cabac.c

H.264编码解码器源码(c语言).zip

  MotionInfoContexts *ctx = img->currentSlice->mot_ctx;
  Macroblock *currMB = &img->mb_data[img->current_mb_nr];

  int   addctx  = 0;
  int   a, b;
  int   act_ctx;
  int   act_sym;
  int** refframe_array = dec_picture->ref_idx[se->value2];
  int   b8a, b8b;

  PixelPos block_a, block_b;
  
  getLuma4x4Neighbour(img->current_mb_nr, img->subblock_x, img->subblock_y, -1,  0, &block_a);
  getLuma4x4Neighbour(img->current_mb_nr, img->subblock_x, img->subblock_y,  0, -1, &block_b);

  b8a=((block_a.x/2)%2)+2*((block_a.y/2)%2);
  b8b=((block_b.x/2)%2)+2*((block_b.y/2)%2);

  if (!block_b.available)
    b=0;
  else if (IS_DIRECT(&img->mb_data[block_b.mb_addr]) || (img->mb_data[block_b.mb_addr].b8mode[b8b]==0 && img->mb_data[block_b.mb_addr].b8pdir[b8b]==2))
//  else if (IS_DIRECT(&img->mb_data[block_b.mb_addr]))
    b=0;
  else 
  {
		if (img->MbaffFrameFlag && (currMB->mb_field == 0) && (img->mb_data[block_b.mb_addr].mb_field == 1))
			b = (refframe_array[block_b.pos_x][block_b.pos_y] > 1 ? 1 : 0);
		else
			b = (refframe_array[block_b.pos_x][block_b.pos_y] > 0 ? 1 : 0);
	}

  if (!block_a.available)
    a=0;
  else if (IS_DIRECT(&img->mb_data[block_a.mb_addr]) || (img->mb_data[block_a.mb_addr].b8mode[b8a]==0 && img->mb_data[block_a.mb_addr].b8pdir[b8a]==2))
//  else if (IS_DIRECT(&img->mb_data[block_a.mb_addr]))
    a=0;
  else 
	{
		if (img->MbaffFrameFlag && (currMB->mb_field == 0) && (img->mb_data[block_a.mb_addr].mb_field == 1))
			a = (refframe_array[block_a.pos_x][block_a.pos_y] > 1 ? 1 : 0);
		else
			a = (refframe_array[block_a.pos_x][block_a.pos_y] > 0 ? 1 : 0);
	}

  act_ctx = a + 2*b;
  se->context = act_ctx; // store context

  act_sym = biari_decode_symbol(dep_dp,ctx->ref_no_contexts[addctx] + act_ctx );

  if (act_sym != 0)
  {
    act_ctx = 4;
    act_sym = unary_bin_decode(dep_dp,ctx->ref_no_contexts[addctx]+act_ctx,1);
    act_sym++;
  }
  se->value1 = act_sym;

#if TRACE
  fprintf(p_trace, "@%d %s\t\t\t%d \n",symbolCount++, se->tracestring, se->value1);
//  fprintf(p_trace," c: %d :%d \n",ctx->ref_no_contexts[addctx][act_ctx].cum_freq[0],ctx->ref_no_contexts[addctx][act_ctx].cum_freq[1]);
  fflush(p_trace);
#endif
}


/*!
 ************************************************************************
 * \brief
 *    This function is used to arithmetically decode the delta qp
 *     of a given MB.
 ************************************************************************
 */
void readDquant_CABAC( SyntaxElement *se,
                       struct inp_par *inp,
                       struct img_par *img,
                       DecodingEnvironmentPtr dep_dp)
{
  MotionInfoContexts *ctx = img->currentSlice->mot_ctx;

  int act_ctx;
  int act_sym;
  int dquant;

  act_ctx = ( (last_dquant != 0) ? 1 : 0);

  act_sym = biari_decode_symbol(dep_dp,ctx->delta_qp_contexts + act_ctx );
  if (act_sym != 0)
  {
    act_ctx = 2;
    act_sym = unary_bin_decode(dep_dp,ctx->delta_qp_contexts+act_ctx,1);
    act_sym++;
  }

  dquant = (act_sym+1)/2;
  if((act_sym & 0x01)==0)                           // lsb is signed bit
    dquant = -dquant;
  se->value1 = dquant;

  last_dquant = dquant;

