+
+ /** Number of macroblock descriptions in the mv_blocks array
+ that have already been passed to the hardware.
+ - application - zeroes it on get_buffer().
+ A successful ff_draw_horiz_band() may increment it
+ with filled_mb_block_num or zero both.
+ - libavcodec - unchanged
+ */
+ int start_mv_blocks_num;
+
+ /** Number of new macroblock descriptions in the mv_blocks array (after
+ start_mv_blocks_num) that are filled by libavcodec and have to be
+ passed to the hardware.
+ - application - zeroes it on get_buffer() or after successful
+ ff_draw_horiz_band().
+ - libavcodec - increment with one of each stored MB
+ */
+ int filled_mv_blocks_num;
+
+ /** Number of the the next free data block; one data block consists of
+ 64 short values in the data_blocks array.
+ All blocks before this one have already been claimed by placing their
+ position into the corresponding block description structure field,
+ that are part of the mv_blocks array.
+ - application - zeroes it on get_buffer().
+ A successful ff_draw_horiz_band() may zero it together
+ with start_mb_blocks_num.
+ - libavcodec - each decoded macroblock increases it by the number
+ of coded blocks it contains.
+ */
+ int next_free_data_block_num;
+
+/** extensions may be placed here */
+#if LIBAVCODEC_VERSION_MAJOR < 53