JP4186066B2 - Client device - Google Patents

Description

  The present invention relates to a client device.

  For example, in order to be able to enjoy audio contents such as music in each room in the home, a network system may be constructed as shown in FIG. At this time, audio contents are prepared in the media server, and an audio playback function is added to the client device to constitute a network audio device. By doing so, audio content can be distributed from the media server to the client device in each room, and music or the like can be listened to in each room (hereinafter referred to as “media server” and “client device” as appropriate). Abbreviated as "server" and "client").

  In such a network audio system, when distributing digital audio data from the server to the client, it is conceivable to use TCP / IP as the protocol. This TCP / IP has become widespread with the development of the Internet and can not only sufficiently withstand the transmission of digital audio data from the viewpoint of transmission speed and reliability, but also the cable can be extended to a maximum of 100 m. Audio content can be distributed anywhere.

  In addition, when considering the communication band, since it is possible to transmit a plurality of digital audio data at a time if the transmission is about the same as the digital audio data, a plurality of servers having a high processing capability are prepared. You can also enjoy separate music in the room at the same time. In addition, since audio contents are prepared in the server, a large number of audio contents can be prepared and managed in an integrated manner.

For example, there are the following prior art documents.
Japanese Patent Laid-Open No. 2001-109877

  Assume that the server stores five directories A to E and 12 files 1 to 12 in a tree structure (hierarchical structure) as shown in FIG. 11, for example. That is, directories A and E and files 11 and 12 are included in the root directory Root, directory B includes files B and 6 to 9, directory B includes directories C and D, and directory C includes Files 1 to 3 are present.

  When a general personal computer or workstation accesses such a server, the display used for those computers has a high display capability, so the directories and files have a tree structure as shown in FIG. However, the tree structure can be displayed on the display as it is, so that the user can easily select the target file with a mouse or the like.

  However, since a client (network audio device) in network audio is configured to have the same appearance as a general audio device, the mounted display has low display capability and can display only about 15 characters per line. Therefore, the client in the network audio cannot display the tree structure as shown in FIG. 11 as it is. Also, you cannot use a mouse to select a file.

  As a result, when the target file is selected from the hierarchy as shown in FIG. 11, for example, the root directory Root → directory A → directory B → directory C → file 1 is sequentially visited through each hierarchy of the tree. As a result, it takes a lot of work, and you may not be able to find files at the lowest level. Further, in the CE device, it is necessary to consider cost in addition to usability.

  The present invention is intended to solve the above problems.

In this invention,
A communication block that communicates with a server that provides content via a network;
First and second operating means;
Display,
Control circuit,
The communication block receives information indicating the storage state of the content from the server,
The control circuit is
The information received by the communication block is mapped to a two-level tree of a directory and files contained in the directory,
When the first operating means is operated, the mapped directories are sequentially selected, and information indicating the selected directory is displayed on the display.
When the second operation means is operated, at least information indicating files included in the directory selected at this time is sequentially displayed on the display.

  According to the present invention, even if the content has a complicated tree structure in the server, the content is mapped and displayed on a simple tree of two layers, so that the content can be displayed even if the display capability of the display is low. Can be displayed, and the contents can be acquired.

  In addition, the tree display is simplified to two levels, and a key for selecting a directory and a key for selecting a file are provided, so that the operation itself becomes simple and easy. Since simplified display and operation can be implemented, a network-compatible client machine can be provided to the user at low cost. In addition, this makes it possible to differentiate from competing network CE devices.

1 UPnP (R) Here, UPnP (R), which is one of protocol groups that can be used in a network audio system, will be described.

1-1 Configuration of UPnP (R) In order to play audio content using UPnP (R), it is necessary to comply with the UPnP (R) AV equipment and service regulations called UPnP (R) AV architecture. UPnP (R) AV equipment based on UPnP (R) AV architecture
Media server: A device that provides audio content Control point: Operation system, control terminal Media renderer: Audio signal processing system, audio playback device Therefore, the server in FIG. 10 constitutes a media server, and the network audio device (client) constitutes a control point and a media renderer.