#if TRACE
  fprintf(p_trace, "@%d %s\t\t\t%d\n",symbolCount++, se->tracestring, se->value1);
  fflush(p_trace);
#endif
}
/*!
 ************************************************************************
 * \brief
 *    This function is used to arithmetically decode the coded
 *    block pattern of a given MB.
 ************************************************************************
 */
void readCBP_CABAC(SyntaxElement *se,
                   struct inp_par *inp,
                   struct img_par *img,
                   DecodingEnvironmentPtr dep_dp)
{
  TextureInfoContexts *ctx = img->currentSlice->tex_ctx;
  Macroblock *currMB = &img->mb_data[img->current_mb_nr];

  int mb_x, mb_y;
  int a, b;
  int curr_cbp_ctx, curr_cbp_idx;
  int cbp = 0;
  int cbp_bit;
  int mask;
  PixelPos block_a;

  //  coding of luma part (bit by bit)
  for (mb_y=0; mb_y < 4; mb_y += 2)
  {
    for (mb_x=0; mb_x < 4; mb_x += 2)
    {
      if (currMB->b8mode[mb_y+(mb_x/2)]==IBLOCK)
        curr_cbp_idx = 0;
      else
        curr_cbp_idx = 1;

      if (mb_y == 0)
      {
        if (currMB->mb_available_up == NULL)
          b = 0;
        else
          b = (( ((currMB->mb_available_up)->cbp & (1<<(2+mb_x/2))) == 0) ? 1 : 0);
      }
      else
        b = ( ((cbp & (1<<(mb_x/2))) == 0) ? 1: 0);

      if (mb_x == 0)
      {
        getLuma4x4Neighbour(img->current_mb_nr, mb_x, mb_y, -1, 0, &block_a);
        if (block_a.available)
        {
          a = (( (img->mb_data[block_a.mb_addr].cbp & (1<<(2*(block_a.y/2)+1))) == 0) ? 1 : 0);
        }
        else
          a=0;
      }
      else
        a = ( ((cbp & (1<<mb_y)) == 0) ? 1: 0);

      curr_cbp_ctx = a+2*b;
      mask = (1<<(mb_y+mb_x/2));
      cbp_bit = biari_decode_symbol(dep_dp, ctx->cbp_contexts[0] + curr_cbp_ctx );
      if (cbp_bit) cbp += mask;
    }
  }


  if ( se->type == SE_CBP_INTRA )
    curr_cbp_idx = 0;
  else
    curr_cbp_idx = 1;

  // coding of chroma part
  b = 0;
  if (currMB->mb_available_up != NULL)
    b = ((currMB->mb_available_up)->cbp > 15) ? 1 : 0;

  a = 0;
  if (currMB->mb_available_left != NULL)
    a = ((currMB->mb_available_left)->cbp > 15) ? 1 : 0;

  curr_cbp_ctx = a+2*b;
  cbp_bit = biari_decode_symbol(dep_dp, ctx->cbp_contexts[1] + curr_cbp_ctx );

  if (cbp_bit) // set the chroma bits
  {
    b = 0;
    if (currMB->mb_available_up != NULL)
      if ((currMB->mb_available_up)->cbp > 15)
        b = (( ((currMB->mb_available_up)->cbp >> 4) == 2) ? 1 : 0);

    a = 0;
    if (currMB->mb_available_left != NULL)
      if ((currMB->mb_available_left)->cbp > 15)
        a = (( ((currMB->mb_available_left)->cbp >> 4) == 2) ? 1 : 0);

    curr_cbp_ctx = a+2*b;
    cbp_bit = biari_decode_symbol(dep_dp, ctx->cbp_contexts[2] + curr_cbp_ctx );
    cbp += (cbp_bit == 1) ? 32 : 16;
  }

  se->value1 = cbp;

  if (!cbp)
  {
    last_dquant=0;
  }

#if TRACE
  fprintf(p_trace, "@%d %s\t\t\t%d\n",symbolCount++, se->tracestring, se->value1);
  fflush(p_trace);
#endif
}

/*!
 ************************************************************************
 * \brief
 *    This function is used to arithmetically decode the chroma
 *    intra prediction mode of a given MB.
 ************************************************************************
 */  //GB
void readCIPredMode_CABAC(SyntaxElement *se,
                          struct inp_par *inp,
                          struct img_par *img,
                          DecodingEnvironmentPtr dep_dp)
{

  TextureInfoContexts *ctx = img->currentSlice->tex_ctx;
  Macroblock          *currMB  = &img->mb_data[img->current_mb_nr];
  int                 act_ctx,a,b;
  int                 act_sym  = se->value1;

  if (currMB->mb_available_up == NULL) b = 0;
  else  b = ( ((currMB->mb_available_up)->c_ipred_mode != 0) ? 1 : 0);

  if (currMB->mb_available_left == NULL) a = 0;
  else  a = ( ((currMB->mb_available_left)->c_ipred_mode != 0) ? 1 : 0);

  act_ctx = a+b;

  act_sym = biari_decode_symbol(dep_dp, ctx->cipr_contexts + act_ctx );

  if (act_sym!=0) 
    act_sym = unary_bin_max_decode(dep_dp,ctx->cipr_contexts+3,0,2)+1;


  se->value1 = act_sym;


