Patent Publication Number: US-2010122277-A1

Title: device and a method for playing audio-video content

Description:
FIELD OF THE INVENTION 
     The invention relates to a device for playing audio-video content. 
     The invention further relates to a method for playing audio-video content. 
     The invention further relates to a program element. 
     The invention further relates to a computer-readable medium. 
     BACKGROUND OF THE INVENTION 
     Consumer Electronics devices provide a wide variety of entertainment experiences to consumers from music and video playback to live television viewing. However, the entertainment experience can be spoilt by interruptions or distractions causing the attention of the consumer to be lost. In US Patent Application 2003/0097659A1 the display of a television program is paused automatically after detecting an event that indicates that the viewing experience of a viewer is likely to have been interrupted. The pausing is achieved by time-shifting the television program using storage. When the interruption is complete the time-shifted program may be resumed such that the viewer can continue viewing without missing a portion of the television program. Interruptions to the viewing experience may be an incoming telephone call, the receipt of an electronic message, or other events occurring in the home or in the environment of the device pausing the television program. 
     Further methods for detecting the loss of attention of a user include detecting the face of a consumer using a camera. Specifically, this may also include detecting whether the eyes of the consumer are open or closed or indeed in which direction the eyes are gazing. Acoustic methods known rely upon detecting predetermined sounds such as a doorbell or telephone ring tone. However, it has been found that the accuracy of detecting the attention loss of a consumer is rarely 100%, which in turn leads to an entertainment experience that is not entirely predictable for the consumer. For example, when the attention loss of a consumer is incorrectly identified automatically pausing the television program is undesired. The consumer may even find this irritating, leading to an entertainment experience that is actually poorer. Furthermore, in some situations the consumer purposely loses attention. For example, during commercial blocks. In these situations the consumer would be subjected to a poorer entertainment experience. 
     The inventors recognising this problem devised the present invention. 
     BRIEF SUMMARY OF THE INVENTION 
     It would be advantageous to achieve an improved entertainment experience for a consumer even when the accuracy of detecting the attention loss of the consumer is not perfect. 
     Accordingly, there is provided, in a first aspect of the present invention, a device for playing audio-video content, the device comprising a storage unit for supplying the content to be played, a playback unit for playing the content from the storage unit, an attention loss detector for detecting at least one point of attention loss by a user during playing of the content by the playback unit, an attention loss storage unit for storing at least one attention loss marker corresponding to the at least one point of attention loss detected by the attention loss detector and a user interface unit for receiving user input from the user indicating that the playback unit should play the content from a point in time corresponding to the at least one attention loss marker. 
     According to a second aspect of the invention a method for playing audio-video content is provided, the method comprising playing the content to a user, detecting at least one point of attention loss by the user during the playing of the content, storing at least one attention loss marker corresponding to the at least one point of attention loss detected, receiving user input from the user indicating that the user desires to play the content from a point in time corresponding to the at least one attention loss marker and playing the content from a point in time corresponding to the at least one attention loss marker in response to the user input. 
     According to a third aspect of the invention a system for playing audio-video content is provided, comprising a first device, for detecting attention loss, and a second device, the second device comprising a playback unit for playing the content, wherein the first device comprises an attention loss detector for detecting at least one point of attention loss by a user during playing of the content by the second device, an attention loss storage unit for storing at least one attention loss marker corresponding to the at least one point of attention loss detected by the attention loss detector, a user interface unit for receiving user input from the user indicating that the content should be played from a point in time corresponding to the at least one attention loss marker and a remote device control unit, for controlling the playback unit of the second device in response to the user input to play the content from the point in time corresponding to the at least one attention loss marker. 
     According to a fourth aspect of the invention a program element directly loadable into a memory of a programmable device is provided, comprising software code portions for performing, when said program element is run on the device, the method steps of playing audio-video content to a user, detecting at least one point of attention loss by the user during the playing of the content, storing at least one attention loss marker corresponding to the at least one point of attention loss detected, receiving user input from the user indicating that the user desires to play the content from a point in time corresponding to the at least one attention loss marker and playing the content from a point in time corresponding to the at least one attention loss marker in response to the user input. 
     According to a fifth aspect of the invention a computer-readable medium directly loadable into a memory of a programmable device is provided, comprising software code portions for performing, when said code portions are run on the device, the method steps of playing audio-video content to a user, detecting at least one point of attention loss by the user during the playing of the content, storing at least one attention loss marker corresponding to the at least one point of attention loss detected, receiving user input from the user indicating that the user desires to play the content from a point in time corresponding to the at least one attention loss marker and playing the content from a point in time corresponding to the at least one attention loss marker in response to the user input. 
