av1代码学习11--av1_encode_sb_row（）

1，函数功能：确定tiles中sb的起始位置，确定平面，开始调用 encode_sb_row（）进行编码

2，代码学习

void av1_encode_sb_row(AV1_COMP *cpi, ThreadData *td, int tile_row,
                       int tile_col, int mi_row) {
  AV1_COMMON *const cm = &cpi->common;
  const int num_planes = av1_num_planes(cm);//确定平面
  const int tile_cols = cm->tile_cols;
  TileDataEnc *this_tile = &cpi->tile_data[tile_row * tile_cols + tile_col];
  const TileInfo *const tile_info = &this_tile->tile_info;
  TOKENEXTRA *tok = NULL;
  const int sb_row_in_tile =
      (mi_row - tile_info->mi_row_start) >> cm->seq_params.mib_size_log2;//确定当前sb在tile中的行
  const int tile_mb_cols =
      (tile_info->mi_col_end - tile_info->mi_col_start + 2) >> 2;
  const int num_mb_rows_in_sb =
      ((1 << (cm->seq_params.mib_size_log2 + MI_SIZE_LOG2)) + 8) >> 4;//确定当前sb在tile中的列

  get_start_tok(cpi, tile_row, tile_col, mi_row, &tok,
                cm->seq_params.mib_size_log2 + MI_SIZE_LOG2, num_planes);
  cpi->tplist[tile_row][tile_col][sb_row_in_tile].start = tok;

  encode_sb_row(cpi, td, this_tile, mi_row, &tok, cpi->sf.use_nonrd_pick_mode);

  cpi->tplist[tile_row][tile_col][sb_row_in_tile].stop = tok;
  cpi->tplist[tile_row][tile_col][sb_row_in_tile].count =
      (unsigned int)(cpi->tplist[tile_row][tile_col][sb_row_in_tile].stop -
                     cpi->tplist[tile_row][tile_col][sb_row_in_tile].start);//记录大小

  assert(
      (unsigned int)(tok -
                     cpi->tplist[tile_row][tile_col][sb_row_in_tile].start) <=
      get_token_alloc(num_mb_rows_in_sb, tile_mb_cols,
                      cm->seq_params.mib_size_log2 + MI_SIZE_LOG2, num_planes));

  (void)tile_mb_cols;
  (void)num_mb_rows_in_sb;
}