Abstract:
A content providing method includes the steps of preparing, on a network, a bulletin board server that provides an electronic bulletin board and a content server that accommodates content; enabling, by the bulletin board server, a second user to make a post on a topic when a first user introduces the topic under a predetermined title on the electronic bulletin board; outputting, by the bulletin board server, a list indicating recommended content as a playlist to an apparatus of a user who accesses via the network when the second user posts information on the recommended content that suits the title in the topic; and outputting, by the content server, designated content to the apparatus of the user to which the playlist is output when the content included in the playlist is designated.

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
     The present invention contains subject matter related to Japanese Patent Application JP 2005-105699 filed in the Japanese Patent Office on Apr. 1, 2005, the entire contents of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a method for providing content, such as a music track, and to a method for providing a playlist of the content. 
     2. Description of the Related Art 
     Music players containing a mass storage device, such as a hard disk device or a nonvolatile memory, are becoming commonplace. Such playback apparatuses are capable of accommodating or storing a huge number of music tracks, such as thousands to tens of thousands of music tracks. 
     For example, for a hard disk device having a capacity of 100 gigabytes, when each music track is three minutes long, 3,000 or more music tracks can be stored. In addition, if digital audio data of a music track is encoded in accordance with an encoding method, such as MP3 (MPEG-1/Audio Layer 3) or ATRAC™ (Adaptive TRansform Acoustic Coding), the amount of data can be compressed to one-tenth to one-twelfth of the original amount of data. Thus, 30,000 or more music tracks can be stored. 
     Thus, users of such music players are able to keep music tracks close to them or able to carry music tracks with them. Such users are able to listen to a favorite music track from among the music tracks. 
     However, when a large number of music tracks are stored in a playback apparatus, as described above, it is difficult for a user to find a particular music track from among the large number of music tracks. In addition, it often happens that the user does not remember what music tracks are stored unless all the titles of the stored music tracks are displayed. Furthermore, since there are many music tracks that the user does not know and many music tracks are released every day, even if the number of music tracks that the user can carry with him or her increases, storing all the music tracks and remembering all the stored music tracks is very difficult. 
     Methods for preparing a playlist are considered. In these methods, a playlist is a list of titles of music tracks selected by a user&#39;s preference. For example, a user collects titles of music tracks that the user wants to listen to when driving along the coast, and a list of the collected titles functions as a playlist. Thus, the user is able to listen to a music track that suits the mood and condition of the user at that time by performing music selection in accordance with such a playlist. 
     In addition, if such playlists are capable of being exchanged between friends and being browsed by the friends, such exchange and browse can help selection of a music track. Thus, users are able to easily select a music track that they want to listen to. 
     In addition, if a community is formed by members having similar preferences and information is exchanged between the members, a member receives the benefit of having a wide range of preferences given by other members. 
     Known technologies are described, for example, in Japanese Unexamined Patent Application Publication Nos. 2004-13653 and 2004-46575. 
     SUMMARY OF THE INVENTION 
     However, in practice, it is very difficult for a user to create a playlist every time by himself or herself so as to be suitable for the mood and condition at that time. In addition, such a playlist includes only music tracks that the user owns, and a new music track is not included in the playlist. 
     In addition, even if such a playlist created by the user is shared with others, since they can only browse the playlist, the user&#39;s preference and taste are just introduced to them. Thus, preference and condition of a person who is browsing the playlist is not taken into consideration. 
     Accordingly, it is desirable to provide a condition in which a music track that suits a user&#39;s preference can be easily selected and in which the user is able to exchange information on a recommended music track with another user and to allow the users to enjoy communication in human relationships. 
     A playlist providing method according to an embodiment of the present invention includes the steps of enabling a second user to make a post on a topic when a first user introduces the topic under a predetermined title on an electronic bulletin board; and outputting a list indicating recommended content as a playlist via a network when the second user posts information on the recommended content that suits the title in the topic. 