#if TRACE
  fprintf(p_trace, "@%d %s\t\t\t%d\n",symbolCount++, se->tracestring, se->value1);
  fflush(p_trace);
#endif

}


static const int maxpos       [] = {16, 15, 64, 32, 32, 16,  4, 15};
static const int c1isdc       [] = { 1,  0,  1,  1,  1,  1,  1,  0};

static const int type2ctx_bcbp[] = { 0,  1,  2,  2,  3,  4,  5,  6}; // 7
static const int type2ctx_map [] = { 0,  1,  2,  3,  4,  5,  6,  7}; // 8
static const int type2ctx_last[] = { 0,  1,  2,  3,  4,  5,  6,  7}; // 8
static const int type2ctx_one [] = { 0,  1,  2,  3,  3,  4,  5,  6}; // 7
static const int type2ctx_abs [] = { 0,  1,  2,  3,  3,  4,  5,  6}; // 7




/*!
 ************************************************************************
 * \brief
 *    Read CBP4-BIT
 ************************************************************************
 */
int read_and_store_CBP_block_bit (Macroblock              *currMB,
                                  DecodingEnvironmentPtr  dep_dp,
                                  struct img_par          *img,
                                  int                     type)
{
#define BIT_SET(x,n)  ((int)(((x)&(1<<(n)))>>(n)))

  int y_ac        = (type==LUMA_16AC || type==LUMA_8x8 || type==LUMA_8x4 || type==LUMA_4x8 || type==LUMA_4x4);
  int y_dc        = (type==LUMA_16DC);
  int u_ac        = (type==CHROMA_AC && !img->is_v_block);
  int v_ac        = (type==CHROMA_AC &&  img->is_v_block);
  int u_dc        = (type==CHROMA_DC && !img->is_v_block);
  int v_dc        = (type==CHROMA_DC &&  img->is_v_block);
  int j           = (y_ac || u_ac || v_ac ? img->subblock_y : 0);
  int i           = (y_ac || u_ac || v_ac ? img->subblock_x : 0);
  int bit         = (y_dc ? 0 : y_ac ? 1 : u_dc ? 17 : v_dc ? 18 : u_ac ? 19 : 23);
  int default_bit = (img->is_intra_block ? 1 : 0);
  int upper_bit   = default_bit;
  int left_bit    = default_bit;
  int cbp_bit     = 1;  // always one for 8x8 mode
  int ctx;
  int bit_pos_a   = 0;
  int bit_pos_b   = 0;

  PixelPos block_a, block_b;
  if (y_ac || y_dc)
  {
    getLuma4x4Neighbour(img->current_mb_nr, i, j, -1,  0, &block_a);
    getLuma4x4Neighbour(img->current_mb_nr, i, j,  0, -1, &block_b);
    if (y_ac)
    {
      if (block_a.available)
        bit_pos_a = 4*block_a.y + block_a.x;
      if (block_b.available)
        bit_pos_b = 4*block_b.y + block_b.x;
    }
  }
  else
  {
    getChroma4x4Neighbour(img->current_mb_nr, i, j, -1,  0, &block_a);
    getChroma4x4Neighbour(img->current_mb_nr, i, j,  0, -1, &block_b);
    if (u_ac||v_ac)
    {
      if (block_a.available)
        bit_pos_a = 2*block_a.y + block_a.x;
      if (block_b.available)
        bit_pos_b = 2*block_b.y + block_b.x;
    }
  }

  if (type!=LUMA_8x8)
  {
    //--- get bits from neighbouring blocks ---
    if (block_b.available)
      upper_bit = BIT_SET(img->mb_data[block_b.mb_addr].cbp_bits,bit+bit_pos_b);
    
    if (block_a.available)
      left_bit = BIT_SET(img->mb_data[block_a.mb_addr].cbp_bits,bit+bit_pos_a);
    
    ctx = 2*upper_bit+left_bit;


    //===== encode symbol =====
    cbp_bit = biari_decode_symbol (dep_dp, img->currentSlice->tex_ctx->bcbp_contexts[type2ctx_bcbp[type]] + ctx);
  }
  