1-2 UPnP (R) Function UPnP (R) is one of communication functions composed of IP, TCP, UDP, etc. on a network such as Ethernet (registered trademark). It is a group of protocols that enable devices to easily authenticate each other and provide services and execute the services provided.

Therefore, UPnP® has a protocol stack as shown in FIG. The UPnP (R) device has the following six functions (1) to (6). That is,
(1) Addressing
A function for UPnP® devices to obtain an IP address on the IEEE 802 network. DHCP or automatic acquisition is used.

(2) Discovery
Function to detect UPnP (R) devices. This is performed after addressing, and the control point can detect the UPnP (R) device to be controlled.
The protocol used here is SSDP. When each device is connected to the IEEE 802 network, it multicasts a message for notifying its own devices and services on the IEEE 802 network.
The control point can know what device is connected to the IEEE 802 network by receiving the multicast message.

(3) Description (Description)
Function to know the details of the function of the counterpart device. A device description URL is described in the SSDP packet output from the control target device discovered by the control point by the discovery. The control point can acquire more detailed device information of the device from the device description by accessing the URL.
This device information includes icon information, model name, producer name, product name, service description in which detailed information on the service of the device is described, and the like. The control point can know the access method to the target from these device descriptions and service descriptions. The device description and service description are expressed in XML.

(4) Control
Function to control the other device. This control is roughly classified into two types, “Action” and “Query”. The action is performed by a method defined in the action information of the service description, and the control point can operate the target by performing the action (Invoke).
The query is used to retrieve the value of device information (stateVariable) of the service description. In the control, a transport protocol called SOAP is used, and XML is used as the expression.

(5) Eventing
A function that notifies the other device of the situation. This eventing is used to notify the control point from the target when the value of the device information is changed. The control point can know the variable held by the target from the device information by analyzing the service description for the target, and can receive a notification from the target when the variable is changed.
In eventing, a transport protocol called GENA is used, and XML is used as its expression.

(6) Presentation
The ability to publish your own functions. This presentation is used to provide the user with control means using a user interface. By accessing the presentation URL described in the device description, a presentation page described in HTML can be obtained. This function makes it possible to prepare an application on the target.

1-3 Functions of Media Server A function called CDS is indispensably incorporated in the media server, and notifies the control point how content is stored in the media server. There are two abstracted objects in CDS called “containers” and “items”. Simply put,
Item: Content or its file.
Container: Group when items are grouped. directory.
It is. The containers and items always have a tree structure (hierarchical structure), and the tree structure in FIG. 11 is an example.

  The control point can obtain URLs (links on which information is written) of each content by acquiring tree information having a tree structure as shown in FIG. 11 from the media server, for example. In addition, when information of desired content (item) can be acquired, operations such as playback and stop of content can be performed using a function called AV transport of the media server.

2. Network Audio Machine (Client) Here, a network audio machine will be described, but the network audio system uses the above-described UPnP®.

2-1. Configuration of Network Audio Machine In FIG. 1, reference numeral 20 denotes an example of a network audio machine, and the network audio machine 20 includes a media renderer 30 and a control point 40. The media renderer 30 is an audio signal processing system. In this example, the media renderer 30 includes an RJ-45 modular jack 31, a communication block 32, an equalizer 33, a D / A converter 34, and output amplifiers 35L and 35R. Is done.

  In this case, the modular plug 61 is inserted into the modular jack 31, and the network audio device 20 is connected to the UPnP® media server through the network through the plug 61 and the LAN cable 62 as shown in FIG. Is done.

  The communication block 32 is an LSI for realizing Ethernet (registered trademark) communication, analyzes packets transmitted and received by TCP / IP, and performs content selection, search, and audio signal reproduction control. is there. Therefore, the communication block 32 is connected to the media server through the modular jack 31 and receives the content sent from the server.