     Accordingly, a music track that suits the mood and condition of a user is registered in a playlist even if the user does not know the music track. In addition, since the contents of the playlist change with time in accordance with the contents of a topic, the user does not lose interest in the playlist. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram showing the structure of the entire system according to an embodiment of the present invention; 
         FIG. 2  shows a display example of a topic; 
         FIG. 3  shows a display example of a playlist; 
         FIG. 4  shows a display example of a recommended music track; 
         FIG. 5  shows a display example when a recommended music track is entered; 
         FIG. 6  shows a description example of the playlist; 
         FIG. 7  is a front view showing the outer appearance of a portable terminal; and 
         FIG. 8  is a schematic diagram showing the circuit structure of the portable terminal. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Terms used in the following description and the outline of an embodiment of the present invention are described first. 
     In the following description, the term “music track” or “music” includes information represented using sound, such as reading of poems and stories, dramatic performance including comic story telling and comic acts, and running commentary for speeches, news, and sports, as well as general music. 
     In the following description, in principle, some terms have the meanings as described below. 
     The term “electronic bulletin board” or “bulletin board” means an electronic bulletin board system in which a terminal is capable of posting and browsing a message via a network. 
     The term “topic” means a sequence of posts on a bulletin board arranged in a predetermined order. A topic is also called a “thread”. The topic is displayed on a terminal as the contents of the electronic bulletin board. A plurality of topics is capable of being dealt with in a bulletin board. Generally, making the first post is called “introducing a topic”. 
     The term “playlist” means a list of titles of music tracks arranged according to a predetermined rule. The playlist may include information such as an artist name, which is associated with a music track. 
     In this embodiment, a playlist is created using an electronic bulletin board system, as described below. 
     A) A user A introduces a topic on a bulletin board on the Internet. In other words, the user A posts, in the topic, a message on the subject of, for example, the mood and condition of the user A, the tone of music that the user A wants to listen to, and the like. 
     B) Users B, C, and so on post recommended music tracks suitable for the subject in the topic. Alternatively, the users B, C, and so on may post comments on the topic. 
     C) The topic can be downloaded as a playlist to terminals of the users A, B, C, and so on. The topic is open to users who do not make a post. 
       FIG. 1  schematically shows an example of the entire system according to this embodiment. In this example, personal computers  11  ( 11 A,  11 B, and so on) are used as music playback terminals. The personal computers  11  are connected to the Internet  20 . A content server  31  and a bulletin board server  32  are connected to the Internet  20 . 
     The content server  31  provides music tracks. Many music tracks are stored as digital audio data in the content server  31 . The content server  31  also contains information on the stored music tracks, such as titles, as a database. In this example, digital audio data stored in the content server  31  is encoded, for example, by the MP3 method for data compression. 
     The bulletin board server  32  provides an electronic bulletin board  33 . Users of the personal computers  11  are capable of browsing the electronic bulletin board  33  and posting messages on the electronic bulletin board  33 . A plurality of topics is formed on the electronic bulletin board  33 , and each of the topics is accessed by a plurality of users. The users are roughly categorized into four types, that is, (1) a topic owner, (2) a music recommender, (3) a comment contributor, and (4) a bulletin board browser. 
     The “topic owner” is a user who posts a subject on the electronic bulletin board  33  to introduce a topic. In other words, when the topic owner makes the first post, the topic is formed. There is only one topic owner for the topic. In the example shown in  FIG. 1 , a user who uses the computer  11 A is a topic owner  12 A. 
     The “music recommender” is a user who recommends a music track suitable for the content of the topic. A playlist including the title of the recommended music track is downloaded to a playback terminal. There may be a music recommender or a plurality of music recommenders for the topic. In the example shown in  FIG. 1 , a user who uses the personal computer  11 B is a music recommender  12 B. 
     The “comment contributor” is a user who does not recommend a music track but who posts a comment. There may be a comment contributor or a plurality of comment contributors for the topic. In the example shown in  FIG. 1 , a user who uses the personal computer  11 C is a comment contributor  12 C. 