     Since the detection accuracy of detecting a loss of attention by the user is rarely perfect the entertainment experience is improved by ensuring that the audio-video content is not automatically paused in response to the detection of a loss of attention, but that a marker is stored indicating the detected point of attention loss. The user may then choose to ignore the detected attention loss or not. The detection accuracy of detecting a loss of attention is therefore less critical and will not automatically lead to a poorer entertainment experience. Furthermore, in situations where the user purposely loses attention the user may be given the option of resuming from the point of attention loss rather than being forced to overrule the automatically paused entertainment experience. 
     In one embodiment the attention loss storage unit may comprise an attention loss marker generator which may be communicatively coupled to the attention loss detector and the playback unit, for generating the at least one attention loss marker based upon a current playback point received from the playback unit and a point of attention loss indication received from the attention loss detector and an attention loss marker database which may be communicatively coupled to the attention loss marker generator and the playback unit, for storing and retrieving the at least one attention loss marker generated by the attention loss marker generator. This allows the playback and the detection of attention loss points to be synchronized and stored for easy retrieval, even when many points of attention loss are detected. 
     In a further embodiment the storage unit may comprise a random access unit for playing the content in a randomly addressable manner. The playback unit may be communicatively coupled to the storage unit to provide a playback pointer to address the content from the storage unit in the randomly addressable manner and the user interface unit may be communicatively coupled to the playback unit to indicate that the playback unit should communicate the playback pointer to the storage unit to play the content from a point in time corresponding to the at least one attention loss marker. This allows the content to be played directly from the point in time corresponding to the at least one attention loss marker without the requirement of rewinding and or searching in the storage unit for the correct point. 
     In another embodiment a recording unit may be provided for recording a broadcast signal, the recording unit may be communicatively coupled to the storage unit to record the broadcast signal. This allows broadcast signals to be recorded and points of attention loss to be detected in live television. 
     In yet another embodiment a content analyser may be provided communicatively coupled to the recording unit for analysing the content and generating at least one content segmentation marker indicating at least one segment within the content. The content analyser may be further communicatively coupled to the storage unit for storing the at least one content segmentation marker and the playback unit may be communicatively coupled to the storage unit to determine a playback pointer based upon the point in time corresponding to the at least one attention loss marker and the at least one content segmentation marker. The playback unit may further be adapted to play the content from a point in time corresponding to the playback pointer. This allows the actual point of resumption of playback of recorded content to be adjusted taking into account the segments or segment boundaries within the actual audio-video content itself. The content may be analysed at recording time or offline before playback. 
     In an embodiment a content analyser may be provided communicatively coupled to the storage unit for analysing the content and generating at least one content segmentation marker indicating at least one segment within the content and the playback unit may be communicatively coupled to the content analyser to determine a playback pointer based upon the point in time corresponding to the at least one attention loss marker and the at least one content segmentation marker. The playback unit may be further adapted to play the content from a point in time corresponding to the playback pointer. This allows the content to be analysed during playback, without any prior analysis, such that the actual point of resumption of playback of the content may be adjusted taking into account the segments or segment boundaries within the actual audio-video content itself. 
     In another embodiment the content analyser may be a commercial block detector and the at least one content segmentation marker may be an at least one commercial block segmentation marker. This allows the actual point of resumption of playback of the content to be adjusted to commercial block boundaries rather than the exact point of attention loss. 
     In another embodiment the playback unit may be arranged to generate an attention loss marker indication, the attention loss marker indication indicating that the at least one point of attention loss has been detected by the attention loss detector and the attention loss marker indication may be made visible to the user. This allows the user to made aware of the fact that a point of attention loss was detected and that the user has the option of resuming playback at such a point. This is a manner of providing useful feedback to the user. 
     In a further embodiment a device according to the invention may be realized as at least one of the group consisting of a Set-Top-Box device, a digital video recording device, a network-enabled device, a conditional access system, a portable audio player, a portable video player, a mobile phone, a DVD player, a CD player, a hard disk based media player, an Internet radio device, a computer, a television, a public entertainment device and an MP3 player. However, these applications are only exemplary. 
     In another embodiment of the third aspect of the invention the first device may further comprise a timer unit communicatively coupled to the attention loss storage unit and to the remote device control unit and the at least one attention loss marker stored by the attention loss storage unit may be determined based upon a first current time generated by the timer unit. The remote device control unit may control the second device based upon an elapsed duration between the at least one attention loss marker stored by the attention loss storage unit and a second current time corresponding to reception of the user input. This allows the first device and the second device to be synchronized in time and for the first device to control the second device in an accurate manner. 
