Patent Publication Number: US-9886502-B2

Title: Providing similar content with similar playback rates

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation of U.S. patent application Ser. No. 12/290,841, filed Nov. 4, 2008, which claims priority from Japanese Patent Application No. JP 2007-292584, filed in the Japanese Patent Office on Nov. 9, 2007, the disclosures of which are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to an information processing apparatus, a music distribution system, a music distribution method and a computer program. 
     Description of the Related Art 
     With a recent trend toward digital audio players, the number of music download distribution sites that distribute music files over the Internet is growing. Further, the variety of music playback applications for playing back music on a personal computer is increasing. 
     A music download distribution site and a music playback application often have close relationship with each other, such as that a music download distribution site is available from a music playback application or, inversely, that a music file downloaded from a music download distribution site is only available on a particular music playback application. 
     BRIEF SUMMARY OF THE INVENTION 
     However, in such relationship, when using a music download distribution site, it is necessary for a user to take some active action such as clicking a button or selecting a menu on the music playback application. 
     Further, when listening to or searching for music on a music download distribution site, a user fails to find desired music without information about the music such as an artist name or a music title. Because it is a necessary condition for searching for music to have information such as an artist name or a music title, a user fails to find desired music if the user does not have such information. 
     In light of the foregoing, it is desirable to provide novel and improved information processing apparatus, music distribution system, music distribution method and computer program capable of analyzing information about music that is played back by a user and distributing music related to the music to the user, thereby allowing the user to receive the provision of new music without having information about target music such as an artist name or a music title. 
     According to an embodiment of the present invention, there is provided an information processing apparatus for playing back music data, connected to a distribution server for distributing music data over a network, which includes a music storage portion to store music data, a music playback portion to play back music data, a metadata acquisition portion to acquire metadata describing information about the music data being played back in the music playback portion, a metadata transmission portion to transmit the metadata acquired in the metadata acquisition portion to the distribution server, a music reception portion to receive music data selected in the distribution server based on the information contained in the metadata and distributed from the distribution server, a music acquisition portion to acquire the music data from the music storage portion based on the information contained in the metadata, and a control portion to control the music playback portion to play back the music data distributed from the distribution server and the music data acquired from the music storage portion by the music acquisition portion. 
     In this configuration, the music storage portion stores music data, the music playback portion plays back music data, the metadata acquisition portion acquires metadata describing information about the music data that is being played back in the music playback portion, and the metadata transmission portion transmits the metadata that is acquired in the metadata acquisition portion to the distribution server. Further, the music reception portion receives music data that is selected in the distribution server based on the information contained in the metadata and distributed from the distribution server, the music acquisition portion acquires the music data from the music storage portion based on the information contained in the metadata, and the control portion controls the music playback portion so as to play back the music data that is distributed from the distribution server and the music data that is acquired from the music storage portion by the music acquisition portion. By receiving music that is distributed based on the information about the music being played back in the information processing apparatus, it is possible for a user to receive the provision of new music without having information about target music such as an artist name or a music title. 
     The control portion may control the music playback portion so as to sequentially play back the music data distributed from the distribution server and the music data acquired from the music storage portion as music having the same or similar feature. It is thereby possible to enjoy not only the music stored in the music storage portion but also the music distributed from the distribution server as the music having the same or similar feature. 
     The information processing apparatus may further include a music analysis portion to analyze music data to be played back in the music playback portion and obtain information about the music data. In this configuration, the music analysis portion analyzes music data to be played back in the music playback portion and obtains information about the music data. It is thereby possible to transmit the information that is obtained as a result of analysis in the music analysis portion in the form of metadata to the distribution server. 
     The music analysis portion may obtain information about a tune of music data, and the metadata acquisition portion may acquire metadata containing the information about the tune. It is thereby possible to transmit the information about a tune of music data that is obtained as a result of analysis in the music analysis portion in the form of metadata to the distribution server. Because the information processing apparatus can receive the distribution of other music with the same tune, it is possible for a user to receive the provision of new music without having information about target music such as an artist name or a music title. 
     In the information processing apparatus, a playback ratio between the music data prestored in the information processing apparatus and the music data received by the music reception portion may be variable in the music playback portion. 
     According to another embodiment of the present invention, there is provided an information processing apparatus for playing back content data, connected to another information processing apparatus over a network, which includes a content storage portion to store content data, a content playback portion to play back content data, a metadata acquisition portion to acquire metadata describing information about the content data being played back in the content playback portion, a metadata transmission portion to transmit the metadata acquired in the metadata acquisition portion to the other information processing apparatus, a content reception portion to receive content data selected in the other information processing apparatus based on the information contained in the metadata and transmitted from the other information processing apparatus, a content acquisition portion to acquire the content data from the content storage portion based on the information contained in the metadata, and a control portion to control the content playback portion to play back the content data transmitted from the other information processing apparatus and the content data acquired from the content storage portion by the content acquisition portion. 
     According to another embodiment of the present invention, there is provided a music distribution system that includes a distribution server for distributing music and an information processing apparatus for playing back music, connected to the distribution server over a network, in which the information processing apparatus includes a music storage portion to store music data, a music playback portion to play back music data, a metadata acquisition portion to acquire metadata describing information about the music data being played back in the music playback portion, a metadata transmission portion to transmit the metadata acquired in the metadata acquisition portion to the distribution server, a music reception portion to receive music data selected in the distribution server based on the information contained in the metadata and distributed from the distribution server, a music acquisition portion to acquire the music data from the music storage portion based on the information contained in the metadata, and a control portion to control the music playback portion to play back the music data distributed from the distribution server and the music data acquired from the music storage portion by the music acquisition portion; and the distribution server includes a music retention portion to retain music, a metadata reception portion to receive the metadata describing information about the music being played back in the information processing apparatus from the information processing apparatus, a music selection portion to select the music retained in the music retention portion based on the information contained in the metadata, and a music distribution portion to distribute the music selected by the music selection portion to the information processing apparatus. 