     The “bulletin board browser” is a user who only browses the topic and downloads the playlist without recommending a music track or posting a comment. There may be a bulletin board browser or a plurality of bulletin board browsers for the topic. In the example shown in  FIG. 1 , a user who uses the personal computer  11 D is a bulletin board browser  12 D. 
     A user of the electronic bulletin board  33  plays a different role, from among a topic owner, a music recommender, a comment contributor, and a bulletin board browser, depending on a case. For example, a music recommender in a case may serve as a topic owner or a comment contributor in a different case. 
     When a topic is introduced, if the music recommender  12 B or the comment contributor  12 C makes a post, the contents of the electronic bulletin board  33  are updated. In accordance with increases in the number of recommended music tracks and the number of comments with the lapse of time, a playlist dynamically changes. 
     A display example of a topic (contents of the electronic bulletin board  33 ) is described next. 
     When a personal computer  11  is connected to the bulletin board server  32  and selects a topic on the electronic bulletin board  33 , the selected topic is displayed on the display of the personal computers  11 , for example, as shown in  FIG. 2 . 
     In the topic, posts are added from top to down in accordance with posting. In the example shown in  FIG. 2 , posts  40  to  45  are made in that order. In this case, the topic owner  12 A introduces the topic under the title “Do you know a good love song?”. 
     In other words, the first post  40  is made by the topic owner  12 A, and the following posts  41  to  45  are made by music recommenders  12 B and comment contributors  12 C (and the topic owner  12 A) for the subject and content brought by the post  40 . 
     The posts  40  to  45  each include a user name  51 , a rating  52 , posted date and time  53 , and a comment  54 . The post  40  also includes a title  50 . The title  50 , the user name  51 , the rating  52 , the posted date and time  53 , and the comment  54  have the meanings described below. 
     The title  50  is provided only to the head of the post  40  made by the topic owner  12 A. The title  50  indicates a heading brought by the topic owner  12 A. 
     The user name  51  indicates the name (or handle name) of a user who makes a post. 
     The rating  52  indicates a numerical value representing a rating for the user who makes the post. It is not uncommon that malicious defamation and slander are committed on an electronic bulletin board on the Internet. In order to avoid this, others evaluate a user who makes a post, and an evaluation result is obtained as the rating  52 . All users can browse the rating  52 . 
     For example, the rating  52  indicates a score calculated from the number of recommended music tracks, the number of downloads of each recommended music track, direct evaluation by other users, and the like. Alternatively, the rating  52  is acquired based on a procedure adopted in auction services on the Internet or the like. When a topic is displayed, only a post with a rating of a predetermined value or more may be displayed. Thus, a post made by a music recommender or a comment contributor with a low rating is not displayed. A post that is not displayed is not reflected in a playlist. 
     The posted date and time  53  indicates the date and time when the post is made (or registered). 
     The comment  54  is a comment contributed by the user who has the user name  51  for the subject and content of the post  40 . The comment  54  serves as text in the post. Generally, the title of a recommended music track, an impression for the music track, and the like are included in the comment  54 . 
     In the example shown in  FIG. 2 , the posts  41 ,  42 , and  45  are made by different music recommenders  12 B. The posts  41 ,  42 , and  45  each include a recommended music track. The posts  43  and  44  are made by a comment contributor  12 C and the topic owner  12 A, respectively. The posts  43  and  44  do not include a recommended music track. 
     Thus, a “acquire playlist” button  55 A, a “playlist detail” button  56 A, and a “preview” button  57  are displayed for the first post  40  made by the topic owner  12 A. An “acquire” button  55 , a “detail” button  56 , and the “preview” button  57  are displayed for the posts  41 ,  42 , and  45  each including the title of a recommended music track. If a corresponding music track has already been purchased, the “preview” button  57  is displayed as a “playback” button  57 . 
     The above-mentioned operation buttons are used for the purposes described below. 
     When the “acquire playlist” button  55 A is operated, the playlist is downloaded from the content server  31  to the personal computer  11 . This downloading processing can be performed even if a music track included in the playlist is not purchased. 
