2 * This file is part of FFmpeg.
4 * FFmpeg is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU Lesser General Public
6 * License as published by the Free Software Foundation; either
7 * version 2.1 of the License, or (at your option) any later version.
9 * FFmpeg is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * Lesser General Public License for more details.
14 * You should have received a copy of the GNU Lesser General Public
15 * License along with FFmpeg; if not, write to the Free Software
16 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21 int ff_tx_type_is_mdct(enum AVTXType type)
24 case AV_TX_FLOAT_MDCT:
25 case AV_TX_DOUBLE_MDCT:
26 case AV_TX_INT32_MDCT:
33 /* Calculates the modular multiplicative inverse, not fast, replace */
34 static av_always_inline int mulinv(int n, int m)
37 for (int x = 1; x < m; x++)
38 if (((n * x) % m) == 1)
40 av_assert0(0); /* Never reached */
43 /* Guaranteed to work for any n, m where gcd(n, m) == 1 */
44 int ff_tx_gen_compound_mapping(AVTXContext *s)
46 int *in_map, *out_map;
49 const int inv = s->inv;
51 const int m_inv = mulinv(m, n);
52 const int n_inv = mulinv(n, m);
53 const int mdct = ff_tx_type_is_mdct(s->type);
55 if (!(s->pfatab = av_malloc(2*len*sizeof(*s->pfatab))))
56 return AVERROR(ENOMEM);
59 out_map = s->pfatab + n*m;
61 /* Ruritanian map for input, CRT map for output, can be swapped */
62 for (int j = 0; j < m; j++) {
63 for (int i = 0; i < n; i++) {
64 /* Shifted by 1 to simplify MDCTs */
65 in_map[j*n + i] = ((i*m + j*n) % len) << mdct;
66 out_map[(i*m*m_inv + j*n*n_inv) % len] = i*m + j;
70 /* Change transform direction by reversing all ACs */
72 for (int i = 0; i < m; i++) {
73 int *in = &in_map[i*n + 1]; /* Skip the DC */
74 for (int j = 0; j < ((n - 1) >> 1); j++)
75 FFSWAP(int, in[j], in[n - j - 2]);
79 /* Our 15-point transform is also a compound one, so embed its input map */
81 for (int k = 0; k < m; k++) {
83 memcpy(tmp, &in_map[k*15], 15*sizeof(*tmp));
84 for (int i = 0; i < 5; i++) {
85 for (int j = 0; j < 3; j++)
86 in_map[k*15 + i*3 + j] = tmp[(i*3 + j*5) % 15];
94 int ff_tx_gen_ptwo_revtab(AVTXContext *s)
96 const int m = s->m, inv = s->inv;
98 if (!(s->revtab = av_malloc(m*sizeof(*s->revtab))))
99 return AVERROR(ENOMEM);
102 for (int i = 0; i < m; i++) {
103 int k = -split_radix_permutation(i, m, inv) & (m - 1);
110 av_cold void av_tx_uninit(AVTXContext **ctx)
115 av_free((*ctx)->pfatab);
116 av_free((*ctx)->exptab);
117 av_free((*ctx)->revtab);
118 av_free((*ctx)->tmp);
123 av_cold int av_tx_init(AVTXContext **ctx, av_tx_fn *tx, enum AVTXType type,
124 int inv, int len, const void *scale, uint64_t flags)
127 AVTXContext *s = av_mallocz(sizeof(*s));
129 return AVERROR(ENOMEM);
132 case AV_TX_FLOAT_FFT:
133 case AV_TX_FLOAT_MDCT:
134 if ((err = ff_tx_init_mdct_fft_float(s, tx, type, inv, len, scale, flags)))
137 case AV_TX_DOUBLE_FFT:
138 case AV_TX_DOUBLE_MDCT:
139 if ((err = ff_tx_init_mdct_fft_double(s, tx, type, inv, len, scale, flags)))
142 case AV_TX_INT32_FFT:
143 case AV_TX_INT32_MDCT:
144 if ((err = ff_tx_init_mdct_fft_int32(s, tx, type, inv, len, scale, flags)))
148 err = AVERROR(EINVAL);