Symmetrically cleaves beta-carotene into two molecules of retinal using a dioxygenase mechanism. {ECO:0000269|PubMed:11401432, ECO:0000269|PubMed:17951468, ECO:0000269|PubMed:24668807}. This is the function of BCO1 (beta-carotene oxygenase 1, ENSG00000135697).