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Diffstat (limited to 'apps/codecs/libwmapro/mdct.c')
-rw-r--r-- | apps/codecs/libwmapro/mdct.c | 232 |
1 files changed, 232 insertions, 0 deletions
diff --git a/apps/codecs/libwmapro/mdct.c b/apps/codecs/libwmapro/mdct.c new file mode 100644 index 0000000000..9d0a59dc84 --- /dev/null +++ b/apps/codecs/libwmapro/mdct.c | |||
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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 | |||
28 | /** | ||
29 | * @file libavcodec/mdct.c | ||
30 | * MDCT/IMDCT transforms. | ||
31 | */ | ||
32 | |||
33 | // Generate a Kaiser-Bessel Derived Window. | ||
34 | #define BESSEL_I0_ITER 50 // default: 50 iterations of Bessel I0 approximation | ||
35 | av_cold void ff_kbd_window_init(float *window, float alpha, int n) | ||
36 | { | ||
37 | int i, j; | ||
38 | double sum = 0.0, bessel, tmp; | ||
39 | double local_window[n]; | ||
40 | double alpha2 = (alpha * M_PI / n) * (alpha * M_PI / n); | ||
41 | |||
42 | for (i = 0; i < n; i++) { | ||
43 | tmp = i * (n - i) * alpha2; | ||
44 | bessel = 1.0; | ||
45 | for (j = BESSEL_I0_ITER; j > 0; j--) | ||
46 | bessel = bessel * tmp / (j * j) + 1; | ||
47 | sum += bessel; | ||
48 | local_window[i] = sum; | ||
49 | } | ||
50 | |||
51 | sum++; | ||
52 | for (i = 0; i < n; i++) | ||
53 | window[i] = sqrt(local_window[i] / sum); | ||
54 | } | ||
55 | |||
56 | #include "mdct_tablegen.h" | ||
57 | |||
58 | /** | ||
59 | * init MDCT or IMDCT computation. | ||
60 | */ | ||
61 | av_cold int ff_mdct_init(FFTContext *s, int nbits, int inverse, double scale) | ||
62 | { | ||
63 | int n, n4, i; | ||
64 | double alpha, theta; | ||
65 | int tstep; | ||
66 | |||
67 | memset(s, 0, sizeof(*s)); | ||
68 | n = 1 << nbits; | ||
69 | s->mdct_bits = nbits; | ||
70 | s->mdct_size = n; | ||
71 | n4 = n >> 2; | ||
72 | s->permutation = FF_MDCT_PERM_NONE; | ||
73 | |||
74 | if (ff_fft_init(s, s->mdct_bits - 2, inverse) < 0) | ||
75 | goto fail; | ||
76 | |||
77 | s->tcos = av_malloc(n/2 * sizeof(FFTSample)); | ||
78 | if (!s->tcos) | ||
79 | goto fail; | ||
80 | |||
81 | switch (s->permutation) { | ||
82 | case FF_MDCT_PERM_NONE: | ||
83 | s->tsin = s->tcos + n4; | ||
84 | tstep = 1; | ||
85 | break; | ||
86 | case FF_MDCT_PERM_INTERLEAVE: | ||
87 | s->tsin = s->tcos + 1; | ||
88 | tstep = 2; | ||
89 | break; | ||
90 | default: | ||
91 | goto fail; | ||
92 | } | ||
93 | |||
94 | theta = 1.0 / 8.0 + (scale < 0 ? n4 : 0); | ||
95 | scale = sqrt(fabs(scale)); | ||
96 | for(i=0;i<n4;i++) { | ||
97 | alpha = 2 * M_PI * (i + theta) / n; | ||
98 | s->tcos[i*tstep] = -cos(alpha) * scale; | ||
99 | s->tsin[i*tstep] = -sin(alpha) * scale; | ||
100 | } | ||
101 | return 0; | ||
102 | fail: | ||
103 | ff_mdct_end(s); | ||
104 | return -1; | ||
105 | } | ||
106 | |||
107 | /* complex multiplication: p = a * b */ | ||
108 | #define CMUL(pre, pim, are, aim, bre, bim) \ | ||
109 | {\ | ||
110 | FFTSample _are = (are);\ | ||
111 | FFTSample _aim = (aim);\ | ||
112 | FFTSample _bre = (bre);\ | ||
113 | FFTSample _bim = (bim);\ | ||
114 | (pre) = _are * _bre - _aim * _bim;\ | ||
115 | (pim) = _are * _bim + _aim * _bre;\ | ||
116 | } | ||
117 | |||
118 | /** | ||
119 | * Compute the middle half of the inverse MDCT of size N = 2^nbits, | ||
120 | * thus excluding the parts that can be derived by symmetry | ||
121 | * @param output N/2 samples | ||
122 | * @param input N/2 samples | ||
123 | */ | ||
124 | void ff_imdct_half_c(FFTContext *s, FFTSample *output, const FFTSample *input) | ||
