KR100313622B1 - Tree structured client-server multi-media system - Google Patents

Abstract

A server computer having an IEEE 1394 interface card and a client-server multimedia system including a plurality of set-top boxes are provided. The server consists of a normal PC with a high-speed, high-capacity hard disk with several types of databases in digital audio / video data formats such as MPEG. The client is a set-top box with an IEEE1394 interface and bitstream playback of digital audio / video data formats such as MPEG. The client connects to the server in a tree fashion. The set-top box communicates with the server in an interactive transaction, selecting the server's digital audio / video database, and the server delivers the selected digital audio / video data to each set-top box in real time. The set-top box has two memory blocks for storing digital audio / video transmitted from the server, and the multimedia data received from the server while the digital video player reads data from the first memory block and plays the multimedia data. Is performed in a so-called double-buffering scheme stored in the second memory block.

Description

Tree structured client-server multi-media system

The present invention relates to a tree-based client-server multimedia system, and more particularly, to a multimedia system configured by connecting a plurality of set-top boxes to a single PC server in a tree-based manner.

Conventional analog audio / video devices such as analog language training system, library system, video room equipment, karaoke device, and the like have problems such as degradation of sound quality / quality and difficulty of preservation, which are fundamental problems of the analog method.

To solve this problem, many digital multimedia systems have emerged. In particular, a multimedia system called Video On Demand (VOD) is in the spotlight. VOD is a method of storing digitally recorded audio / video data on a server, and then transmitting the video data stream to the user so that it can be played back in real time or at a short time interval. It is a system for viewing and listening to multimedia data.

However, despite the development of compression technology, digital multimedia data requires a large bandwidth in order to transmit multimedia data because the amount of data is huge. Therefore, in the related art, only a LAN using a high speed ATM network or an Ethernet and a fast switching hub may be implemented.

However, such a system uses a high-speed ATM network or a high-speed LAN to implement broadband communication, and also uses a PC as both a server and a client, and thus has a disadvantage in that an expensive cost is required to have an entire VOD system.

The present invention has been made in view of this point, and an object thereof is to provide a client-server multimedia system that can be implemented at low cost.

Another object of the present invention is to provide a tree client-server multimedia system that is easy to install.

1 is a schematic diagram showing a server and a set-top box is connected in a tree manner in the multimedia system of the present invention.

2 is a schematic block diagram schematically showing the internal configuration of the set-top box.

Figure 3 is a block diagram showing the internal configuration of the set-top box in more detail.

4 is a flowchart illustrating operations of the 1394 and MPEG controllers when the set-top box is powered on.

FIG. 5 is a time chart illustrating a method of data coming and going between a server and a client in a client-server multimedia system of the present invention.

6 is a time chart for explaining the time relationship between the reception and decoding of multimedia data in the set-top box of the present invention.

7 is an example of a command format between a server and a client.

8 is an example of a command / response and a client screen according to an operation of a set top box of a user.

The client-server multimedia system of the present invention connects a server and a client using an IEEE 1394 serial bus. The server consists of a normal PC with a high-speed, high-capacity hard disk with several types of databases in digital audio / video data formats such as MPEG. The client is a set-top box having an IEEE1394 function and a function of playing back a bitstream of a digital video data format such as MPEG. The client connects to the server in a tree fashion. The set-top box communicates with the server in an interactive transaction, selecting the server's digital audio / video database, and the server delivers the selected digital audio / video data to each set-top box in real time. The set-top box has two memory blocks for storing digital audio / video transmitted from the server, and the multimedia data received from the server while the digital video player reads data from the first memory block and plays the multimedia data. Is performed in a so-called double-buffering scheme stored in the second memory block.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic diagram showing how the server 100 and the set-top box (200a..200s) are connected in a tree manner in the multimedia system of the present invention.

Between the server and the set-top box, and between the set-top box and the set-top box is connected by the IEEE1394 serial bus. Each node in the server and set-top box has multiple IEEE1394 serial bus ports, so multiple devices can be connected.

1 illustrates an embodiment in which three nodes of the server and the set-top box has three IEEE1394 serial bus ports, and up to three set-top boxes 200a..200c are connected to the server 100. In the set-top box, one of the three connection terminals is connected to the line coming from the upper device, and the lower two devices can be connected using the remaining two terminals, so up to two set-top boxes are connected. That is, in the set-top box 200a, one line comes from the server 100 which is the upper device, and the other two terminals are connected to the set-top box 200d and the set-top box 200e, which are lower devices.

By continuing to be connected to subordinate devices in this way, the server and the set-top box are connected in a tree way.

Next, the internal structure of a server is demonstrated.