     In this configuration, in the information processing apparatus, the music storage portion stores music data, the music playback portion plays back music data, the metadata acquisition portion acquires metadata describing information about the music data that is being played back in the music playback portion, the metadata transmission portion transmits the metadata that is acquired in the metadata acquisition portion to the distribution server, and the music reception portion receives music data that is selected in the distribution server based on the information contained in the metadata and distributed from the distribution server. Further, the music acquisition portion acquires the music data from the music storage portion based on the information contained in the metadata, and the control portion controls the music playback portion so as to play back the music data that is distributed from the distribution server and the music data that is acquired from the music storage portion by the music acquisition portion. In the distribution server, the music retention portion retains music, the metadata reception portion receives the metadata describing information about the music that is being played back in the information processing apparatus from the information processing apparatus, the music selection portion selects the music that is retained in the music retention portion based on the information contained in the metadata, and the music distribution portion distributes the music that is selected by the music selection portion to the information processing apparatus. By distributing music from the distribution server based on the information about the music being played back in the information processing apparatus, it is possible for a user to receive the provision of new music without having information about target music such as an artist name or a music title. 
     The music selection portion may select music having the same or similar feature as the music being played back in the music playback portion or may select music related to the music being played back in the music playback portion. 
     The control portion may control the music playback portion so as to sequentially play back the music data distributed from the distribution server and the music data acquired from the music storage portion as music having the same or similar feature. It is thereby possible to enjoy not only the music stored in the music storage portion but also the music distributed from the distribution server as the music having the same or similar feature. 
     The information processing apparatus may further include a first music analysis portion to analyze music data to be played back in the music playback portion and obtain information about the music data. In this configuration, the first music analysis portion analyzes music data to be played back in the music playback portion and obtains information about the music data. It is thereby possible to transmit the information that is obtained as a result of analysis in the first music analysis portion in the form of metadata to the distribution server. 
     The first music analysis portion may obtain information about a tune of music data, and the metadata acquisition portion may acquire metadata containing the information about the tune. It is thereby possible to transmit the information about a tune of music that is obtained as a result of analysis in the first music analysis portion in the form of metadata to the distribution server. Because the information processing apparatus can receive the distribution of other music with the same tune, it is possible for a user to receive the provision of new music without having information about target music such as an artist name or a music title. 
     The distribution server may further include a second music analysis portion to analyze music data retained in the music retention portion and obtain information about a tune, and the music selection portion may select music from the music retention portion so that the tune of the music analyzed in the second music analysis portion matches information about a tune of music contained in the metadata. 
     According to another embodiment of the present invention, there is provided a music distribution method for distributing music data from a distribution server to an information processing apparatus over a network, which includes the steps of storing music data in the information processing apparatus, playing back music data in the information processing apparatus, acquiring metadata describing information about the music being played back in the playback step in the information processing apparatus, transmitting the metadata acquired in the metadata acquiring step from the information processing apparatus to the distribution server, receiving the metadata describing the information about the music being played back in the information processing apparatus and transmitted in the transmitting step by the distribution server, selecting music to be distributed over the network based on the information contained in the metadata received in the metadata receiving step by the distribution server, distributing the music selected in the music selecting step from the distribution server to the information processing apparatus over the network, acquiring the music data stored in the storing step based on the information contained in the metadata, and controlling music playback to play back the music data distributed from the distribution server and the music data acquired in the music acquiring step. 
     According to another embodiment of the present invention, there is provided a computer program for playing back music in a computer connected to a distribution server for distributing music over a network, the computer program causing the computer to execute a process including the steps of storing music data, playing back music data, acquiring metadata describing information about the music being played back in the playback step, transmitting the metadata acquired in the metadata acquiring step to the distribution server, receiving music selected in the distribution server based on the information contained in the metadata and distributed from the distribution server, acquiring the music data stored in the storing step based on the information contained in the metadata, and controlling music playback to play back the music data distributed from the distribution server and the music data acquired in the music acquiring step. 
     According to the embodiments of the present invention described above, there are provided novel and improved information processing apparatus, music distribution system, music distribution method and computer program capable of analyzing information about music that is played back by a user and distributing music related to the music to the user, thereby allowing the user to receive the provision of new music without having information about target music such as an artist name or a music title. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an explanatory view illustrating the configuration of a music distribution system according to one embodiment of the present invention. 
         FIG. 2  is an explanatory view illustrating the hardware configuration of a distribution server  100  according to one embodiment of the present invention. 
         FIG. 3  is an explanatory view illustrating the functional configuration of the distribution server  100  according to one embodiment of the present invention. 
         FIG. 4  is an explanatory view illustrating the hardware configuration of an information processing apparatus  200  according to one embodiment of the present invention. 
         FIG. 5  is an explanatory view illustrating the functional configuration of the information processing apparatus  200  according to one embodiment of the present invention. 
         FIG. 6  is an explanatory view illustrating a music playback application  242 . 
         FIG. 7  is a flowchart illustrating the process of registering music information into a music information database  128  according to one embodiment of the present invention. 
         FIG. 8  is an explanatory view illustrating an example of information registered in the music information database  128  according to one embodiment of the present invention. 
         FIG. 9  is a flowchart illustrating the process of transmitting music information from the information processing apparatus  200  to the distribution server  100  according to one embodiment of the present invention. 
         FIG. 10  is a flowchart illustrating the process of distributing music data from the distribution server  100  to the information processing apparatus  200  according to one embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the appended drawings. Note that, in this specification and the appended drawings, structural elements that have substantially the same function and structure are denoted with the same reference numerals, and repeated explanation of these structural elements is omitted. 
     A music distribution system according to one embodiment of the present invention is described firstly. 
       FIG. 1  is an explanatory view illustrating the configuration of a music distribution system according to one embodiment of the present invention. A music distribution system according to one embodiment of the present invention is described hereinafter with reference to  FIG. 1 . 
