Imported Debian version 2.5.3~trusty1
[deb_ffmpeg.git] / ffmpeg / libavcodec / mdct_template.c
CommitLineData
2ba45a60
DM
1/*
2 * MDCT/IMDCT transforms
3 * Copyright (c) 2002 Fabrice Bellard
4 *
5 * This file is part of FFmpeg.
6 *
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22#include <stdlib.h>
23#include <string.h>
24#include "libavutil/common.h"
25#include "libavutil/mathematics.h"
26#include "fft.h"
27#include "fft-internal.h"
28
29/**
30 * @file
31 * MDCT/IMDCT transforms.
32 */
33
34#if FFT_FLOAT
35# define RSCALE(x) (x)
36#else
37#if FFT_FIXED_32
38# define RSCALE(x) (((x) + 32) >> 6)
39#else /* FFT_FIXED_32 */
40# define RSCALE(x) ((x) >> 1)
41#endif /* FFT_FIXED_32 */
42#endif
43
44/**
45 * init MDCT or IMDCT computation.
46 */
47av_cold int ff_mdct_init(FFTContext *s, int nbits, int inverse, double scale)
48{
49 int n, n4, i;
50 double alpha, theta;
51 int tstep;
52
53 memset(s, 0, sizeof(*s));
54 n = 1 << nbits;
55 s->mdct_bits = nbits;
56 s->mdct_size = n;
57 n4 = n >> 2;
58 s->mdct_permutation = FF_MDCT_PERM_NONE;
59
60 if (ff_fft_init(s, s->mdct_bits - 2, inverse) < 0)
61 goto fail;
62
63 s->tcos = av_malloc_array(n/2, sizeof(FFTSample));
64 if (!s->tcos)
65 goto fail;
66
67 switch (s->mdct_permutation) {
68 case FF_MDCT_PERM_NONE:
69 s->tsin = s->tcos + n4;
70 tstep = 1;
71 break;
72 case FF_MDCT_PERM_INTERLEAVE:
73 s->tsin = s->tcos + 1;
74 tstep = 2;
75 break;
76 default:
77 goto fail;
78 }
79
80 theta = 1.0 / 8.0 + (scale < 0 ? n4 : 0);
81 scale = sqrt(fabs(scale));
82 for(i=0;i<n4;i++) {
83 alpha = 2 * M_PI * (i + theta) / n;
84 s->tcos[i*tstep] = FIX15(-cos(alpha) * scale);
85 s->tsin[i*tstep] = FIX15(-sin(alpha) * scale);
86 }
87 return 0;
88 fail:
89 ff_mdct_end(s);
90 return -1;
91}
92
93/**
94 * Compute the middle half of the inverse MDCT of size N = 2^nbits,
95 * thus excluding the parts that can be derived by symmetry
96 * @param output N/2 samples
97 * @param input N/2 samples
98 */
99void ff_imdct_half_c(FFTContext *s, FFTSample *output, const FFTSample *input)
100{
101 int k, n8, n4, n2, n, j;
102 const uint16_t *revtab = s->revtab;
103 const FFTSample *tcos = s->tcos;
104 const FFTSample *tsin = s->tsin;
105 const FFTSample *in1, *in2;
106 FFTComplex *z = (FFTComplex *)output;
107
108 n = 1 << s->mdct_bits;
109 n2 = n >> 1;
110 n4 = n >> 2;
111 n8 = n >> 3;
112
113 /* pre rotation */
114 in1 = input;
115 in2 = input + n2 - 1;
116 for(k = 0; k < n4; k++) {
117 j=revtab[k];
118 CMUL(z[j].re, z[j].im, *in2, *in1, tcos[k], tsin[k]);
119 in1 += 2;
120 in2 -= 2;
121 }
122 s->fft_calc(s, z);
123
124 /* post rotation + reordering */
125 for(k = 0; k < n8; k++) {
126 FFTSample r0, i0, r1, i1;
127 CMUL(r0, i1, z[n8-k-1].im, z[n8-k-1].re, tsin[n8-k-1], tcos[n8-k-1]);
128 CMUL(r1, i0, z[n8+k ].im, z[n8+k ].re, tsin[n8+k ], tcos[n8+k ]);
129 z[n8-k-1].re = r0;
130 z[n8-k-1].im = i0;
131 z[n8+k ].re = r1;
132 z[n8+k ].im = i1;
133 }
134}
135
136/**
137 * Compute inverse MDCT of size N = 2^nbits
138 * @param output N samples
139 * @param input N/2 samples
140 */
141void ff_imdct_calc_c(FFTContext *s, FFTSample *output, const FFTSample *input)
142{
143 int k;
144 int n = 1 << s->mdct_bits;
145 int n2 = n >> 1;
146 int n4 = n >> 2;
147
148 ff_imdct_half_c(s, output+n4, input);
149
150 for(k = 0; k < n4; k++) {
151 output[k] = -output[n2-k-1];
152 output[n-k-1] = output[n2+k];
153 }
154}
155
156/**
157 * Compute MDCT of size N = 2^nbits
158 * @param input N samples
159 * @param out N/2 samples
160 */
161void ff_mdct_calc_c(FFTContext *s, FFTSample *out, const FFTSample *input)
162{
163 int i, j, n, n8, n4, n2, n3;
164 FFTDouble re, im;
165 const uint16_t *revtab = s->revtab;
166 const FFTSample *tcos = s->tcos;
167 const FFTSample *tsin = s->tsin;
168 FFTComplex *x = (FFTComplex *)out;
169
170 n = 1 << s->mdct_bits;
171 n2 = n >> 1;
172 n4 = n >> 2;
173 n8 = n >> 3;
174 n3 = 3 * n4;
175
176 /* pre rotation */
177 for(i=0;i<n8;i++) {
178 re = RSCALE(-input[2*i+n3] - input[n3-1-2*i]);
179 im = RSCALE(-input[n4+2*i] + input[n4-1-2*i]);
180 j = revtab[i];
181 CMUL(x[j].re, x[j].im, re, im, -tcos[i], tsin[i]);
182
183 re = RSCALE( input[2*i] - input[n2-1-2*i]);
184 im = RSCALE(-input[n2+2*i] - input[ n-1-2*i]);
185 j = revtab[n8 + i];
186 CMUL(x[j].re, x[j].im, re, im, -tcos[n8 + i], tsin[n8 + i]);
187 }
188
189 s->fft_calc(s, x);
190
191 /* post rotation */
192 for(i=0;i<n8;i++) {
193 FFTSample r0, i0, r1, i1;
194 CMUL(i1, r0, x[n8-i-1].re, x[n8-i-1].im, -tsin[n8-i-1], -tcos[n8-i-1]);
195 CMUL(i0, r1, x[n8+i ].re, x[n8+i ].im, -tsin[n8+i ], -tcos[n8+i ]);
196 x[n8-i-1].re = r0;
197 x[n8-i-1].im = i0;
198 x[n8+i ].re = r1;
199 x[n8+i ].im = i1;
200 }
201}
202
203av_cold void ff_mdct_end(FFTContext *s)
204{
205 av_freep(&s->tcos);
206 ff_fft_end(s);
207}