First, the server 100 has the same configuration as a general personal computer (PC). However, the server 100 is different from the general PC is that the IEEE1394 interface card for communication with the set-top box is plugged in. In addition, a separate large capacity hard disk or disk array may be connected for a large capacity multimedia database. Alternatively, a CD-ROM driver or a multi-CD changer (a device capable of playing one of a plurality of CDs) may be used as the multimedia database. Other parts are the same as a general personal computer, detailed description thereof will be omitted.

Next, an internal configuration of the set top box will be described.

2 is a schematic block diagram schematically showing the internal configuration of the set-top box.

The user interface unit 210 is a part for the interface between the user and the device, and comprises a conventional keyboard, key buttons, or touch screen. A remote control interface may be employed for the user's convenience of operation.

The IEEE 1394 interface unit 220 is for communication with the server 100. In three IEEE1394 interface terminals, one is connected to an upper device and the other two are connected to a lower device to form a tree structure.

The memory controller 230 temporarily stores the multimedia data stream coming through the IEEE1394 interface 220.

The OSD unit 240 is a part for implementing an on-screen display (OSD) function for displaying a character on a video image from the server 100 or for displaying various function menus to a user. The character screen is superimposed on the video signal from the video signal), and then converted into a signal that can be displayed on the monitor.

The digital audio / video player 250 decodes the digital data format from the server 100 stored in the memory controller 230 and converts the digital data format into an analog audio / video signal.

The reproduced multimedia signal is visually displayed through the monitor 260, and is converted into an audio signal through a speaker or earphone and output.

Next, the configuration of the set-top box will be described in more detail with reference to FIGS. 3 and 4. 3 is a block diagram illustrating an internal configuration of the set-top box in more detail, and FIG. 4 is a flowchart illustrating operations of the 1394 and MPEG controllers when the set-top box is powered on.

In FIG. 3, the remote control / button input unit 211 and the user interface control unit 212 correspond to the user interface unit 210 of FIG. 2, and the 1394 control unit 221, the 1394 link layer unit 222, and the 1394 physical layer unit ( 223 corresponds to the IEEE 1394 interface 220.

In addition, portions corresponding to the memory controller of FIG. 3 are an ISO (Isochronous) data controller 231 and two SRAM memories 232 and 233. The video mixer 241 corresponds to the OSD unit 240 of FIG. 3. Parts corresponding to the digital audio / video player 250 of FIG. 3 are the MPEG controller 251, the TV encoder 252, the MPEG encoder 253, the audio DAC 254, and the video RAM 255.

In the example of FIG. 3, the MPEG format is used as the digital audio / video signal as an example, but the present invention is not limited to a specific digital audio / video format.

An initialization process and operations after each control unit of the set-top box at power on will be described with reference to FIG. 4. In the set-top box, operations of the entire system are controlled by three key parts of the user interface controller 212, the 1394 controller 221, and the MPEG controller 251.

<1394 Initialization Process and Role of Control Unit>

The 1394 controller 221 performs functions of a transaction layer, a serial bus manager, and an application layer of the IEEE1394 in the protocol stack of the IEEE1394 serial bus, and processes a command from the user interface controller 212 or delivers the function to the MPEG controller. In charge. The 1394 MCU performs the following initialization process at power-on.

1) Initialization of program variables: Initializes various variables used in the program.

2) Initialization of 1394 MCU: Initializes interrupt register and serial port. Communication between the 1394 MCU and the MPEG MCU can be performed by serial communication.

3) Initialization of the 1394 link layer chip: Initializes the register map of the link layer chip in accordance with the IEEE1394 protocol. This includes general link control, Async Tx / Rx, Iso Tx / Rx, and initialization of various interrupts.

4) Self-ID Verification for IEEE1394 Topology Configuration: IEEE1394 configures the 1394 serial bus topology through bus initialization, tree identification, and self identification. Each node (set-top box) Performs the self-ID check process from the 'Self-ID Packet' that is input, and through this, it knows the Root Node_ID, its Node_ID, and the total number of nodes.

5) Main loop execution: It handles user command set and Async and ISO transactions of IEEE1394 by polling and interrupt-driven method.

In the IEEE 1394 standard, channel setting for data transmission is made dynamic, but a separate isochronous resource management device is required for dynamic channel setting. However, in the present invention, a unique channel ID is assigned to each set-top box in advance by means of a dip switch or the like in the initialization process after the Powell-On reset of each set-top box, and the server is informed of this, so that the server is connected to each node (client set-top). By setting a unique channel ID for a box in advance, the need for an isochronous resource management device is eliminated. That is, the present invention eliminates the need to dynamically allocate channel IDs by limiting the number of devices that can be connected by the maximum number of channels (63) provided by IEEE1394.

The set-top box 200 compares the channel ID included in the isochronous multimedia data with its channel ID and accepts the data only when it matches, and bypasses it when it does not match, thereby bypassing the specific set top in the client-server structure of the tree structure. It allows you to transfer multimedia data to the box. In addition, 63 (3Fh) among the channel IDs is allocated to broadcasting so that when the ID is 63, all set-top boxes accept multimedia data.