       FIG. 1  is an explanatory view illustrating the configuration of a music distribution system  10  according to one embodiment of the present invention. The music distribution system  10  distributes music data to a user of the music distribution system  10  over a network  20  that is configured by a network available to the public such as the Internet, a corporate network of a music distribution system operator such as an intranet or the like. Referring to  FIG. 1 , the music distribution system  10  according to one embodiment of the present invention includes a distribution server  100  and an information processing apparatus  200  such as a personal computer or a music playback device. 
     The distribution server  100 , which is an example of “another information processing apparatus” according to the present invention, stores music data in the form of files and, in response to a request from a user who owns the information processing apparatus  200 , distributes music data corresponding to the request over the network  20 . The music data may be distributed by transmission of a file or may be distributed in the form of streaming in which distributed music is played back in the information processing apparatus  200  but not stored into the information processing apparatus  200 . Further, when the distribution server  100  receives information about music that is being played back in the information processing apparatus  200  from the information processing apparatus  200 , the distribution server  100  selects music data to be distributed to the information processing apparatus  200  from the music data that are stored in the distribution server  100  based on the received information and distributes the selected music data to the information processing apparatus  200  via the network  20 . 
     The information processing apparatus  200  may be a desktop personal computer or a notebook personal computer as shown in  FIG. 1 , for example, and plays back a music file that is created in a format such as MPEG-1 audio layer-3 (MP3) or adaptive transform acoustic coding (ATRAC). 
     The information processing apparatus  200  requests distribution of music data that is desired by a user to the distribution server  100  over the network  20 . Further, when the information processing apparatus  200  plays back music, the information processing apparatus  200  transmits information about the currently played back music to the distribution server  100  via the network  20 . 
     The network  20  is configured by a network available to the public such as the Internet, a corporate network of a music distribution system operator such as an intranet or the like, as described earlier. 
     Although one distribution server  100  is shown in the music distribution system  10  of  FIG. 1 , the present invention is not limited thereto, and two or more distribution servers  100  may be placed. 
     The configuration of the music distribution system according to one embodiment of the present invention is described in the foregoing. In the following, the hardware configuration of the distribution server  100  according to one embodiment of the present invention is described. 
       FIG. 2  is an explanatory view illustrating the hardware configuration of the distribution server  100  according to one embodiment of the present invention. The hardware configuration of the distribution server  100  according to one embodiment of the present invention is described hereinafter with reference to  FIG. 2 . 
     Referring to  FIG. 2 , the distribution server  100  according to one embodiment of the present invention includes a central processing unit (CPU)  102 , read only memory (ROM)  104 , random access memory (RAM)  106 , an internal bus  108 , an input/output interface  110 , a display portion  112 , an input portion  114 , a hard disk drive (HDD)  116 , a network interface  118  and an external interface  119 . 
     The CPU  102  performs numerical calculation, information processing, device control and so on. The CPU  102  performs numerical calculation, information processing and device control by sequentially reading a program stored in the ROM  104  or data stored in the RAM  106 , or based on a signal corresponding to a command input via the input portion  114  by an administrator of the distribution server  100 , for example, or a signal transmitted via the network interface  118  from the information processing apparatus  200 . 
     The ROM  104  stores fixed data that is basically not altered in programs and operation parameters to be used by the CPU  102  when performing numerical calculation, information processing, device control and so on. The RAM  106  stores data that basically varies during processing in programs and operation parameters to be used by the CPU  102  when performing numerical calculation, information processing, device control and so on. 
     The internal bus  108  is a path for data exchange inside the distribution server  100 . The CPU  102 , the ROM  104  and the RAM  106  are connected to each other through the internal bus  108 . The internal bus  108  is also connected to the input/output interface  110  and supplies a signal corresponding to a command input via the input portion  114  and a signal transmitted via the network interface  118  from the information processing apparatus  200  that are sent through the input/output interface  110  to the CPU  102 . 
     The input/output interface  110  mediates input and output of information. The input/output interface  110  is connected to the display portion  112 , the input portion  114 , the HDD  116 , the network interface  118  and the external interface  119 . The input/output interface  110  is also connected to the internal bus  108  as described above and supplies a signal corresponding to a command input via the input portion  114  and a signal transmitted via the network interface  118  from the information processing apparatus  200  to the CPU  102  through the internal bus  108 . 
     The display portion  112  displays information about an input from the input portion  114 , a result of performing numerical calculation, information processing, device control or the like in the CPU  102 , and so on. The display portion  112  may be a cathode ray tube (CRT), a liquid crystal display device, an organic electroluminescence (EL) display device or the like, for example. 
     The input portion  114  is operated by an administrator of the distribution server  100 , for example, when inputting various kinds of commands to the CPU  102 . The input portion  114  may be a keyboard, a mouse, a touch pad, a pen tablet or the like, for example. 
     The HDD  116  has a hard disk inside and drives the hard disk to record or play back program or information (e.g. music data) that are read out and executed by the CPU  102 . 
     The network interface  118  is connected to the network  20  and exchanges information with the information processing apparatus  200  or the like over the network  20 . The external interface  119  mediates exchange of information with a peripheral device that is connected to the distribution server  100 . The external interface  119  may be a universal serial bus (USB) port or the like, for example. An information input device such as a keyboard and a mouse, which is an example of the input portion  114 , may be used by being connected to the external interface  119 . 
     The hardware configuration of the distribution server  100  according to one embodiment of the present invention is described in the foregoing with reference to  FIG. 2 . In the following, the functional configuration of the distribution server  100  according to one embodiment of the present invention is described. 
       FIG. 3  is an explanatory view illustrating the functional configuration of the distribution server  100  according to one embodiment of the present invention. The functional configuration of the distribution server  100  according to one embodiment of the present invention is described hereinafter with reference to  FIG. 3 . 
