Abstract:
A content playback system includes a content server providing content, a plurality of content playback apparatuses playing back the content, and a portable terminal capable of communicating with each of the plurality of content playback apparatuses at least in accordance with a short-distance communication method. The content playback apparatuses each includes playback means for playing back the content, detecting means for detecting the portable terminal, transmitting means for transmitting to the portable terminal playback interruption information, and provision request means for receiving the playback interruption information and requesting the content server to provide the corresponding content. The portable terminal includes storing means for receiving and storing the playback interruption information from a first content playback apparatus, and playback request means for transmitting the playback interruption information to a second content playback apparatus and requesting the second content playback apparatus to play back the corresponding content.

Description:
CROSS REFERENCES TO RELATED APPLICATIONS  
       [0001]     The present invention contains subject matter related to Japanese Patent Application JP 2005-119706 filed in the Japanese Patent Office on Apr. 18, 2005, the entire contents of which are incorporated herein by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a content playback system including a plurality of content playback apparatuses, a content playback apparatus, and a content playback method in the content playback system, and more particularly, to a content playback system, a content playback apparatus, and a content playback method in which continuous playback of the same content can be performed between content playback apparatuses.  
         [0004]     2. Description of the Related Art  
         [0005]     Recently, in general, image signals and audio signals are handled as digital data. For example, playback apparatuses for music compact discs (CDs) and digital versatile discs (DVDs) on which video content is recorded are widely used in homes. In particular, instead of known recorders using videotapes, recorders capable of recording video content on DVDs or hard disk drives (HDDs) are becoming commonplace. In addition, playing back video and audio content using personal computers (PCs) and downloading such data via the Internet is becoming popular.  
         [0006]     In addition, commonly, even in homes, a local-area network (LAN) system is established by connecting a PC to a peripheral apparatus, and files and a printer are shared between the PC and the peripheral apparatus. Recently, connecting the above-mentioned recording/playback apparatuses for video and audio content to a home network is considered. For example, a system in which video and audio content that is collectively stored on a relatively high-capacity storage device, such as an HDD, can be distributed via the network to playback apparatuses installed in different rooms is considered.  
         [0007]     When such a distribution system for video and audio content via a home network is used, for example, a user who is viewing or listening to content using a player in a room may need to move to another room due to an unexpected visitor or the like. In such a case, the user stops a playback operation of the player that is installed in the room in which the user is staying and starts a player that is installed in the other room to which the user moves. In order to view or listen to the content from a position where the user stopped viewing or listening, the user needs to remember the name of the content and the final position where the user viewed or listened to so that such information can be set to the player by which the content is to be played back.  
         [0008]     In such circumstances, a data transmission apparatus that is capable of continuous viewing or listening of content by causing a server that distributes the content to store content management information indicating playback interruption when a client terminal, that is, a player in each room interrupts playback and by causing another client terminal to resume playback of the content in accordance with the stored content management information is described, for example, in Japanese Unexamined Patent Application Publication No. 2004-102415 (paragraphs [0037] to [0049] and FIG. 2).  
       SUMMARY OF THE INVENTION  
       [0009]     However, even in a system including the data transmission apparatus disclosed in Japanese Unexamined Patent Application Publication No. 2004-102415, for example, when an input operation for a client terminal to interrupt playback of content is complicated, when an input operation for another client terminal to resume playback of the same content is complicated, or when an operation procedure or an operation key is different depending on the client terminal, a user feels confused, and the feature of continuous playback may not be used.  
         [0010]     It is desirable to provide a content playback system in which playback of content that is played back by an apparatus can be continued by another apparatus with a simple user operation.  
         [0011]     It is also desirable to provide a content playback apparatus in which playback of content that is played back by a content playback apparatus can be continued by another content playback apparatus with a simple user operation.  
         [0012]     It is also desirable to provide a content playback method in which playback of content that is played back by an apparatus can be continued by another apparatus with a simple user operation.  
         [0013]     A content playback system according to an embodiment of the present invention includes a content server that provides content, a plurality of content playback apparatuses that plays back the content provided from the content server, and a portable terminal that is capable of communicating with each of the plurality of content playback apparatuses at least in accordance with a short-distance communication method. Each of the plurality of content playback apparatuses includes playback means for playing back the content provided from the content server, detecting means for detecting the portable terminal in accordance with the short-distance communication method, transmitting means for transmitting to the portable terminal detected by the detecting means playback interruption information including content identification information for identifying the content when playback of the content by the playback means is interrupted, and provision request means for receiving the playback interruption information from the portable terminal detected by the detecting means and for requesting the content server to provide the corresponding content in accordance with the playback interruption information. The portable terminal includes storing means for receiving and storing the playback interruption information from a first content playback apparatus that detects the portable terminal by the detecting means, and playback request means for transmitting the playback interruption information stored in the storing means to a second content playback apparatus that detects the portable terminal by the detecting means after the portable terminal receives the playback interruption information and for requesting the second content playback apparatus to play back the corresponding content.  
         [0014]     In such a content playback system, when, in a first content playback apparatus, playback of content by playback means is interrupted, detecting means of the first content playback apparatus detects a portable terminal in accordance with a short-distance communication method. Transmitting means transmits to the detected portable terminal playback interruption information including content identification information for identifying the content, and the playback interruption information is stored in storing means of the portable terminal.  
         [0015]     Then, when detecting means of a second content playback apparatus detects the portable terminal, playback request means of the portable terminal transmits to the second content playback apparatus the playback interruption information stored in the storing means, and requests the second content playback apparatus to play back the corresponding content. Provision request means of the second content playback apparatus receives the playback interruption information from the portable terminal, and requests a content server to provide the corresponding content in accordance with the playback interruption information. Thus, the interrupted content is provided to the second content playback apparatus, and played back by playback means.  