     The data processing required according to the invention can be realized by a computer program, that is to say by software, or by using one or more special electronic optimization circuits, that is to say in hardware, or in hybrid form, that is to say by means of software components and hardware components. 
     The aspects defined above and further aspects of the invention are apparent from the examples of embodiment to be described hereinafter and are explained with reference to these examples of embodiment. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be described in more detail hereinafter with reference to examples of embodiment but to which the invention is not limited. 
         FIG. 1  illustrates a practical embodiment of the invention. 
         FIG. 2  illustrates a further embodiment of the invention. 
         FIG. 3  illustrates an embodiment of the invention making use of a storage unit providing random access. 
         FIG. 4  illustrates an embodiment suitable for recording live television. 
         FIG. 5  illustrates an embodiment suitable for detecting commercial blocks. 
         FIG. 6  illustrates a flowchart for detecting attention loss by a user during playback. 
         FIG. 7  illustrates a flowchart for resuming playback at a point of attention loss of a user. 
         FIG. 8   a  illustrates a flowchart for analysing content. 
         FIG. 8   b  illustrates a flowchart for resuming playback taking into account the point of attention loss of a user and segments of content within the content. 
         FIG. 8   c  illustrates a flowchart for determining whether a commercial block boundary or the point of attention loss of a user should be stored as the attention loss marker. 
         FIG. 9  illustrates an embodiment of a system wherein a first device may control a conventional playback device to provide detection of points of attention loss by a user. 
         FIG. 10  illustrates an embodiment suitable for analysing content during playback without any requirements for pre-processing of the content. 
         FIG. 11  illustrates a selection of user attention states that may be detected. 
     
    
    
     The Figures are schematically drawn and not true to scale, and the identical reference numerals in different Figures refer to corresponding elements. It will be clear for those skilled in the art, that alternative but equivalent embodiments of the invention are possible without deviating from the true inventive concept, and that the scope of the invention will be limited by the claims only. 
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows a device  100  according to an embodiment of the invention. The device  100  comprises a storage unit  170 , which may be a hard disk drive, a floppy disc drive, a flash memory device, an optical drive or equivalent. The storage unit  170  may be used to store audio-video content  205  that a user  192  would like to preserve or render. The device  100  may, for example, be a hard disk drive/DVD recorder. The device  100  may also comprise a playback unit  220  for decoding the content  205  for display on a display  160 . Alternatively, a processor  120  or a codec (not shown) may be used to decode the content  205 . Further rendering devices (not shown), such as a speakers, may also be present in the device  100  or externally connected to the device  100 . The device  100  may also comprise a communication unit  130 , such as an Ethernet interface, in wired or wireless form, a WiFi interface, a Bluetooth interface or a mobile phone network interface. A network interface controller may also be understood as a communication unit  130 . The device  100  may then also receive one or more data streams via the communication unit  130  for playing using the playback unit  220  and further display on the display  160  or for storing in the storage unit  170 . The communication unit  130  may also be used to transmit data streams to a remote display on a remote device  165  via network  180 . The network  180  may be a local network or a worldwide network such as the Internet. The user  192  may interact with the device  100  using a user interface  190 . Typically, the user  192  interacts with the user interface  190  using a remote control  191 , but other means of interaction are also possible. For example, the user  192  may interact with the device  100  using a touchscreen, a scroll wheel, buttons, a mouse or other pointer device, a keyboard etc. 
     An attention loss detector  200  may be provided to detect instants when the user  192  is distracted from the content  205  being played back and loses attention. The attention loss detector  200  may detect the loss of attention in a variety of ways. For example, when using a camera  135  connected to the attention loss detector  200  face detection and pose estimation may be applied.  FIG. 11  illustrates several states or poses that can be identified in order to detect loss of attention. For example, distraction  1110  can be characterized by a change of pose such that the viewer does not face the TV display for a prolonged period of time. This state can be detected with a face detector to localize the faces of the viewers and a pose estimation to detect if any of the faces moves for a long period of time from the frontal state. A sleep state  1120  can also be characterized in the same way, but only if the pose of the viewer changes significantly to a direction other than that of the display. The sleep state  1120  may in some situations occur where the user  192  falls asleep or into a state of drowsiness without his/her pose changing. In that case, the combination of face detection and pose estimation may not suffice to detect that the lost of attention of the user  192 . To detect such states, techniques that have been used in the automotive environment to determine the level of a vehicle driver&#39;s drowsiness can be used instead. Such techniques are described in U.S. Pat. No. 5,786,765. 
