266 Personal Content Experience: Managing Digital Life in the Mobile Age an image and deleting it immediately if the capture had failed. Con- sequently, it is imperative to consider the UI structure and what are the next tasks, and in which order to design tasks fl ows that are mean- ingful and relevant to the user. 6.5.3 Enjoy Content Enjoying can only start once the user has got the content object, for instance, after a completed download (although some download clients allow enjoying partial content while it is still being downloaded). If the content is already stored in the device, the user may access it by browsing or searching. It should be noted that the content, which is being enjoyed, may be sensitive and private. Therefore the user should always have absolute control over where, when, and how the enjoying occurs. The user interface for enjoying relies greatly on the object’s type. In this section, we present only the main tasks. Enjoying – as any use of – content should affect metadata as it implies importance and/or relevance of the object. A typical example is the “use count”, such as the play count for a song: the song rating could be suggested by the system, based on the play count. Playback is related to temporal media types, including music, audio books, video, animations (like Machinima as discussed in section 7.4, 17 or Flash), slideshow, podcasts, and videocasts. The most common controls are play (that often acts as a play/pause toggle), and move to the previous or next item (track, scene, or image). In some cases, the controls include functions for stopping the playback, starting to record content, and changing the volume or the media source (video, audio). Depending on the device category, the playback controls are either drawn on the screen, or the device has dedicated hardware keys (as in Apple iPod or Nokia N91 (Figure 6-5)). Although watching a video or listening to a song requires similar controls (such as play, pause, stop, rewind, and fast forward) for manipulating the temporal dimension, the view they demand differs greatly due to the modalities they need. Mostly this relates to informa- tion that needs to be presented on the screen. For instance, while studying mobile TV broadcasting, Knoche et al. (2005) found that images should not be smaller than 168 × 126 pixels, because otherwise 17 Podcast refers to audio fi les (typically in MP3 format) that are downloaded over the Internet. The fi les may form a show, as in radio, and the user can receive the latest episodes with the aid of an RSS feed. Videocast extends the content from audio to video (MP4).