X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=libavcodec%2Fbitstream.c;h=f77b9c4e3f624a088745daceab790af6271a24d2;hb=bd17a40a7e0eba21b5d27c67aff795e2910766e4;hp=a04c4a0ddf92dacab7637fac7512d546d84ece98;hpb=769c4975654407eee8c4d5ae27d7366a97bd1fda;p=ffmpeg diff --git a/libavcodec/bitstream.c b/libavcodec/bitstream.c index a04c4a0ddf9..f77b9c4e3f6 100644 --- a/libavcodec/bitstream.c +++ b/libavcodec/bitstream.c @@ -2,28 +2,29 @@ * Common bit i/o utils * Copyright (c) 2000, 2001 Fabrice Bellard * Copyright (c) 2002-2004 Michael Niedermayer + * Copyright (c) 2010 Loren Merritt * * alternative bitstream reader & writer by Michael Niedermayer * - * This file is part of FFmpeg. + * This file is part of Libav. * - * FFmpeg is free software; you can redistribute it and/or + * Libav 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, + * Libav 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 + * License along with Libav; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ /** - * @file libavcodec/bitstream.c + * @file * bitstream api. */ @@ -31,20 +32,18 @@ #include "get_bits.h" #include "put_bits.h" -const uint8_t ff_log2_run[32]={ +const uint8_t ff_log2_run[41]={ 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 + 8, 9,10,11,12,13,14,15, +16,17,18,19,20,21,22,23, +24, }; -void align_put_bits(PutBitContext *s) +void avpriv_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 *pb, const char *string, int terminate_string) @@ -57,7 +56,7 @@ void ff_put_string(PutBitContext *pb, const char *string, int terminate_string) put_bits(pb, 8, 0); } -void ff_copy_bits(PutBitContext *pb, const uint8_t *src, int length) +void avpriv_copy_bits(PutBitContext *pb, const uint8_t *src, int length) { int words= length>>4; int bits= length&15; @@ -80,8 +79,6 @@ void ff_copy_bits(PutBitContext *pb, const uint8_t *src, int length) /* VLC decoding */ -//#define DEBUG_VLC - #define GET_DATA(v, table, i, wrap, size) \ {\ const uint8_t *ptr = (const uint8_t *)table + i * wrap;\ @@ -106,7 +103,7 @@ static int alloc_table(VLC *vlc, int size, int use_static) vlc->table_size += size; if (vlc->table_size > vlc->table_allocated) { if(use_static) - abort(); //cant do anything, init_vlc() is used with too little memory + abort(); // cannot do anything, init_vlc() is used with too little memory vlc->table_allocated += (1 << vlc->bits); vlc->table = av_realloc(vlc->table, sizeof(VLC_TYPE) * 2 * vlc->table_allocated); @@ -116,110 +113,116 @@ static int alloc_table(VLC *vlc, int size, int use_static) 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) +static av_always_inline uint32_t bitswap_32(uint32_t x) { + return (uint32_t)av_reverse[x&0xFF]<<24 + | (uint32_t)av_reverse[(x>>8)&0xFF]<<16 + | (uint32_t)av_reverse[(x>>16)&0xFF]<<8 + | (uint32_t)av_reverse[x>>24]; +} + +typedef struct { + uint8_t bits; + uint16_t symbol; + /** codeword, with the first bit-to-be-read in the msb + * (even if intended for a little-endian bitstream reader) */ + uint32_t code; +} VLCcode; + +static int compare_vlcspec(const void *a, const void *b) +{ + const VLCcode *sa=a, *sb=b; + return (sa->code >> 1) - (sb->code >> 1); +} + +/** + * Build VLC decoding tables suitable for use with get_vlc(). + * + * @param vlc the context to be initted + * + * @param table_nb_bits max length of vlc codes to store directly in this table + * (Longer codes are delegated to subtables.) + * + * @param nb_codes number of elements in codes[] + * + * @param codes descriptions of the vlc codes + * These must be ordered such that codes going into the same subtable are contiguous. + * Sorting by VLCcode.code is sufficient, though not necessary. + */ +static int build_table(VLC *vlc, int table_nb_bits, int nb_codes, + VLCcode *codes, int flags) { - int i, j, k, n, table_size, table_index, nb, n1, index, code_prefix2, symbol; + int table_size, table_index, index, code_prefix, symbol, subtable_bits; + int i, j, k, n, nb, inc; uint32_t code; VLC_TYPE (*table)[2]; table_size = 1 << table_nb_bits; table_index = alloc_table(vlc, table_size, flags & 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 + av_dlog(NULL, "new table index=%d size=%d\n", table_index, table_size); if (table_index < 0) return -1; table = &vlc->table[table_index]; - for(i=0;i 0) { - if(flags & INIT_VLC_LE) - code_prefix2= code & (n_prefix>=32 ? 