cycles += count1;
+ mdct->cycles += (count2 - count1);
+#endif
+}
+
+#ifdef LTP_DEC
+void faad_mdct(mdct_info *mdct, real_t *X_in, real_t *X_out)
+{
+ uint16_t k;
+
+ complex_t x;
+ ALIGN complex_t Z1[512];
+ 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;
+
+#ifndef FIXED_POINT
+ real_t scale = REAL_CONST(N);
+#else
+ real_t scale = REAL_CONST(4.0/N);
+#endif
+
+#ifdef ALLOW_SMALL_FRAMELENGTH
+#ifdef FIXED_POINT
+ /* detect non-power of 2 */
+ if (N & (N-1))
+ {
+ /* adjust scale for non-power of 2 MDCT */
+ /* *= sqrt(2048/1920) */
+ scale = MUL_C(scale, COEF_CONST(1.0327955589886444));
+ }
+#endif
+#endif
+
+ /* 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];
+
+ ComplexMult(&RE(Z1[k]), &IM(Z1[k]),
+ RE(x), IM(x), RE(sincos[k]), IM(sincos[k]));
+
+ RE(Z1[k]) = MUL_R(RE(Z1[k]), scale);
+ IM(Z1[k]) = MUL_R(IM(Z1[k]), scale);
+
+ RE(x) = X_in[N2 - 1 - n] - X_in[ n];
+ IM(x) = X_in[N2 + n] + X_in[N - 1 - n];
+
+ ComplexMult(&RE(Z1[k + N8]), &IM(Z1[k + N8]),
+ RE(x), IM(x), RE(sincos[k + N8]), IM(sincos[k + N8]));
+
+ RE(Z1[k + N8]) = MUL_R(RE(Z1[k + N8]), scale);
+ IM(Z1[k + N8]) = MUL_R(IM(Z1[k + N8]), scale);
+ }
+
+ /* 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;
+ ComplexMult(&RE(x), &IM(x),
+ RE(Z1[k]), IM(Z1[k]), RE(sincos[k]), IM(sincos[k]));
+
+ 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
|