A method of delivering video content to a client device from a server, said video content comprising a sequence of segments and wherein each of the segments is encoded at a plurality of bit rates, said method comprising: a) receiving information at the client device about each segment, wherein the information comprises the bit rates, the duration, and a viewer importance parameter associated with each segment; b) estimating the network bit rate between the server and the client device; c) determining the duration of video content buffered at the client device; d) calculating the time available to download a first segment using the duration of the video content buffered at the client device, the duration of the first segment, the minimum buffer duration to avoid buffer underflow, and an adjustment; e) determining a maximum segment bit rate in dependence on the estimated network bitrate, on the duration of said first segment and on said time available to download; f) identifying a bit rate for the first segment that is no greater than the maximum segment bitrate; g) delivering the identified first segment to the client device; wherein, the adjustment is at least dependent both on the viewer importance of said first segment and on the viewer importance parameter associated with at least a further segment, and wherein the adjustment is set to be higher for the first segment than for said further segment when the viewer importance parameter associated with the first segment is lower than the viewer importance parameter associated with the further segment, and wherein, when the viewer importance parameter associated with said first segment is higher than the viewer importance parameter associated with the further segment, the identified bit rate is higher for the first segment than for the further segment. a) receiving information at the client device about each segment, wherein the information comprises the bit rates, the duration, and a viewer importance parameter associated with each segment; b) estimating the network bit rate between the server and the client device; c) determining the duration of video content buffered at the client device; d) calculating the time available to download a first segment using the duration of the video content buffered at the client device, the duration of the first segment, the minimum buffer duration to avoid buffer underflow, and an adjustment; e) determining a maximum segment bit rate in dependence on the estimated network bitrate, on the duration of said first segment and on said time available to download; f) identifying a bit rate for the first segment that is no greater than the maximum segment bitrate; g) delivering the identified first segment to the client device; the adjustment is at least dependent both on the viewer importance of said first segment and on the viewer importance parameter associated with at least a further segment, and wherein the adjustment is set to be higher for the first segment than for said further segment when the viewer importance parameter associated with the first segment is lower than the viewer importance parameter associated with the further segment, and wherein, when the viewer importance parameter associated with said first segment is higher than the viewer importance parameter associated with the further segment, the identified bit rate is higher for the first segment than for the further segment.