     The absence state  1130  may be easily detected using face detection. If the face of a viewer is detected before he/she leaves the camera view, absence is determined simply by not being able to detect the face of the viewer for some period of time. Algorithms for face detection and pose estimation are known from the paper “Towards a real-time and distributed system for face detection, pose estimation and face-related features”, Nesvadba et al., Invited Paper, Proc. Int. Con. on Methods and Techniques in Behavioural Research, Wageningen, The Netherlands, 2005. The camera  135  may also be used to focus upon the eyes of the user  192  and detect the direction of gaze or whether the eyes are open or closed. 
     Of course, there are numerous other methods of detection a loss of attention by the user  192 . For example, motion sensors may be used that allow the detection of instants when the user  192  leaves his/her viewing position, a microphone  145  may be employed to detect acoustic signals that may cause distraction. Such acoustic signals may be a door chime or a phone ring tone etc. A telephone  125  or similar communication device may also be directly connected to the attention loss detector  200  to provide a direct signal. Movement of the user  192  may also be detected by tracking his/her movement using an electronic card. For example, as disclosed in US patent application 2004/0104806A1. 
     An especially useful method of detecting attention loss by the user  192  is by detecting a remote control command from the user  192 . Such a remote control command may be transmitted by the remote control  191  and may be a pause command. 
     An attention loss storage unit  210  may be provided to store points of attention loss detected by the attention loss detector  200 . The detection and storing of the points of attention loss may be achieved by the use of a control program running on the processor  120  and making use of a system bus  140 . The system bus  140  may interconnect all of the component units comprised within the device  100 , allowing the processor  120  to control each component unit. The device  100  may be realized as a Set-Top-Box device, a digital video recording device, a network-enabled device, a conditional access system, a portable audio player, a portable video player, a mobile phone, a DVD player, a CD player, a hard disk based media player, an Internet radio device, a computer, a television, a public entertainment device or an MP3 player. These examples are merely exemplary. 
     The embodiment of  FIG. 2  further elucidates upon the invention. In  FIG. 2  the content  205  is retrieved from the storage unit  170  by the playback unit  220  for playback on the display  160 . Also in  FIG. 2  an interface unit  250  is provided. The interface unit  250  allows many different forms of sensors to be used by the attention loss detector  200  to detect the loss of attention of the user  192 . For example, the interface unit  250  may translate a sensor specific value into a reference value or standardised value understood by the attention loss detector  200  of the device  100 . The attention loss detector  200  may produce a point of attention loss indication  215  at an instant in time when the user  192  loses attention from the playback of the content  205 . The point of attention loss indication  215  may be communicated directly to the attention loss storage unit  210  or via the system bus  140 . The attention loss storage unit  210  may generate an attention loss marker  255 . Of course, multiple attention loss markers may also be generated and stored in the attention loss storage unit  210  should multiple points of attention loss be detected. 
     The playback unit  220  may communicate a current playback point  225  to the attention loss storage unit  210  to assist in the generation of the attention loss marker  255 . When at least one point of attention loss indication  215  has been detected, or at least one attention loss marker  255  has been generated, the playback unit  220  may in communication with the attention loss storage unit  210  generate an attention loss marker indication  260  for display on the display  160 . This indicates to the user  192  that the possibility exists to resume playback from a point in time corresponding to the at least one point of attention loss indication  215  or the at least one attention loss marker  255 . The user  192  may then choose to resume playback from a point in time corresponding to the at least one point of attention loss indication  215  by providing user input  245  via the remote control  191  or he/she may ignore the attention loss marker indication  260 . Reasons for ignoring the attention loss marker indication  260  could be that the attention loss detector  200  falsely detected the point of attention loss indication  215  or that the user  192  wilfully lost attention due to the content  205  containing a commercial block or other uninteresting segment. Other reasons may also exist for which the user  192  would choose to ignore the attention loss marker indication  260 . 
     Should the user  192  provide the user input  245  to indicate that the user  192  would prefer to resume playback of the content  205  from a point in time corresponding to the point of attention loss  215 , the user interface  190  may receive such user input  245 . The user interface  190  may then communicate to the playback unit  220  that the point of playback should be changed. The playback unit  220  may then receive a playback pointer  235  from the attention loss storage unit  210 . The playback pointer  235  may then be a pointer to a position in the content  205  corresponding to the point of attention loss indication  215 . The playback pointer  235  may be a timestamp, or other equivalent indicating a position within the content  205  in time. The playback pointer  235  may also be a file pointer or other equivalent indicating a position in a file representing the content  205 . The playback pointer  235  may also be a stream pointer or other equivalent indicating a bit or byte position in a stream representing the content  205 . Other examples are also possible. The mere existence of the playback pointer  235  may be used to represent the attention loss marker  255 . In such a situation the playback pointer  235  and the attention loss marker  255  may be one and the same. The playback unit  220  makes use of the playback pointer  235  to control the point of playback and sets the playback point to a point corresponding to the playback pointer  235 . The user  192  may then view the content  205  on the display  160  from a point in time corresponding to the point of his/her attention loss. Playback may also be resumed a predetermined time before the point corresponding to the playback pointer  235 . The predetermined time may be of the order of a few seconds to allow the user  192  to regain context of the content  205 . In such a situation the user  192  would first see again a few seconds of the content  205  which were previously displayed on the display  160 . In this way the user  192  may regain context and the user  192  may be assured that none of the content  205  has been missed. 
