mirror of https://github.com/FFmpeg/FFmpeg.git
bitstream.c is currently the disjoint union of three parts: The first part is ff_log2_run, the second part are some auxiliary functions for the PutBits-API; and the third part is the code for creating VLCs. This commit moves the latter into a file of its own. This has the advantage of making one of the hacks in tableprint_vlc.h redundant as vlc.c does not include config.h (whereas the PutBits-API part does). Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>release/5.1
Andreas Rheinhardt
3 years ago
parent
b303f1e083
commit
495de744fa
4 changed files with 380 additions and 352 deletions
@ -0,0 +1,378 @@ |
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/*
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* API for creating VLC trees |
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* Copyright (c) 2000, 2001 Fabrice Bellard |
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* Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at> |
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* Copyright (c) 2010 Loren Merritt |
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* |
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* This file is part of FFmpeg. |
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* |
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* FFmpeg is free software; you can redistribute it and/or |
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* modify it under the terms of the GNU Lesser General Public |
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* License as published by the Free Software Foundation; either |
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* version 2.1 of the License, or (at your option) any later version. |
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* |
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* FFmpeg is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of |
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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* Lesser General Public License for more details. |
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* |
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* You should have received a copy of the GNU Lesser General Public |
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* License along with FFmpeg; if not, write to the Free Software |
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
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*/ |
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#include <inttypes.h> |
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#include <stdint.h> |
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#include <stdlib.h> |
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#include <string.h> |
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#include "libavutil/attributes.h" |
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#include "libavutil/avassert.h" |
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#include "libavutil/error.h" |
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#include "libavutil/internal.h" |
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#include "libavutil/log.h" |
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#include "libavutil/macros.h" |
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#include "libavutil/mem.h" |
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#include "libavutil/qsort.h" |
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#include "libavutil/reverse.h" |
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#include "vlc.h" |
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#define GET_DATA(v, table, i, wrap, size) \ |
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{ \
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const uint8_t *ptr = (const uint8_t *)table + i * wrap; \
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switch(size) { \
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case 1: \
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v = *(const uint8_t *)ptr; \
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break; \
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case 2: \
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v = *(const uint16_t *)ptr; \
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break; \
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case 4: \
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default: \
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av_assert1(size == 4); \
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v = *(const uint32_t *)ptr; \
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break; \
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} \
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} |
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static int alloc_table(VLC *vlc, int size, int use_static) |
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{ |
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int index = vlc->table_size; |
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vlc->table_size += size; |
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if (vlc->table_size > vlc->table_allocated) { |
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if (use_static) |
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abort(); // cannot do anything, init_vlc() is used with too little memory
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vlc->table_allocated += (1 << vlc->bits); |
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vlc->table = av_realloc_f(vlc->table, vlc->table_allocated, sizeof(VLC_TYPE) * 2); |
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if (!vlc->table) { |
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vlc->table_allocated = 0; |
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vlc->table_size = 0; |
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return AVERROR(ENOMEM); |
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} |
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memset(vlc->table + vlc->table_allocated - (1 << vlc->bits), 0, sizeof(VLC_TYPE) * 2 << vlc->bits); |
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} |
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return index; |
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} |
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#define LOCALBUF_ELEMS 1500 // the maximum currently needed is 1296 by rv34
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static av_always_inline uint32_t bitswap_32(uint32_t x) |
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{ |
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return (uint32_t)ff_reverse[ x & 0xFF] << 24 | |
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(uint32_t)ff_reverse[(x >> 8) & 0xFF] << 16 | |
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(uint32_t)ff_reverse[(x >> 16) & 0xFF] << 8 | |
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(uint32_t)ff_reverse[ x >> 24]; |
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} |
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typedef struct VLCcode { |
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uint8_t bits; |
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VLC_TYPE symbol; |
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/** codeword, with the first bit-to-be-read in the msb
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* (even if intended for a little-endian bitstream reader) */ |
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uint32_t code; |
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} VLCcode; |
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static int vlc_common_init(VLC *vlc, int nb_bits, int nb_codes, |
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VLCcode **buf, int flags) |
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{ |
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vlc->bits = nb_bits; |
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vlc->table_size = 0; |
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if (flags & INIT_VLC_USE_NEW_STATIC) { |
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av_assert0(nb_codes <= LOCALBUF_ELEMS); |
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} else { |
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vlc->table = NULL; |
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vlc->table_allocated = 0; |
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} |
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if (nb_codes > LOCALBUF_ELEMS) { |
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*buf = av_malloc_array(nb_codes, sizeof(VLCcode)); |
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if (!*buf) |
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return AVERROR(ENOMEM); |
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} |
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return 0; |
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} |
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static int compare_vlcspec(const void *a, const void *b) |
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{ |
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const VLCcode *sa = a, *sb = b; |
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return (sa->code >> 1) - (sb->code >> 1); |
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} |
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/**
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* Build VLC decoding tables suitable for use with get_vlc(). |
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* |