<Initialization Process and Role of MPEG MCU>

The main task of the MPEG MCU is to deliver the ISO data (MPEG bit stream) input from the server to the MPEG decoder in real time at the request of the set-top box. The MPEG MCU performs the following initialization process at power-on.

1) Initialization of program variables: Initializes various variables used in the program.

2) Initialize MPEG MCU: Initialize interrupt register and serial port register.

3) Port address setting of MPEG decoder chip

4) Initialization of the Control and Status Register (CSR) of the MPEG Decoder: In the MPEG decoder, the CSR register area stores various variables necessary for decoding and display management processes. Initialize these variables through a reset and initialization process.

5) Main loop execution: The decoding process of the MPEG bit stream is performed by polling and interrupt-driven.

<Operation of ISO Data Controller>

The multimedia system of the present invention transmits multimedia data in a time compression manner. Therefore, multimedia data transmitted at a higher data rate than the actual data bit rate by the time compression method should be received and temporarily stored for a short time, and then outputted over a long time according to the actual data bit rate when the MPEG decoder is to play back. . This operation is performed by the control of the ISO data controller 231.

The operation of the ISO data controller 231 will be described in detail with reference to FIGS. 5 and 6. FIG. 5 is a time chart illustrating a method of data coming and going between a server and a client in a client-server multimedia system of the present invention. FIG. 6 is a time between reception and decoding of multimedia data in a set-top box of the present invention. Time chart for explaining the relationship.

In the system of the present invention, data transmission between the server 100 and the client (set-top box) is performed by dividing the cycle into 8000 cycles per second as shown in FIG. In addition, in each cycle section, isochronous multimedia data is transmitted at the beginning of the cycle section, and an asynchronous command set is transmitted at the back section as shown in FIG. 5 (b). Of course, it is also possible to reverse the order of the isochronous multimedia data and the asynchronous command set.

Multimedia data is transmitted to several clients in successive cycles. That is, as shown in FIG. 5B, isochronous multimedia data for one client is transmitted during n cycle periods.

The allocation of cycle intervals is done by request from the client. That is, only when a data request comes from a specific client to the server, the multimedia data is transmitted by allocating a predetermined cycle section to the client and inserting ID data to distinguish the client in front of each cycle section. Each client accepts only data that matches its ID.

5C and 5D show data transmission examples in this case. In the figure, requests from each client are arriving in the order of Node 1 (Client 1), Node 2, Node 4, Node 1, ... It can be seen that they are allocated in the order of node 2, node 4, node 1, ... (Fig. 5 (c)).

Here, the transmission of the time compression method means that the isochronous multimedia data shown in FIG. 5B is transmitted by being compressed in time. In other words, the multimedia data transmitted for a very short time shown in FIG. 5 (b) is actually a quantity of data that can be reproduced for a much longer time than this.

Therefore, for real-time playback, the set-top box receives the data and plays it back according to the actual playback time, and also receives the data for the next playback during the playback. Therefore, in the present invention, two memories 232 and 233 are provided in the memory controller 230.

Thus, as shown in Fig. 6, while reproducing to one memory (decoding Mem 1 of Fig. 6), data is received into the remaining memory (storing Mem 2 of Fig. 6), and the data is transmitted to the server when the reproducing is finished in one memory. At the same time as the data transmission request for sending the data (req. Data transmission req. In FIG. 6), the playback of the data received in the remaining memory is started (decoding of Mem 2 in FIG. 6), and data is received again in one memory. (Save Mem 1). In this case, since the time compression method is used as described above, the period of receiving and storing data from the server is very short, while the period of decoding is relatively long.

<Operation of digital audio / video player>

The ISO data controller 231 notifies the fact by sending an interrupt to the MPEG controller 251 when the multimedia data storage from the server is completed in one memory. Upon receiving the interrupt signal, the MPEG controller 251 reads MPEG data from the ISO data controller 231 and sends the MPEG data to the MPEG decoder 253 to start decoding, and at the same time, the / ISOREQ interrupt for requesting ISO multimedia data to the 1394 controller 221. Send a signal The 1394 controller 221 receiving the / ISOREQ interrupt signal transmits an ISO data request signal for storing data in another memory to the server 100.

By repeating such an operation, the multimedia data from the server is transmitted to the client, and the client reproduces the multimedia data in real time.

The decoding of the digital audio / video signal is performed in the MPEG decoder 253, and the video RAM 255 is used for temporary storage during decoding.

The reproduced video signal is input to the TV encoder 252 and converted into an analog TV signal. The video signal output from the TV encoder 252 is combined with the text signal from the user interface controller 212 in the video mixer 241 to implement an On-Screen Display (OSD) function. The final video signal from the video mixer 241 is input to the monitor 260 so that the video signal sent from the server is displayed on the user's set-top box screen.

