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author | Michael Niedermayer <michaelni@gmx.at> | 2004-12-29 17:50:25 +0000 |
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committer | Michael Niedermayer <michaelni@gmx.at> | 2004-12-29 17:50:25 +0000 |
commit | caa336b4cc1c946409decd6af964a44afb59c43a (patch) | |
tree | 71bf85effee9bc0e8d985f0dd3274f7d67f4c5f5 /libavcodec/bitstream.c | |
parent | 6143607303de40f4647fe9ba10c4b36909ba0f1f (diff) | |
download | ffmpeg-streaming-caa336b4cc1c946409decd6af964a44afb59c43a.zip ffmpeg-streaming-caa336b4cc1c946409decd6af964a44afb59c43a.tar.gz |
common.c -> bitstream.c (and the single non bitstream func -> utils.c)
common.h -> common.h/bitstream.h
Originally committed as revision 3777 to svn://svn.ffmpeg.org/ffmpeg/trunk
Diffstat (limited to 'libavcodec/bitstream.c')
-rw-r--r-- | libavcodec/bitstream.c | 287 |
1 files changed, 287 insertions, 0 deletions
diff --git a/libavcodec/bitstream.c b/libavcodec/bitstream.c new file mode 100644 index 0000000..2678772 --- /dev/null +++ b/libavcodec/bitstream.c @@ -0,0 +1,287 @@ +/* + * Common bit i/o utils + * Copyright (c) 2000, 2001 Fabrice Bellard. + * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at> + * + * This library 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 of the License, or (at your option) any later version. + * + * This library 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 this library; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + * + * alternative bitstream reader & writer by Michael Niedermayer <michaelni@gmx.at> + */ + +/** + * @file bitstream.c + * bitstream api. + */ + +#include "avcodec.h" +#include "bitstream.h" + +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 put_string(PutBitContext * pbc, char *s, int put_zero) +{ + while(*s){ + put_bits(pbc, 8, *s); + s++; + } + if(put_zero) + put_bits(pbc, 8, 0); +} + +/* bit input functions */ + +/** + * reads 0-32 bits. + */ +unsigned int get_bits_long(GetBitContext *s, int n){ + if(n<=17) return get_bits(s, n); + else{ + int ret= get_bits(s, 16) << (n-16); + return ret | get_bits(s, n-16); + } +} + +/** + * shows 0-32 bits. + */ +unsigned int show_bits_long(GetBitContext *s, int n){ + if(n<=17) return show_bits(s, n); + else{ + GetBitContext gb= *s; + int ret= get_bits_long(s, n); + *s= gb; + return ret; + } +} + +void align_get_bits(GetBitContext *s) +{ + int n= (-get_bits_count(s)) & 7; + if(n) skip_bits(s, n); +} + +int check_marker(GetBitContext *s, const char *msg) +{ + int bit= get_bits1(s); + if(!bit) + av_log(NULL, AV_LOG_INFO, "Marker bit missing %s\n", msg); + + return bit; +} + +/* 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) { + vlc->table_allocated += (1 << vlc->bits); + if(use_static) + vlc->table = av_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, + uint32_t code_prefix, int n_prefix, int use_static) +{ + int i, j, k, n, table_size, table_index, nb, n1, index; + uint32_t code; + VLC_TYPE (*table)[2]; + + table_size = 1 << table_nb_bits; + table_index = alloc_table(vlc, table_size, use_static); +#ifdef DEBUG_VLC + printf("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 defined(DEBUG_VLC) && 0 + printf("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 (n > 0 && (code >> n) == 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++) { +#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] = i; //code + j++; + } + } else { + n -= table_nb_bits; + j = (code >> n) & ((1 << table_nb_bits) - 1); +#ifdef DEBUG_VLC + printf("%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, + (code_prefix << table_nb_bits) | i, + n_prefix + table_nb_bits, use_static); + 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. + + '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' and 'codes' 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(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, + int use_static) +{ + vlc->bits = nb_bits; + if(!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 + printf("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, + 0, 0, use_static) < 0) { + av_free(vlc->table); + return -1; + } + return 0; +} + + +void free_vlc(VLC *vlc) +{ + av_free(vlc->table); +} + |