         [0016]     According to the above-described content playback system, a first content playback apparatus by which playback of content is interrupted transmits playback interruption information including content identification information on the interrupted content to a portable terminal detected in a short-distance communication method, and the portable terminal stores the playback interruption information. Then, when a second content playback apparatus detects the portable terminal, the playback interruption information stored in the portable terminal is transmitted to the second content playback apparatus. The second content playback apparatus that receives the playback interruption information requests, in accordance with the playback interruption information, a content server to provide the content whose playback is interrupted, and plays back the content. As described above, by causing each of the content playback apparatuses to detect the portable terminal in accordance with the short-distance communication method, a user does not need to perform a setting operation, for example, for selecting content to be played back. Thus, playback of the same content can be continued by the second content playback apparatus with a simple operation.  
         [0017]     A content playback system according to another embodiment of the present invention includes a plurality of content playback apparatuses that plays back content, and a portable terminal that is capable of communicating with each of the plurality of content playback apparatuses at least in accordance with a short-distance communication method. Each of the plurality of content playback apparatuses includes playback means for playing back the content, detecting means for detecting the portable terminal in accordance with the short-distance communication method, storing means for receiving from the portable terminal detected by the detecting means terminal identification information for identifying the portable terminal and for storing, in association with the received terminal identification information, playback interruption information including content identification information for identifying content whose playback is interrupted when playback of the content by the playback means is interrupted, transmission request means for multicasting the terminal identification information to other content playback apparatuses and for requesting transmission of playback interruption information corresponding to the terminal identification information when the terminal identification information of the portable terminal and a playback request for the content are received from the portable terminal detected by the detecting means, playback interruption information transmitting means for reading the playback interruption information corresponding to the received terminal identification information from the storing means and for transmitting the read playback interruption information when a transmission request for the playback interruption information is received from another content playback apparatus, and playback control means for acquiring the corresponding content in accordance with the playback interruption information and for causing the playback means to play back the acquired content when the playback interruption information transmitted in response to the transmission request by the transmission request means is received. The portable terminal includes terminal identification information transmitting means for transmitting the terminal identification information of the portable terminal to a first content playback apparatus that detects the portable terminal by the detecting means, and playback request means for transmitting the terminal identification information of the portable terminal to a second content playback apparatus and for requesting the second content playback apparatus to play back the corresponding content when the portable terminal is detected by the detecting means of the second content playback apparatus after the terminal identification information transmitting means transmits the terminal identification information.  
         [0018]     In such a content playback system, when playback of content by playback means in a first content playback apparatus is interrupted, detecting means of the first content playback apparatus detects a portable terminal in accordance with a short-distance communication method, and terminal identification information transmitting means of the portable terminal transmits to the first content playback apparatus terminal identification information of the portable terminal. Storing means of the first content playback apparatus receives the terminal identification information from the portable terminal, and stores, in association with the received terminal identification information, playback interruption information including content identification information for identifying the content whose playback is interrupted.  
         [0019]     Then, when detecting means of a second content playback apparatus detects the portable terminal, playback request means of the portable terminal transmits to the second content playback apparatus the terminal identification information of the portable terminal and requests the second content playback apparatus to play back the corresponding content. Transmission request means of the second content playback apparatus that receives the playback request multicasts the received terminal identification information to other content playback apparatuses, and requests transmission of playback interruption information corresponding to the terminal identification information. When receiving the transmission request for the playback interruption information from the second content playback apparatus, playback interruption transmitting means of the first content playback apparatus reads the playback interruption information corresponding to the received terminal identification information from the storing means and transmits the read playback interruption information. Playback control means of the second content playback apparatus acquires the corresponding content in accordance with the transmitted playback interruption information, and causes the playback means to play back the acquired content.  
         [0020]     According to the content playback system described above, a first content playback apparatus by which playback of content is interrupted receives terminal identification information from a portable terminal detected in accordance with a short-distance communication method, and stores, in association with the terminal identification information, playback interruption information including content identification information on the interrupted content. Then, when a second content playback apparatus detects the portable terminal, the terminal identification information of the portable terminal is transmitted to the second content playback apparatus. The second content playback apparatus that receives the terminal identification information acquires playback interruption information by querying other content playback apparatuses as to the terminal identification information. The second content playback apparatus plays back the corresponding content in accordance with the acquired playback interruption information. Thus, playback of the interrupted content is continued. As described above, by causing each of the content playback apparatuses to detect the portable terminal in accordance with the short-distance communication method, the user does not need to perform a setting operation, for example, for selecting content to be played back. Thus, playback of the same content can be continued by the second content playback apparatus with a simple operation. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0021]      FIG. 1  schematically shows an example of the structure of an AV server system according to an embodiment of the present invention;  
         [0022]      FIG. 2  is a block diagram showing an example of the internal structure of an HDD recorder;  
         [0023]      FIG. 3  is a block diagram showing an example of the internal structure of a network AV player;  
         [0024]      FIG. 4  is a block diagram showing an example of the internal structure of a portable terminal;  
         [0025]      FIG. 5  schematically shows a first example of a continuous playback operation;  
         [0026]      FIG. 6  shows a processing sequence performed when playback of content is interrupted in the first example of the continuous playback operation;  
         [0027]      FIG. 7  shows a processing sequence performed when another playback apparatus starts continuous playback of the content in the first example of the continuous playback operation;  
         [0028]      FIG. 8  schematically shows a second example of a continuous playback operation;  
         [0029]      FIG. 9  shows a processing sequence performed when playback of content is interrupted in the second example of the continuous playback operation; and  
         [0030]      FIG. 10  shows a processing sequence performed when another playback apparatus starts continuous playback of the content in the second example of the continuous playback operation. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0031]     Embodiments of the present invention will be described with reference to the drawings. An audio visual (AV) server system according to an embodiment of the present invention capable of distributing video and audio content from an AV server to a client terminal in each room using a LAN system installed at home will be described as an example.  