In addition, the audio signal reproduced by the MPEG decoder 253 is converted into an analog signal by an audio digital to analog converter (DAC) 254 and converted into an audio signal through a stereo phone jack 270 or a speaker built into the monitor. .

Next, the transmission and reception of commands between the server and the client will be described with reference to FIG. 7.

The transmission and reception of commands between the server and the client is performed by an asynchronous transaction of IEEE1394. That is, it is made in the asynchronous command transmission section shown in FIG. An example of the format of the command at this time is shown in FIG.

Each set-top box is configured to set a node ID according to the IEEE1394 standard at the time of initialization. The set-top box 200 recognizes that the command comes to itself only when the node ID and the Destination_ID of the command match.

Commands (commands from server to set-top box) or requests (requests from set-top box to server) are sent in a 'Command frame / Request frame'.

Next, with reference to Figure 8 will be described the operation of the apparatus of the present invention according to the user's functional operation in the set-top box. 8 is an example of a command / response and a client screen according to an operation of a set top box of a user.

First, when the set-top box 200 is connected to the system, the server 100 sends a time set command and information about a menu (Menu Info Command) to the set-top box 200. The menu information may include several levels of menus.

Then, the set-top box 200 displays a menu on the screen using an OSD function according to the information about the menu. When a user selects a desired function using an input device such as a remote controller or a button, a submenu of the corresponding function is displayed. In Figure 8, the user is a '2. The video shows an example of selecting 'Video'.

When the user selects one of the submenus again, the contents related to the function are displayed again. When the menu needs to be transmitted from the server 100, the set top box 200 transmits a request (Top menu display data request) to the server 100 requesting menu information. The server 100 receiving the request sends the information to the set-top box 200. The set top box 200 receiving the information is displayed on the screen again.

When the user selects the desired multimedia data, for example, a specific movie or a specific educational video, the server 100 reads the multimedia data from the database and transmits the multimedia data to the corresponding set-top box as isochronous multimedia data. Then, the movie or video is screened on the screen of the set-top box.

According to the above configuration, when the set-top box sends OSD data using the asynchronous command from the server according to the request, and the user selects the desired multimedia data from the set-top box, the server attaches the channel ID of the set-top box to the isochronous property. By transmitting multimedia data, the set-top box receives, decodes and displays multimedia data corresponding to its channel ID on a monitor, thereby implementing a VOD function between the server and the set-top box connected by a tree structure.

As mentioned above, although some Example was given and demonstrated this invention, this invention is not limited to this. Those skilled in the art will appreciate that many modifications and variations can be made without departing from the spirit of the invention.

As described above, according to the present invention, since the tree-based client-server multimedia system according to the IEEE1394 protocol is provided, it is possible to implement a multimedia system having a plurality of terminal devices at low cost.

In addition, it is possible to implement a multimedia system at low cost by using a dedicated set-top box without using an expensive personal computer as a terminal device.

In addition, the present invention has an effect that the installation of the system is easy because the server and the set-top box is connected in a tree manner.

Claims (5)

In a multimedia system consisting of a server computer having an IEEE1394 interface card and a plurality of set-top boxes, The set top box is A user interface unit for user's device operation and menu selection, An IEEE1394 interface for performing data communication with the server computer; A memory controller for temporarily storing multimedia data from the IEEE1394 interface; A digital video player for reading and playing multimedia data stored in the memory controller; An OSD unit for generating and outputting a video signal obtained by superimposing a text signal from the user interface unit on a video signal from the digital video reproduction unit; A monitor for reproducing the video signal from the OSD unit Multimedia system comprising a. The method of claim 1, The memory controller of the set top box has at least two memory blocks, And the multimedia data received from the server is stored in the second memory block while the digital video player reads data from the first memory block and plays the multimedia data. The method of claim 2, When the reproduction of the data from the first memory block is completed, the memory controller sends an interrupt request to the server computer by sending an interrupt to the IEEE1394 interface, And the server computer transmits the next block of multimedia data to the set-top box that sends a command for requesting the multimedia data. The method according to any one of claims 1 to 3, The multimedia data is MPEG data, The digital video playback unit MPEG decoder, A video RAM used by the MPEG decoder to temporarily store data during decoding; A digital-analog converter for converting digital voice data extracted from the MPEG decoder into an analog signal; A TV encoder for converting the digital video data extracted from the MPEG decoder into an analog TV signal; MPEG control unit for reading multimedia data from the memory control unit and delivering the multimedia data to the MPEG decoder. Multimedia system comprising a. The method according to any one of claims 1 to 3, The set-top box is provided with a means for setting a fixed channel ID and allowing the server to know it in advance, wherein the set-top box accepts only multimedia data having an ID that matches the set channel ID.