0xffffffff : (1 << n_prefix)-1); - else - code_prefix2= code >> n; - if (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> n_prefix) + (k<> ((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 + for (i = 0; i < nb_codes; i++) { + n = codes[i].bits; + code = codes[i].code; + symbol = codes[i].symbol; + av_dlog(NULL, "i=%d n=%d code=0x%x\n", i, n, code); + if (n <= table_nb_bits) { + /* no need to add another table */ + j = code >> (32 - table_nb_bits); + nb = 1 << (table_nb_bits - n); + inc = 1; + if (flags & INIT_VLC_LE) { + j = bitswap_32(code); + inc = 1 << n; + } + for (k = 0; k < nb; k++) { + av_dlog(NULL, "%4x: code=%d n=%d\n", j, i, n); + 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 += inc; } - } - } - - /* second pass : fill auxillary tables recursively */ - for(i=0;i table_nb_bits) { - n = table_nb_bits; - table[i][1] = -n; //bits + } else { + /* fill auxiliary table recursively */ + n -= table_nb_bits; + code_prefix = code >> (32 - table_nb_bits); + subtable_bits = n; + codes[i].bits = n; + codes[i].code = code << table_nb_bits; + for (k = i+1; k < nb_codes; k++) { + n = codes[k].bits - table_nb_bits; + if (n <= 0) + break; + code = codes[k].code; + if (code >> (32 - table_nb_bits) != code_prefix) + break; + codes[k].bits = n; + codes[k].code = code << table_nb_bits; + subtable_bits = FFMAX(subtable_bits, n); } - 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); + subtable_bits = FFMIN(subtable_bits, table_nb_bits); + j = (flags & INIT_VLC_LE) ? bitswap_32(code_prefix) >> (32 - table_nb_bits) : code_prefix; + table[j][1] = -subtable_bits; + av_dlog(NULL, "%4x: n=%d (subtable)\n", + j, codes[i].bits + table_nb_bits); + index = build_table(vlc, subtable_bits, k-i, codes+i, flags); if (index < 0) return -1; /* note: realloc has been done, so reload tables */ table = &vlc->table[table_index]; - table[i][0] = index; //code + table[j][0] = index; //code + i = k-1; } } return table_index; @@ -250,14 +253,17 @@ static int build_table(VLC *vlc, int table_nb_bits, (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. + with av_free_static(), 0 if ff_free_vlc() will be used. */ -int init_vlc_sparse(VLC *vlc, int nb_bits, int nb_codes, +int ff_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) { + VLCcode *buf; + int i, j, ret; + vlc->bits = nb_bits; if(flags & INIT_VLC_USE_NEW_STATIC){ if(vlc->table_size && vlc->table_size == vlc->table_allocated){ @@ -271,15 +277,38 @@ int init_vlc_sparse(VLC *vlc, int nb_bits, int nb_codes, vlc->table_size = 0; } -#ifdef DEBUG_VLC - av_log(NULL,AV_LOG_DEBUG,"build table nb_codes=%d\n", nb_codes); -#endif + av_dlog(NULL, "build table nb_codes=%d\n", nb_codes); + + buf = av_malloc((nb_codes+1)*sizeof(VLCcode)); + + assert(symbols_size <= 2 || !symbols); + j = 0; +#define COPY(condition)\ + for (i = 0; i < nb_codes; i++) {\ + GET_DATA(buf[j].bits, bits, i, bits_wrap, bits_size);\ + if (!(condition))\ + continue;\ + GET_DATA(buf[j].code, codes, i, codes_wrap, codes_size);\ + if (flags & INIT_VLC_LE)\ + buf[j].code = bitswap_32(buf[j].code);\ + else\ + buf[j].code <<= 32 - buf[j].bits;\ + if (symbols)\ + GET_DATA(buf[j].symbol, symbols, i, symbols_wrap, symbols_size)\ + else\ + buf[j].symbol = i;\ + j++;\ + } + COPY(buf[j].bits > nb_bits); + // qsort is the slowest part of init_vlc, and could probably be improved or avoided + qsort(buf, j, sizeof(VLCcode), compare_vlcspec); + COPY(buf[j].bits && buf[j].bits <= nb_bits); + nb_codes = j; - 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) { + ret = build_table(vlc, nb_bits, nb_codes, buf, flags); + + av_free(buf); + if (ret < 0) { av_freep(&vlc->table); return -1; } @@ -289,8 +318,7 @@ int init_vlc_sparse(VLC *vlc, int nb_bits, int nb_codes, } -void free_vlc(VLC *vlc) +void ff_free_vlc(VLC *vlc) { av_freep(&vlc->table); } -