Systems, methods and apparatus for processing image data are described. One example method includes performing a conversion between a visual media file and a bitstream. The visual media file comprises image items each comprising a sequence of one or more pictures according to a media file format, and the bitstream includes access units each consisting of one or more pictures each belonging to a layer according to a video coding format. The media file format specifies that image items comprising pictures originated from the bitstream are allowed to be associated with different instances of a property descriptor that indicates high-level characteristics of the bitstream.