  Furthermore, the equalizer 33 is for performing selection of an input signal and equalizing processing for the selected signal. Therefore, the equalizer 33 is connected to the communication block 32 and supplied with digital audio data, and an analog audio signal is supplied to the A / D converter 38 through the analog input terminals 37L and 37R, and its A / D conversion output is supplied. It is supplied to the equalizer 33. A digital audio signal is supplied to the equalizer 33 through the digital input terminal 39.

  Then, the equalizer 33 selects the signal supplied thereto, performs equalizing processing, and supplies the equalizing output to the D / A converter 34. The D / A converter 34 D / A converts the digital signal supplied thereto into left and right channel analog audio signals L and R, and the output amplifiers 35L and 35R output the D / A conversion result audio signal. L and R are supplied to the speakers 63L and 63R through the output terminals 36L and 36R.

  On the other hand, the control point 40 is a control system of the network audio machine 20, and is constituted by a microcomputer, for example. Therefore, the control point 40 includes a CPU 41 that executes various programs, a ROM 42 in which the programs are written, a RAM 43 for a work area, and a nonvolatile memory 44 that holds various data when the power is turned off. These memories 42 to 44 are connected to the CPU 41 through the system bus 49.

  Further, in the ROM 42, for example, a routine 100 as shown in FIG. 2 is prepared as a part of the program executed by the CPU 41. When the containers and items stored in the media server have a tree structure as shown in FIG. 11, for example, this routine 100 is used to map this to a two-level tree structure as shown in FIG. is there. Although details of the routine 100 will be described later, in FIG. 2, the routine 100 shows only a portion related to the present invention.

  Further, the control point 40 is provided with an operation key 45 and a display 47 as a user interface. In this case, the operation key 45 is configured by a non-lock type push switch, and in addition to the general operation keys, for example, as shown in FIG. 3, forward and reverse content keys KC +, KC-, and forward direction And reverse item keys KI + and KI-. These keys 45 are connected to the system bus 49 through the interface 46.

  The display 47 is composed of a fluorescent display tube, an LCD, or the like. For example, as shown in FIG. 4, the display 47 has a container mark MC and an item mark MI, and displays a character string of one line × 15 characters in a dot matrix. Display area AS. The display 47 is connected to the system bus 49 through the display controller 48.

  Further, the system bus 49 is connected to the communication block 32 through the interface 51, and various data and commands are exchanged between the control point (microcomputer) 40 and the communication block 32.

  A system bus 49 is connected to the equalizer 33 through the interface 52, and the equalizer 33 is controlled by the control point 40. As a result of this control, the digital audio data obtained from each of the communication block 32, the A / D converter 38 and the input terminal 39 is selected by the equalizer 33, and the selected digital audio data is as described above. The equalizing process is executed at the same time.

  When the digital audio data is sent from the media server, the digital audio data is processed and extracted by the communication block 32, equalized by the equalizer 33, and then converted to analog audio signals L and R by the D / A converter 34. Converted. The audio signals L and R are supplied to the speakers 63L and 63R through the amplifiers 35L and 35R and output as sound.

2-2 Tree Structure Mapping Process This is a process for mapping the tree structure of containers and items in the media server to a two-level tree structure as shown in FIG. 5, for example. It is realized by executing. In the following, a case where the tree structure of FIG. 11 is mapped to the tree structure of FIG. 5 will be described as an example.

  When the network audio device 20 is connected to the media server by UPnP® and a predetermined command is sent to the media server, the tree structure information shown in FIG. 11 is sent to the network audio device 20 from the CDS of the media server. come. The tree structure information is extracted from the communication block 32 and supplied to the control point 40.

  Then, in the control point 40, the processing of the CPU 41 starts from step 101 of the routine 100. Next, in step 102, the processing target moves to the highest hierarchy (root directory) of the tree structure of FIG. Hereinafter, the highest hierarchy is regarded as one container, and a temporary name such as “Root” is given. The RAM 43 has a stack area.