     Referring to  FIG. 3 , the distribution server  100  according to one embodiment of the present invention includes a music storage portion  124 , a storage monitoring portion  126 , a music information database  128 , a music analysis portion  130 , a metadata reception portion  132 , a music selection portion  134  and a music distribution portion  136 . 
     The music storage portion  124  stores a music file  122  that is music data converted into a file format. The music file  122  is created by encoding music according to a standard such as MP3 or ATRAC. In the music file  122 , music and basic information about the music such as an artist who sings or plays the music, a single or album title that includes the music, a playback time, a lyric writer name, a music composer name, a release year and a genre of the music are recorded. The music storage portion  124  may be a particular folder that is created inside the HDD  116  so as to store the music file  122 , for example. 
     The storage monitoring portion  126  periodically monitors new storage of the music file  122  into the music storage portion  124 . When the storage monitoring portion  126  detects that the music file  122  is newly stored into the music storage portion  124 , the storage monitoring portion  126  registers basic information (e.g. a music title, an artist name, a single or album title that includes the music etc.) about the newly stored music file  122  into the music information database  128 . The storage monitoring portion  126  may be a resident program that is stored in the HDD  116 , for example, and programmed to monitor new storage of a music file into a prescribed folder on a regular basis. 
     The music information database  128  records information about music with respect to the music file  122  that is stored in the music storage portion  124 . The music information database  128  is stored inside the distribution server  100 , such as in the HDD  116 , for example. The music information database  128  also records information about the tune of music that is obtained as a result of analyzing the music file  122  that is newly stored into the music storage portion  124  by the music analysis portion  130 , which is described later. The information about the tune of music may be “music suitable for morning wake-up”, “heavy rock music” and so on, for example, which are determined by analyzing the tempo, rhythm or the like of music. 
     Further, the music information database  128  may store a uniform resource locator (URL) on the Internet for purchasing music so as to enable purchase of music from a website on the Internet. 
     The music analysis portion  130  analyzes the music file  122  that is stored in the music storage portion  124  and obtains information about the tune of music. The information about the tune of music that is obtained as a result of analyzing the music file  122  by the music analysis portion  130  is recorded into the music information database  128 . 
     The processing of analyzing the music file  122  by the music analysis portion  130  may be performed using the technique disclosed in Japanese Patent Application Publication No. 2005-275068, for example. Japanese Patent Application Publication No. 2005-275068 discloses the method that divides an audio signal which is divided into a plurality of frequency ranges (e.g. 12 frequency ranges) into a plurality of octave signals by means of downsampling and analyzes the divided octave signals by means of filtering. 
     In order to use the technique disclosed in Japanese Patent Application Publication No. 2005-275068, the music analysis portion  130  may include an octave dividing means that performs downsampling of an audio signal by dividing it into a plurality of frequency ranges so as to divide the audio signal into a plurality of octave signals and a filtering means that performs filtering of the divided octave signals. 
     The metadata reception portion  132  receives metadata that is transmitted from the information processing apparatus  200 . As described later, when the information processing apparatus  200  plays back music, it transmits information about the currently played back music (the information about the music that is being played back in the information processing apparatus  200  is referred to hereinafter as “playback music information”) to the music distribution server  100  via the network  20 . In this embodiment, the playback music information is transmitted to the music distribution server  100  in the form of metadata. 
     The music selection portion  134  selects music from the music storage portion  124  that stores the music file  122  based on the playback music information, which is information about the music being played back in the information processing apparatus  200 , that is contained in the metadata received by the metadata reception portion  132 . When selecting music, the music selection portion  134  refers to the music information database  128  and selects music that matches information about the music being played back in the information processing apparatus  200  from the music storage portion  124 . 
     When the music selection portion  134  selects music, it may select music of the same artist from the music storage portion  124 . By selecting music of the same artist, a user of the music distribution system  10  might be able to find music of the artist that is unknown to the user, so that the user is provided with new finding. 
     Besides music of the same artist, the music selection portion  134  may select music of the same feature (e.g. a music tune, a tempo etc.) from the music storage portion  124 . By providing music to a user in terms of the tune of music, not limited to the same artist, it is possible to provide a user with significantly new finding about music compared with the case of selecting music of the same artist. 
     The number of music that is selected by the music selection portion  134  may be one or two or more. The music that is selected by the music selection portion  134  may be the one that is given priority pursuant to a recommendation of a music distributor or a music label. The music selection portion  134  may be in the form of a computer program that is recorded inside the distribution server  100  (e.g. in the HDD  116 ) and read and executed by the CPU  102 . 
     The music distribution portion  136  distributes the music selected by the music selection portion  134  via the network  20  to the information processing apparatus  200  from which playback music information is transmitted. 
     When the distribution server  100  distributes music to the information processing apparatus  200 , the whole or a part of the music may be distributed. In the case of distributing a part of the music, the part for a prescribed time from the beginning of the music, or the chorus part of the music may be distributed. 
     The configuration shown in  FIG. 3  includes the storage monitoring portion  126 , and when the storage monitoring portion  126  detects that the music file  122  is newly stored into the music storage portion  124 , basic information about the newly stored music file  122  is recorded into the music information database  128  in this embodiment. The present invention, however, is not limited thereto. For example, when music is stored into the distribution server  100 , basic information about the newly stored music file may be recorded into the music information database  128  manually by an administrator of the distribution server  100 , and the stored music file may be analyzed using a dedicated program and an analysis result may be recorded into the music information database  128  manually. 
     The functional configuration of the distribution server  100  according to one embodiment of the present invention is described in the foregoing. In the following, the hardware configuration of the information processing apparatus  200  according to one embodiment of the present invention is described. 
       FIG. 4  is an explanatory view illustrating the hardware configuration of the information processing apparatus  200  according to one embodiment of the present invention. The hardware configuration of the information processing apparatus  200  according to one embodiment of the present invention is described hereinafter with reference to  FIG. 4 . 