     In the embodiment of  FIG. 3  the attention loss storage unit  210  is shown as comprising an attention loss marker generator  300 . The attention loss marker generator  300  may receive the current playback point  225  from the playback unit  220 . This may be provided continuously or upon request of the attention loss storage unit  210 . The latter whilst not shown in  FIG. 3  is nevertheless possible. The attention loss marker generator  300  may generate the attention loss marker  255  from the current playback point  225  and the point of attention loss indication  215  received from the attention loss detector  200 . The attention loss marker  255  may be stored in an attention loss marker database  310 . This allows multiple attention loss markers to be stored and retrieved providing the user  192  with more flexibility. The playback pointer  235  may also be stored in the attention loss marker database  310 . The relationship between the attention loss marker  255  and the playback pointer  235  has already been described in the text relating to  FIG. 2 . From this it should be clear that again the attention loss marker  255  and the playback pointer  235  may be one and the same information unit stored in the attention loss marker database  310 . Alternatively, the playback pointer  235  may be generated at the time of storing the attention loss marker  255  in the attention loss marker database  310  or at the time of querying the attention loss marker  255  from the attention loss marker database  310 . Therefore, the attention loss marker database  310  may be queried by the playback unit  220  to provide the playback pointer  235 . 
     In the embodiment of  FIG. 3  the storage unit  170  comprises a random access unit  320 . The random access unit  320  permits the storage unit  170  to access the content  205  in a randomly addressable manner. This may be achieved in a variety of ways depending upon the exact form taken by the storage unit  170 . For example, if the storage unit  170  is a hard disk drive or a flash memory device the random access unit  320  may make use of addressable sectors. The addressable sectors may further represent logical or physical sectors in the hard disk drive. Such logical sectors have addresses that are commonly referred to as Logical Block Addresses, or LBA&#39;s. When the storage unit  170  takes the form of an optical disk drive the addressable sectors may also represent logical or physical sectors in the accompanying optical medium. Whatever form taken by the storage unit  170 , the random access unit  320  may accept an address, such as the playback pointer  235  or an address corresponding to the playback pointer  235 , and move a read/write head within the storage unit  170  to a location indicated by the playback pointer  235  or the address corresponding to the playback pointer  235 . 
     In the embodiment of  FIG. 4  a recording unit  400  may be used to record a broadcast signal  405 . The broadcast signal  405  may be television signal received via a broadcast receiver  410 . The broadcast receiver  410  may be an antenna, a cable receiver, a satellite receiver, an Internet Protocol television (IPTV) receiver or the like. The broadcast signal  405  may also be a radio signal. The broadcast signal may, in fact, be any form of audio-visual signal. The recording unit  400  may demodulate or demultiplex content to be recorded  415 . The content to be recorded  415  may then be directly stored on the storage unit  170  or may also be analysed by a content analyser  420 . The content analyser  420  may analyse the content to be recorded  405  in real-time during recording or it may analyse the content to be recorded  405  offline at a time later than the actual recording time. The task of the content analyser  420  is to segment the content to be recorded  415  into various segments. Content segmentation markers  425 , which may be stored in the storage unit  170  or elsewhere, may identify the various segments. The content segmentation markers  425  may alternatively be embedded within the content to be recorded  415  as an auxiliary stream of information. The segments may be portions of the content  205  that may possess a semantic relationship to each other for the user  192 . For example, the segments may be a number of scenes all shot in the same location, or they may be a number of scenes comprising of alternating faces of characters in a film having a conversation. The exact semantic relationship is not important for the invention. 
