A system for rendering a video stream for display on a display device, comprising: - a network interface for receiving the video stream by streaming; - a processor subsystem configured to: - select a version of the video stream for streaming having a spatial resolution and/or a bitrate from a list, the list identifying versions of the video stream having different spatial resolutions and/or bitrates; - generate display data defining a visible display area to be displayed by the display device using an active display area having a display resolution, wherein said generating of the display data comprises rendering the video stream in a sub-area of the visible display area, characterized in that said generating the display data comprises rendering a 3D environment from a viewing position in the 3D environment and said rendering the video stream comprises rendering the video stream on a virtual display in the 3D environment; and, in response to a change in a relative position and/or a relative orientation between the viewing position and the virtual display which results in a change in the size of the sub-area: - determine an equivalent display resolution for a part of the active display area with which the sub-area of the visible display area is to be displayed; - select the version of the video stream for streaming from the list having a spatial resolution which best matches the equivalent display resolution of the sub-area. - a network interface for receiving the video stream by streaming; - a processor subsystem configured to: - select a version of the video stream for streaming having a spatial resolution and/or a bitrate from a list, the list identifying versions of the video stream having different spatial resolutions and/or bitrates; - generate display data defining a visible display area to be displayed by the display device using an active display area having a display resolution, wherein said generating of the display data comprises rendering the video stream in a sub-area of the visible display area, characterized in that said generating the display data comprises rendering a 3D environment from a viewing position in the 3D environment and said rendering the video stream comprises rendering the video stream on a virtual display in the 3D environment; and, in response to a change in a relative position and/or a relative orientation between the viewing position and the virtual display which results in a change in the size of the sub-area: - determine an equivalent display resolution for a part of the active display area with which the sub-area of the visible display area is to be displayed; - select the version of the video stream for streaming from the list having a spatial resolution which best matches the equivalent display resolution of the sub-area. - select a version of the video stream for streaming having a spatial resolution and/or a bitrate from a list, the list identifying versions of the video stream having different spatial resolutions and/or bitrates; - generate display data defining a visible display area to be displayed by the display device using an active display area having a display resolution, wherein said generating of the display data comprises rendering the video stream in a sub-area of the visible display area, characterized in that said generating the display data comprises rendering a 3D environment from a viewing position in the 3D environment and said rendering the video stream comprises rendering the video stream on a virtual display in the 3D environment; and, - determine an equivalent display resolution for a part of the active display area with which the sub-area of the visible display area is to be displayed; - select the version of the video stream for streaming from the list having a spatial resolution which best matches the equivalent display resolution of the sub-area.