JP2000284800A - Digital data transmitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To output audio data to a requesting side without interruption even when a network is congested. SOLUTION: The device consists of a data accumulating means 30 which accumulates audio data, a data inputting section 20 which compresses and supplies the data to the means 30, and a data outputting section 40 which accumulates the audio data accumulated in the section 20 for every transmitting program. These sections conduct mutual communication through a network LAN25. In the section 40, a buffer memory means is provided to temporarily store prescribed amount of data of the audio data to be outputted. When a transfer request is received, requested audio data are read from the buffer memory means. If the capacity of the means becomes less than a prescribed amount, the audio data accumulated in the means 30 are read while conducting the data reading from the means and the read data are stored in the means. Thus, the audio data are transmitted without interruption and continuous transmission of audio data is secured even while the network is in its busy condition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a digital data transmission device. Specifically, digital data such as music and video is stored in a server device, and the real-time property (continuity) of the data is lost even when a transmission request is made almost simultaneously for a plurality of channels of the stored digital data. Instead, the desired digital data requested for these multiple channels can be distributed.

[0002]

2. Description of the Related Art When delivering music or video to a specific user (contractor), it is conceivable that the digital data is transmitted from a digital data transmitting apparatus having a server connected to a network using a public line or the like. FIG. 6 shows an example of a configuration that can be considered as such a digital data transmission device.
Shown in In FIG. 6, an input terminal device 20 functioning as a data input unit is a data processing device that compresses various music signals, video signals, and the like that are sound sources. The compressed music data, video data, and the like are supplied to the server device 30 via a network, in this example, a LAN (Local Area Network), and are stored in the server device 30 as files for each genre (channel). for that reason,
The server device 30 is provided with a file management means 31 and controls input / output of data so that simultaneous access for n channels is possible.

An output terminal device 40 which functions as an output data portion corresponding to n channels, in this example, output terminal devices 40A to 40D for 4 channels, is connected to the LAN 25 so as to respond to a request externally accessed through the LAN 25. Accordingly, the target data is read from the server device 30 via the corresponding output terminal device 40, and is subjected to decompression processing in the output terminal device 40 to return to the original analog signal. (Such as music signals and video signals).

[0004]

By the way, when such a digital data transmitting apparatus 10 is constructed, a TCP / IP protocol (Transmissi protocol), which is a global standard, is used as a communication protocol used in the network.
On Control Protocol / Internet Protocol), when a plurality of clients (here, the output terminal device 40) make requests to the server device 30 at the same time, a line is first secured to the server device 30. All the clients other than the client in the waiting state are in a waiting state, and the client in the waiting state secures access to the server device 30 only when this client leaves the communication line.

As described above, when a plurality of clients 40 make requests to the server device 30 at the same time, some clients are in a standby state and cannot read data from the server device 30. Therefore, if the requested data is data that requires real-time transmission (continuous transmission) such as music data or video data, the sound may be partially interrupted, or noise may appear in the video due to discontinuity of the data. The image quality is degraded by running. In view of the above, the present invention has been made to solve such a conventional problem, and proposes a digital data transmitting apparatus capable of transmitting data without interruption even when multiple accesses are made.

[0006]

According to a first aspect of the present invention, there is provided a digital data transmitting apparatus according to the present invention, comprising: a data storage unit for storing audio data; A data input unit for supplying the data to the data storage unit, and a data output unit for storing the audio data and the like stored in the data storage unit for each transmission program, and these are mutually communicated by a network. At the same time, the data output unit is provided with buffer memory means for temporarily storing only a predetermined data amount of audio data to be output, and the like,
When a transfer request is made, the requested audio data and the like are read from the buffer memory means, and when the capacity of the buffer memory means falls below a predetermined amount, the data is read and stored in the data storage means simultaneously. The read audio data and the like are read and stored in the buffer memory means, so that the audio data and the like can be transmitted without interruption.

According to the present invention, data buffer means are provided in a plurality of output terminal devices corresponding to service channels connected to a network, and compression of channels corresponding to all output terminal devices is performed before service provision is started. Data is read from the server device and stored. When the service is started, all output terminal devices are operated in a multitasking manner.

[0008] The data of the requested channel is decompressed to provide the service to the end user, and when the data amount of the data buffer means becomes a predetermined amount or less, the compressed data of the corresponding channel is transmitted from the server device. Read and store sequentially.

Thus, even if a waiting time due to multiple access occurs, the data from the data buffer means can be continuously used during the waiting time, so that no data interruption occurs. That is, real-time transmission (continuous transmission) by multiple access becomes possible. The software only needs to be loaded with a program for realizing multitasking.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a digital data transmitting apparatus according to the present invention applied to a multi-channel data distribution apparatus will be described in detail with reference to the drawings. FIG. 1 shows an embodiment of a digital data transmission device 10 functioning as a multi-channel data distribution device. The input terminal device 20, which is a data input unit, is a data processing device for compressing and transferring music signals, video signals, and the like as in the related art, and compresses data such as music data to the server device 30 functioning as data storage means. , In this example LA
The data is transferred via N25, and the data is respectively filed and stored.