  //--- set bits for current block ---
  bit         = (y_dc ? 0 : y_ac ? 1+4*j+i : u_dc ? 17 : v_dc ? 18 : u_ac ? 19+2*j+i : 23+2*j+i);
  
  if (cbp_bit)
  {
    if (type==LUMA_8x8)
    {
      currMB->cbp_bits   |= (1<< bit   );
      currMB->cbp_bits   |= (1<<(bit+1));
      currMB->cbp_bits   |= (1<<(bit+4));
      currMB->cbp_bits   |= (1<<(bit+5));
    }
    else if (type==LUMA_8x4)
    {
      currMB->cbp_bits   |= (1<< bit   );
      currMB->cbp_bits   |= (1<<(bit+1));
    }
    else if (type==LUMA_4x8)
    {
      currMB->cbp_bits   |= (1<< bit   );
      currMB->cbp_bits   |= (1<<(bit+4));
    }
    else
    {
      currMB->cbp_bits   |= (1<<bit);
    }
  }

  return cbp_bit;
}





//===== position -> ctx for MAP =====
//--- zig-zag scan ----
static const int  pos2ctx_map8x8 [] = { 0,  1,  2,  3,  4,  5,  5,  4,  4,  3,  3,  4,  4,  4,  5,  5,
                                        4,  4,  4,  4,  3,  3,  6,  7,  7,  7,  8,  9, 10,  9,  8,  7,
                                        7,  6, 11, 12, 13, 11,  6,  7,  8,  9, 14, 10,  9,  8,  6, 11,
                                       12, 13, 11,  6,  9, 14, 10,  9, 11, 12, 13, 11 ,14, 10, 12, 14}; // 15 CTX
static const int  pos2ctx_map8x4 [] = { 0,  1,  2,  3,  4,  5,  7,  8,  9, 10, 11,  9,  8,  6,  7,  8,
                                        9, 10, 11,  9,  8,  6, 12,  8,  9, 10, 11,  9, 13, 13, 14, 14}; // 15 CTX
static const int  pos2ctx_map4x4 [] = { 0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 14}; // 15 CTX
static const int* pos2ctx_map    [] = {pos2ctx_map4x4, pos2ctx_map4x4, pos2ctx_map8x8, pos2ctx_map8x4,
                                       pos2ctx_map8x4, pos2ctx_map4x4, pos2ctx_map4x4, pos2ctx_map4x4};
//--- interlace scan ----
static const int  pos2ctx_map8x8i[] = { 0,  1,  1,  2,  2,  3,  3,  4,  5,  6,  7,  7,  7,  8,  4,  5,
                                        6,  9, 10, 10,  8, 11, 12, 11,  9,  9, 10, 10,  8, 11, 12, 11,
                                        9,  9, 10, 10,  8, 11, 12, 11,  9,  9, 10, 10,  8, 13, 13,  9,
                                        9, 10, 10,  8, 13, 13,  9,  9, 10, 10, 14, 14, 14, 14, 14, 14}; // 15 CTX
static const int  pos2ctx_map8x4i[] = { 0,  1,  2,  3,  4,  5,  6,  3,  4,  5,  6,  3,  4,  7,  6,  8,
                                        9,  7,  6,  8,  9, 10, 11, 12, 12, 10, 11, 13, 13, 14, 14, 14}; // 15 CTX
static const int  pos2ctx_map4x8i[] = { 0,  1,  1,  1,  2,  3,  3,  4,  4,  4,  5,  6,  2,  7,  7,  8,
                                        8,  8,  5,  6,  9, 10, 10, 11, 11, 11, 12, 13, 13, 14, 14, 14}; // 15 CTX
static const int* pos2ctx_map_int[] = {pos2ctx_map4x4, pos2ctx_map4x4, pos2ctx_map8x8i,pos2ctx_map8x4i,
                                       pos2ctx_map4x8i,pos2ctx_map4x4, pos2ctx_map4x4, pos2ctx_map4x4};


//===== position -> ctx for LAST =====
static const int  pos2ctx_last8x8 [] = { 0,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,
                                         2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,  2,
                                         3,  3,  3,  3,  3,  3,  3,  3,  4,  4,  4,  4,  4,  4,  4,  4,
                                         5,  5,  5,  5,  6,  6,  6,  6,  7,  7,  7,  7,  8,  8,  8,  8}; //  9 CTX
static const int  pos2ctx_last8x4 [] = { 0,  1,  1,  1,  1,  1,  1,  1,  2,  2,  2,  2,  2,  2,  2,  2,
                                         3,  3,  3,  3,  4,  4,  4,  4,  5,  5,  6,  6,  7,  7,  8,  8}; //  9 CTX

static const int  pos2ctx_last4x4 [] = { 0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15}; // 15 CTX
static const int* pos2ctx_last    [] = {pos2ctx_last4x4, pos2ctx_last4x4, pos2ctx_last8x8, pos2ctx_last8x4,
                                        pos2ctx_last8x4, pos2ctx_last4x4, pos2ctx_last4x4, pos2ctx_last4x4};