  Next, in step 111, it is determined whether or not there is an unprocessed container in the current processing target container. In this case, the current processing target container is the container Root (the highest hierarchy), and the containers A and E are unprocessed. Therefore, the process proceeds from step 111 to step 112. In this step 112, the unprocessed container Move to. In this case, for example, it moves to container A.

  Subsequently, the process proceeds to step 113, where it is determined whether there is an item in the moved container. In this case, the container after movement is container A, and there are items 6-8. If there is an item, the process proceeds from step 113 to step 114, where the name of the container after the movement and the name of the item included in the container are set as one set, and the set is the stack of the RAM 43. Pushed to. In this case, one set of the name of container A and the names of items 6 to 9 is pushed onto the stack.

  The process then proceeds to step 115 where it is determined whether there is an unprocessed container in the current container. In this case, the current container is container A and there is an unprocessed container B. If there is an unprocessed container, the process returns from step 115 to step 112.

  Accordingly, the processing target is moved to the container B in step 112, and then the presence or absence of an item is determined in step 113. However, in this case, since there is no item in the current container B, the processing is performed from step 113 to step 115. Proceed to

  In step 115, it is determined whether or not there is an unprocessed container in the current container. In this case, the current container is container B, and there are unprocessed containers C and D. Therefore, the process returns from step 115 to step 112 as described above. As a result, steps 112 to 114 are executed again, and for container C, one set of the name of container C and the names of items 1 to 3 is pushed onto the stack.

  Subsequently, the process proceeds to step 115, but in this case, since there is no unprocessed container in container C, the process proceeds from step 115 to step 121. In this step 121, the container to be processed is one higher level container. It is determined whether or not it is possible to return to (hierarchy), and in this case, since the container C is returned to the container B, the process proceeds from step 121 to step 122. In this step 122, the process returns to the next higher container, and then The process returns to step 111. In this case, the processing returns to step 111 after the processing target returns to container B.

  Therefore, thereafter, step 111 is executed, and in this case, for container D, one set of the name of container D and the names of items 4 and 5 is pushed onto the stack.

  In this way, steps 111 to 122 are repeated to determine whether or not there is an unprocessed container. If there is an unprocessed container, the name of the container and the name of the item included in the container are determined by step 114. Is pushed onto the stack. At this time, containers that do not contain items in step 113 are not pushed onto the stack.

  For container E, when one set of the name of container E and the names of items 10 and 11 is pushed onto the stack in step 114, the process proceeds from step 115 to step 121 to step 122, and the processing target is While returning to the topmost container Root, the processing returns to Step 111.

  When the process returns to step 111, since there is no unprocessed container in this case, the process proceeds from step 111 to step 113 to determine the presence or absence of an item. In this case, the container Root includes the item 11 , 12 are included, step 114 pushes one set of the name of container Root and the names of items 11 and 12 onto the stack.

  At this time, the specification or format of the item (audio content) is checked, and the item of the specification or format that does not correspond to the network audio device 20 is not pushed onto the stack. Therefore, when all items of a container have a format that cannot be played back by the network audio device 20, the container is not pushed onto the stack.

  Then, the process proceeds to step 115 following step 114. In this case, since there is no unprocessed container in the container Root, the process proceeds from step 121 to step 131. The set of the name of the container pushed to the item and the name of the item are popped in order, and then the routine 100 is ended by step 132.

  In this case, since the container name and the item name are pushed onto the stack as a set in step 114, the result pushed to the stack and the result popped from the stack in step 131 are shown in FIG. As shown, the container name and the item name have a two-level tree structure. That is, the deep hierarchy tree structure as shown in FIG. 12 is mapped to the two hierarchy tree structure as shown in FIG. At this time, since no item is included in the container B in FIG. 12, the container B is not included in the tree in FIG.

