509 lines
12 KiB
C
509 lines
12 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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/**
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* @file cabac.h
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* Context Adaptive Binary Arithmetic Coder.
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*/
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//#undef NDEBUG
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#include <assert.h>
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#define CABAC_BITS 16
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#define CABAC_MASK ((1<<CABAC_BITS)-1)
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typedef struct CABACContext{
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int low;
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int range;
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int outstanding_count;
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#ifdef STRICT_LIMITS
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int symCount;
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#endif
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uint8_t lps_range[2*66][4]; ///< rangeTabLPS
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uint8_t lps_state[2*65]; ///< transIdxLPS
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uint8_t mps_state[2*65]; ///< transIdxMPS
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const uint8_t *bytestream_start;
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const uint8_t *bytestream;
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const uint8_t *bytestream_end;
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PutBitContext pb;
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}CABACContext;
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extern const uint8_t ff_h264_lps_range[64][4];
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extern const uint8_t ff_h264_mps_state[64];
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extern const uint8_t ff_h264_lps_state[64];
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extern const uint8_t ff_h264_norm_shift[128];
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void ff_init_cabac_encoder(CABACContext *c, uint8_t *buf, int buf_size);
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void ff_init_cabac_decoder(CABACContext *c, const uint8_t *buf, int buf_size);
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void ff_init_cabac_states(CABACContext *c, uint8_t const (*lps_range)[4],
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uint8_t const *mps_state, uint8_t const *lps_state, int state_count);
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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= c->lps_range[*state][c->range>>6];
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if(bit == ((*state)&1)){
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c->range -= RangeLPS;
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*state= c->mps_state[*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= c->lps_state[*state];
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}
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renorm_cabac_encoder(c);
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#ifdef STRICT_LIMITS
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c->symCount++;
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#endif
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}
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static void put_cabac_static(CABACContext *c, int RangeLPS, int bit){
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assert(c->range > RangeLPS);
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if(!bit){
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c->range -= RangeLPS;
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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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}
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renorm_cabac_encoder(c);
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#ifdef STRICT_LIMITS
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c->symCount++;
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#endif
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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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#ifdef STRICT_LIMITS
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c->symCount++;
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#endif
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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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assert(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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#ifdef STRICT_LIMITS
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c->symCount++;
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#endif
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return (put_bits_count(&c->pb)+7)>>3;
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}
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/**
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* put (truncated) unary binarization.
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*/
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static void put_cabac_u(CABACContext *c, uint8_t * state, int v, int max, int max_index, int truncated){
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int i;
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assert(v <= max);
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#if 1
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for(i=0; i<v; i++){
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put_cabac(c, state, 1);
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if(i < max_index) state++;
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}
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if(truncated==0 || v<max)
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put_cabac(c, state, 0);
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#else
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if(v <= max_index){
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for(i=0; i<v; i++){
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put_cabac(c, state+i, 1);
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}
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if(truncated==0 || v<max)
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put_cabac(c, state+i, 0);
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}else{
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for(i=0; i<=max_index; i++){
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put_cabac(c, state+i, 1);
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}
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for(; i<v; i++){
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put_cabac(c, state+max_index, 1);
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}
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if(truncated==0 || v<max)
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put_cabac(c, state+max_index, 0);
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}
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#endif
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}
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/**
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* put unary exp golomb k-th order binarization.
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*/
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static void put_cabac_ueg(CABACContext *c, uint8_t * state, int v, int max, int is_signed, int k, int max_index){
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int i;
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if(v==0)
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put_cabac(c, state, 0);
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else{
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const int sign= v < 0;
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if(is_signed) v= ABS(v);
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if(v<max){
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for(i=0; i<v; i++){
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put_cabac(c, state, 1);
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if(i < max_index) state++;
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}
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put_cabac(c, state, 0);
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}else{
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int m= 1<<k;
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for(i=0; i<max; i++){
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put_cabac(c, state, 1);
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if(i < max_index) state++;
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}
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v -= max;
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while(v >= m){ //FIXME optimize
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put_cabac_bypass(c, 1);
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v-= m;
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m+= m;
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}
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put_cabac_bypass(c, 0);
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while(m>>=1){
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put_cabac_bypass(c, v&m);
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}
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}
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if(is_signed)
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put_cabac_bypass(c, sign);
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}
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}
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static void refill(CABACContext *c){
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if(c->bytestream <= c->bytestream_end)
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#if CABAC_BITS == 16
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c->low+= (c->bytestream[0]<<9) + (c->bytestream[1]<<1);
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#else
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c->low+= c->bytestream[0]<<1;
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#endif
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c->low -= CABAC_MASK;
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c->bytestream+= CABAC_BITS/8;
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}
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static void refill2(CABACContext *c){
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int i, x;
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x= c->low ^ (c->low-1);
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i= 7 - ff_h264_norm_shift[x>>(CABAC_BITS+1)];
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x= -CABAC_MASK;
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if(c->bytestream <= c->bytestream_end)
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#if CABAC_BITS == 16
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x+= (c->bytestream[0]<<9) + (c->bytestream[1]<<1);
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#else
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x+= c->bytestream[0]<<1;
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#endif
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c->low += x<<i;
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c->bytestream+= CABAC_BITS/8;
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}
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static inline void renorm_cabac_decoder(CABACContext *c){
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while(c->range < (0x200 << CABAC_BITS)){
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c->range+= c->range;
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c->low+= c->low;
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if(!(c->low & CABAC_MASK))
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refill(c);
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}
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}
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static inline void renorm_cabac_decoder_once(CABACContext *c){
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#ifdef ARCH_X86_DISABLED
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int temp;
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#if 0
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//P3:683 athlon:475
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asm(
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"lea -0x2000000(%0), %2 \n\t"
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"shr $31, %2 \n\t" //FIXME 31->63 for x86-64
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"shl %%cl, %0 \n\t"
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"shl %%cl, %1 \n\t"
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: "+r"(c->range), "+r"(c->low), "+c"(temp)
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);
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#elif 0
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//P3:680 athlon:474
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asm(
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"cmp $0x2000000, %0 \n\t"
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"setb %%cl \n\t" //FIXME 31->63 for x86-64
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"shl %%cl, %0 \n\t"
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"shl %%cl, %1 \n\t"
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: "+r"(c->range), "+r"(c->low), "+c"(temp)
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);
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#elif 1
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int temp2;
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//P3:665 athlon:517
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asm(
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"lea -0x2000000(%0), %%eax \n\t"
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"cdq \n\t"
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"mov %0, %%eax \n\t"
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"and %%edx, %0 \n\t"
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"and %1, %%edx \n\t"
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"add %%eax, %0 \n\t"
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"add %%edx, %1 \n\t"
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: "+r"(c->range), "+r"(c->low), "+a"(temp), "+d"(temp2)
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);
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#elif 0
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int temp2;
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//P3:673 athlon:509
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asm(
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"cmp $0x2000000, %0 \n\t"
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"sbb %%edx, %%edx \n\t"
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"mov %0, %%eax \n\t"
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"and %%edx, %0 \n\t"
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"and %1, %%edx \n\t"
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"add %%eax, %0 \n\t"
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"add %%edx, %1 \n\t"
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: "+r"(c->range), "+r"(c->low), "+a"(temp), "+d"(temp2)
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);
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#else
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int temp2;
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//P3:677 athlon:511
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asm(
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"cmp $0x2000000, %0 \n\t"
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"lea (%0, %0), %%eax \n\t"
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"lea (%1, %1), %%edx \n\t"
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"cmovb %%eax, %0 \n\t"
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"cmovb %%edx, %1 \n\t"
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: "+r"(c->range), "+r"(c->low), "+a"(temp), "+d"(temp2)
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);
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#endif
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#else
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//P3:675 athlon:476
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int shift= (uint32_t)(c->range - (0x200 << CABAC_BITS))>>31;
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c->range<<= shift;
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c->low <<= shift;
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#endif
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if(!(c->low & CABAC_MASK))
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refill(c);
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}
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static int get_cabac(CABACContext *c, uint8_t * const state){
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//FIXME gcc generates duplicate load/stores for c->low and c->range
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//START_TIMER
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int s = *state;
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int RangeLPS= c->lps_range[s][c->range>>(CABAC_BITS+7)]<<(CABAC_BITS+1);
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int bit, lps_mask attribute_unused;
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c->range -= RangeLPS;
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#if 1
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if(c->low < c->range){
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bit= s&1;
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#ifdef ARCH_X86
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//P3:627
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asm(
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"addb $2, %b0 \n\t"
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" js 1f \n\t"
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"movb %b0, %1 \n\t"
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"1: \n\t"
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: "+q"(s), "=m"(*state)
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);
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#else
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*state= c->mps_state[s]; //P3:655
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/* if(s<126) //P3:657
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*state= s+2;*/
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s+=2; //P3:631
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if(s<128)
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*state= s;
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#endif
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renorm_cabac_decoder_once(c);
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}else{
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bit= ff_h264_norm_shift[RangeLPS>>19];
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c->low -= c->range;
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*state= c->lps_state[s];
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c->range = RangeLPS<<bit;
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c->low <<= bit;
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bit= (s&1)^1;
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if(!(c->low & 0xFFFF)){
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refill2(c);
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}
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}
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#else
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lps_mask= (c->range - c->low)>>31;
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c->low -= c->range & lps_mask;
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c->range += (RangeLPS - c->range) & lps_mask;
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bit= (s^lps_mask)&1;
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*state= c->mps_state[s - (128&lps_mask)];
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lps_mask= ff_h264_norm_shift[c->range>>(CABAC_BITS+2)];
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c->range<<= lps_mask;
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c->low <<= lps_mask;
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if(!(c->low & CABAC_MASK))
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refill2(c);
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#endif
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//STOP_TIMER("get_cabac")
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return bit;
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}
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static int get_cabac_bypass(CABACContext *c){
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c->low += c->low;
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if(!(c->low & CABAC_MASK))
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refill(c);
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if(c->low < c->range){
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return 0;
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}else{
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c->low -= c->range;
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return 1;
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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 read or 0 if no end
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*/
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static int get_cabac_terminate(CABACContext *c){
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c->range -= 4<<CABAC_BITS;
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if(c->low < c->range){
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renorm_cabac_decoder_once(c);
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return 0;
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}else{
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return c->bytestream - c->bytestream_start;
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}
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}
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/**
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* get (truncated) unnary binarization.
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*/
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static int get_cabac_u(CABACContext *c, uint8_t * state, int max, int max_index, int truncated){
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int i;
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for(i=0; i<max; i++){
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if(get_cabac(c, state)==0)
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return i;
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if(i< max_index) state++;
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}
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return truncated ? max : -1;
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}
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/**
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* get unary exp golomb k-th order binarization.
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*/
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static int get_cabac_ueg(CABACContext *c, uint8_t * state, int max, int is_signed, int k, int max_index){
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int i, v;
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int m= 1<<k;
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if(get_cabac(c, state)==0)
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return 0;
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if(0 < max_index) state++;
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for(i=1; i<max; i++){
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if(get_cabac(c, state)==0){
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if(is_signed && get_cabac_bypass(c)){
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return -i;
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}else
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return i;
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}
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if(i < max_index) state++;
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}
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while(get_cabac_bypass(c)){
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i+= m;
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m+= m;
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}
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v=0;
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while(m>>=1){
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v+= v + get_cabac_bypass(c);
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}
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i += v;
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if(is_signed && get_cabac_bypass(c)){
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return -i;
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}else
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return i;
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}
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