/* * This file is part of FFmpeg. * * FFmpeg is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * FFmpeg 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 * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with FFmpeg; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ #ifndef AVCODEC_VLC_H #define AVCODEC_VLC_H #include <stddef.h> #include <stdint.h> #include "libavutil/macros.h" #define VLC_MULTI_MAX_SYMBOLS … // When changing this, be sure to also update tableprint_vlc.h accordingly. VLCBaseType; VLCElem; VLC; VLC_MULTI_ELEM; VLC_MULTI; RL_VLC_ELEM; #define vlc_init(vlc, nb_bits, nb_codes, \ bits, bits_wrap, bits_size, \ codes, codes_wrap, codes_size, \ flags) … /** * Build VLC decoding tables suitable for use with get_vlc2(). * * @param[in,out] vlc The VLC to be initialized; table and table_allocated * must have been set when initializing a static VLC, * otherwise this will be treated as uninitialized. * @param[in] nb_bits The number of bits to use for the VLC table; * higher values take up more memory and cache, but * allow to read codes with fewer reads. * Corresponds to the `bits` parameter of get_vlc2(). * @param[in] nb_codes The number of provided bits, codes and (if supplied) * symbol entries. * @param[in] bits The lengths (in bits) of the codes. Entries > 0 * correspond to valid codes; entries == 0 will be skipped. * @param[in] bits_wrap Stride (in bytes) of the bits table. * @param[in] codes_size Size of the bits. 1, 2 and 4 are supported. * @param[in] codes Table which gives the bit pattern of of each vlc code. * @param[in] codes_wrap Stride (in bytes) of the codes table. * @param[in] codes_size Size of the codes. 1, 2 and 4 are supported. * @param[in] symbols The symbols, i.e. what is returned from get_vlc2() * when the corresponding code is encountered. * May be NULL, then 0, 1, 2, 3, 4,... will be used. * @param[in] symbols_wrap Stride (in bytes) of the symbols table. * @param[in] symbols_size Size of the symbols. 1 and 2 are supported. * @param[in] flags A combination of the VLC_INIT_* flags. * * 'wrap' and 'size' make it possible to use any memory configuration and types * (byte/word/int) to store the 'bits', 'codes', and 'symbols' tables. */ int ff_vlc_init_sparse(VLC *vlc, int nb_bits, int nb_codes, const void *bits, int bits_wrap, int bits_size, const void *codes, int codes_wrap, int codes_size, const void *symbols, int symbols_wrap, int symbols_size, int flags); /** * Build VLC decoding tables suitable for use with get_vlc2() * * This function takes lengths and symbols and calculates the codes from them. * For this the input lengths and symbols have to be sorted according to "left * nodes in the corresponding tree first". * * @param[in,out] vlc The VLC to be initialized; table and table_allocated * must have been set when initializing a static VLC, * otherwise this will be treated as uninitialized. * @param[in] nb_bits The number of bits to use for the VLC table; * higher values take up more memory and cache, but * allow to read codes with fewer reads. * @param[in] nb_codes The number of provided length and (if supplied) symbol * entries. * @param[in] lens The lengths of the codes. Entries > 0 correspond to * valid codes; entries == 0 will be skipped and entries * with len < 0 indicate that the tree is incomplete and * has an open end of length -len at this position. * @param[in] lens_wrap Stride (in bytes) of the lengths. * @param[in] symbols The symbols, i.e. what is returned from get_vlc2() * when the corresponding code is encountered. * May be NULL, then 0, 1, 2, 3, 4,... will be used. * @param[in] symbols_wrap Stride (in bytes) of the symbols. * @param[in] symbols_size Size of the symbols. 1 and 2 are supported. * @param[in] offset An offset to apply to all the valid symbols. * @param[in] flags A combination of the VLC_INIT_* flags; notice that * VLC_INIT_INPUT_LE is pointless and ignored. */ int ff_vlc_init_from_lengths(VLC *vlc, int nb_bits, int nb_codes, const int8_t *lens, int lens_wrap, const void *symbols, int symbols_wrap, int symbols_size, int offset, int flags, void *logctx); /** * Build VLC decoding tables suitable for use with get_vlc_multi() * * This function takes lengths and symbols and calculates the codes from them. * For this the input lengths and symbols have to be sorted according to "left * nodes in the corresponding tree first". * * @param[in,out] vlc The VLC to be initialized; table and table_allocated * must have been set when initializing a static VLC, * otherwise this will be treated as uninitialized. * @param[in,out] multi The VLC_MULTI to be initialized; table and table_allocated * must have been set when initializing a static VLC, * otherwise this will be treated as uninitialized. * @param[in] nb_bits The number of bits to use for the VLC table; * higher values take up more memory and cache, but * allow to read codes with fewer reads. * @param[in] nb_elems The max possible number of elements. * @param[in] nb_codes The number of provided length and (if supplied) symbol * entries. * @param[in] lens The lengths of the codes. Entries > 0 correspond to * valid codes; entries == 0 will be skipped and entries * with len < 0 indicate that the tree is incomplete and * has an open end of length -len at this position. * @param[in] lens_wrap Stride (in bytes) of the lengths. * @param[in] symbols The symbols, i.e. what is returned from get_vlc2() * when the corresponding code is encountered. * May be NULL, then 0, 1, 2, 3, 4,... will be used. * @param[in] symbols_wrap Stride (in bytes) of the symbols. * @param[in] symbols_size Size of the symbols. 1 and 2 are supported. * @param[in] offset An offset to apply to all the valid symbols. * @param[in] flags A combination of the VLC_INIT_* flags; notice that * VLC_INIT_INPUT_LE is pointless and ignored. */ int ff_vlc_init_multi_from_lengths(VLC *vlc, VLC_MULTI *multi, int nb_bits, int nb_elems, int nb_codes, const int8_t *lens, int lens_wrap, const void *symbols, int symbols_wrap, int symbols_size, int offset, int flags, void *logctx); void ff_vlc_free_multi(VLC_MULTI *vlc); void ff_vlc_free(VLC *vlc); #define VLC_INIT_USE_STATIC … #define VLC_INIT_STATIC_OVERLONG … /* If VLC_INIT_INPUT_LE is set, the LSB bit of the codes used to * initialize the VLC table is the first bit to be read. */ #define VLC_INIT_INPUT_LE … /* If set the VLC is intended for a little endian bitstream reader. */ #define VLC_INIT_OUTPUT_LE … #define VLC_INIT_LE … /** * For static VLCs, the number of bits can often be hardcoded * at each get_vlc2() callsite. Then using a full VLC would be uneconomical, * because only VLC.table would ever be accessed after initialization. * The following functions provide wrappers around the relevant ff_vlc_init_* * functions suitable for said task. * * The ff_vlc_init_tables_* functions are intended to be used for initializing * a series of VLCs. The user initializes a VLCInitState with the details * about the underlying array of VLCElem; it is automatically updated by * the ff_vlc_init_tables_* functions (i.e. table is incremented and size * decremented by the number of elements of the current table). * The VLC_INIT_STATIC_OVERLONG flag is also automatically added. * These functions return a pointer to the table just initialized, * potentially to be used in arrays of pointer to VLC tables. * * The ff_vlc_init_table_* functions are intended to be used for initializing * a single VLC table, given by table and table_size. The VLC_INIT_USE_STATIC * flag is automatically added. */ VLCInitState; #define VLC_INIT_STATE(_table) … void ff_vlc_init_table_from_lengths(VLCElem table[], int table_size, int nb_bits, int nb_codes, const int8_t *lens, int lens_wrap, const void *symbols, int symbols_wrap, int symbols_size, int offset, int flags); const VLCElem *ff_vlc_init_tables_from_lengths(VLCInitState *state, int nb_bits, int nb_codes, const int8_t *lens, int lens_wrap, const void *symbols, int symbols_wrap, int symbols_size, int offset, int flags); void ff_vlc_init_table_sparse(VLCElem table[], int table_size, int nb_bits, int nb_codes, const void *bits, int bits_wrap, int bits_size, const void *codes, int codes_wrap, int codes_size, const void *symbols, int symbols_wrap, int symbols_size, int flags); const VLCElem *ff_vlc_init_tables_sparse(VLCInitState *state, int nb_bits, int nb_codes, const void *bits, int bits_wrap, int bits_size, const void *codes, int codes_wrap, int codes_size, const void *symbols, int symbols_wrap, int symbols_size, int flags); static inline const VLCElem *ff_vlc_init_tables(VLCInitState *state, int nb_bits, int nb_codes, const void *bits, int bits_wrap, int bits_size, const void *codes, int codes_wrap, int codes_size, int flags) { … } #define VLC_INIT_STATIC_SPARSE_TABLE(vlc_table, nb_bits, nb_codes, \ bits, bits_wrap, bits_size, \ codes, codes_wrap, codes_size, \ symbols, symbols_wrap, symbols_size, \ flags) … #define VLC_INIT_STATIC_TABLE(vlc_table, nb_bits, nb_codes, \ bits, bits_wrap, bits_size, \ codes, codes_wrap, codes_size, \ flags) … #define VLC_INIT_STATIC_TABLE_FROM_LENGTHS(vlc_table, nb_bits, nb_codes, \ lens, lens_wrap, \ syms, syms_wrap, syms_size, \ offset, flags) … #endif /* AVCODEC_VLC_H */
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