/* * Common bit i/o utils * Copyright (c) 2000, 2001 Fabrice Bellard * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at> * * alternative bitstream reader & writer by Michael Niedermayer <michaelni@gmx.at> * * 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 */ /** * @file libavcodec/bitstream.c * bitstream api. */ #include "avcodec.h" #include "get_bits.h" #include "put_bits.h" const uint8_t ff_log2_run[32]={ 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 9,10,11,12,13,14,15 }; #if LIBAVCODEC_VERSION_MAJOR < 53 /** * Same as av_mallocz_static(), but does a realloc. * * @param[in] ptr The block of memory to reallocate. * @param[in] size The requested size. * @return Block of memory of requested size. * @deprecated. Code which uses ff_realloc_static is broken/misdesigned * and should correctly use static arrays */ attribute_deprecated av_alloc_size(2) static void *ff_realloc_static(void *ptr, unsigned int size); static void *ff_realloc_static(void *ptr, unsigned int size) { return av_realloc(ptr, size); } #endif void align_put_bits(PutBitContext *s) { #ifdef ALT_BITSTREAM_WRITER put_bits(s,( - s->index) & 7,0); #else put_bits(s,s->bit_left & 7,0); #endif } void ff_put_string(PutBitContext * pbc, const char *s, int terminate_string) { while(*s){ put_bits(pbc, 8, *s); s++; } if(terminate_string) put_bits(pbc, 8, 0); } void ff_copy_bits(PutBitContext *pb, const uint8_t *src, int length) { int words= length>>4; int bits= length&15; int i; if(length==0) return; if(CONFIG_SMALL || words < 16 || put_bits_count(pb)&7){ for(i=0; i<words; i++) put_bits(pb, 16, AV_RB16(src + 2*i)); }else{ for(i=0; put_bits_count(pb)&31; i++) put_bits(pb, 8, src[i]); flush_put_bits(pb); memcpy(put_bits_ptr(pb), src+i, 2*words-i); skip_put_bytes(pb, 2*words-i); } put_bits(pb, bits, AV_RB16(src + 2*words)>>(16-bits)); } /* VLC decoding */ //#define DEBUG_VLC #define GET_DATA(v, table, i, wrap, size) \ {\ const uint8_t *ptr = (const uint8_t *)table + i * wrap;\ switch(size) {\ case 1:\ v = *(const uint8_t *)ptr;\ break;\ case 2:\ v = *(const uint16_t *)ptr;\ break;\ default:\ v = *(const uint32_t *)ptr;\ break;\ }\ } static int alloc_table(VLC *vlc, int size, int use_static) { int index; index = vlc->table_size; vlc->table_size += size; if (vlc->table_size > vlc->table_allocated) { if(use_static>1) abort(); //cant do anything, init_vlc() is used with too little memory vlc->table_allocated += (1 << vlc->bits); if(use_static) vlc->table = ff_realloc_static(vlc->table, sizeof(VLC_TYPE) * 2 * vlc->table_allocated); else vlc->table = av_realloc(vlc->table, sizeof(VLC_TYPE) * 2 * vlc->table_allocated); if (!vlc->table) return -1; } return index; } static int build_table(VLC *vlc, int table_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, uint32_t code_prefix, int n_prefix, int flags) { int i, j, k, n, table_size, table_index, nb, n1, index, code_prefix2, symbol; uint32_t code; VLC_TYPE (*table)[2]; table_size = 1 << table_nb_bits; table_index = alloc_table(vlc, table_size, flags & (INIT_VLC_USE_STATIC|INIT_VLC_USE_NEW_STATIC)); #ifdef DEBUG_VLC av_log(NULL,AV_LOG_DEBUG,"new table index=%d size=%d code_prefix=%x n=%d\n", table_index, table_size, code_prefix, n_prefix); #endif if (table_index < 0) return -1; table = &vlc->table[table_index]; for(i=0;i<table_size;i++) { table[i][1] = 0; //bits table[i][0] = -1; //codes } /* first pass: map codes and compute auxillary table sizes */ for(i=0;i<nb_codes;i++) { GET_DATA(n, bits, i, bits_wrap, bits_size); GET_DATA(code, codes, i, codes_wrap, codes_size); /* we accept tables with holes */ if (n <= 0) continue; if (!symbols) symbol = i; else GET_DATA(symbol, symbols, i, symbols_wrap, symbols_size); #if defined(DEBUG_VLC) && 0 av_log(NULL,AV_LOG_DEBUG,"i=%d n=%d code=0x%x\n", i, n, code); #endif /* if code matches the prefix, it is in the table */ n -= n_prefix; if(flags & INIT_VLC_LE) code_prefix2= code & (n_prefix>=32 ? 