set_auxC_property 1491 libheif-1.3.2/libheif/heif_context.cc     m_heif_context->m_heif_file->set_auxC_property(alpha_image_id, "urn:mpeg:hevc:2015:auxid:1");
set_auxC_property  119 libheif-1.3.2/libheif/heif_file.h     void set_auxC_property(heif_item_id id, std::string type);