Concerning the Image Pyramid Entity Group Box 'pymd' in WG03N1157_23524 HEIF Ed3 Amd2 Prelim WD:
The following four variables seem redundant and could be removed to greatly simplify the 'pymd' box:
tile_size_x
tile_size_y
tiles_in_layer_row_minus1
tiles_in_layer_column_minus1
pymd
ImageGrid
tiles_in_layer_row_minus1
rows_minus_one
tiles_in_layer_column_minus1
columns_minus_one
tile_size_x
(output_width / columns_minus_one)
tile_size_y
(output_height / rows_minus_one)
If the gridding is handled within the codec, then the codec specific boxes would be used instead. For example, the uncompressed codec would use the uncC box:
pymd
uncC
tiles_in_layer_row_minus1
num_tile_rows_minus_one
tiles_in_layer_column_minus1
num_tile_cols_minus_one
tile_size_x
(ispe image_width / num_tile_cols_minus_one)
tile_size_y
(ispe image_height / num_tile_rows_minus_one)
I imagine these variables were originally placed here for convenience. However, there are already well defined mechanisms for accessing them. In my opinion, duplicating them in the pymd box adds complexity for very little gain.
Concerning the Image Pyramid Entity Group Box 'pymd' in WG03N1157_23524 HEIF Ed3 Amd2 Prelim WD:
The following four variables seem redundant and could be removed to greatly simplify the 'pymd' box:
If the gridding is handled within the codec, then the codec specific boxes would be used instead. For example, the uncompressed codec would use the uncC box:
I imagine these variables were originally placed here for convenience. However, there are already well defined mechanisms for accessing them. In my opinion, duplicating them in the pymd box adds complexity for very little gain.