A packet-based video network comprising: a plurality of packetized video data nodes (120, 130, 150) acting as packetized video data sources and/or packetized video data destinations; packet switch circuitry (170, 140) configured to provide at least two selectable video packet routes amongst the plurality of nodes and to switch from one of the video packet routes to another of the video packet routes at a switching operation; and video synchroniser circuitry configured to synchronise the video frame periods of at least those nodes acting as packetized video data sources; in which: each node acting as a packetized video data source (120, 130) is configured to launch onto the network packetized video data such that, for at least those video frame periods adjacent to a switching operation: the node launches onto the network packetized video data required for decoding that frame during a predetermined active video data portion of the video frame period, and the node does not launch onto the network packetized video data required for decoding that frame during a predetermined remaining portion of the video frame period; and the network is configured so that a switching operation from one of the video packet routes to another of the video packet routes is implemented during a time period corresponding to the predetermined remaining portion. a plurality of packetized video data nodes (120, 130, 150) acting as packetized video data sources and/or packetized video data destinations; packet switch circuitry (170, 140) configured to provide at least two selectable video packet routes amongst the plurality of nodes and to switch from one of the video packet routes to another of the video packet routes at a switching operation; and video synchroniser circuitry configured to synchronise the video frame periods of at least those nodes acting as packetized video data sources; in which: each node acting as a packetized video data source (120, 130) is configured to launch onto the network packetized video data such that, for at least those video frame periods adjacent to a switching operation: the node launches onto the network packetized video data required for decoding that frame during a predetermined active video data portion of the video frame period, and the node does not launch onto the network packetized video data required for decoding that frame during a predetermined remaining portion of the video frame period; and the network is configured so that a switching operation from one of the video packet routes to another of the video packet routes is implemented during a time period corresponding to the predetermined remaining portion. each node acting as a packetized video data source (120, 130) is configured to launch onto the network packetized video data such that, for at least those video frame periods adjacent to a switching operation: the node launches onto the network packetized video data required for decoding that frame during a predetermined active video data portion of the video frame period, and the node does not launch onto the network packetized video data required for decoding that frame during a predetermined remaining portion of the video frame period; the node launches onto the network packetized video data required for decoding that frame during a predetermined active video data portion of the video frame period, and the node does not launch onto the network packetized video data required for decoding that frame during a predetermined remaining portion of the video frame period; and the network is configured so that a switching operation from one of the video packet routes to another of the video packet routes is implemented during a time period corresponding to the predetermined remaining portion.