125 | { | ||
126 | int k, n8, n4, n2, n, j; | ||
127 | const uint16_t *revtab = s->revtab; | ||
128 | const FFTSample *tcos = s->tcos; | ||
129 | const FFTSample *tsin = s->tsin; | ||
130 | const FFTSample *in1, *in2; | ||
131 | FFTComplex *z = (FFTComplex *)output; | ||
132 | |||
133 | n = 1 << s->mdct_bits; | ||
134 | n2 = n >> 1; | ||
135 | n4 = n >> 2; | ||
136 | n8 = n >> 3; | ||
137 | |||
138 | /* pre rotation */ | ||
139 | in1 = input; | ||
140 | in2 = input + n2 - 1; | ||
141 | for(k = 0; k < n4; k++) { | ||
142 | j=revtab[k]; | ||
143 | CMUL(z[j].re, z[j].im, *in2, *in1, tcos[k], tsin[k]); | ||
144 | in1 += 2; | ||
145 | in2 -= 2; | ||
146 | } | ||
147 | ff_fft_calc(s, z); | ||
148 | |||
149 | /* post rotation + reordering */ | ||
150 | for(k = 0; k < n8; k++) { | ||
151 | FFTSample r0, i0, r1, i1; | ||
152 | CMUL(r0, i1, z[n8-k-1].im, z[n8-k-1].re, tsin[n8-k-1], tcos[n8-k-1]); | ||
153 | CMUL(r1, i0, z[n8+k ].im, z[n8+k ].re, tsin[n8+k ], tcos[n8+k ]); | ||
154 | z[n8-k-1].re = r0; | ||
155 | z[n8-k-1].im = i0; | ||
156 | z[n8+k ].re = r1; | ||
157 | z[n8+k ].im = i1; | ||
158 | } | ||
159 | } | ||
160 | |||
161 | /** | ||
162 | * Compute inverse MDCT of size N = 2^nbits | ||
163 | * @param output N samples | ||
164 | * @param input N/2 samples | ||
165 | */ | ||
166 | void ff_imdct_calc_c(FFTContext *s, FFTSample *output, const FFTSample *input) | ||
167 | { | ||
168 | int k; | ||
169 | int n = 1 << s->mdct_bits; | ||
170 | int n2 = n >> 1; | ||
171 | int n4 = n >> 2; | ||
172 | |||
173 | ff_imdct_half_c(s, output+n4, input); | ||
174 | |||
175 | for(k = 0; k < n4; k++) { | ||
176 | output[k] = -output[n2-k-1]; | ||
177 | output[n-k-1] = output[n2+k]; | ||
178 | } | ||
179 | } | ||
180 | |||
181 | /** | ||
182 | * Compute MDCT of size N = 2^nbits | ||
183 | * @param input N samples | ||
184 | * @param out N/2 samples | ||
185 | */ | ||
186 | void ff_mdct_calc_c(FFTContext *s, FFTSample *out, const FFTSample *input) | ||
187 | { | ||
188 | int i, j, n, n8, n4, n2, n3; | ||
189 | FFTSample re, im; | ||
190 | const uint16_t *revtab = s->revtab; | ||
191 | const FFTSample *tcos = s->tcos; | ||
192 | const FFTSample *tsin = s->tsin; | ||
193 | FFTComplex *x = (FFTComplex *)out; | ||
194 | |||
195 | n = 1 << s->mdct_bits; | ||
196 | n2 = n >> 1; | ||
197 | n4 = n >> 2; | ||
198 | n8 = n >> 3; | ||
199 | n3 = 3 * n4; | ||
200 | |||
201 | /* pre rotation */ | ||
202 | for(i=0;i<n8;i++) { | ||
203 | re = -input[2*i+3*n4] - input[n3-1-2*i]; | ||
204 | im = -input[n4+2*i] + input[n4-1-2*i]; | ||
205 | j = revtab[i]; | ||
206 | CMUL(x[j].re, x[j].im, re, im, -tcos[i], tsin[i]); | ||
207 | |||
208 | re = input[2*i] - input[n2-1-2*i]; | ||
209 | im = -(input[n2+2*i] + input[n-1-2*i]); | ||
210 | j = revtab[n8 + i]; | ||
211 | CMUL(x[j].re, x[j].im, re, im, -tcos[n8 + i], tsin[n8 + i]); | ||
212 | } | ||
213 | |||
214 | ff_fft_calc(s, x); | ||
215 | |||
216 | /* post rotation */ | ||
217 | for(i=0;i<n8;i++) { | ||
218 | FFTSample r0, i0, r1, i1; | ||
219 | CMUL(i1, r0, x[n8-i-1].re, x[n8-i-1].im, -tsin[n8-i-1], -tcos[n8-i-1]); | ||
220 | CMUL(i0, r1, x[n8+i ].re, x[n8+i ].im, -tsin[n8+i ], -tcos[n8+i ]); | ||
221 | x[n8-i-1].re = r0; | ||
222 | x[n8-i-1].im = i0; | ||
223 | x[n8+i ].re = r1; | ||
224 | x[n8+i ].im = i1; | ||
225 | } | ||
226 | } | ||
227 | |||
228 | av_cold void ff_mdct_end(FFTContext *s) | ||
229 | { | ||
230 | av_freep(&s->tcos); | ||
231 | ff_fft_end(s); | ||
232 | } | ||