For this reason, in this example, a RAID (Redundant Arrays of Inexpe
nsive Discs) format storage means. Accordingly, the server device 30 is composed of the server main body 31 in the RAID format and the user management means 32 for providing input / output of data to / from the server main body 31 to the client (data output unit 40 described later) over multiple channels. I have. In this example, the server main body 31 is configured to have a capacity of several Gbytes (for example, 4 Gbytes) so that thousands to tens of thousands of songs can be stored as a sound source.

An output terminal device 40 is further connected to the LAN 25. The output terminal device 40 includes a plurality of output terminal devices 40A, 40B,.
・ Consists of In the illustrated embodiment, four output terminal devices 40A to 40D are connected to enable simultaneous transmission of four channels, but actually output terminal devices for 20 to 30 channels are prepared. In order to enable high-speed data transfer and cope with multiple accesses, the above-mentioned network 25 is constructed by a client / server type LAN network, and both the input terminal device 20 and the output terminal device 40 are used. In this embodiment, they are connected in a bus type.

The LAN 25 uses the Ethernet standard (IEEE 8
02.3) cable (10 transmission speed of 10 Mbps)
BASE-T and 100Mbps 100BASE-TX
And the like, are used as a communication cable, and a TCP / IP protocol, which is a global standard protocol, is applied as a communication protocol. The basic software OS installed in the data input unit 20 and the data output unit 40 is Wind so that a multitasking and multi-user time sharing system can be constructed.
ows NT (trade name) and Unix can be used. These are only examples.

The input terminal device 20 has a personal computer main body 21 composed of a personal computer as shown in FIG. 1 and a monitor means 22, and various input signals are supplied to the personal computer main body 21.
As an input signal, a music signal can be used. The music signal handles a large number of music signals according to each genre, such as classical, popular, latin, pop, and tango. As the sound source medium 23, a compact disc CD, a mini disc MD, a CD-R (CD-Rewritable), a CD
-The type of the medium, such as a ROM or a tape, does not matter. The example in the figure illustrates a CD-ROM as the sound source medium 23. In addition, a source such as a video signal is supplied.

FIG. 2 shows the configuration of the personal computer main body 21. This is a well-known configuration, and a memory means (ROM or the like) 52 storing various programs for performing data processing or data transmission including a CPU 51 and a memory means (RAM or the like) 53 as a working memory are connected by a bus 54. It is connected. An interface 59 for an input source is provided, and a communication buffer means (I / O buffer) 56 is connected via an interface 55 to transfer data to the LAN 25. Further, a data compressor 57 is provided to compress the input signal. In this example, MPEG (Moving Picture Exp
ert Groups), data compression is performed in accordance with the standard, and the compressed data is transferred to the server device 30 and accumulated.

On the other hand, the output terminal device 40 is also constituted by a personal computer, like the input terminal device 20. Therefore, in addition to having the CPU 61 as shown in FIG.
63, the same parts as those in FIG. 2 are denoted by the corresponding reference numerals, and description thereof is omitted.

The output terminal device 40 is provided with buffer memory means 68 for temporarily storing compressed data. This buffer memory means 68 converts the analog signal to 1
A memory having a memory capacity capable of accumulating a signal amount of about 10 to 10 minutes (a fraction of the compression amount) is used. As will be described later, the buffer memory means 68 must perform data write processing in parallel with data read. Therefore, in the case of a hard disk HDD device or a semiconductor memory, a dual port type memory means is used. used. Of course, the RAM 63 built into the personal computer can also be used as the buffer memory means. Further, the output terminal device 40 further includes a data decompressor (encoder) 67 for decompressing the compressed data.
Is provided.

The data decompressor 67 is an MPEG encoder. The compressed data of the specific channel read from the server device 30 is temporarily stored in the buffer memory unit 6 described above.
The compressed data stored in the storage unit 8 is expanded to the original data in the data expander 67, and the expanded data is sent out to the LAN 25 toward the end user.

Next, the digital data transmitting apparatus 10 according to the present invention will be described. First, the input terminal device 20
In the process, the process of organizing the contents of the program to be transmitted is performed using the compressed data (audio data, video data, etc.) stored in the server device 30 or the like. In rare cases, the transmission schedule data related to each channel is stored in the RAM 63 of the corresponding output terminal device 40.

On the other hand, in the output terminal device 40 in which the unique transmission schedules are stored, compressed data corresponding to the first program among the organized programs is read out a predetermined time before the program transmission available time, and this is read out. Store until the buffer memory means 68 becomes full. The data store process to the buffer memory means 68 is TCP / IP
Since the processing is performed in accordance with the protocol, when the server device 30 is accessed and the server device 30 is idle, the requested data can be read immediately. However, when the request timing overlaps with the request of another client and the line is already occupied, the retry mode (re-request mode) is set. Since this access request is made with a margin, even in the case of such a retry mode, all the target program data are stored in the corresponding buffer memory means 68 by all output terminal devices 40 immediately before the program transmission available time. Can be stored.