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* @param vlc the context to be initialized |
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* |
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* @param table_nb_bits max length of vlc codes to store directly in this table |
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* (Longer codes are delegated to subtables.) |
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* |
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* @param nb_codes number of elements in codes[] |
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* |
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* @param codes descriptions of the vlc codes |
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* These must be ordered such that codes going into the same subtable are contiguous. |
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* Sorting by VLCcode.code is sufficient, though not necessary. |
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*/ |
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static int build_table(VLC *vlc, int table_nb_bits, int nb_codes, |
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VLCcode *codes, int flags) |
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{ |
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int table_size, table_index; |
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VLC_TYPE (*table)[2]; |
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if (table_nb_bits > 30) |
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return AVERROR(EINVAL); |
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table_size = 1 << table_nb_bits; |
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table_index = alloc_table(vlc, table_size, flags & INIT_VLC_USE_NEW_STATIC); |
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ff_dlog(NULL, "new table index=%d size=%d\n", table_index, table_size); |
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if (table_index < 0) |
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return table_index; |
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table = &vlc->table[table_index]; |
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/* first pass: map codes and compute auxiliary table sizes */ |
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for (int i = 0; i < nb_codes; i++) { |
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int n = codes[i].bits; |
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uint32_t code = codes[i].code; |
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int symbol = codes[i].symbol; |
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ff_dlog(NULL, "i=%d n=%d code=0x%"PRIx32"\n", i, n, code); |
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if (n <= table_nb_bits) { |
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/* no need to add another table */ |
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int j = code >> (32 - table_nb_bits); |
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int nb = 1 << (table_nb_bits - n); |
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int inc = 1; |
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if (flags & INIT_VLC_OUTPUT_LE) { |
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j = bitswap_32(code); |
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inc = 1 << n; |
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} |
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for (int k = 0; k < nb; k++) { |
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int bits = table[j][1]; |
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int oldsym = table[j][0]; |
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ff_dlog(NULL, "%4x: code=%d n=%d\n", j, i, n); |
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if ((bits || oldsym) && (bits != n || oldsym != symbol)) { |
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av_log(NULL, AV_LOG_ERROR, "incorrect codes\n"); |
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return AVERROR_INVALIDDATA; |
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} |
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table[j][1] = n; //bits
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table[j][0] = symbol; |
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j += inc; |
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} |
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} else { |
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/* fill auxiliary table recursively */ |
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uint32_t code_prefix; |
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int index, subtable_bits, j, k; |
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n -= table_nb_bits; |
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code_prefix = code >> (32 - table_nb_bits); |
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subtable_bits = n; |
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codes[i].bits = n; |
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codes[i].code = code << table_nb_bits; |
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for (k = i + 1; k < nb_codes; k++) { |
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n = codes[k].bits - table_nb_bits; |
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if (n <= 0) |
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break; |
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code = codes[k].code; |
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if (code >> (32 - table_nb_bits) != code_prefix) |
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break; |
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codes[k].bits = n; |
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codes[k].code = code << table_nb_bits; |
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subtable_bits = FFMAX(subtable_bits, n); |
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} |
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subtable_bits = FFMIN(subtable_bits, table_nb_bits); |
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j = (flags & INIT_VLC_OUTPUT_LE) ? bitswap_32(code_prefix) >> (32 - table_nb_bits) : code_prefix; |
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table[j][1] = -subtable_bits; |
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ff_dlog(NULL, "%4x: n=%d (subtable)\n", |
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j, codes[i].bits + table_nb_bits); |
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index = build_table(vlc, subtable_bits, k-i, codes+i, flags); |
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if (index < 0) |
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return index; |
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/* note: realloc has been done, so reload tables */ |
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table = &vlc->table[table_index]; |
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table[j][0] = index; //code
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if (table[j][0] != index) { |
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avpriv_request_sample(NULL, "strange codes"); |
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return AVERROR_PATCHWELCOME; |
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} |
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i = k-1; |
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} |
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} |
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for (int i = 0; i < table_size; i++) { |
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if (table[i][1] == 0) //bits
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table[i][0] = -1; //codes
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} |
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return table_index; |
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} |
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static int vlc_common_end(VLC *vlc, int nb_bits, int nb_codes, VLCcode *codes, |
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int flags, VLCcode localbuf[LOCALBUF_ELEMS]) |
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{ |
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int ret = build_table(vlc, nb_bits, nb_codes, codes, flags); |
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if (flags & INIT_VLC_USE_NEW_STATIC) { |
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if (vlc->table_size != vlc->table_allocated && |
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!(flags & (INIT_VLC_STATIC_OVERLONG & ~INIT_VLC_USE_NEW_STATIC))) |
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av_log(NULL, AV_LOG_ERROR, "needed %d had %d\n", vlc->table_size, vlc->table_allocated); |
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av_assert0(ret >= 0); |
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} else { |
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if (codes != localbuf) |
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av_free(codes); |
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if (ret < 0) { |
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av_freep(&vlc->table); |
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return ret; |
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} |
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} |
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return 0; |
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} |
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/* Build VLC decoding tables suitable for use with get_vlc().
