A method comprising: encoding a first picture on a first scalability layer and on a lowest temporal sub-layer; encoding a second picture on a second scalability layer and on the lowest temporal sub-layer, wherein the first picture and the second picture represent the same time instant, encoding one or more first syntax elements, associated with the first picture, with a value indicating that a picture type of the first picture is other than a step-wise temporal sub-layer access (STSA) picture; encoding one or more second syntax elements, associated with the second picture, with a value indicating that a picture type of the second picture is a step-wise temporal sub-layer access picture; and encoding at least a third picture on a second scalability layer and on a temporal sub-layer higher than the lowest temporal sub-layer.