         [0032]      FIG. 1  shows an example of the structure of the AV server system according to this embodiment. In the AV server system shown in  FIG. 1 , an HDD recorder  10  having a function as an AV server, network AV players  20   a  and  20   b  functioning as client terminals, and a wireless LAN access point  30  are connected to each other via a LAN  100 . A portable terminal  40  is capable of performing communication via the LAN  100  by being wirelessly connected to the LAN  100  via the wireless LAN access point  30 .  
         [0033]     The HDD recorder  10  has a function to convert content received, for example, via broadcast radio waves, into digital data, to store the digital data onto an HDD contained in the HDD recorder  10 , and to play back the content. The HDD recorder  10  also has a function to distribute the stored content via the LAN  100  to the network AV players  20   a  and  20   b  by streaming. Each of the network AV players  20   a  and  20   b  has a function to play back, in real time, the content distributed from the HDD recorder  10  via the LAN  100 .  
         [0034]     The wireless LAN access point  30  is connected to the LAN  100  via a wired cable. Since a wireless LAN remote station (in this example, the portable terminal  40 ) is wirelessly connected to this circuit, the wireless LAN access point  30  functions as a master station. In addition, the wireless LAN access point  30  may have various security functions necessary for radio transmission and reception.  
         [0035]     The portable terminal  40  functions as a remote station to be connected to the LAN  100  via the wireless LAN access point  30 . In this embodiment, the portable terminal  40  functions as a conversation terminal of an Internet protocol (IP) telephone service based on a voice over Internet protocol (VoIP) due to connection with the wireless LAN access point  30 . In addition; the portable terminal  40  is provided with a communication interface for short-distance wireless communication. Thus, the portable terminal  40  is capable of performing non-contact communication with the HDD recorder  10  and the network AV players  20   a  and  20   b  via short-distance wireless communication.  
         [0036]     In the AV server system, for example, the HDD recorder  10 , the network AV player  20   a , and the network AV player  20   b  are installed in different rooms, and content stored in an AV player can be viewed or listened to in any room in which the HDD recorder  10 , the network AV player  20   a , or the network AV player  20   b  is installed. In addition, the portable terminal  40  is capable of communicating with the HDD recorder  10  and the network AV players  20   a  and  20   b  via short-distance wireless communication. When the HDD recorder  10 , the network AV player  20   a , or the network AV player  20   b  executes an application for content playback processing (recording processing, channel selection processing, and the like may be included for the HDD recorder  10 ), the HDD recorder  10 , the network AV player  20   a , or the network AV player  20   b  detects the portable terminal  40  via short-distance wireless communication. When the portable terminal  40  is authenticated, the HDD recorder  10 , the network AV player  20   a , or the network AV player  20   b  is capable of transmitting and receiving information to and from the portable terminal  40  via short-distance wireless communication. Alternatively, then, the HDD recorder  10 , the network AV player  20   a , or the network AV player  20   b  is capable of receiving, for example, a control command from the portable terminal  40  by being connected to the portable terminal  40  via the LAN  100 , and performing an operation.  
         [0037]     In this embodiment, in particular, when a playback operation of one of playback apparatuses, that is, one of the HDD recorder  10 , the network AV player  20   a , and the network AV player  20   b  is interrupted during the playback of content, the use of the portable terminal  40  allows playback of the content to be continued by another playback apparatus with a simple operation. Hereinafter, such an operation will be referred to as a “continuous playback operation” and the portable terminal  40  functions as an “electronic bookmark terminal” that holds identification information of content whose playback is interrupted and information on the interrupted position (or information necessary for acquiring such information when playback resumes).  
         [0038]      FIG. 2  is a block diagram showing an example of the internal structure of the HDD recorder  10 .  
         [0039]     Referring to  FIG. 2 , the HDD recorder  10  includes a television (TV) tuner  11 , a content recording/playback processor  12 , a content distribution processor  13 , an HDD  14 , a connection controller  15 , a LAN interface  16 , a short-distance wireless interface  17 , and an input unit  18 .  
         [0040]     The TV tuner  11  receives broadcast radio waves, and selects and demodulates a signal in a broadcast channel designated via the recording/playback processor  12 . The TV tuner  11  converts the demodulated signal into video and audio digital data, and supplies the video and audio digital data to the recording/playback processor  12 .  
         [0041]     The recording/playback processor  12  receives content via the TV tuner  11  and performs an operation for recording and playing back the content onto and from the HDD  14  in accordance with a control signal input via the input unit  18  or the connection controller  15 .  
         [0042]     When content is recorded, content received and converted into digital data by the TV tuner  11  is input to the recording/playback processor  12 . The recording/playback processor  12  encodes the content in accordance with a predetermined format, such as moving picture experts group (MPEG)  2 , and records the encoded content onto the HDD  14  as stream data. For example, content input from an external input terminal or content received via the LAN interface  16  may be recorded onto the HDD  14 .  
         [0043]     When content is played back, the recording/playback processor  12  decodes stream data read from the HDD  14 , and converts the decoded data into analog data. The recording/playback processor  12  outputs the analog data to an external monitor, an audio amplifier, or the like via an output terminal. Thus, a user is able to view or listen to the content.  