     Referring to  FIG. 4 , the information processing apparatus  200  according to one embodiment of the present invention includes a CPU  202 , ROM  204 , RAM  206 , an internal bus  208 , an input/output interface  210 , a display portion  212 , an input portion  214 , an audio output portion  215 , a HDD  216 , a drive  217 , a network interface  218  and an external interface  219 . 
     The CPU  202  performs numerical calculation, information processing, device control and so on, like the CPU  102  described earlier. The CPU  202  performs numerical calculation, information processing and device control by sequentially reading a program stored in the ROM  204  or data stored in the RAM  206 , or based on a signal corresponding to a command input via the input portion  214  by a user of the information processing apparatus  200 , for example, or a signal transmitted via the network interface  218  from the distribution server  100 . 
     The ROM  204  stores fixed data that is basically not altered in programs and operation parameters to be used by the CPU  202  when performing numerical calculation, information processing, device control and so on, like the ROM  104  described earlier. The RAM  206  stores data that basically varies during processing in programs and operation parameters to be used by the CPU  202  when performing numerical calculation, information processing, device control and so on, like the RAM  106  described earlier. 
     The internal bus  208  is a path for data exchange inside the information processing apparatus  200 , like the internal bus  108  described earlier. The CPU  202 , the ROM  204  and the RAM  206  are connected to each other through the internal bus  208 . The internal bus  208  is also connected to the input/output interface  210  and supplies a signal corresponding to a command input via the input portion  214  and a signal transmitted via the network interface  218  from the distribution server  100  that are sent through the input/output interface  210  to the CPU  202 . 
     The input/output interface  210  mediates input and output of information, like the input/output interface  110  described earlier. The input/output interface  210  is connected to the display portion  212 , the input portion  214 , the audio output portion  215 , the HDD  116 , the drive  217 , the network interface  218  and the external interface  219 . The input/output interface  210  is also connected to the internal bus  208  as described above and supplies a signal corresponding to a command input via the input portion  214  and a signal transmitted via the network interface  218  from the distribution server  100  to the CPU  202  through the internal bus  208 . 
     The display portion  212  displays information about an input from the input portion  214 , a result of performing numerical calculation, information processing, device control or the like in the CPU  202  and so on, like the display portion  112  described earlier. The display portion  212  may be a CRT, a liquid crystal display device, an organic EL display device or the like, for example. 
     The input portion  214  is operated by a user of the information processing apparatus  200 , for example, when inputting various kinds of commands to the CPU  202 . The input portion  214  may be a keyboard, a mouse, a touch pad, a pen tablet or the like, for example. 
     The audio output portion  215  outputs a sound that is generated when the information processing apparatus  200  executes processing that accompanies the output of a sound. In this embodiment, when playing back music data that is stored in the HDD  216  or distributed from the distribution server  100 , music is output from the audio output portion  215 , so that a user of the information processing apparatus  200  can enjoy the music. 
     The HDD  216  has a hard disk inside and drives the hard disk to record or play back program or information (e.g. music data) that are read out and executed by the CPU  202 . A portable recording medium is inserted into the drive  217 , and data is exchanged between the inserted recording medium and the information processing apparatus  200 . A portable recording medium may be a magnetic disk, an optical disk, a magneto-optical disk, a semiconductor memory or the like, and the drive  217  may be a device capable of reading such a recording medium. 
     The network interface  218  is connected to the network  20  and exchanges information with the distribution server  100  or the like via the network  20 . The external interface  219  mediates exchange of information with a peripheral device that is connected to the information processing apparatus  200 . The external interface  219  may be a USB port or the like, for example. An information input device such as a keyboard and a mouse, which is an example of the input portion  214 , may be used by being connected to the external interface  219 . 
     The hardware configuration of the information processing apparatus  200  according to one embodiment of the present invention is described in the foregoing with reference to  FIG. 4 . In the following, the functional configuration of the information processing apparatus  200  according to one embodiment of the present invention is descried. 
       FIG. 5  is an explanatory view illustrating the functional configuration of the information processing apparatus  200  according to one embodiment of the present invention. The functional configuration of the information processing apparatus  200  according to one embodiment of the present invention is descried hereinafter with reference to  FIG. 5 . 
     Referring to  FIG. 5 , the information processing apparatus  200  according to one embodiment of the present invention includes a music storage portion  224 , a music acquisition portion  225 , a storage monitoring portion  226 , a music information database  228 , a music analysis portion  230 , a music reception portion  232 , a control portion  233 , a music playback portion  234 , a metadata creation portion  235 , a metadata acquisition portion  236  and a metadata transmission portion  237 . 
     The music storage portion  224 , the storage monitoring portion  226 , the music information database  228  and the music analysis portion  230  have the similar functions as the music storage portion  124 , the storage monitoring portion  126 , the music information database  128  and the music analysis portion  130  in the distribution server  100  described earlier. 
     The music storage portion  224  stores a music file  222  that is music data converted into a file format. The music file  222  is created by encoding music according to a standard such as MP3 or ATRAC. In the music file  222 , music and basic information about the music such as an artist who sings or plays the music, a single or album title that includes the music, a playback time, a lyric writer name, a music composer name, a release year and a genre of the music are recorded. The music storage portion  224  may be a particular folder that is created inside the HDD  216  so as to store the music file  222 , for example. 
     The music acquisition portion  225  acquires music data that is stored in the music storage portion  224 . In this embodiment, the music acquisition portion  225  acquires music data from the music storage portion  224  based on information contained in metadata that is acquired by the metadata acquisition portion  236 , which is described later. 
     The storage monitoring portion  226  periodically monitors new storage of the music file  222  into the music storage portion  224 . When the storage monitoring portion  226  detects that the music file  222  is newly stored into the music storage portion  224 , the storage monitoring portion  226  registers basic information (e.g. an artist name, a single or album title etc.) about the newly stored music file  222  into the music information database  228 . 