     The content analyser  420  may use any known algorithm to identify the various segments within the content. For example, the content analyser  420  may analyse the compressed or decompressed pixel values to determine scene or shot changes. The content analyser  420  may also analyse the compressed or decompressed audio signal to determine explicit events or regions of high volume indicating exciting portions of the content to be recorded  415 . Content analysis algorithms are known which may detect sky, grass, faces, explosions etc. The exact algorithm used to analyse the content to be recorded  415  is not important. The content segmentation markers  425  may be communicated to the playback unit  220  such that the playback unit  220  may adjust the playback pointer  235  received from the attention loss storage unit  210  to coincide with one of the content segmentation markers  425 . This permits the resumption of playback to become context aware. For example, playback may be resumed from the start of a scene or shot rather than at an arbitrary point in time located within the content  205  where the user  192  lost attention. Playback may also be resumed a predetermined time before the point in time where the user  192  lost attention or a predetermined time before one of the content segmentation markers  425 . The predetermined time may be of the order of a few seconds to allow the user  192  to regain a context of the content  205 . The possibilities may be explained more thoroughly by referring to the embodiment of  FIG. 5  in which commercial blocks are detected. 
     The embodiment of  FIG. 5  shows a device  100  capable of analysing the content to be recorded  415  for commercial blocks, i.e. advertisements. In  FIG. 5  the content analyser  420  may be a commercial block detector  500  and the content segmentation markers  425  may be commercial block segmentation markers  505 . As is known the commercial block detector  500  may use a variety of low level features of the content to be recorded  415  to determine commercial blocks. For example, the appearance and disappearance of channel logo&#39;s may be detected. Shot cuts, cross fades or black frames may be detected. Changes in the audio level may be detected. Again any suitable commercial block detection algorithm may be used. The commercial block segmentation markers  505  may be used, by the playback unit  220 , to determine from which point the content  205  should be played. For example, if the playback unit  220  determines that the playback pointer  235  received from the attention loss storage unit  210  corresponds to a point in time during a commercial block then the playback unit  220  may decide to play the content  205  from the end of the commercial block, rather than the playback pointer  235 . In other words the playback pointer  235  may be modified by taking into account the commercial block segmentation markers  505 . This modified playback pointer may then be used to address the content  205  on the storage unit  170 . In such a situation the user  192  would view the content  205 , after supplying the user input  245 , from the end of the commercial block rather than from the exact point in time when the user  192  lost attention. This would, in most cases, be a far more preferable mode of operation for the user  192 . 
     In the embodiment of  FIG. 10  the content analyser  420  is positioned to analyse the content  205  during playback. The content analyser  420  would preferably run at real-time or even faster than real-time in such an embodiment. This embodiment would be useful when the content  205  arrives from a source that is not capable of providing the content segmentation markers  425 . The arrival may be from a network connection via the communication unit  130  or via a removable storage medium in cooperation with the storage unit  170 . The content analyser  420  may operate in a manner equivalent to that as described in the text relating to  FIG. 4 . The content analyser  420  of  FIG. 10  may also be a commercial block detector  500  and may operate as described in the text relating to  FIG. 5 . 
     In  FIG. 6  a flowchart is shown that illustrates a method for detecting attention loss by the user  192  during playback of the content  205 . The method of  FIG. 6  may be implemented in a control program running on the processor  120  of the device  100 . Initially at step  600 , the content  205  may be played. The content  205  may be played on the display  160  or rendered on a display on, or connected to, the remote device  165 . At step  610  the attention of the user  192  may be detected and as such attention loss may be detected at decision point step  620 . Steps  610  and  620  may be combined into a single step of detecting user attention loss. Step  620  may generate the point of attention loss indication  215 . The point of attention loss indication  215  may be used in step  630  to store a marker, such as the attention loss marker  255 . At this point the process of detecting and storing any points of attention loss by the user  192  is complete. 
       FIG. 7  illustrates a flowchart for resuming playback at a point of attention loss of the user  192 . The process of  FIG. 7  may also be implemented in a control program running on the processor  120  of the device  100 . The process of  FIG. 7  begins at step  700  by receiving a user request to resume playback of the content  205  from a point in time corresponding to a point of attention loss by the user  192 . Such a user request may be the user input  245 . At step  710  a check is performed upon whether or not the attention loss marker  255  exists. If not, playback is continued at step  740  without any modification of the point of playback. If the attention loss marker  255  does exist the playback pointer  235  is retrieved from the attention loss storage unit  210  or determined by the playback unit  220 . The playback unit  220  and the storage unit  170  cooperate such that the content  205  is played from a point in time corresponding to the loss of attention by the user  192 . The attention loss marker  255  may then be deleted in step  730 , before playback is resumed in step  740 . However, playback now proceeds from the modified point of playback, i.e. the point in time corresponding to the loss of attention by the user  192 . 
       FIG. 8   a  illustrates a flowchart for analysing content that may also be implemented in a control program running on the processor  120 . In step  800  the content  205  is stored. This may optionally be performed outside of the device  100 , in which case step  800  merely comprises a step of accessing the content  205 . This would be the case when the content  205  originates from another source. For example, when the content  205  is transferred using an optical disc medium. In step  810  the content  205  is analysed. The various methods of analysing the content  205  have been described in the text relating to the embodiments of  FIG. 4 ,  FIG. 5  and  FIG. 10 . In step  820  a decision point is reached wherein it is decided whether any segments have been detected within the content  205 . If not, then the remaining portions of the content  205  may be analysed. If segments are detected within the content  205  then one or more of the content segmentation markers  425  may be generated and stored in step  830 , before the remaining portions of the content  205  may be analysed. 
       FIG. 8   b  illustrates a process for resuming playback taking into account the point of attention loss of the user  192  and segments of content within the content  205 . Again the process of  FIG. 8   b  may be implemented in a control program running on the processor  120 . In  FIG. 8   b  the process begins at step  600  where the content  205  is being played or playing is initiated. At step  700  a user request is received. The user request indicates that the user  192  would wish to resume playback of the content  205  from a point in time corresponding to a point of attention loss by the user  192 . Such a user request may be the user input  245 . In step  840  the content segmentation markers  425  generated during analysis of the content  205  may be retrieved. In step  850  the attention loss marker  255  or the playback pointer  235  may be retrieved. In step  860  a modified playback pointer may be determined taking into account the content segmentation markers  425  and the playback pointer  235  or the attention loss marker  255 . This has been described in detail in the text describing the embodiments of  FIG. 4 ,  FIG. 5  and  FIG. 10 . The playback unit  220  may use the modified playback pointer to resume playback of the content  205  from a point in time more preferable to the user  192  than the actual point in time where attention of the user  192  was lost. 
     In  FIG. 8   c  a flowchart is shown that illustrates a method for determining whether a commercial block boundary or a point of attention loss of the user  192  should be stored as the attention loss marker  255 . The process of  FIG. 8   c  may also be implemented in a control program running on the processor  120 . The process of  FIG. 8   c  may be used when recording in real-time or when playing back content from a source that does not provide any information about commercial block boundaries. This is not however a limitation of the process of  FIG. 8   c  and information about commercial block boundaries may equally well be provided and used by the process of  FIG. 8   c . The process of  FIG. 8   c  begins at step  600  where the content  205  is played. At step  610  any points where the user  192  loses attention are detected. An especially useful method of detecting attention loss by the user  192  is by detecting a remote control command from the user  192 . Such a remote control command may be transmitted by the remote control  191  and may be a pause command. In this example, the content  205  may still be played, i.e. the pause command may not be honoured, but the point of attention loss indication  215  will be generated. In step  620  the process may diverge based upon whether the user  192  has lost attention or not. If not, the attention loss detection process of step  610  is repeated. If a point of attention loss is detected then at step  870  it is decided whether or not the content  205  currently being played is a commercial block or not. The step  870  may comprise the process of analysis of the content  205  or may comprise merely of the process of retrieving any previously stored commercial block segmentation markers  505 . If the point of attention loss is not within a commercial block then the process proceeds to step  630  where the point of attention loss indication  215  may be used to store a marker, such as the attention loss marker  255 . At this point the process of detecting and storing any points of attention loss by the user  192  is complete. The process may then be restarted. 
     If the point of attention loss is within a commercial block then the process proceeds to step  880  where a check is performed as to whether the user  192  is to resume viewing of the content  205  within the commercial block. If this is so then the process proceeds further by progressing to step  610  wherein any new points of attention loss by the user  192  may be detected. If the user  192  has not resumed viewing of the content  205  by the time of the end of the commercial block then in step  890  the end of the commercial block may be stored as the instant of attention loss rather than the actual point of attention loss by the user  192 . In other words, the attention loss marker  255  may be modified from referring to the point of attention loss indication  215  to refer to the end of the commercial block instead. This is a preferable point in time to resume viewing for the user  192  than actual point of attention loss. The playback pointer  235  may also be modified to refer to the end of the commercial block depending upon the exact implementation. Modification of the attention loss marker  255  and/or the playback pointer  235  may therefore be performed during the storing of the content  205 , i.e. when attention loss and commercial blocks have actually been detected, or during the resumption of the playback of the content subsequent to the reception of the user input  245 , i.e. after a request by the user  192  to resume playback from a point in time corresponding to the loss of attention by the user  192 . 
