void(* diff_pixels_unaligned)(int16_t *av_restrict block, const uint8_t *s1, const uint8_t *s2, ptrdiff_t stride)
void(* get_pixels)(int16_t *av_restrict block, const uint8_t *pixels, ptrdiff_t stride)
void(* diff_pixels)(int16_t *av_restrict block, const uint8_t *s1, const uint8_t *s2, ptrdiff_t stride)
main external API structure.