         [0044]     The distribution processor  13  performs server processing of distributing content within the HDD  14  to another playback apparatus connected to the LAN  100 . More specifically, the distribution processor  13  receives designation of content and a distribution request for the content from the network AV player  20   a  or  20   b  via the LAN interface  16 , reads stream data of the corresponding content from the HDD  14 , and sequentially transmits, via the LAN interface  16 , the read stream data to the network AV player  20   a  or  20   b , which is a request source.  
         [0045]     The connection controller  15  executes various applications using the portable terminal  40  detected by the short-distance wireless interface  17 . For example, the connection controller  15  controls an operation of the recording/playback processor  12  for recording and playing back content and an operation of the distribution processor  13  in accordance with a control command received from the portable terminal  40  via the short-distance wireless interface  17  or the LAN interface  16 . In this case, the portable terminal  40  is capable of functioning as a remote controller for the HDD recorder  10 . In this embodiment, in particular, the connection controller  15  performs processing for realizing a continuous playback operation between the above-mentioned playback apparatuses. In addition, the connection controller  15  performs authentication processing and apparatus management processing for the portable terminal  40  detected by the short-distance wireless interface  17 .  
         [0046]     The LAN interface  16  controls signal transmission and reception via the LAN  100 . The short-distance wireless interface  17  is an interface used for communicating with the portable terminal  40  via short-distance wireless communication. In this embodiment, an electromagnetic induction communication method using a wireless IC chip is adopted as a short-distance wireless communication method. The short-distance wireless interface  17  includes a reader/writer that performs power supply and signal transmission and reception to and from the wireless IC chip provided in the portable terminal  40 . The input unit  18  includes an input key and the like. The input unit  18  outputs to the connection controller  15  or the recording/playback processor  12  a control signal based on an input user operation.  
         [0047]      FIG. 3  is a block diagram showing an example of the internal structure of the network AV player  20   a  or  20   b.    
         [0048]     The network AV players  20   a  and  20   b  have the same structure. Referring to  FIG. 3 , each of the network AV players  20   a  and  20   b  includes a content playback processor  21 , a connection controller  22 , a LAN interface  23 , a short-distance wireless interface  24 , and an input unit  25 .  
         [0049]     The playback processor  21  performs playback processing for content distributed from the HDD recorder  10 . More specifically, the playback processor  21  receives distributed stream data of content via the LAN interface  23 , decodes the stream data in accordance with a predetermined format, converts the decoded data into an analog signal, and outputs the analog signal to an external monitor, an audio amplifier, or the like via an output terminal.  
         [0050]     The connection controller  22  is a functional block corresponding to the connection controller  15  of the HDD recorder  10 . The connection controller  22  performs processing of various applications using the portable terminal  40  detected by the short-distance wireless interface  24 , such as an operation of the playback processor  21  for playing back content and a continuous playback operation between playback apparatuses, and processing for authentication and apparatus management for the portable terminal  40 .  
         [0051]     The LAN interface  23  controls signal transmission and reception via the LAN  100 . The short-distance wireless interface  24  is an interface used for communicating with the portable terminal  40  via short-distance wireless communication. In this embodiment, similarly to the HDD recorder  10 , the short-distance wireless interface  24  performs communication based on the electromagnetic induction communication method using a wireless IC chip, and includes a reader/writer that performs power supply and signal transmission and reception to and from the wireless IC chip provided in the portable terminal  40 . The input unit  25  includes an input key and the like. The input unit  25  outputs to the connection controller  22  or the playback processor  21  a control signal based on an input user operation.  
         [0052]     The HDD recorder  10 , the network AV player  20   a , and the network AV player  20   b  each have a function to execute various applications using the portable terminal  40 . In a case where the portable terminal  40  is usable, for example, when the portable terminal  40  approaches the HDD recorder  10 , the short-distance wireless interface  17  detects the portable terminal  40  and reports to the connection controller  15  a detection result. The connection controller  15  performs authentication with the portable terminal  40  via the short-distance wireless interface  17 . If authentication is successfully achieved, the HDD recorder  10  receives a control signal from the portable terminal  40  via the short-distance wireless interface  17  or the LAN interface  16 . Thus, the HDD recorder  10  is capable of controlling predetermined processing, such as a content recording operation and a continuous playback operation.  
         [0053]     Such a function may be prepared as an apparatus independent of the HDD recorder  10 , the network AV player  20   a , or the network AV player  20   b . In this case, for example, the HDD recorder  10 , the network AV player  20   a , and the network AV player  20   b  each include an interface for the LAN  100  and performs transmission and reception of video and audio data by communicating with another apparatus on the network. In addition, the function of the connection controller  15  or  22  and the function of the short-distance wireless interface  17  or  24  are prepared as an external expansion device. By connecting such an expansion device to the HDD recorder  10 , the network AV players  20   a , or the network AV player  20   b  via a communication medium, such as a universal serial bus (USB), communication via the LAN  100  by the HDD recorder  10 , the network AV player  20   a , or the network AV player  20   b  is performed through the expansion device. Thus, each of the HDD recorder  10 , the network AV player  20   a , and the network AV player  20   b  is capable of using the portable terminal  40  as a control terminal.  
         [0054]      FIG. 4  is a block diagram showing an example of the internal structure of the portable terminal  40 .  
         [0055]     Referring to  FIG. 4 , the portable terminal  40  includes a controller  41 , a wireless LAN interface  42 , a short-distance wireless interface  43 , an audio processor  44 , a display processor  45 , a microphone  44   a , a speaker  44   b , a monitor  45   a , and an input unit  46 .  