     There are many methods of operation possible. For example, when the attention loss is indicated by a pause command received from the user  192  and within a commercial block, the content  205  may actually be paused but the device  100  may continuously search for the end of the commercial block and automatically move the paused location to coincide with the end of a commercial block when detected. Another possibility is that the content is not paused, but the attention loss marker  255  is generated and stored and the attention loss marker indication  260  is generated to acknowledge to the user  192  that a resume point has been preserved. This resume point may again be modified when the point of attention loss coincides with a commercial block and the resume point may be moved to coincide with the end of the commercial block. 
     Since the attention loss marker  255  and/or the playback pointer  235  may have been modified to refer to the end of the commercial block the process of  FIG. 7  may be used unmodified to resume playback from a suitable point. 
       FIG. 9  shows a system comprising a first device  900  and a second device  940 . The second device  940  may be a traditional device for playing back the content  205 . The second device  940  may be a VHS tape player/recorder, a personal video recorder (PVR) such as a hard disk drive recorder, a DVD/optical disc recorder, etc. The second device  940  may comprise the playback unit  220  to play back the content  205  and a control unit  950  capable of receiving external commands for controlling the playback of the content  205 . The external commands may be normal remote control commands, such as a play command  925 , a pause command, a rewind command  915 , a forward command etc. and may be received from a remote control or another equivalent control. The external commands may also be received via a digital control interface  930 , such as an IEEE1394 interface, a SCART interface, etc. The remote control commands should, in this embodiment, at least be able to control the playback of the content  205  using the playback unit  220 . The second device  940  may present the content  205  on the display  160 . 
     The first device  900  may comprise the attention loss detector  200  and as described earlier may generate the point of attention loss indication  215 . The point of attention loss indication  215  may be communicated to the attention loss storage unit  210  of the first device  900 . The attention loss storage unit  210  may generate the attention loss marker  255  based upon the point of attention loss indication  215  and a first current time  965 . The first current time  965  may be the current time as generated by a timer unit  960  at the instant that the point of attention loss indication  215  is detected. The timer unit  960  may be a real time clock, a crystal time base or the like. The attention loss marker  255  may be generated by the attention loss marker generator  300  and stored in the attention loss marker database  310 . The first device  900  may further comprise a remote device control unit  910 . The remote device control unit  910  may receive the user input  245  via the user interface  190  and control the second device  940  such that the second device  940  plays and/or resumes playback of the content  205  from a point in time corresponding to the point of attention loss of the user  192 . The remote device control unit  910  may, upon receiving the user input  245 , acquire a second current time  975  from the timer unit  960 . The second current time  975  may be the current time as generated by the timer unit  960  at the instant that the user input  245  is received. This allows the duration to be determined between the first current time  965  and the second current time  975 . 
     Based upon this duration the remote device control unit  910  may control the second device  940  using predetermined knowledge of remote control commands, second device reaction times etc. The remote control commands, such as the rewind command  915  and the play command  925 , may be communicated from the first device  900  to the second device  940  via a remote control transmitter  920  of the first device  900  or via the digital control interface  930 , or via another suitable manner. The attention loss marker indication  260  may be produced in the first device  900  in response to the detection of at least one point of attention loss of the user  192 . The attention loss marker indication  260  may be as simple as a visual indication visible to the user  192 , such as a light emitting diode, LED, or may be as complicated as a video overlay mixed over the content  205 . In the latter case the content  205  may be diverted from the second device  940  through the first device  900  and then displayed upon the display  160 . 
     In summary the invention discloses methods and devices for playing audio-video content  205  during which loss of attention of the user  192  is detected. Any loss of attention of the user  192  generates the at least one attention loss marker  255 , or bookmark, that is stored in an attention loss storage unit  210 . The user  192  may revert playback to a point in time corresponding to the attention loss marker using the user interface unit  190 . By storing markers corresponding to points of attention loss by the user  192  and requiring explicit user input  245 , the attention loss detector may detect attention loss with an accuracy lower than would otherwise be the case. Optionally, storing of the attention loss markers may be made conditional upon a content analysis unit  420 , such as a commercial block detector  500 . An attention loss marker indication  260  may be made visible to the user to indicate that at least one attention loss marker has been detected. 
     It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be capable of designing many alternative embodiments without departing from the scope of the invention as defined by the appended claims. Furthermore, any of the embodiments described comprise implicit features, such as, an internal current supply, for example, a battery or an accumulator. In the claims, any reference signs placed in parentheses shall not be construed as limiting the claims. The word “comprising” and “comprises”, and the like, does not exclude the presence of elements or steps other than those listed in any claim or the specification as a whole. The singular reference of an element does not exclude the plural reference of such elements and vice-versa. In a device claim enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.