     The music information database  228  records information about music with respect to the music file  222  that is stored in the music storage portion  224 . The music information database  228  is stored inside the information processing apparatus  200 , such as in the HDD  216 , for example. The music information database  228  also records information about the tune of music that is obtained as a result of analyzing the music file  222  that is newly stored into the music storage portion  224  by the music analysis portion  230 , which is described later. The information about the tune of music may be “music suitable for morning wake-up”, “heavy rock music” and so on, for example, which are determined by analyzing the tempo, rhythm or the like of music. 
     The music analysis portion  230  analyzes the music file  222  that is stored in the music storage portion  224  and obtains information about the tune of music. The information about the tune of music that is obtained as a result of analyzing the music file  222  by the music analysis portion  230  is recorded into the music information database  228 . 
     The processing of analyzing the music file  222  in the music analysis portion  230  may be performed using the technique disclosed in Japanese Patent Application Publication No. 2005-275068, for example, like the processing in the music analysis portion  130  described earlier. In order to use the technique disclosed in Japanese Patent Application Publication No. 2005-275068, the music analysis portion  230  may include an octave dividing means that performs downsampling of an audio signal by dividing it into a plurality of frequency ranges so as to divide the audio signal into a plurality of octave signals and a filtering means that performs filtering of the divided octave signals. 
     The music reception portion  232  receives music data that is distributed from the distribution server  100  over the network  20 . The music data that is received by the music reception portion  232  may be stored into the music storage portion  224  so as to be played back by the music playback portion  234 , which is described later, or put into the music playback wait state in the music playback portion  234  without being stored into the music storage portion  224 . 
     The control portion  233  controls the music playback portion  234 , which is described later, so as to playback the music data that is distributed from the distribution server  100  and the music data that is acquired from the music storage portion  224  by the music acquisition portion  225 . 
     The music playback portion  234  plays back the music file  222  that is stored in the music storage portion  224  and the music data that is distributed from the distribution server  100 . The music playback portion  234  is capable of playing back the music having the same or similar feature (e.g. a music tune, a music tempo etc.) in succession. During playback, the music playback portion  234  sequentially plays back the music that is stored in the music storage portion  224  and the music that is distributed from the distribution server  100 . 
       FIG. 6  is an explanatory view illustrating a music playback application  242 , which is an example of the music playback portion  234  according to one embodiment of the present invention. The configuration of the music playback application  242  is described hereinafter with reference to  FIG. 6 . 
     The music playback application  242  provides music playback function by means of graphical user interface (GUI), and a user of the music playback application  242  can play back music data by manipulating, through mouse clicking or the like, a button or the like that is displayed on the music playback application  242 . The music playback application  242  is stored in the HDD  216  of the information processing apparatus  200 , for example, and, when activated by a user, the music playback application  242  provides the music playback function. The music playback application  242  includes a music playback window  244  that performs processing related to music playback and a music information window  246  that displays information about the music being played back in the music playback window  244  or the like. 
     The music playback window  244  is a screen that receives various kinds of user operations related to music playback. The function of each portion of the music playback window  244  is described hereinbelow. 
     The numeral  248  indicates the channel of music that is played back by the music playback application  242  and the number of pieces of music that belong to the channel. The channel is associated with the feature (e.g. a music tune, a music tempo etc.) of music that is obtained as a result of analysis in the music analysis portion  230 . If a certain channel is selected and played back, music data that belong to the selected channel are sequentially played back. 
     The buttons denoted by  250   a  and  250   b  are channel selection buttons for selecting a channel. By manipulating the channel selection buttons denoted by  250   a  and  250   b  through mouse clicking or the like, a channel to be played back can be selected. 
     The button denoted by  252  is a playback/stop button for playing back or stopping music. If the playback/stop button is manipulated through mouse clicking or the like when music is played back, playback of the music stops, and if the playback/stop button is manipulated through mouse clicking or the like when music stops, playback of the music resumes from the part at which the music stops. 
     The buttons denoted by  254   a  and  254   b  are skip buttons for skipping music. If the skip button denoted by  254   a  is manipulated through mouse clicking or the like, playback starts by skipping to one track before the currently played back music, and if the skip button denoted by  254   b  is manipulated through mouse clicking or the like, playback starts by skipping to one track after the currently played back music. 
     The numeral  256  is a volume control portion for controlling the volume of music that is played back by the music playback application  242  through manipulation of a slide bar. By manipulating the volume control portion, the volume of the music that is output from the audio output portion  215  can be controlled. 
     The function of each portion of the music playback window  244  is described above. 
     The music information window  246  displays information about the music being played back in the music playback window  244  or the like. For example, if the music being played back in the music playback window  244  is music that is distributed from the distribution server  100 , a website on the Internet for purchasing the music or an album including the music may be displayed as the information displayed in the music information window  246 . 
     The configuration of the music playback application  242  is described in the foregoing. 
     The metadata creation portion  235  creates playback music information in the form of metadata in order to transmit playback music information in the form of metadata to the distribution server  100  while music is being played back in the music playback portion  234 . The metadata that is created in the metadata creation portion  235  is acquired by the metadata acquisition portion  236 . The metadata that is acquired by the metadata acquisition portion  236  is supplied to the metadata transmission portion  237 . The playback music information includes information such as an artist name, a music title, an album name, a channel name corresponding to the tune, a lyric writer name, a music composer name, a release year and a genre of the music being played back. 
     The metadata acquisition portion  236  acquires the metadata that is created by the metadata creation portion  235 . The metadata that is acquired by the metadata acquisition portion  236  is sent out to the network  20  from the metadata transmission portion  237 . 
     The metadata transmission portion  237  transmits the metadata of the playback music information that is generated in the music playback portion  234  to the distribution server  100  via the network  20 . By transmitting the playback music information from the information processing apparatus  200  to the distribution server  100 , the distribution server  100  can analyze the playback music information and select the music to be distributed to the information processing apparatus  200  from which the playback music information is transmitted. 