         [0056]     The controller  41  includes a central processing unit (CPU), a memory in which programs and various data executed by the CPU are stored, and the like. The controller  41  generally controls each block within the portable terminal  40 . More specifically, the controller  41  performs conversation processing over IP telephone via the wireless LAN interface  42 , in other words, outputs to the wireless LAN interface  42  an audio signal received from the audio processor  44  and outputs to the audio processor  44  an audio signal received via the wireless LAN interface  42 . In addition, the controller  41  performs processing of transmitting and receiving various data, such as address information and a control command, via the wireless LAN interface  42  or the short-distance wireless interface  43 , processing of generating display information for the monitor  45   a  and outputting the display information to the display processor  45 , and the like.  
         [0057]     The wireless LAN interface  42  is an interface circuit for connecting the portable terminal  40  to the LAN  100  via the wireless LAN access point  30 . The wireless LAN interface  42  demodulates a signal received from the wireless LAN access point  30 , and supplies the demodulated signal to the controller  41 . The wireless LAN interface  42  also modulates a signal output from the controller  41 , and wirelessly transmits the modulated signal to the wireless LAN access point  30 .  
         [0058]     The short-distance wireless interface  43  includes a wireless IC chip for communication based on the electromagnetic induction communication method, an antenna used for signal transmission and reception, a semiconductor memory that stores transmission and reception information, and the like. The short-distance wireless interface  43  operates by generating electric power in accordance with radio waves received from the reader/writer (the short-distance wireless interface  17  or  24 ) provided in the HDD recorder  10 , the network AV player  20   a , or the network AV player  20   b , and transmits and receives signals to and from the HDD recorder  10 , the network AV player  20   a , or the network AV player  20   b.    
         [0059]     The audio processor  44  converts an audio signal received from the microphone  44   a  into a digital signal, encodes the digital signal into a predetermined format, and outputs the encoded signal to the controller  41 . In addition, the audio processor  44  decodes an audio signal received from the controller  41  into an analog signal, and outputs the analog signal to the speaker  44   b  to be played back. The display processor  45  generates a video signal in accordance with display information generated by the controller  41 , and outputs the video signal to the monitor  45   a , which is, for example, a liquid crystal display (LCD), to be displayed. The input unit  46  includes an input key and the like. The input unit  46  outputs to the controller  41  a control signal based on an input user operation.  
         [0060]     As described above, the portable terminal  40  functions as an electronic bookmark terminal used by a user to change a playback apparatus that plays back content. This function may be installed in a portable information processor, such as a personal digital assistant (PDA) or a remote controller for each playback apparatus, instead of the telephone terminal described in this embodiment. However, when the portable terminal  40  is used as an electronic bookmark terminal, a user carries the portable terminal  40  with him or her when moving between rooms. Thus, it is preferable that such a function be installed in an apparatus owned by each individual, such as a telephone terminal, or an apparatus that each user normally carries with him or her.  
         [0061]     Although the electromagnetic induction communication method is adopted as a short-distance wireless communication method for direct communication with each of the HDD recorder  10 , the network AV player  20   a , and the network AV player  20   b  in this embodiment, for example, Bluetooth™ or infrared-ray communication may be used. In addition, instead of wireless communication, a communication method using a relatively short wired-cable, such as a USB or IEEE (institute of electrical and electronic engineers) 1394, may be used.  
         [0062]     An operation performed by such an AV server system, for example, when a continuous playback operation is performed between the HDD recorder  10  and the network AV player  20   a  will now be described.  
         [0063]      FIG. 5  schematically shows a first example of a continuous playback operation.  
         [0064]     For example, in the HDD recorder  10 , content within the HDD  14  is being played back. When playback of the content needs to be interrupted, a user brings the portable terminal  40  closer to the HDD recorder  10 , so that the HDD recorder  10  can detect the portable terminal  40  via short-distance communication (S 11 ). When the HDD recorder  10  detects the portable terminal  40  via the short-distance wireless interface  17 , the HDD recorder  10  performs authentication processing with the portable terminal  40 . Then, the HDD recorder  10  interrupts playback of the content, generates playback interruption information indicating information on the playback interruption, and transmits the playback interruption information to the portable terminal  40  (step S 12 ). Here, the playback interruption information may be transmitted via short-distance wireless communication or via the LAN  100  using the wireless LAN access point  30 .  
         [0065]     The playback interruption information includes, for example, content identification information (for example, the title name or ID of a CD album, a track number, or directory information of a corresponding file within the HDD recorder  10 ) for identifying the content whose playback is interrupted, interrupted position information (for example, elapsed time information of a track) indicating a playback position of the content when playback is interrupted, the IP address of an apparatus from which the content is distributed (in this case, the HDD recorder  10 ).  
         [0066]     After the portable terminal  40  receives and stores the transmitted playback interruption information, the user carries the portable terminal  40  with him or her to another room. Then, the user brings the portable terminal  40  closer to the network AV player  20   a , which is installed in the room to which the user moves, so that the network AV player  20   a  can detect the portable terminal  40  (step S 13 ). When the network AV player  20   a  detects the portable terminal  40  via the short-distance wireless interface  24 , the network AV player  20   a  performs authentication processing with the portable terminal  40 . When authentication is successfully achieved, the portable terminal  40  transmits the playback interruption information to the network AV player  20   a , and requests the network AV player  20   a  to continue playback of the content whose playback is interrupted (step S 14 ). Here, the playback interruption information and the playback request may be transmitted via short-distance wireless communication or via the LAN  100  using the wireless LAN access point  30 .  
