/* * H.26L/H.264/AVC/JVT/14496-10/... encoder/decoder * Copyright (c) 2003 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 * Context Adaptive Binary Arithmetic Coder. */ #include <string.h> #include "libavutil/common.h" #include "libavutil/timer.h" #include "get_bits.h" #include "cabac.h" #include "cabac_functions.h" #include "cabac_tablegen.h" /** * * @param buf_size size of buf in bits */ void ff_init_cabac_encoder(CABACContext *c, uint8_t *buf, int buf_size){ init_put_bits(&c->pb, buf, buf_size); c->low= 0; c->range= 0x1FE; c->outstanding_count= 0; c->pb.bit_left++; //avoids firstBitFlag } /** * * @param buf_size size of buf in bits */ void ff_init_cabac_decoder(CABACContext *c, const uint8_t *buf, int buf_size){ c->bytestream_start= c->bytestream= buf; c->bytestream_end= buf + buf_size; #if CABAC_BITS == 16 c->low = (*c->bytestream++)<<18; c->low+= (*c->bytestream++)<<10; #else c->low = (*c->bytestream++)<<10; #endif c->low+= ((*c->bytestream++)<<2) + 2; c->range= 0x1FE; } void ff_init_cabac_states(void) { static int initialized = 0; if (initialized) return; cabac_tableinit(); initialized = 1; } #ifdef TEST #define SIZE 10240 #include "libavutil/lfg.h" #include "avcodec.h" static inline void put_cabac_bit(CABACContext *c, int b){ put_bits(&c->pb, 1, b); for(;c->outstanding_count; c->outstanding_count--){ put_bits(&c->pb, 1, 1-b); } } static inline void renorm_cabac_encoder(CABACContext *c){ while(c->range < 0x100){ //FIXME optimize if(c->low<0x100){ put_cabac_bit(c, 0); }else if(c->low<0x200){ c->outstanding_count++; c->low -= 0x100; }else{ put_cabac_bit(c, 1); c->low -= 0x200; } c->range+= c->range; c->low += c->low; } } static void put_cabac(CABACContext *c, uint8_t * const state, int bit){ int RangeLPS= ff_h264_lps_range[2*(c->range&0xC0) + *state]; if(bit == ((*state)&1)){ c->range -= RangeLPS; *state = ff_h264_mlps_state[128 + *state]; }else{ c->low += c->range - RangeLPS; c->range = RangeLPS; *state= ff_h264_mlps_state[127 - *state]; } renorm_cabac_encoder(c); } /** * @param bit 0 -> write zero bit, !=0 write one bit */ static void put_cabac_bypass(CABACContext *c, int bit){ c->low += c->low; if(bit){ c->low += c->range; } //FIXME optimize if(c->low<0x200){ put_cabac_bit(c, 0); }else if(c->low<0x400){ c->outstanding_count++; c->low -= 0x200; }else{ put_cabac_bit(c, 1); c->low -= 0x400; } } /** * * @return the number of bytes written */ static int put_cabac_terminate(CABACContext *c, int bit){ c->range -= 2; if(!bit){ renorm_cabac_encoder(c); }else{ c->low += c->range; c->range= 2; renorm_cabac_encoder(c); av_assert0(c->low <= 0x1FF); put_cabac_bit(c, c->low>>9); put_bits(&c->pb, 2, ((c->low>>7)&3)|1); flush_put_bits(&c->pb); //FIXME FIXME FIXME XXX wrong } return (put_bits_count(&c->pb)+7)>>3; } int main(void){ CABACContext c; uint8_t b[9*SIZE]; uint8_t r[9*SIZE]; int i; uint8_t state[10]= {0}; AVLFG prng; av_lfg_init(&prng, 1); ff_init_cabac_encoder(&c, b, SIZE); ff_init_cabac_states(); for(i=0; i<SIZE; i++){ if(2*i<SIZE) r[i] = av_lfg_get(&prng) % 7; else r[i] = (i>>8)&1; } for(i=0; i<SIZE; i++){ START_TIMER put_cabac_bypass(&c, r[i]&1); STOP_TIMER("put_cabac_bypass") } for(i=0; i<SIZE; i++){ START_TIMER put_cabac(&c, state, r[i]&1); STOP_TIMER("put_cabac") } put_cabac_terminate(&c, 1); ff_init_cabac_decoder(&c, b, SIZE); memset(state, 0, sizeof(state)); for(i=0; i<SIZE; i++){ START_TIMER if( (r[i]&1) != get_cabac_bypass(&c) ) av_log(NULL, AV_LOG_ERROR, "CABAC bypass failure at %d\n", i); STOP_TIMER("get_cabac_bypass") } for(i=0; i<SIZE; i++){ START_TIMER if( (r[i]&1) != get_cabac_noinline(&c, state) ) av_log(NULL, AV_LOG_ERROR, "CABAC failure at %d\n", i); STOP_TIMER("get_cabac") } if(!get_cabac_terminate(&c)) av_log(NULL, AV_LOG_ERROR, "where's the Terminator?\n"); return 0; } #endif /* TEST */