     The destination of transmitting metadata from the metadata transmission portion  237  is previously registered in the information processing apparatus  200 . For example, URL of the distribution server  100  may be specified by the setting of the music playback application  242 , and the metadata may be transmitted to the specified URL of the distribution server  100  from the metadata transmission portion  237 . 
     The functional configuration of the information processing apparatus  200  according to one embodiment of the present invention is described in the foregoing. In the following, the operation of the music distribution system  10  according to one embodiment of the present invention is described. The process of registering music information into the music information database  128  in the distribution server  100  is described firstly. 
       FIG. 7  is a flowchart illustrating the process of registering music information into the music information database  128  according to one embodiment of the present invention. The process of registering music information into the music information database  128  according to one embodiment of the present invention is described hereinafter with reference to  FIG. 7 . 
     First, the music file  122  is stored into a monitoring target folder as the music storage portion  124  to be monitored by the storage monitoring portion  126  (step S 102 ). When the music file is stored into the monitoring target folder, the storage monitoring portion  126  detects new storage of music into the monitoring target folder (step S 104 ). 
     When the storage monitoring portion  126  detects new storage of music into the monitoring target folder, basic information of the newly stored music is registered into the music information database  128  (step S 106 ). The basic information of music contains a music title, an artist name, a single or album title including the music and so on, as described earlier. 
     After the basic information of the newly stored music is registered into the music information database  128 , the music analysis portion  130  analyzes the newly stored music and obtains information about the tune of the music (step S 108 ). Then, the analysis result of the music in the music analysis portion  130  is additionally registered into the music information database  128  (step S 110 ). 
       FIG. 8  is an explanatory view illustrating an example of information that is registered in the music information database  128  according to one embodiment of the present invention. In the example of  FIG. 8 , information that contains a music title, an artist name, an album including the music, a channel to which the music belongs that is obtained as a result of analyzing the music, a distribution priority of the music, URL for purchasing the music is registered in the music information database  128 . 
     The URL for purchasing the music may be manually input after music information is registered into the music information database  128 , or it may be registered by a computer program that automatically registers URL retrieved by searching the Internet based on an artist name, an album title or the like. 
     The process of registering music information into the music information database  128  according to one embodiment of the present invention is described in the foregoing. Although the process of registering music information into the music information database  128  in the distribution server  100  is described above, the process of registering music information into the music information database  228  in the information processing apparatus  200  is also performed in the same manner as shown in  FIG. 7 . In the music information database  228  in the information processing apparatus  200 , information necessary for music distribution such as a distribution priority of music, URL for purchasing music may not be stored. 
     The process of transmitting music information from the information processing apparatus  200  to the distribution server  100  according to one embodiment of the present invention is described next.  FIG. 9  is a flowchart illustrating the process of transmitting music information from the information processing apparatus  200  to the distribution server  100  according to one embodiment of the present invention. 
     Firstly, the music playback portion  234  in the information processing apparatus  200  starts playback of the music file  222  that is stored in the music storage portion  224  (step S 112 ). After the music playback portion  234  starts playback of the music file  222 , it acquires playback music information by reading information about the currently played back music from the music information database  228  (step S 114 ). The playback music information acquired in this step may contain information about a channel to which the music belongs in addition to basic information of the music such as a music title, an artist name and an album title including the music. 
     After acquiring the playback music information by reading information about the music from the music information database  228 , the metadata creation portion  235  creates metadata from the acquired playback music information (step S 116 ). The metadata that is created in the metadata creation portion  235  is acquired by the metadata acquisition portion  236  (step S 118 ), and the metadata that is acquired by the metadata acquisition portion  236  is transmitted from the metadata transmission portion  237  to the distribution server  100  (step S 120 ). The destination of transmitting the metadata of the playback music information from the metadata transmission portion  237  is previously set to the information processing apparatus  200  as described above. The metadata transmission portion  237  transmits the metadata of the playback music information to the specified location. 
     The process of transmitting music information from the information processing apparatus  200  to the distribution server  100  according to one embodiment of the present invention is described in the foregoing. The process of distributing music data from the distribution server  100  to the information processing apparatus  200  according to one embodiment of the present invention is described below. 
       FIG. 10  is a flowchart illustrating the process of distributing music data from the distribution server  100  to the information processing apparatus  200  according to one embodiment of the present invention. The process of distributing music data from the distribution server  100  to the information processing apparatus  200  according to one embodiment of the present invention is described hereinafter with reference to  FIG. 10 . 
     In the process of distributing music data from the distribution server  100  to the information processing apparatus  200 , the metadata reception portion  132  first receives metadata of playback music information that is transmitted from the information processing apparatus  200  (step S 122 ). 
     After receiving the metadata of the playback music information that is transmitted from the information processing apparatus  200 , the music selection portion  134  analyzes the received metadata of the playback music information. The music selection portion  134  analyzes the metadata of the playback music information and acquires a music file or a music list of a channel that matches the channel to which the music belongs that is contained in the metadata of the playback music information from the music storage portion  124  (step S 124 ). The music list is a collection of a plurality of music files. Thus, the music selection portion  134  may select a single music file or a plurality of music files. 
     In the case of selecting a plurality of pieces of music, the music selection portion  134  may select music with a high priority that is registered in the music information database  128 . Further, in the case of selecting a plurality of pieces of music, it is preferred to set an upper limit to the number of pieces of music to be selected in order to prevent distribution of a large number of pieces of music at a time to the information processing apparatus  200 . 
     After the music selection portion  134  acquires a music file or a music list from the music storage portion  124 , the music distribution portion  136  distributes the acquired music file or music list to the information processing apparatus  200  from which the metadata of the playback music information is transmitted (step S 126 ). The distributed music file or music list reaches the information processing apparatus  200  through the network  20 . 