  Thus, according to the routine 100, whatever kind of tree structure the containers and items in the media server are mapped to, for example, a two-level tree structure of containers and items as shown in FIG. In this tree structure, all containers are in a higher hierarchy, and items included in the containers are in a lower hierarchy.

  Therefore, when using audio contents stored in the media server, it is necessary to trace a large number of containers to a deep container regardless of the tree structure (for example, FIG. 11) on the media server. There is no need to select a corresponding container and select a target audio content (item) from the container.

2-3 Selection and Playback of Audio Content The present invention is intended to enable extraction of target audio content from a two-level tree mapped as shown in FIG. 5, for example. It is made possible by key operation. In the following, the case of the tree structure of FIG. 5 will be described as an example.

  When the routine 100 described above is executed and a two-level tree structure is mapped, a desired item (audio content) can be subsequently selected. This item selection is realized by selecting a container with the container keys KC + and KC− and selecting an item with the item keys KI + and KI− in the selected container, as will be described below.

2-3-1 Container Selection When the routine 100 is executed and a two-level tree structure is mapped, information indicating the last item (the audio content item that was listened to when the power was turned off last time) is stored in the memory 44. In accordance with the extracted information, the display area AS of the display 47 displays the name of the last item as shown in FIG. 6A, for example. FIG. 6A shows a case where the character “Item 7” is displayed because the last item is item 7.

  The display state of FIG. 6A continues until the other key operation is performed, but when in this display state, when the container key KC + is pressed, the tree structure of FIG. 5 is currently displayed. Characters indicating a container next to the container including the item are displayed on the display 47. In this case, according to FIG. 5, the container including the item 7 is container A, and the next container is container C. Therefore, as shown in FIG. 6B, the character “Container C” is displayed in the display area AS of the display 47. Is displayed.

  In the display state of FIG. 6B, when the container key KC + is pressed, characters indicating the next container are also displayed on the display 47. In the case of FIG. 5, since the container next to the container C is the container D, the characters “Container D” are displayed in the display area AS of the display 47 as shown in FIG. 6C.

  Thus, as shown in FIG. 7, every time the container key KC + in the forward direction is pressed, the containers A, C, D, E, and Root in FIG. The name of the selected container is displayed. Similarly, each time the container key KC- in the reverse direction is pressed, the containers A, C, D, E, and Root are selected in the reverse order, and the name of the selected container is displayed. To go.

  Therefore, an arbitrary container can be selected by the container keys KC + and KC-. When a container can be selected in this way, a container mark MC is displayed on the display 47 as shown in FIGS.

  For example, as shown in FIG. 6B, if no key operation is performed for one second from the state in which the container C is selected, the container C whose name is displayed at this time is shown in FIG. 6E. A character “Item 1” indicating the first item 1 is displayed in the display area AS of the display 47.

  Similarly, when another container is selected, if the key operation is not performed for 1 second, for example, from the state in which the container is selected, the first container of the name displayed at this time is displayed. Characters indicating items are displayed in the display area AS of the display 47.

2-3-2 Selection of Item For example, as shown in FIG. 8A, when an item key KI + is pressed when the name of an arbitrary item is displayed, the item currently displayed in the tree structure of FIG. Characters indicating the next item are displayed on the display 47. In this case, the name of the item 6 is displayed, and according to FIG. 5, the next item after the item 6 is the item 7, so that “Item 7” is displayed in the display area AS of the display 47 as shown in FIG. 8B. Is displayed.

  Then, when the item key KI + is pressed in the display state of FIG. 8B, characters indicating the item next to the currently displayed item are similarly displayed on the display 47. In the case of FIG. 5, since the item next to the item 7 is the item 8, the characters “Item 8” are displayed in the display area AS of the display 47 as shown in FIG. 6C.

