JPH02121548A - Peak speed control circuit for variable rate transmission device - Google Patents

Abstract

PURPOSE:To control the peak speed for transmission of data by performing the variable control for the data transfer speed between a 1st store means which stores temporarily the produced data and a 2nd store means which transmits the data to a transmission line. CONSTITUTION:The coding information produced by a picture coder 21 is sequentially stored in a buffer memory 22 at a fixed rate. When the quantity of data stored in the memory 22 is approximate to an overflow state, a control signal is sent to the coder 21. Thus the coder 21 omits the frames to suppress the quantity of produced information and the prevent the overflow of the memory 22. Then the data stored in the memory 22 are transferred to a buffer memory 23 at a variable rate decided by the frequency of a variable oscillator 25. The frequency of the oscillator 25 is varied by the situation of a network. Thus the generating frequency of the packet to be transferred is controlled according to the network situation. Then the peak speed is controlled for transmission of data.

Description

[Detailed Description of the Invention] [Summary] Peak speed for controlling the peak speed of transmission data in a variable rate transmission device that transmits data generated at a variable rate, such as band compression coded signals of audio and images, etc. Regarding the control circuit.

The purpose is to improve terminal accommodating efficiency by controlling the peak speed of each communication path according to the usage status of the transmission path.

A first storage means that temporarily stores data generated at a data generation source, and when a predetermined amount of data is stored by receiving data transfer from the first storage means, the stored data is sent to a transmission path as transmission data. and a control means for variably controlling the data transfer rate from the first accumulation means to the second accumulation means, and the peak of the transmitted data is controlled by changing the data transfer rate by the control means. Configured to control speed.

[Industrial application field]

The present invention relates to a peak speed control circuit that controls the peak speed of transmission data in a variable rate transmission device that transmits data generated at a variable rate, such as band compression encoded signals of audio and images, at a variable rate.

[Conventional technology]

Conventionally, in the fixed rate transmission system used for boat fishing, when multiple data terminals are accommodated on a transmission path using a multiplexer, etc., the number of data terminals that can be accommodated is determined by the peak speed of each data terminal. 0For example, the transmission speed of the transmission path is 1.5 Mbps, and the peak speed of the data terminal is 38
If the speed is 4 kbps, the number of terminals that can be accommodated is four.

In this manner, in the case of fixed rate transmission, the number of communication buses (that is, the number of data terminals) that can be accommodated in a transmission path is determined by the peak rate (peak value) of generated information that can occur on each communication path. However, since the peak speed does not actually occur, the number of accommodations determined based on this peak speed cannot be said to have good accommodation efficiency.

On the other hand, variable rate transmission systems have been proposed in recent years. This variable rate transmission method is a transmission method mainly used in packet communication networks (in addition to conventional packet networks, it also includes networks called 15DN, B-ISDN, ATM, or high-speed packet networks). This method changes the transmission information rate from the terminal depending on the amount of information generated from the encoder or the availability of the network.

[Problem to be solved by the invention]

However, even though it is a packet communication network, the transmission capacity within the network is limited, so assuming that any terminal communicates at any speed, there is a certain limit to the number of communication paths that can be accommodated at the same time.

One guideline is the same as the fixed rate transmission method.

Transmission path speed ≧ Σ (peak speed of communication bus i).Of course, the probability that all terminals transmit at the peak speed at the same time is usually small, so it is possible to increase the accommodation efficiency from the above inequality. .

Therefore, it can be said that terminal accommodation efficiency can be improved by reducing the peak speed of each communication path or by controlling the peak speed according to the idle state of the transmission path.

Therefore, an object of the present invention is to improve the terminal accommodation efficiency in a variable rate transmission system by controlling the peak speed of each communication bus according to the usage status of the transmission path.

Note that when the encoder is coupled to a communication device capable of accommodating variable rates, such as a packet network, the user/network interface between the encoder and the communication device is usually one with a fixed line speed; When accommodating a single medium, such as only audio, only audio, or only data,
By changing this line speed, peak speed control can be achieved. However, 1.Usually, the user/network interface section extracts the clock from the data in order to reduce the number of signals.In this case, it is necessary to adjust the tuning frequency parameter of the timing extraction circuit at the same time, which increases the processing time. It becomes complicated.

Otherwise, it is necessary to transmit the clock on a separate line and increase the number of signal lines. For this reason, a method of making the line speed of the user/network interface variable variable is not generally adopted.

Furthermore, when realizing a multimedia terminal that integrates and transmits audio and images through one user/network interface, it is impossible to control the peak value by adjusting the line speed of the user/network interface. .

[Means to solve the problem]

FIG. 1 is a diagram explaining the principle of the present invention.

The peak speed control circuit of the variable rate transmission device according to the present invention includes a generation source 51 that generates data at a variable rate,
In a variable rate transmission device configured to change the amount of transmitted data according to the amount of data generated by this source, 1
a first storage means 52 for temporarily storing data generated by the generation source 51;

A second storage means 53 which receives data transfer from the first storage means 52 and sends the stored data to the transmission line as transmission data when a predetermined amount of data is stored, and a first Ml! 4
and a control means 54 for variably controlling the data transfer rate from the means 52 to the second storage means 53, and is configured to control the peak rate of transmitted data by changing the data transfer rate by the control means 54. Ru.