     Although the music file is distributed to the information processing apparatus  200  when the music distribution portion  136  performs distribution in the above-described step S 126  in this embodiment, the present invention is not limited thereto. For example, so-called streaming distribution in which the distributed music is played back in the information processing apparatus  200  but not stored into the information processing apparatus  200  may be performed. When performing the streaming distribution, metadata that describes information about distributed music may be transmitted from the distribution server  100  to the information processing apparatus  200 . 
     By receiving the distribution of music data from the distribution server  100 , the information processing apparatus  200  can play back not only the music file that is stored in the music storage portion  224  but also the music data that is distributed over the network in the music playback portion  234 . When the music playback portion  234  plays back music, the control portion  233  makes control so as to play back the music file stored in the music storage portion  224  and the music data distributed over the network which have the same or similar feature (e.g. the same channel). The music file stored in the music storage portion  224  is acquired by the music acquisition portion  225 , and the acquired music data is played back in the music playback portion  234 . 
     When the music selection portion  134  selects a music file or a music list, it may select music of the same artist, besides music belonging to the same channel as the music being played back in the information processing apparatus  200 . 
     Further, when the music playback portion  234  plays back music by specifying a channel, the playback ratio between the music belonging to the specified channel that is stored locally (i.e. stored in the music storage portion  224 ) and the music belonging to the specified channel that is distributed over the network may be set. The playback ratio may be set from a setting screen of the music playback application  242  or may be determined arbitrarily in the music distribution end by distributing information about the playback ratio between the music stored locally and the music distributed over the network from the distribution server  100  to provide music, for example. 
     Furthermore, when the distribution server  100  distributes music data to the information processing apparatus  200 , it may distribute information about URL for purchasing the music in addition to the music data. By distributing the information about URL for purchasing the music in addition to the music data, it is possible to display a website on the Internet for purchasing the music or an album including the music in the music information window  246  when playing back the distributed music in the music playback application  242  that is executed in the information processing apparatus  200 . If a user likes the distributed music, the user can purchase the music or the album including the music from the displayed website. 
     The process of distributing music data from the distribution server  100  to the information processing apparatus  200  according to one embodiment of the present invention is described in the foregoing. 
     As described above, according to one embodiment of the present invention, the distribution server  100  analyzes metadata of playback music information that is transmitted from the information processing apparatus  200 , selects music belonging to the same channel as the music being played back in the information processing apparatus  200 , and distributes the music data to the information processing apparatus  200  from which the metadata of the playback music information is transmitted, thereby allowing a user of the information processing apparatus  200  to find new music. 
     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. 
     For example, although when the information processing apparatus  200  transmits metadata of playback music information to the distribution server  100 , the metadata is created by acquiring the playback music information about the currently played back music from the music information database in the above-described embodiment, the present invention is not limited thereto. For example, a record of the music that has been played back in the music playback portion  234  may be held inside the information processing apparatus  200  (e.g. in the HDD  216 ), and the record of the played back music may be transmitted in the form of metadata from the metadata transmission portion  237  to the distribution server  100 . 
     Then, receiving the record of the music that has been played back in the music playback portion  234  from the information processing apparatus  200 , the distribution server  100  may select music to be distributed to the information processing apparatus  200  based on the received record by means of the music selection portion  134 . For example, if the rate of playing back Japanese music is high, the music selection portion  134  may select a relatively large number of pieces of Japanese music that belong to the channel of the music being played back in the music playback portion  234  from the music storage portion  124  of the distribution server  100 , and if the rate of playing back classical music is high, the music selection portion  134  may select a relatively large number of pieces of classical music that belong to the channel of the music being played back in the music playback portion  234  from the music storage portion  124  of the distribution server  100 . 
     Further, in the case of performing streaming distribution in which music data is not stored into the information processing apparatus  200  when distributing music from the distribution server  100 , the record of the music that has been distributed from the distribution server  100  and information (e.g. a music title, an artist name, an album title, a channel to which the music belongs etc.) about the music that has been distributed from the distribution server  100  and played back may be held inside the information processing apparatus  200  (e.g. in the HDD  216 ), so that they can be referred to from an application or the like (e.g. the music playback application  242 ) later. By enabling reference to the record of the music that has been distributed from the distribution server  100 , a user can check information about the music that is distributed by streaming, so that it is possible to find out a music title when a user forgets the title of the music which the user likes. 
     Although metadata that describes information about music to be played back is created in the metadata creation portion  235  and the created metadata is transmitted from the metadata transmission portion  237  when playing back the music in the information processing apparatus  200  in the above-described embodiment, the present invention is not limited thereto. For example, metadata that describes information about music may be created in advance before playing back music in the information processing apparatus  200 , and upon playback of the music, the metadata that describes information about the music to be played back may be acquired by the metadata acquisition portion  236  and transmitted from the metadata transmission portion  237 . 
     Further, although the case where data that is handled in the music distribution system  10  is music data is described in the above-described embodiment, the present invention is not limited thereto. For example, instead of music data, content data such as animation data and video data may be distributed and played back in the information processing apparatus  200 . In such a case, besides the feature of music (e.g. a music tune and a music tempo) that is obtained as a result of analysis in the music analysis portion  230 , the feature of an image (e.g. a color, a subject etc.) that is obtained by analyzing the image of animation data or video data may be stored as information about moving images. Then, content data having the same or similar feature as the content data played back in the information processing apparatus  200  may be received from the distribution server  100 , thereby improving the content availability for a user. 
     Furthermore, although the music distribution system  10  in which the distribution server  100  and the information processing apparatus  200  are connected over the network is described in the above-described embodiment, the present invention is not limited thereto. For example, an information processing apparatus and another information processing apparatus may be connected to a home network, or an information processing apparatus and another information processing apparatus may be directly connected via peer to peer (P2P) to exchange content data between the information processing apparatus and the other information processing apparatus. 
     Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims.