The disclosed subject matter provides techniques for coding overlays in a scalable bitstream environment. H.265's Video Parameter Set (VPS) may be augmented to include syntax elements indicative of a type of an auxiliary picture, which can, for example, be an overlay picture, an overlay layout, an alpha picture (which controls semi-transparency of pictures), and so on. A Supplementary Enhancement Information (SEI-) message may be used to describe the overlay layout and associate the aux type layers.