     As described later, when playback is performed using the playlist, music tracks for preview (normally, only a part of each music track) are played back, and then, each music track can be purchased by an operation of a personal computer. The number of music tracks included in the playlist is indicated on the “acquire playlist” button  55 A. In the example shown in  FIG. 2 , the “acquire playlist” button  55 A represents that the playlist includes eighteen music tracks. 
     When the title of a purchased (paid) music track is selected from among the titles included in the playlist and the “acquire” button  55  is operated, digital audio data of the selected music track is downloaded from the content server  31  to the personal computer  11 . 
     When the “playlist detail” button  56 A is operated, the corresponding playlist is downloaded from the bulletin board server  32 , and the contents of the playlist are displayed. When the “detail” button  56  is operated, data of a music track included in a post for which the “detail” button  56  is displayed is downloaded from the bulletin board server  32 , and the contents are displayed. 
     Contents to be displayed when the “playlist detail” button  56 A or the “detail” button  56  is operated will be described later. The number of music tracks included in the corresponding playlist is indicated on the “playlist detail” button  56 A. In the example shown in  FIG. 2 , the “playlist detail” button  56 A represents that the playlist includes eighteen music tracks. 
     When the “preview” button  57  for a music track that is not purchased from among music tracks included in the playlist is operated, part of digital audio data of the music track is provided in a streaming method from the content server  31  to the personal computer  11 . Accordingly, the music track can be previewed. When the “playback” button  57  for a purchased music track is operated, the music track, which is contained in the personal computer  11 , can be played back. 
     When a music track is selected without using a playlist, similar processing can be achieved. In addition, a plurality of topics on the electronic bulletin board  33  may be hierarchically arranged and displayed with a tree structure. 
     An example of a display screen displayed when the “playlist detail” button  56 A is operated is described next. 
     When the “playlist detail” button  56 A for the topic shown in  FIG. 2  is operated, the topic is shaped to create a playlist. The created playlist is downloaded to the personal computer  11 , and displayed on the personal computer  11 . 
       FIG. 3  shows a display example of the playlist. The contents of the playlist are displayed as described below.  FIG. 3  shows a case where three music tracks are recommended for the topic shown in  FIG. 2 . 
     A “playlist title” field indicates the subject of the playlist. The playlist title is identical to the title  50  of the post  40 . A user of the personal computer  11  may change the playlist title. 
     A “topic owner” field indicates the user name  51 , the rating  52 , and the posted date and time  53  for the post  40 . Thus, the “topic owner” field indicates the name of the topic owner  12 A who introduces the topic, the rating for the topic owner  12 A, and the date and time when the topic is introduced. 
     A “last update” field indicates the date and time when the last post is made by the topic owner  12 A, the music recommender  12 B, or the comment contributor  12 C. 
     A “present number of tracks” field indicates the number of recommended music tracks provided by the music recommender  12 B for the topic. The present number of music tracks may increase as long as the topic exists. A case where the topic is deleted will be described later. 
     A “number of downloads” field indicates the number of downloads of the playlist. 
     A “rating” field indicates, by the number of stars, the rating for the playlist provided by the present user. 
     When a “display all comments” button  61  is operated, the contents (all the posts) of the topic for which the playlist is created are displayed, for example, as shown in  FIG. 2 . Thus, all the posts can be browsed. All the comments may be displayed in a different way. 
     When a “bulk purchase” button  62  is operated, a mode in which unpurchased music tracks included in the playlist are purchased altogether is set. 
     Music track information  63  is information on a music track included in the topic for which the playlist is created. The music track information  63  is displayed for each music track and includes basic information about the music track, such as a picture of an album jacket, a title, an artist name, and a playtime. In addition, the music track information  63  includes the user name  51  of a music recommender, the rating  52  for the music recommender, and the posted date and time  53  (that is, the date and time when the recommendation is made). 
