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
24 #define VLC_TYPE int16_t
28 VLC_TYPE (*table)[2]; ///< code, bits
29 int table_size, table_allocated;
32 typedef struct RL_VLC_ELEM {
38 #define init_vlc(vlc, nb_bits, nb_codes, \
39 bits, bits_wrap, bits_size, \
40 codes, codes_wrap, codes_size, \
42 ff_init_vlc_sparse(vlc, nb_bits, nb_codes, \
43 bits, bits_wrap, bits_size, \
44 codes, codes_wrap, codes_size, \
47 int ff_init_vlc_sparse(VLC *vlc, int nb_bits, int nb_codes,
48 const void *bits, int bits_wrap, int bits_size,
49 const void *codes, int codes_wrap, int codes_size,
50 const void *symbols, int symbols_wrap, int symbols_size,
54 * Build VLC decoding tables suitable for use with get_vlc2()
56 * This function takes lengths and symbols and calculates the codes from them.
57 * For this the input lengths and symbols have to be sorted according to "left
58 * nodes in the corresponding tree first".
60 * @param[in,out] vlc The VLC to be initialized; table and table_allocated
61 * must have been set when initializing a static VLC,
62 * otherwise this will be treated as uninitialized.
63 * @param[in] nb_bits The number of bits to use for the VLC table;
64 * higher values take up more memory and cache, but
65 * allow to read codes with fewer reads.
66 * @param[in] nb_codes The number of provided length and (if supplied) symbol
68 * @param[in] lens The lengths of the codes. Entries > 0 correspond to
69 * valid codes; entries == 0 will be skipped and entries
70 * with len < 0 indicate that the tree is incomplete and
71 * has an open end of length -len at this position.
72 * @param[in] lens_wrap Stride (in bytes) of the lengths.
73 * @param[in] symbols The symbols, i.e. what is returned from get_vlc2()
74 * when the corresponding code is encountered.
75 * May be NULL, then 0, 1, 2, 3, 4,... will be used.
76 * @param[in] symbols_wrap Stride (in bytes) of the symbols.
77 * @param[in] symbols_size Size of the symbols. 1 and 2 are supported.
78 * @param[in] offset An offset to apply to all the valid symbols.
79 * @param[in] flags A combination of the INIT_VLC_* flags; notice that
80 * INIT_VLC_INPUT_LE is pointless and ignored.
82 int ff_init_vlc_from_lengths(VLC *vlc, int nb_bits, int nb_codes,
83 const int8_t *lens, int lens_wrap,
84 const void *symbols, int symbols_wrap, int symbols_size,
85 int offset, int flags, void *logctx);
87 void ff_free_vlc(VLC *vlc);
89 /* If INIT_VLC_INPUT_LE is set, the LSB bit of the codes used to
90 * initialize the VLC table is the first bit to be read. */
91 #define INIT_VLC_INPUT_LE 2
92 /* If set the VLC is intended for a little endian bitstream reader. */
93 #define INIT_VLC_OUTPUT_LE 8
94 #define INIT_VLC_LE (INIT_VLC_INPUT_LE | INIT_VLC_OUTPUT_LE)
95 #define INIT_VLC_USE_NEW_STATIC 4
96 #define INIT_VLC_STATIC_OVERLONG (1 | INIT_VLC_USE_NEW_STATIC)
98 #define INIT_CUSTOM_VLC_SPARSE_STATIC(vlc, bits, a, b, c, d, e, f, g, \
99 h, i, j, flags, static_size) \
101 static VLC_TYPE table[static_size][2]; \
102 (vlc)->table = table; \
103 (vlc)->table_allocated = static_size; \
104 ff_init_vlc_sparse(vlc, bits, a, b, c, d, e, f, g, h, i, j, \
105 flags | INIT_VLC_USE_NEW_STATIC); \
108 #define INIT_VLC_SPARSE_STATIC(vlc, bits, a, b, c, d, e, f, g, h, i, j, static_size) \
109 INIT_CUSTOM_VLC_SPARSE_STATIC(vlc, bits, a, b, c, d, e, f, g, \
110 h, i, j, 0, static_size)
112 #define INIT_LE_VLC_SPARSE_STATIC(vlc, bits, a, b, c, d, e, f, g, h, i, j, static_size) \
113 INIT_CUSTOM_VLC_SPARSE_STATIC(vlc, bits, a, b, c, d, e, f, g, \
114 h, i, j, INIT_VLC_LE, static_size)
116 #define INIT_CUSTOM_VLC_STATIC(vlc, bits, a, b, c, d, e, f, g, flags, static_size) \
117 INIT_CUSTOM_VLC_SPARSE_STATIC(vlc, bits, a, b, c, d, e, f, g, \
118 NULL, 0, 0, flags, static_size)
120 #define INIT_VLC_STATIC(vlc, bits, a, b, c, d, e, f, g, static_size) \
121 INIT_VLC_SPARSE_STATIC(vlc, bits, a, b, c, d, e, f, g, NULL, 0, 0, static_size)
123 #define INIT_LE_VLC_STATIC(vlc, bits, a, b, c, d, e, f, g, static_size) \
124 INIT_LE_VLC_SPARSE_STATIC(vlc, bits, a, b, c, d, e, f, g, NULL, 0, 0, static_size)
126 #define INIT_VLC_STATIC_FROM_LENGTHS(vlc, bits, nb_codes, lens, len_wrap, \
127 symbols, symbols_wrap, symbols_size, \
128 offset, flags, static_size) \
130 static VLC_TYPE table[static_size][2]; \
131 (vlc)->table = table; \
132 (vlc)->table_allocated = static_size; \
133 ff_init_vlc_from_lengths(vlc, bits, nb_codes, lens, len_wrap, \
134 symbols, symbols_wrap, symbols_size, \
135 offset, flags | INIT_VLC_USE_NEW_STATIC, \
139 #endif /* AVCODEC_VLC_H */