         [0067]     The network AV player  20   a  requests, in accordance with the received playback interruption information, the HDD recorder  10 , which is a distribution source, to distribute the content whose playback is interrupted. Here, the network AV player  20   a  can request the HDD recorder  10  to start distribution from a particular position in accordance with the interrupted position information. In response to the distribution request, the HDD recorder  10  distributes the corresponding content to the network AV player  20   a  by streaming, and the network AV player  20   a  starts to play back the distributed content (step S 15 ).  
         [0068]     According to the above-described procedure, by bringing the portable terminal  40  closer to each of an apparatus by which playback is interrupted and the next apparatus by which playback is to be continued, continuous playback of the same content can be realized without directly operating each apparatus. In addition, when interrupted position information of the content is included in playback interruption information, the next apparatus is capable of starting playback of the content from the position where playback is interrupted. Thus, the user is able to perform such a continuous playback operation by performing a simple operation using the portable terminal  40 .  
         [0069]     The above-described operation will be described more in detail with reference to  FIGS. 6 and 7 .  
         [0070]      FIG. 6  shows a processing sequence performed when playback of content is interrupted.  
         [0071]     Referring to  FIG. 6 , in the initial state, in the HDD recorder  10 , predetermined content stored in the HDD  14  is being played back (step S 101 ). When the user brings the portable terminal  40  closer to the HDD recorder  10 , the HDD recorder  10  detects the portable terminal  40  via the short-distance wireless interface  17  (step S 102 ). Necessary information is transferred between the HDD recorder  10  and the HDD  14  via short-distance wireless communication, and authentication processing is performed (steps S 103  and S 104 ). When authentication is successfully achieved, communication via the LAN  100  can be performed between the portable terminal  40  and the HDD recorder  10  using IP addresses exchanged in the authentication processing.  
         [0072]     In the authentication processing, for example, the HDD recorder  10  receives in advance registration of the portable terminal  40  that is capable of functioning as an electronic bookmark terminal. Alternatively, such registration may be performed for another management server on the LAN  100  so that authentication can be received by accessing the management server in accordance with authentication information when the HDD recorder  10  detects the portable terminal  40 .  
         [0073]     When the HDD recorder  10  successfully achieves authentication by the processing of the connection controller  15 , the connection controller  15  requests the recording/playback processor  12  to stop playback, and an operation for playing back the content is interrupted (step S 105 ). Here, for example, playback may be automatically interrupted after authentication is successfully achieved. However, for example, after authentication is successfully achieved, a request for stopping playback may be transmitted via the LAN  100  in accordance with a user operation input to the portable terminal  40 , and playback may be interrupted in accordance with the request for stopping playback. Alternatively, after playback is stopped by a direct user operation for the HDD recorder  10 , when the portable terminal  40  is detected and authenticated, processing in step S 106  and the subsequent processing may be performed.  
         [0074]     When playback is stopped, the connection controller  15  receives from the recording/playback processor  12  content identification information and interrupted position information of content whose playback is interrupted, generates playback interruption information in accordance with the received content identification information and interrupted position information, and transmits the generated playback interruption information to the portable terminal  40  via the LAN interface  16  (step S 106 ). The portable terminal  40  receives the playback interruption information via the LAN  100 , and stores the playback interruption information, for example, into a random-access memory (RAM) within the controller  41 . Then, the portable terminal  40  enters a standby state for causing another playback apparatus to continue playback. For example, the portable terminal  40  reports to the user, by display on the monitor  45   a , that continuous playback can be performed (step S 107 ).  
         [0075]      FIG. 7  shows a processing sequence performed when another playback apparatus (in this case, the network AV player  20   a ) starts continuous playback of the content.  
         [0076]     After the processing sequence shown in  FIG. 6  is completed, the user carries the portable terminal  40  with him or her to the room where the network AV player  20   a  is installed, and brings the portable terminal  40  closer to the network AV player  20   a . Then, the network AV player  20   a  detects the portable terminal  40  via the short-distance wireless interface  24  (step S 201 ). Authentication processing similar to the processing in steps S 103  and S 104  shown in  FIG. 6  is performed between the network AV player  20   a  and the portable terminal  40  (steps S 202  and S 203 ).  
         [0077]     When authentication is successfully achieved, the network AV player  20   a  and the portable terminal  40  are capable of communicating with each other via the LAN  100 . The portable terminal  40  transmits the stored playback interruption information to the network AV player  20   a  via the wireless LAN interface  42  (step S 204 ). The network AV player  20   a  transmits, by the processing of the connection controller  22 , to the HDD recorder  10  via the LAN  100  a distribution request in which the content whose playback is to be continued and a playback start position of the content are designated in accordance with the received playback interruption information (step S 205 ). Here, for example, after the user performs a distribution request operation for the portable terminal  40 , the network AV player  20   a  that receives the request via the LAN  100  may request distribution. However, when the network AV player  20   a  holds the playback interruption information, if distribution can be automatically requested after authentication is successfully achieved, a user operation can be simplified and user-friendliness can be further improved.  
         [0078]     When receiving the distribution request, the HDD recorder  10  reads the corresponding content from the HDD  14  by the processing of the distribution processor  13 , and starts streaming distribution from the designated position to the network AV player  20   a  (step S 206 ). The network AV player  20   a  sequentially plays back the received content (step S 207 ). Thus, the network AV player  20   a  is capable of performing continuous playback of the same content from the position where playback is interrupted by the HDD recorder  10 .  
         [0079]     In accordance with the processing described above, the user does not need to perform an operation for setting information on content whose playback is interrupted and an interrupted position of the content. By a simple and intuitive operation for bringing the portable terminal  40  closer to the apparatus by which playback is interrupted and to the apparatus by which playback is to be continued in that order, playback of the content interrupted by the previous apparatus can be continued by the subsequent apparatus.  