  Further, when the item key KI + is pressed in the display state of FIG. 8C, characters indicating the next item are also displayed on the display 47. In the case of FIG. 5, there is no next item in the container A including the currently displayed item 9, but in the item hierarchy, the next item after the item 8 is the item 1, so as shown in FIG. 8D, The characters “Item 1” are displayed in the display area AS of the display 47.

  Thus, as shown in FIG. 9, each time the item key KI + in the forward direction is pressed, the items 6, 7,..., 12 in FIG. In the same container, the items are selected in the normal order, and the names of the selected items are displayed. Similarly, every time the item key KI- in the reverse direction is pressed, the items 6, 7,..., 11 are selected in reverse order for each container and in reverse order in the same container. The name of the selected item is displayed.

  Accordingly, any item can be selected by the item keys KI + and KI−. Further, when an item can be selected in this way, an item mark MI is displayed on the display 47 as shown in FIGS.

  As shown in FIG. 9, when the container key KC +, KC- is pressed while the item is being selected, the state transitions to the container selection state shown in FIG. The name of the container that contains the item is displayed.

  When any item name is displayed, a command instructing reproduction of the digital audio data of the item is transmitted from the control point 40 to the media server through the communication block 32. As a result, the digital audio data of the item designated by the control point 40 is sequentially extracted from the media server, and this digital audio data is transmitted to the network audio device 20 in a streaming format.

  Therefore, when an item such as the target music is displayed on the display 47, if the operation of the keys KC +, KC-, KI +, KI- is stopped, the target music is output from the speakers 69L, 69R. The user can listen to this.

  When an item is selected and digital audio data of the item is transmitted, information indicating the item is written in the memory 44 as last item information. This written information is used when displaying the name of the last item, for example, as shown in FIG. 6A.

2-3-3 Summary of Container and Item Selection In the network audio device 20 described above, when the container key KC +, KC- is pressed, the container can be selected and the name of the selected container is displayed on the display 47. Is displayed.

  When the name of an arbitrary container is displayed, pressing the item key KI +, KI- displays the item name on the display 47, and the digital audio data of the item is streamed from the media server, It is reproduced as music or the like on the network audio device 40. At this time, the display of the name of the item and the music piece to be played back are sequentially switched each time the item keys KI + and KI- are pressed.

3 Summary According to the network audio device 20 described above, since the audio content has any complicated tree structure in the media server, it is displayed by being mapped to a simple tree of two layers. Even if the display capability is low, the name of the audio content can be displayed and the audio content can be acquired.

  In addition, the tree display is simplified to a container for the first hierarchy and an item for the second hierarchy, and since a key for selecting a container and a key for selecting an item are provided, the operation itself is also simplified. It will be easy.

  Furthermore, since the content that cannot be handled by the network audio device 20 is not displayed, it is not necessary to take extra time for the content that cannot be handled by the user. In addition, by displaying in two layers, not only the procedure can be simplified, but also the data to be displayed at a time can be simplified. Therefore, a display 47 that is inexpensive in design can be used.

  Furthermore, since simplified display and operation can be implemented, a network-compatible audio device can be provided to the user at low cost. In addition, this makes it possible to differentiate from competing network CE devices. Furthermore, by bringing the media called UPnP® AV architecture device, which is expected to become popular in the future, to the conventional operation, it can be handled as an audio device without feeling uncomfortable with the new network CE device.

4 Others In the above, for example, as shown in FIG. 8C, when the item key KI + is pressed while the name “Item 8” of the item 8 is displayed, as shown in FIG. 8D, the next item in the item hierarchy is displayed. Although the name “Item 1” of the item 1 is displayed, the name “Item 6” of the first item 6 of the container A including the item 8 can also be displayed. That is, when the item keys KI + and KI− are pressed, the item names of the items contained in the container at that time can be displayed cyclically in the forward direction or the reverse direction.

