/* * H.26L/H.264/AVC/JVT/14496-10/... encoder/decoder * Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at> * * This file is part of Libav. * * 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. * * 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 Libav; 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. */ #ifndef AVCODEC_CABAC_H #define AVCODEC_CABAC_H #include <stddef.h> #include "put_bits.h" //#undef NDEBUG #include <assert.h> #define CABAC_BITS 16 #define CABAC_MASK ((1<<CABAC_BITS)-1) typedef struct CABACContext{ int low; int range; int outstanding_count; #ifdef STRICT_LIMITS int symCount; #endif const uint8_t *bytestream_start; const uint8_t *bytestream; const uint8_t *bytestream_end; PutBitContext pb; }CABACContext; extern uint8_t ff_h264_mlps_state[4*64]; extern uint8_t ff_h264_lps_range[4*2*64]; ///< rangeTabLPS extern uint8_t ff_h264_mps_state[2*64]; ///< transIdxMPS extern uint8_t ff_h264_lps_state[2*64]; ///< transIdxLPS extern const uint8_t ff_h264_norm_shift[512]; #if ARCH_X86 # include "x86/cabac.h" #endif void ff_init_cabac_encoder(CABACContext *c, uint8_t *buf, int buf_size); void ff_init_cabac_decoder(CABACContext *c, const uint8_t *buf, int buf_size); void ff_init_cabac_states(CABACContext *c); 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 refill(CABACContext *c){ #if CABAC_BITS == 16 c->low+= (c->bytestream[0]<<9) + (c->bytestream[1]<<1); #else c->low+= c->bytestream[0]<<1; #endif c->low -= CABAC_MASK; c->bytestream+= CABAC_BITS/8; } static inline void renorm_cabac_decoder(CABACContext *c){ while(c->range < 0x100){ c->range+= c->range; c->low+= c->low; if(!(c->low & CABAC_MASK)) refill(c); } } static inline void renorm_cabac_decoder_once(CABACContext *c){ int shift= (uint32_t)(c->range - 0x100)>>31; c->range<<= shift; c->low <<= shift; if(!(c->low & CABAC_MASK)) refill(c); } #ifndef get_cabac_inline static void refill2(CABACContext *c){ int i, x; x= c->low ^ (c->low-1); i= 7 - ff_h264_norm_shift[x>>(CABAC_BITS-1)]; x= -CABAC_MASK; #if CABAC_BITS == 16 x+= (c->bytestream[0]<<9) + (c->bytestream[1]<<1); #else x+= c->bytestream[0]<<1; #endif c->low += x<<i; c->bytestream+= CABAC_BITS/8; } static av_always_inline int get_cabac_inline(CABACContext *c, uint8_t * const state){ int s = *state; int RangeLPS= ff_h264_lps_range[2*(c->range&0xC0) + s]; int bit, lps_mask; c->range -= RangeLPS; lps_mask= ((c->range<<(CABAC_BITS+1)) - c->low)>>31; c->low -= (c->range<<(CABAC_BITS+1)) & lps_mask; c->range += (RangeLPS - c->range) & lps_mask; s^=lps_mask; *state= (ff_h264_mlps_state+128)[s]; bit= s&1; lps_mask= ff_h264_norm_shift[c->range]; c->range<<= lps_mask; c->low <<= lps_mask; if(!(c->low & CABAC_MASK)) refill2(c); return bit; } #endif static int av_noinline av_unused get_cabac_noinline(CABACContext *c, uint8_t * const state){ return get_cabac_inline(c,state); } static int av_unused get_cabac(CABACContext *c, uint8_t * const state){ return get_cabac_inline(c,state); } static int av_unused get_cabac_bypass(CABACContext *c){ int range; c->low += c->low; if(!(c->low & CABAC_MASK)) refill(c); range= c->range<<(CABAC_BITS+1); if(c->low < range){ return 0; }else{ c->low -= range; return 1; } } #ifndef get_cabac_bypass_sign static av_always_inline int get_cabac_bypass_sign(CABACContext *c, int val){ int range, mask; c->low += c->low; if(!(c->low & CABAC_MASK)) refill(c); range= c->range<<(CABAC_BITS+1); c->low -= range; mask= c->low >> 31; range &= mask; c->low += range; return (val^mask)-mask; } #endif /** * * @return the number of bytes read or 0 if no end */ static int av_unused get_cabac_terminate(CABACContext *c){ c->range -= 2; if(c->low < c->range<<(CABAC_BITS+1)){ renorm_cabac_decoder_once(c); return 0; }else{ return c->bytestream - c->bytestream_start; } } #if 0 /** * Get (truncated) unary binarization. */ static int get_cabac_u(CABACContext *c, uint8_t * state, int max, int max_index, int truncated){ int i; for(i=0; i<max; i++){ if(get_cabac(c, state)==0) return i; if(i< max_index) state++; } return truncated ? max : -1; } /** * get unary exp golomb k-th order binarization. */ static int get_cabac_ueg(CABACContext *c, uint8_t * state, int max, int is_signed, int k, int max_index){ int i, v; int m= 1<<k; if(get_cabac(c, state)==0) return 0; if(0 < max_index) state++; for(i=1; i<max; i++){ if(get_cabac(c, state)==0){ if(is_signed && get_cabac_bypass(c)){ return -i; }else return i; } if(i < max_index) state++; } while(get_cabac_bypass(c)){ i+= m; m+= m; } v=0; while(m>>=1){ v+= v + get_cabac_bypass(c); } i += v; if(is_signed && get_cabac_bypass(c)){ return -i; }else return i; } #endif /* 0 */ #endif /* AVCODEC_CABAC_H */