         [0080]     Although a case where a playback operation is shifted from the HDD recorder  10  to the network AV player  20   a  is described in the first example of the continuous playback operation, this operation example may also be applicable to a case where the playback operation is shifted from the network AV player  20   a  to the HDD recorder  10 . In this case, playback interruption information generated in the network AV player  20   a  is stored into the portable terminal  40 . The HDD recorder  10  by which playback is to be continued reads Corresponding content from the HDD  14  contained in the HDD recorder  10  in accordance with the playback interruption information, and plays back the read content by the processing of the recording/playback processor  12 . In addition, this operation example can also be applied to a case where the playback operation is shifted between the network AV player  20   a  and the network AV player  20   b.    
         [0081]      FIG. 8  schematically shows a second example of the continuous playback operation.  
         [0082]     In the second example of the continuous playback operation, the portable terminal  40  stores terminal identification information for identifying itself. The terminal identification information is, for example, an IP address or a media access control (MAC) address assigned to the portable terminal  40 . Such terminal identification information is stored, for example, in a memory within the short-distance wireless interface  43 . Alternatively, such terminal identification information may be temporary information, such as key information or time information, generated when the information is transmitted.  
         [0083]     In a state in which content within the HDD  14  of the HDD recorder  10  is being played back, the user brings the portable terminal  40  closer to the HDD recorder  10 , so that the HDD recorder  10  can detect the portable terminal  40  via short-distance communication (step S 21 ). After the portable terminal  40  is detected, the portable terminal  40  transmits terminal identification information on the portable terminal  40  via short-distance wireless communication or via the LAN  100  (step S 22 ). The HDD recorder  10  generates playback interruption information indicating information on playback interruption, and stores, for example, into the HDD  14  the playback interruption information in association with the terminal identification information received from the portable terminal  40  (step S 23 ).  
         [0084]     Then, the user carries the portable terminal  40  with him or her to the room where the network AV player  20   a  is installed. The user brings the portable terminal  40  closer to the network AV player  20   a , so that the network AV player  20   a  can detect the portable terminal  40  via short-distance wireless communication (step S 24 ). After the network AV player  20   a  detects the portable terminal  40 , the portable terminal  40  transmits the terminal identification information of the portable terminal  40  to the network AV player  20   a  via short-distance wireless communication or via the LAN  100 , and requests the network AV player  20   a  to continue playback of the content whose playback is interrupted (step S 25 ).  
         [0085]     The network AV player  20   a  transmits the received terminal identification information to each apparatus on the LAN  100 . In response to this, the HDD recorder  10  transmits to the network AV player  20   a  the playback interruption information corresponding to the received terminal identification information (step S 26 ). In accordance with the received playback interruption information, the network AV player  20   a  requests the HDD recorder  10  to distribute the content. In response to the request, the HDD recorder  10  starts distributing the corresponding content by streaming, and the network AV player  20   a  plays back the distributed content (step S 27 ).  
         [0086]     According to the above-described procedure, as in the first example of the continuous playback operation, by bringing the portable terminal  40  closer to a corresponding playback apparatus when playback is interrupted and to a corresponding playback apparatus when playback is resumed, continuous playback of the same content can be realized without directly operating each apparatus, and playback can be started from the position where playback is interrupted. In addition, since information that is uniquely assigned in advance to the portable terminal  40  as terminal identification information, such as a MAC address, is used, a memory that stores such information does not need to be rewritable. Thus, the hardware structure of the portable terminal  40  can be simplified, and the production cost can be reduced.  
         [0087]     The above-described operation will be described more in detail with reference to  FIGS. 9 and 10 .  
         [0088]      FIG. 9  shows a processing sequence performed when playback of the content is interrupted.  
         [0089]     In a state in which predetermined content stored in the HDD  14  of the HDD recorder  10  is being played back (step S 301 ), the user brings the portable terminal  40  closer to the HDD recorder  10 , so that the HDD recorder  10  detects the portable terminal  40  via the short-distance wireless interface  17  (step S 302 ). Authentication processing is performed between the HDD recorder  10  and the portable terminal  40  (steps S 303  and S 304 ). When authentication is successfully achieved, the portable terminal  40  transmits terminal identification information to the HDD recorder  10  (step S 305 ).  
         [0090]     When receiving the terminal identification information, the HDD recorder  10  interrupts playback of the content (step S 306 ). The HDD recorder  10  generates playback interruption information on the interrupted content, and stores into the HDD  14  or the like the generated playback interruption information in association with the terminal identification information received from the portable terminal  40  (step S 307 ). Then, the HDD recorder  10  reports to the portable terminal  40  that playback interruption processing is completed (step S 308 ). The portable terminal  40  enters a standby state for causing another playback apparatus to continue playback. For example, the portable terminal  40  reports to the user, by display on the monitor  45   a , that continuous playback can be performed (step S 309 ).  
         [0091]     In the processing in steps S 303  to S 305 , as in the first example of the continuous playback operation shown in  FIG. 6 , after the portable terminal  40  and the HDD recorder  10  enter a state in which communication between the portable terminal  40  and HDD recorder  10  via the LAN  100  can be performed by successful authentication, the terminal identification information may be transferred by communication via the LAN  100 . In this case, for example, the portable terminal  40  may automatically transmit the terminal identification information when authentication is successfully achieved. Alternatively, the portable terminal  40  may transmit the terminal identification information in accordance with a user operation after authentication is successfully achieved.  
         [0092]     In addition, in a case where the terminal identification information is used as authentication information for the HDD recorder  10  when authentication processing is performed, the HDD recorder  10  can perform processing of step S 307  using the terminal identification information, such as an IP address or a MAC address, received via short-distance wireless communication when authentication processing is performed. Thus, communication via the LAN  100  in step S 305  is not necessary.  