  In the above description, for example, as shown in FIG. 8, when the next item is selected by the item keys KI + and KI− in the item selection state, playback of digital audio data of the item is instructed. The command is sent to the media server, but even if an item is selected, the command to play the digital audio data of the item is not sent, and when the play key is pressed after selecting the item, A command instructing reproduction of the digital audio data of the item can be transmitted to the media server.

  Further, for example, as shown in FIG. 8, when the stop key is pressed instead of the item keys KI + and KI− in the item selection state, the display changes to the container selection state as shown in FIG. It can also be made. In the above description, the audio content is extracted from the media server. However, the present invention can be applied to the case of extracting content stored in a hierarchical manner. Furthermore, the operation keys KC +, KC- and KI +, KI- can be used as operation dials, respectively.

  In the above description, UPnP (R) is used as a protocol. The tree structure of directories (containers) and files (items) in the media server can be transmitted to the network audio device 20 through the network, and from the client. Any device can be used as long as it can instruct playback or stop of the content, and Jini (R), HAVi (R), or the like can also be used.

[List of abbreviations]
A / D: Analog to Digital
AV: Audio and Visual
CDS: Contents Directory Service
CE: Consumer Electronics
CPU: Central Processing Unit
D / A: Digital to Analog
DHCP: Dynamic Host Configuration Protocol
GENA: General Event Notification Architecture
HAVi (R): Home Audio / Video interoperability (R)
HTML: Hyper Text Markup Language
IEEE: Institute of Electrical and Electronics Engineers
IP: Internet Protocol
LAN: Local Area Network
LCD: Liquid Crystal Display
RAM: Random Access Memory
ROM: Read Only Memory
SOAP: Simple Object Access Protocol
SSDP: Simple Service Discovery Protocol
TCP: Transmission Control Protocol
TCP / IP: Transmission Control Protocol / Internet Protocol
UDP: User Datagram Protocol
UPnP (R): Universal Plug and Play (R)
URL: Uniform Resource Locator
XML: eXtensible Markup Language

It is a systematic diagram showing one embodiment of the present invention. It is a flowchart which shows one form of the process sequence which can be used for this invention. It is a figure which shows one form of the operation key which can be used for this invention. It is a figure which shows one form of the display which can be used for this invention. It is a figure for demonstrating this invention. It is a figure for demonstrating this invention. It is a figure for demonstrating this invention. It is a figure for demonstrating this invention. It is a figure for demonstrating this invention. It is a figure which shows a server client system. It is a figure for demonstrating this invention. It is a figure which shows the protocol stack of UPnP (R).

Explanation of symbols

  DESCRIPTION OF SYMBOLS 20 ... Network audio machine, 30 ... Media renderer, 31 ... Modular jack, 32 ... Communication block, 33 ... Equalizer, 34 ... D / A converter, 35L and 35R ... Output amplifier, 40 ... Control point, 41 ... CPU, 42 ... ROM, 43 ... RAM, 44 ... nonvolatile memory, 45 ... operation keys, 47 ... display, 61 ... modular plug, 62 ... LAN cable, 63L and 63R ... speaker

Claims (4)

A communication block for communicating through a network to a server storing content in a hierarchical structure;
First and second operating means;
Display,
Control circuit,
The communication block receives information indicating the hierarchical structure of the content from the server,
The control circuit is
The information received by the communication block is mapped to a two-level tree of a directory and files contained in the directory,
When the first operating means is operated, the mapped directory is sequentially selected for each operation, and information indicating the selected directory is displayed on the display.
When the second operating means is operated, a client device configured to sequentially display information indicating files included in at least the directory selected at this time on the display for each operation. The client device according to claim 1,
Instructing the server to transmit the file selected by the first and second operation means through the communication block,
A client device configured to take out the transmitted file from the communication block when the instructed file is transmitted. The client device according to claim 2,
Having a D / A converter,
A client device that reproduces an original analog signal by supplying data of the file extracted from the communication block to the D / A converter. The client device according to claim 3.
The above file is a digital audio data file,
A client device that obtains an analog audio signal from the D / A converter.

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