     In addition, a “comment” button  64  for reading the posted comment  54 , the “preview” button  57 , and a “purchase” button  65  are also displayed. When the “preview” button  57  is operated, the music track for which the “preview” button  57  is displayed can be previewed. After the music track is previewed, when the “purchase” button  65  is operated in order to purchase the music track, digital audio data of the music track is downloaded from the content server  31  to the personal computer  11 . Thus, when the “purchase” button  65  is operated, each music track can be purchased. 
     A rating filter  66  is a filter for displaying the music track information  63  whose rating  52  indicating the rating for a music recommender is more than a predetermined value.  FIG. 3  shows a case where the music track information  63  provided by the music recommender  12 B whose rating is more than five is displayed. 
     By setting the rating filter  66 , a music track recommended by a music recommender with a low rating is not included in the playlist. In order to avoid so-called trolling or harassment, an ignore list may be created in order to exclude recommendation from a particular person, and filtering may be performed using the ignore list. 
     An example of a display screen displayed when the “detail” button  56  is operated is described next. 
     When the “detail” button  56  provided for the post  41 ,  42 , or  45  shown in  FIG. 2  is operated, the details of a music track included in the corresponding post  41 ,  42 , or  45  for which the “detail” button  56  is provided are displayed. 
       FIG. 4  shows a display example of the corresponding music track. The music track information  63  on the corresponding music track is displayed as shown in  FIG. 3 , and a “list of topics including recommendation of this song” button  67  and a “list of recommenders of this song” button  68  are displayed. 
     The “list of topics including recommendation of this song” button  67  is used for displaying a list of topics in which the corresponding music track is also recommended. If the same music track is recommended in another topic, the other topic is likely to be related to this topic. Thus, other music tracks recommended in the other topics are likely to be highly related to this topic. 
     When the “list of recommenders of this song” button  68  is operated, a list of users who recommend the corresponding music track is displayed, irrespective of a topic. Thus, other music tracks recommended by a user who recommends the corresponding music track can be known. For example, whether or not the recommender who recommends the corresponding music track has a preference for rock music or whether or not the recommender who recommends the corresponding music track has no particular preference can be known. In addition, comments for different music tracks can be compared with each other. Thus, efficient information for deciding whether or not to purchase the recommended music track can be acquired. 
     A display example and an operation procedure for recommending a music track are described next. 
       FIG. 5  shows an example of a display screen used when a user (music recommender  12 B) recommends a music track. When a “recommend music” button or an “entry comment” button displayed on the display screen for the topic, for example, shown in  FIG. 2  is operated, the display screen for recommending a music track is displayed. 
     On the screen shown in  FIG. 5 , the music recommender  12 B enters a comment in an entry field  71 , and operates a “post” button  72 . Then, the entered comment  54  is added to the topic as a new post. 
     Then, the music recommender  12 B enters the title of a music track to be recommended. The title registered in advance in the bulletin board server  32  is searched for and selected, instead of entering a character string. 
     In other words, the music recommender  12 B enters at least one of an artist name, an album name, and a title (or part of the artist name, the album name, and the title) in a search word entry field  73 , and operates a “search” button  74 . Then, searching is performed for a database in the bulletin board server  32  using the characters entered in the search word entry field  73  as a search word. Then, a list of corresponding titles and relating information are displayed as a list  75 . A “recommend” button  76  provided for the corresponding title in the list  75  is operated. Then, the bulletin board server  32  specifies the title, and internally establishes a link. 
     Accordingly, recommendation of a music track is completed, and the display screen for the topic shown in  FIG. 2  is recovered. Since the post including the recommendation is made by the music recommender  12 B, the comment  54  entered in the entry field  71 , the “acquire” button  55 , the “detail” button  56 , and the “preview” button  57  are displayed, as in the case for the post  41 ,  42 , or  45  shown in  FIG. 2 . 
     When a music track is recommended, a title of the music track is searched for and selected, as described above. This is because that content needs to be identified using an identification code and the like in order to perform management by internally associating the content database with a button on the electronic bulletin board. In addition, operations for displaying a “detail” button and a “preview” button next to the entry field  71  and for accessing digital audio data of a music track, independent of a comment, from a dedicated terminal can be facilitated. 