When there is an access from the end user via the LAN 25, the corresponding output terminal device 40 enters the data transmission mode (service mode), and the following multitask processing is performed. First, in the data transmission task (task A), as shown in FIG. 4, when there is a data read request from the end user (read request from the higher-level program) (step 71), the compressed data stored in the buffer memory means 68 is received. Is read out, decompressed and delivered to an end-user terminal device (not shown) in which the host program is stored (step 72). The end user can now obtain the requested information.

Here, since the corresponding data is sequentially read out from the buffer memory means 68, if the requested information is music, there is no sound interruption as long as the data is stored in the buffer memory means 68. .
If the amount of data in the buffer memory means 68 decreases, data may be interrupted. Therefore, the data amount in the buffer memory means 68 is constantly monitored, and data supplement processing is performed.

This is the second task processing (task B), which monitors the amount of stored data as shown in FIG.
1, 82), a data read request is made to the server device 30 (step 83). This read request is made via a normal network driver. If access is not possible, retry mode is set. The prescribed data amount can be, for example, about 1/3 of the total capacity. Therefore, the time for reading the remaining capacity is about 1 to 3 minutes.

The data read from the server device 30 is stored in the buffer memory means 68, and the data replenishment processing is performed concurrently with the data transmission processing to the end user. As a result, even if the data is transmitted to the end user, the data in the buffer memory means 68 does not become empty, so that the data is continuously transmitted (data for ensuring continuity when viewed as an analog signal). Transmission) can be secured.

Here, even in the task B mode, the data store processing to the buffer memory means 68 is performed by TCP / IP
Since the processing is performed in accordance with the protocol, when the server device 30 is accessed and the server device 30 is idle, the requested data can be read immediately. However, when the request timing overlaps with the request of another client and the line is already occupied, the retry mode (re-request mode) is set.

Since this access request is made with a margin, even in such a retry mode, it is not possible to wait for the remaining capacity of the buffer memory means 68 to become zero. A situation in which data transmission becomes discontinuous does not occur. The data to be read is not limited to music data, but can be applied to video data and other data for which real-time properties must be ensured.

[0027]

As described above, according to the present invention, a buffer memory means for temporarily storing audio data to be transmitted to the data transmitting unit is prepared, and when a transfer request is issued from the user, this memory means is provided. When the remaining capacity of the memory means becomes equal to or less than a predetermined amount, the corresponding sound data and the like are read out from the data storage means and can be stored in the memory means. According to this, when reading audio data from the data storage means via the network,
The discontinuous data reading that occurs when the network is in use by another terminal device and the data reading standby state is eliminated is eliminated.

That is, according to the present invention, the audio data requested to be transferred is read from the buffer memory means, and when the data storage amount is reduced, the data storage means reads out the data from the data storage means concurrently with the read operation of the audio data. Multi-task processing such as writing data to the buffer memory means that even if data reading from the data storage means is interrupted temporarily due to network congestion, data written to the buffer The data read out from the memory means is continuously performed only by interruption.

As a result, since the continuity of data reading can be ensured, there is a feature that an unforeseen situation in the data transmission processing system can be avoided, in which interruption of an audio signal or temporary interruption of a video must not occur. Therefore, the present invention is extremely suitable for application to a digital data transmission system in which continuity is a lifeline, such as audio data and video data, as described above.

[Brief description of the drawings]

FIG. 1 is a system diagram of a main part showing an embodiment of a digital data transmission device according to the present invention.

FIG. 2 is a system diagram of a main part showing an embodiment of an input terminal device 20 constituting a data input unit.

FIG. 3 is a system diagram of a main part showing an embodiment of an output terminal device 40 constituting a data output unit.

FIG. 4 is a flowchart illustrating an embodiment of a data reading system for a buffer memory unit for explaining multitask processing.

FIG. 5 is a flowchart illustrating an embodiment of a data writing system for buffer memory means for explaining multitask processing.

FIG. 6 is a system diagram of a digital data transmission device for explaining the present invention.

[Explanation of symbols]

 Reference Signs List 10 digital data transmission device 20 data input unit (input terminal device) 30 data storage unit 40 data output unit (output terminal device) 57 data compressor 67 data decompressor 68 buffer memory unit

Claims (3)

[Claims] 1. A data storage means for storing audio data and the like, a data input section for compressing the audio data and supplying the data to the data storage means, and sending out of the audio data and the like stored in the data storage means A data output unit for storing each program, these are mutually communicated by a network, and the data output unit temporarily stores a predetermined amount of data such as audio data to be output. When a transfer request is received, the requested audio data and the like are read from the buffer memory means, and when the capacity of the buffer memory means becomes a predetermined amount or less, the data readout is performed. At the same time, the audio data and the like stored in the data storage means are read out and stored in the buffer memory means. By store, digital data transmission apparatus being characterized in that to allow delivery without interruption like the audio data. 2. The digital data transmitting apparatus according to claim 1, wherein said network is a network capable of constructing a multi-tasking, multi-user type time sharing system. 3. The digital data transmitting apparatus according to claim 1, wherein said buffer memory means is a dual port type memory means capable of simultaneously reading data and writing data.