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