     In addition, a method for searching for and selecting the title of a music track is also effective in charging and counting the number of playbacks and the number of downloads. In addition, the title of a music track can be searched for and an internal link can be established in accordance with a procedure practically used in sites for Internet auction or shopping. 
     Furthermore, although the comment  54  is entered in the entry field  71  and the “post” button  72  is operated in the above example, if the display screen for the topic shown in  FIG. 2  is recovered without entering a recommended music track, a post made at that time serves as a post made by a comment contributor. Thus, for example, only the comment  54  entered in the entry field  71  is displayed, as in the post  43  or  44  shown in  FIG. 2 . 
     A description content of a playlist and a method for describing the playlist are described next. 
       FIG. 6  shows an example of a method for describing a playlist. The playlist is structured in XML (extensible Markup Language) by poster information, comment content, recommended music track information, and the like in the topic on the electronic bulletin board. 
     The playlist is formed by a topic block and a playlist block. The topic block is a block mainly used for displaying a topic. The playlist block is used for displaying the topic and the playlist, and is used as a playlist in the personal computer  11 . 
     Tags used in the playlist have meanings as described below. 
     A &lt;topic&gt; tag represents a detailed block of the topic. 
     A &lt;title&gt; tag represents the title of the topic. In the topic (shown in  FIG. 2 ), in principle, the &lt;title&gt; tag indicates the title  50 . In the playlist (shown in  FIG. 3 ), in principle, the &lt;title&gt; tag indicates the playlist title. 
     A &lt;comment&gt; tag indicates a comment block. In the topic block, there is only one comment block for the post  40 . In the playlist block, a comment block is formed for each post and is added to the end of the playlist block. 
     A &lt;name&gt; tag indicates the name of a user who writes the comment block. In the topic and the playlist, the &lt;name&gt; tag is displayed as the user name  51 . 
     An &lt;eva&gt; tag indicates a rating for the user who writes the comment block. In the topic and the playlist, the &lt;eva&gt; tag is displayed as the rating  52 . 
     A &lt;date&gt; tag indicates the date and time when the comment block is written. In the topic and the playlist, the &lt;date&gt; tag is displayed as the posted date and time  53 . 
     A &lt;body&gt; tag indicates the text of the comment. In the topic and the playlist, the &lt;body&gt; tag is displayed as the comment  54 . 
     A &lt;playlist&gt; tag indicates a playlist block. 
     A &lt;rating&gt; tag indicates a rating for the playlist provided by the present user. In the topic and the playlist, the &lt;rating&gt; tag is displayed as the number of stars. 
     A &lt;recommend&gt; tag indicates a URL (Uniform Resource Locator) for accessing digital audio data of a recommended music track. In the example shown in  FIG. 1 , the &lt;recommend&gt; tag indicates a directory in the content server  31  in which the digital audio data is stored. When the comment contributor  12 C posts only the comment  54 , the &lt;recommend&gt; tag is not included in the comment block. When a music track has already been downloaded, the &lt;recommend&gt; tag may be displayed as a local file path in the personal computer  11  or a music track ID (Identification). 
     A topic and a playlist are displayed using the tags described above, or a playlist for selecting a music track is formed using the tags described above. 
     A configuration example of a playback apparatus is described next. 
     Although a case where the personal computer  11  is used as a playback terminal has been described above,  FIG. 7  shows a case where a dedicated portable terminal  100  is used. 
     Referring to  FIG. 7 , the portable terminal  100  is configured as a flat rectangular parallelepiped. A display  111  is provided on the upper front face of the portable terminal  100 . An operation key section  112 , a mode key section  113 , and an enter key  114  are provided below the display  111 . The display  111  includes, for example, a color LCD (Liquid Crystal Display) panel. The display  111  is capable of displaying various characters (including numbers, symbols, and the like, which applies to the following description) in color by combination of dots. A playlist and the like are displayed on the display  111  when a music track is selected, and information on a music track is displayed on the display  111  during the playback of the music track. 