         [0093]      FIG. 10  shows a processing sequence performed when another playback apparatus (in this case, the network AV player  20   a ) starts continuous playback of the content.  
         [0094]     After the processing sequence shown in  FIG. 9  is completed, the user carries the portable terminal  40  with him or her to the room where the network AV player  20   a  is installed. The user brings the portable terminal  40  closer to the network AV player  20   a . The network AV player  20   a  detects the portable terminal  40  via the short-distance wireless interface  24  (step S 401 ), and authentication processing is performed between the network AV player  20   a  and the portable terminal  40  (steps S 402  and  403 ). When authentication is successfully achieved, the portable terminal  40  transmits the terminal identification information to the network AV player  20   a  (step S 404 ).  
         [0095]     When receiving the terminal identification information, the network AV player  20   a  broadcasts to each apparatus on the LAN  100  a query for retrieving playback interruption information corresponding to the terminal identification information (step S 405 ). In response to the query, the HDD recorder  10 , which stores the identical terminal identification information, transmits the playback interruption information that is associated with the terminal identification information to the network AV player  20   a  via the LAN  100  (step S 406 ).  
         [0096]     Subsequently, as in the first example of the continuous playback operation, the network AV player  20   a  transmits to the HDD recorder  10  via the LAN  100  a distribution request in which the content whose playback is to be continued and a playback start position of the content are designated in accordance with the received playback interruption information (step S 407 ). When receiving the distribution request, the HDD recorder  10  reads the corresponding content from the HDD  14 , and starts streaming distribution from the designated position to the network AV player  20   a  (step S 408 ). The network AV player  20   a  sequentially plays back the received content (step S 409 ). Thus, the network AV player  20   a  is capable of performing continuous playback of the same content from the position where playback is interrupted by the HDD recorder  10 .  
         [0097]     In the processing in steps S 402  to S 404 , as in the processing in steps S 303  to S 305  shown in  FIG. 9 , the terminal identification information may be transmitted via the LAN  100  after authentication is successfully achieved. Alternatively, the terminal identification information may be transmitted to the network AV player  20   a  when authentication processing is performed.  
         [0098]     In accordance with the processing described above, the user does not need to perform an operation for setting information on content whose playback is interrupted and an interrupted position of the content. By an intuitive and simple operation using the portable terminal  40 , playback of content whose playback is interrupted by a playback apparatus can be continued from the interrupted position by another playback apparatus.  
         [0099]     Not only in a case where the playback operation is shifted from the HDD recorder  10  to the network AV player  20   a , but also in cases where the playback operation is shifted from the network AV player  20   a  to the HDD recorder  10  and where the playback operation is shifted between the network AV player  20   a  and the network AV player  20   b , continuous playback can be realized by transmitting terminal identification information from the portable terminal  40  to each playback apparatus, as described above.  
         [0100]     In addition, the second example of the continuous playback operation may also be applied to a case where each playback apparatus stores data of content to be played back, as well as a system in which content is distributed from a server. For example, when playback of content in a first playback apparatus is interrupted and playback is to be continued by a second playback apparatus, the second playback apparatus queries, on the network, as to terminal identification information received from the portable terminal  40 . In response to the query, the first playback apparatus transmits playback interruption information to the second playback apparatus. If the corresponding content is stored in the second playback apparatus, the second playback apparatus reads the content and starts playback of the content from the designated position in accordance with the playback interruption information. In this case, continuous playback can also be performed without performing an operation for designating content and a playback position using the second playback apparatus.  
         [0101]     In addition, the second example of the continuous playback operation is also applicable to a case where, for example, content stored in a portable storage medium, such as an optical disc, is played back. For example, an optical disc used in the first playback apparatus is ejected. The optical disc is inserted into the second playback apparatus, and continuous playback is performed. If compressed data of mass content is recorded in the optical disc, an operation for selecting desired content from the mass content can be eliminated.  
         [0102]     In addition, the second example of the continuous playback operation is also applicable to channel selection of broadcast content received via, for example, broadcast radio waves, as well as content stored in a storage medium. For example, when viewing on a first TV receiver is interrupted, the portable terminal  40  transmits terminal identification information to the first TV receiver. The first TV receiver includes a selected channel number in playback interruption information and stores the playback interruption information together with the terminal identification information. Then, when content in the same channel is viewed on a second TV receiver, the portable terminal  40  transmits the terminal identification information to the second TV receiver. The second TV receiver acquires the corresponding playback interruption information from the first TV receiver. The second TV receiver selects the same channel in accordance with the playback interruption information, and plays back the content. According to the above-described procedure, for example, in a case where a large number of selectable channels are provided, for example, for cable TV broadcasting or communications satellite (CS) broadcasting, not only a channel selection operation but an effort required for the user to remember the channel number can also be eliminated. Thus, user-friendliness can be improved.  
         [0103]     However, for a system in which each TV receiver designates a reception channel to a server and the server transmits a reception signal in the selected channel to the TV receiver, a method in which the portable terminal  40  stores playback interruption information, as in the first example of the continuous playback operation, can also be applied.  
         [0104]     In addition, although a continuous playback operation of video and audio content is described in the foregoing embodiment, the continuous playback operation can also be applied to other types of content, such as document data, diagram data, or a Web page. For document data, for example, when the number of a page and the number of a row are stored as playback position information within playback interruption information, if a corresponding document file is opened in another playback apparatus, the designated page and row can be displayed.  
         [0105]     It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and alterations may occur depending on design requirements and other factors insofar as they are within the scope of the appended claims or the equivalents thereof.