0xffffffff : (1 << n_prefix)-1); else code_prefix2= code >> n; if (n > 0 && code_prefix2 == code_prefix) { if (n <= table_nb_bits) { /* no need to add another table */ j = (code << (table_nb_bits - n)) & (table_size - 1); nb = 1 << (table_nb_bits - n); for(k=0;k<nb;k++) { if(flags & INIT_VLC_LE) j = (code >> n_prefix) + (k<<n); #ifdef DEBUG_VLC av_log(NULL, AV_LOG_DEBUG, "%4x: code=%d n=%d\n", j, i, n); #endif if (table[j][1] /*bits*/ != 0) { av_log(NULL, AV_LOG_ERROR, "incorrect codes\n"); return -1; } table[j][1] = n; //bits table[j][0] = symbol; j++; } } else { n -= table_nb_bits; j = (code >> ((flags & INIT_VLC_LE) ? n_prefix : n)) & ((1 << table_nb_bits) - 1); #ifdef DEBUG_VLC av_log(NULL,AV_LOG_DEBUG,"%4x: n=%d (subtable)\n", j, n); #endif /* compute table size */ n1 = -table[j][1]; //bits if (n > n1) n1 = n; table[j][1] = -n1; //bits } } } /* second pass : fill auxillary tables recursively */ for(i=0;i<table_size;i++) { n = table[i][1]; //bits if (n < 0) { n = -n; if (n > table_nb_bits) { n = table_nb_bits; table[i][1] = -n; //bits } index = build_table(vlc, n, nb_codes, bits, bits_wrap, bits_size, codes, codes_wrap, codes_size, symbols, symbols_wrap, symbols_size, (flags & INIT_VLC_LE) ? (code_prefix | (i << n_prefix)) : ((code_prefix << table_nb_bits) | i), n_prefix + table_nb_bits, flags); if (index < 0) return -1; /* note: realloc has been done, so reload tables */ table = &vlc->table[table_index]; table[i][0] = index; //code } } return table_index; } /* Build VLC decoding tables suitable for use with get_vlc(). 'nb_bits' set thee decoding table size (2^nb_bits) entries. The bigger it is, the faster is the decoding. But it should not be too big to save memory and L1 cache. '9' is a good compromise. 'nb_codes' : number of vlcs codes 'bits' : table which gives the size (in bits) of each vlc code. 'codes' : table which gives the bit pattern of of each vlc code. 'symbols' : table which gives the values to be returned from get_vlc(). 'xxx_wrap' : give the number of bytes between each entry of the 'bits' or 'codes' tables. 'xxx_size' : gives the number of bytes of each entry of the 'bits' or 'codes' tables. 'wrap' and 'size' allows to use any memory configuration and types (byte/word/long) to store the 'bits', 'codes', and 'symbols' tables. 'use_static' should be set to 1 for tables, which should be freed with av_free_static(), 0 if free_vlc() will be used. */ int init_vlc_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) { vlc->bits = nb_bits; if(flags & INIT_VLC_USE_NEW_STATIC){ if(vlc->table_size && vlc->table_size == vlc->table_allocated){ return 0; }else if(vlc->table_size){ abort(); // fatal error, we are called on a partially initialized table } }else if(!(flags & INIT_VLC_USE_STATIC)) { vlc->table = NULL; vlc->table_allocated = 0; vlc->table_size = 0; } else { /* Static tables are initially always NULL, return if vlc->table != NULL to avoid double allocation */ if(vlc->table) return 0; } #ifdef DEBUG_VLC av_log(NULL,AV_LOG_DEBUG,"build table nb_codes=%d\n", nb_codes); #endif if (build_table(vlc, nb_bits, nb_codes, bits, bits_wrap, bits_size, codes, codes_wrap, codes_size, symbols, symbols_wrap, symbols_size, 0, 0, flags) < 0) { av_freep(&vlc->table); return -1; } if((flags & INIT_VLC_USE_NEW_STATIC) && vlc->table_size != vlc->table_allocated) av_log(NULL, AV_LOG_ERROR, "needed %d had %d\n", vlc->table_size, vlc->table_allocated); return 0; } void free_vlc(VLC *vlc) { av_freep(&vlc->table); }