     The operation key section  112  functions as a pointing device. The operation key section  112  includes cursor keys  112 A for moving a cursor  11 D displayed on the display  111  in vertical and horizontal directions and a set key  112 B for selecting or setting an item in the position of the cursor  111 D. The mode key section  113  includes control keys, for example, for playing back a music track or stopping playback of the music track. The enter key  114  is used for entering characters, such as the comment  54 . 
     In addition, an extensible antenna  115  and a headphone jack  116  are provided on the top of the portable terminal  100 . The antenna  115  is provided for achieving wireless access to data in the content server  31  and the bulletin board server  32 . A headphone  117  is connected to the headphone jack  116 . 
     A circuit example of the portable terminal  100  is described next. 
       FIG. 8  shows an example of the circuit structure of the portable terminal  100 . In this example, the portable terminal  100  has normal bus architecture, and a control circuit  120  is a microcomputer. In other words, a CPU (Central Processing Unit)  121  is connected to a bus  129 , and a ROM (Read Only Memory)  122  in which various programs are written, a RAM (Random Access Memory)  123  used as a work area, and a nonvolatile memory  124 , such as a flash memory, are connected to the bus  129 . 
     In addition, in this example, a hard disk device  126  is provided as a mass storage device for storing music tracks. The hard disk device  126  is connected to the bus  129  via a hard disk controller  125 . In this case, a music track is stored as digital audio data in the hard disk device  126 . In this example, the digital audio data is encoded, for example, in the MP3 method for data compression. The hard disk controller  125  reads and writes the digital audio data from and to the hard disk device  126  in accordance with an instruction from the CPU  121 . 
     In addition, a transmitter/receiver circuit  128  is connected to the bus  129  via an interface circuit  127 . The transmitter/receiver circuit  128  is provided for wirelessly connecting the portable terminal  100  to the content server  31  and the bulletin board server  32  (or their access points) and for realizing downloading of digital audio data of a music track, reception of the digital audio data in the streaming method, downloading of a playlist, access to an electronic bulletin board, and the like. The antenna  115  is connected to the transmitter/receiver circuit  128 . 
     In addition, the display  111  is connected to the bus  129  via a display controller  131 , and the operation key section  112 , the mode key section  113 , and the enter key  114  are connected to the bus  129  via an interface circuit  132 . In this case, when data for display is supplied from the CPU  121 , the display controller  131  converts the data into a display signal and supplies the converted display signal to the display  111 . Thus, characters corresponding to the data for display supplied from the CPU  121  are displayed on the display  111 . 
     In addition, a decoder circuit  133  is connected to the bus  129 , and the decoder circuit  133  is connected to the headphone jack  116  via an output circuit  134 . The decoder circuit  133  is provided for decoding digital audio data in the MP3 method supplied to the decoder circuit  133  into original linear digital audio data and for supplying the linear digital audio data to the output circuit  134 . The output circuit  134  includes a D/A (Digital to Analog) converter circuit and an output amplifier. The output circuit  134  converts the digital audio data supplied to the output circuit  134  into an analog audio signal, and outputs the analog audio signal to the headphone jack  116 . 
     An operation of the portable terminal  100  is described next. 
     When a topic or a playlist is displayed, as shown in  FIG. 2  or  FIG. 3 , a music track stored in the hard disk device  126  is searched for. When the music track included in the displayed topic or playlist is stored in the hard disk device  126 , the “playback” button  57  is displayed. 
     When the “playback” button  57  is operated, digital audio data of the designated music track is read from the hard disk device  126  by the hard disk controller  125 . The read digital audio data is supplied from the hard disk controller  125  to the decoder circuit  133  via the CPU  121 , and decoded into original linear digital audio data. 
     The decoded digital audio data is converted into an analog audio signal in the output circuit  134 , and the analog audio signal is supplied to the headphone  117  via the headphone jack  116 . Thus, the music track stored in the hard disk device  126  can be listened to via the headphone  117 . At that time, for music tracks stored in the hard disk device  126 , from among music tracks included in the displayed playlist, selection and playback can skip by using the mode key section  113 . 
