A method for operating a mobile device, wherein the mobile device is configured to download a media stream comprising a plurality of data segments (S1-Sn) and to playback the media stream during download, wherein the media stream is downloaded as a plurality of blocks of data segments, each block of data segments comprising a set of the plurality of data segments (S1-Sn) representing a corresponding media stream portion of the media stream, wherein at least some of the data segments of the media stream are each available in a plurality of different coding formats (Q1, Q2, Q3), wherein the different coding formats (Q1, Q2, Q3) cause different amounts of data to be transferred for downloading the data segment (S1-Sn), wherein the method comprises: - determining a required playback time for a next block of data segments to be downloaded depending on a predetermined required minimum playback time defining a required minimum time duration for playing back the media stream portion provided by the next block of data segments, characterized by further comprising: - determining a recent playback time of a block of data segments which has been downloaded recently, - determining a recent download time required for downloading the block of data segments which has been downloaded recently, - determining the required playback time for the next block of data segments to be downloaded depending on the recent playback time and the recent download time by - determining a ratio of the recent playback time to the recent download time, and - setting selectively, based on the determined ratio, the required playback time for the next block of data segments to be downloaded to either the predetermined required minimum playback time or to a maximum of the predetermined required minimum playback time and a time derived from a reduction of the recent playback time, - selecting, for the next block of data segments to be downloaded, a coding format of the available plurality of different coding formats (Q1, Q2, Q3) depending on the recent playback time and the recent download time, and - requesting by the mobile device a download of a plurality of next blocks of data segments having the required playback time, wherein a gap between a download of the next block of data segments and a download of the block after the next block is long enough to enable a receiver unit of the mobile device to be powered down during the gap. - determining a required playback time for a next block of data segments to be downloaded depending on a predetermined required minimum playback time defining a required minimum time duration for playing back the media stream portion provided by the next block of data segments, characterized by further comprising: - determining a recent playback time of a block of data segments which has been downloaded recently, - determining a recent download time required for downloading the block of data segments which has been downloaded recently, - determining the required playback time for the next block of data segments to be downloaded depending on the recent playback time and the recent download time by - determining a ratio of the recent playback time to the recent download time, and - setting selectively, based on the determined ratio, the required playback time for the next block of data segments to be downloaded to either the predetermined required minimum playback time or to a maximum of the predetermined required minimum playback time and a time derived from a reduction of the recent playback time, - determining a ratio of the recent playback time to the recent download time, and - setting selectively, based on the determined ratio, the required playback time for the next block of data segments to be downloaded to either the predetermined required minimum playback time or to a maximum of the predetermined required minimum playback time and a time derived from a reduction of the recent playback time, - selecting, for the next block of data segments to be downloaded, a coding format of the available plurality of different coding formats (Q1, Q2, Q3) depending on the recent playback time and the recent download time, and - requesting by the mobile device a download of a plurality of next blocks of data segments having the required playback time, wherein a gap between a download of the next block of data segments and a download of the block after the next block is long enough to enable a receiver unit of the mobile device to be powered down during the gap.