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'nb_bits' sets the decoding table size (2^nb_bits) entries. The |
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bigger it is, the faster is the decoding. But it should not be too |
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big to save memory and L1 cache. '9' is a good compromise. |
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'nb_codes' : number of vlcs codes |
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'bits' : table which gives the size (in bits) of each vlc code. |
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'codes' : table which gives the bit pattern of of each vlc code. |
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'symbols' : table which gives the values to be returned from get_vlc(). |
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'xxx_wrap' : give the number of bytes between each entry of the |
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'bits' or 'codes' tables. |
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'xxx_size' : gives the number of bytes of each entry of the 'bits' |
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or 'codes' tables. Currently 1,2 and 4 are supported. |
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'wrap' and 'size' make it possible to use any memory configuration and types |
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(byte/word/long) to store the 'bits', 'codes', and 'symbols' tables. |
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*/ |
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int ff_init_vlc_sparse(VLC *vlc, int nb_bits, int nb_codes, |
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const void *bits, int bits_wrap, int bits_size, |
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const void *codes, int codes_wrap, int codes_size, |
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const void *symbols, int symbols_wrap, int symbols_size, |
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int flags) |
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{ |
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VLCcode localbuf[LOCALBUF_ELEMS], *buf = localbuf; |
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int j, ret; |
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ret = vlc_common_init(vlc, nb_bits, nb_codes, &buf, flags); |
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if (ret < 0) |
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return ret; |
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av_assert0(symbols_size <= 2 || !symbols); |
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j = 0; |
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#define COPY(condition)\ |
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for (int i = 0; i < nb_codes; i++) { \
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unsigned len; \
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GET_DATA(len, bits, i, bits_wrap, bits_size); \
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if (!(condition)) \
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continue; \
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if (len > 3*nb_bits || len > 32) { \
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av_log(NULL, AV_LOG_ERROR, "Too long VLC (%u) in init_vlc\n", len);\
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if (buf != localbuf) \
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av_free(buf); \
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return AVERROR(EINVAL); \
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} \
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buf[j].bits = len; \
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GET_DATA(buf[j].code, codes, i, codes_wrap, codes_size); \
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if (buf[j].code >= (1LL<<buf[j].bits)) { \
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av_log(NULL, AV_LOG_ERROR, "Invalid code %"PRIx32" for %d in " \
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"init_vlc\n", buf[j].code, i); \
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if (buf != localbuf) \
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av_free(buf); \
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return AVERROR(EINVAL); \
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} \
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if (flags & INIT_VLC_INPUT_LE) \
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buf[j].code = bitswap_32(buf[j].code); \
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else \
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buf[j].code <<= 32 - buf[j].bits; \
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if (symbols) \
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GET_DATA(buf[j].symbol, symbols, i, symbols_wrap, symbols_size) \
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else \
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buf[j].symbol = i; \
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j++; \
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} |
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COPY(len > nb_bits); |
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// qsort is the slowest part of init_vlc, and could probably be improved or avoided
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AV_QSORT(buf, j, struct VLCcode, compare_vlcspec); |
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COPY(len && len <= nb_bits); |
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nb_codes = j; |
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return vlc_common_end(vlc, nb_bits, nb_codes, buf, |
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flags, localbuf); |
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} |
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int ff_init_vlc_from_lengths(VLC *vlc, int nb_bits, int nb_codes, |
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const int8_t *lens, int lens_wrap, |
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const void *symbols, int symbols_wrap, int symbols_size, |
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int offset, int flags, void *logctx) |
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{ |
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VLCcode localbuf[LOCALBUF_ELEMS], *buf = localbuf; |
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uint64_t code; |
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int ret, j, len_max = FFMIN(32, 3 * nb_bits); |
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ret = vlc_common_init(vlc, nb_bits, nb_codes, &buf, flags); |
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if (ret < 0) |
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return ret; |
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j = code = 0; |
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for (int i = 0; i < nb_codes; i++, lens += lens_wrap) { |
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int len = *lens; |
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if (len > 0) { |
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unsigned sym; |
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buf[j].bits = len; |
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if (symbols) |
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GET_DATA(sym, symbols, i, symbols_wrap, symbols_size) |
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else |
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sym = i; |
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buf[j].symbol = sym + offset; |
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buf[j++].code = code; |
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} else if (len < 0) { |
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len = -len; |
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} else |
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continue; |
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if (len > len_max || code & ((1U << (32 - len)) - 1)) { |
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av_log(logctx, AV_LOG_ERROR, "Invalid VLC (length %u)\n", len); |
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goto fail; |
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} |
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code += 1U << (32 - len); |
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if (code > UINT32_MAX + 1ULL) { |
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av_log(logctx, AV_LOG_ERROR, "Overdetermined VLC tree\n"); |
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goto fail; |
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} |
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} |
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return vlc_common_end(vlc, nb_bits, j, buf, flags, localbuf); |
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fail: |
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if (buf != localbuf) |
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av_free(buf); |
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return AVERROR_INVALIDDATA; |
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} |
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void ff_free_vlc(VLC *vlc) |
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{ |
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av_freep(&vlc->table); |
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} |
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