     In contrast, when a topic or a playlist is displayed as shown in  FIG. 2  or  FIG. 3 , if a music track included in the topic or the playlist is not stored in the hard disk device  126 , the “preview” button  57  is displayed. 
     When the “preview” button  57  is operated, an instruction for preview of the corresponding music track is reported to the content server  31 . Digital audio data of the music track is extracted from the content server  31 , and wirelessly transmitted in the streaming method. 
     The transmission signal is received at the antenna  115 , and supplied to the transmitter/receiver circuit  128 . Digital audio data of the designated music track is output from the transmitter/receiver circuit  128 . The digital audio data is supplied from the interface circuit  127  to the decoder circuit  133  via the CPU  121 , and decoded into original linear digital audio data. 
     Thus, since the decoded digital audio data is converted into an analog audio signal in the output circuit  134  and the analog audio signal is supplied to the headphone  117 , the music track stored in the content server  31  can be listened to via the headphone  117 . In this case, only part of a target music track, for example, initial thirty seconds or a refrain part can be previewed. Thus, users are able to decide whether or not to purchase the music track. 
     When the music track is to be purchased, the “acquire” button  55  or the “purchase” button  65  is operated. Then, digital data of the music track having the title is downloaded from the content server  31 , and stored into the hard disk device  126 . A general method in practical use may be adopted as a method for user authentication and payment necessary for purchase. 
     Thus, in the subsequent stages, the “playback” button  57  shown in  FIG. 2  or  FIG. 3  is displayed. When playback of the music track is set, the music track stored in the hard disk device  126  is played back. 
     According to the personal computer  11  or the portable terminal  100 , in order words, according to a playback terminal, for example, when a message “Tell me a good song for spending Christmas Eve with my girlfriend!” is posted, many others who read the message recommend music tracks with comments, and the recommendations and the comments serve as a playlist for the playback terminal. Thus, even a music track that a user does not know and that suits the mood and condition of the user can be registered in the playlist. In addition, the contents of the playlist dynamically change with time in accordance with posts on a topic, and new music tracks are added. Thus, the user does not lose interest in the playlist. 
     Furthermore, exchanging comments on a bulletin board system brings communication in new human relationships. Users are able to enjoy the benefits that are not provided by known players. For example, a user is able to listen to a music track recommended by a reliable person with ease or the user makes a friend with a recommender who recommends an unexpected music track. 
     In addition, users are able to feel the joy of receiving recommendation of music tracks from others. In addition, people who have a liking for music are able to be satisfied when others appreciate their recommendations. In addition, users are able to enjoy the unpredictability of registration of unknown music tracks in a playlist and are able to enjoy getting to know new music tracks. 
     In addition, a playlist that is not accessed can be weeded out by limiting the number of topics displayed on the electronic bulletin board  33  or by displaying popular topics determined in accordance with the number of downloads of a playlist in a top portion of the electronic bulletin board  33 . Thus, the quality of the entire playlists improves, and user satisfaction also improves. 
     In addition, when a music track is being played back, a user is able to view posts made by recommenders or comment contributors for the music track. Thus, the user is able to enjoy new communication through music as well as playback of the music track. In addition, a new business model for music distribution can be created, and this stimulates the music industry itself. In addition, an affiliate system can be adopted for music recommenders. Thus, recommenders&#39; motivation for recommending music tracks is improved, and the improvement in the motivation stimulates electronic bulletin boards. Thus, a culture based on electronic bulletin board playlists is created, and the music industry and the network business industry are stimulated. 
     In the above description, only limited members may be able to use the content server  31  and the bulletin board server  32 . In addition, the content server  31  and the bulletin board server  32  may be configured on an intranet. In addition, although a case where sound content, such as a music track, is used is described in the foregoing embodiment, the present invention is also applicable to a case where video content, such as a moving image or a static image, is used or a case where a program or data in a database is used as content. 
     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.