[Effect]

The control means 54 controls the transfer rate of data transferred from the first storage means 52 to the second storage means 53. As a result, the time required to accumulate a predetermined amount of data in the second storage means changes, and therefore the time interval at which the transmission data is transmitted block by block from the second storage means 53 changes.

This ultimately makes it possible to control the peak rate of transmitted data.

〔Example〕

The present invention will be described in detail below with reference to nine drawings. Second
The figure shows a peak speed control circuit of a variable rate transmission device as an embodiment of the present invention.

This embodiment device realizes multiplex transmission of a plurality of media. In Fig. 2, ■ is a coding transmission device, 2
3 is a communication device capable of accommodating a variable rate terminal such as a packet network, and 3 is a user/network interface between the encoding/transmission device 1 and the communication device 2.

This user-network interface 3 normally has a fixed line speed.

The encoding/transmission device 1 includes an audio encoder 11. Image encoder 21. Data transfer file 31. Buffer memories 12 and 22. FIFO buffer memories 13, 23 and 33. Fixed oscillators 14 and 24. Variable oscillators 15 and 25. Transfer lock source 40. It is configured to include a selector 41 and the like.

The audio encoder 11 is an encoder that performs band compression encoding of the audio signal, and the encoding information is stored in the buffer memory 12.

Further, the image encoder 21 is an encoder that performs band compression encoding of the image signal, and the encoded information is stored in the buffer memory 22. This image code 521 generally has a relationship of information generation speed ≧ peak transfer speed, and when the buffer memory 22 is likely to overflow, the screen is dropped depending on the storage state of the buffer memory 22. It is configured so that the amount of generated information can be limited.

The fixed oscillator 14 or 24 is a circuit that supplies an operating clock to the audio encoder 11 or the image encoder 21 and generates a fixed-speed clock for writing the generated encoded information into the buffer memory 12 or 22.

Buffer memory 13, 23. 33 is a FIFO type memory circuit, and buffer memories 12, 22 . Alternatively, it receives the storage data transferred from the data transfer file 31 and stores it. These buffer memories 13, 23 .
or 33 has a function of transferring the accumulated data to the user/network interface 3 once a certain amount of data has been accumulated. .23 or 33 accumulated data will be transferred in fixed block units.

Variable oscillator 15.25. or 35 is buffer memory 1
3,23. or 33, and is a clock generation source for controlling the data transfer rate to the buffer memory 15, 25.
．． Or the read clock for the data transfer file 31, and the buffer memories 13, 23 . or 33, it supplies a write clock, and the PLL
Various implementations are possible, such as a circuit voltage controlled oscillator or frequency division of a fixed oscillator output.

These variable oscillators 15, 25 . Alternatively, the excavation frequency of 35 can be preset or can be varied by control from the terminal or network. In the latter case, dynamic peak value control becomes possible by controlling according to the availability status of the network.

The transfer lock source 40 is a circuit that generates a transfer lock timing for the user/network interface 3, and may be configured to supply the clock from the terminal itself or from the communication device 2 via the downlink. There are cases where it is configured as follows.

The selector 41 selects the buffer memories 13, 23 . or 33
This circuit selects one of these and sends it to the user/network interface 3.

The operation of the embodiment apparatus will be described below using the circuit operation of a two-image encoder system as an example.

The encoded information generated by the image encoder 21 is sequentially stored in the buffer memory 22 at a fixed rate.

At this time, when the amount of M-product data in the buffer memory 22 approaches an overflow state, a control signal is issued to the two-image encoder 21, which causes the image encoder 21 to drop frames, thereby suppressing the amount of generated information and preventing overflow. To prevent.

The data multiplied by M in the buffer memory 22 is then transferred to the buffer memory 2 at a variable rate determined by the frequency of the variable oscillation 525.
Transferred to 3. The frequency of this variable oscillator 25 is varied depending on the network situation. For example, when the network is free, the frequency increases, and when the network is busy, the frequency decreases.

When the buffer memory 23 accumulates a certain amount of data,
This is transferred to the user/network interface 3 via the selector 41 at the speed of the transfer lock source 40. Normally, this block is associated with a packet and transferred in the form of a packet. This packet length does not necessarily have to be a fixed length, but may be a variable length. Note that the packet assembling section is not shown in FIG. 2.

As described above, the frequency of occurrence of packets to be transferred is controlled according to the network situation, and the peak value is eventually controlled.

The circuit operations of the audio encoder system or the data transfer file system are also similar to those described above, so detailed explanations will be omitted.

〔Effect of the invention〕

As described above, according to the present invention, it becomes possible to control the peak speed of each communication path according to the usage status of the transmission path, and therefore it is possible to improve the efficiency of accommodating terminals.

data transfer file User network interface transfer lock source selector

[Brief explanation of drawings]

FIG. 1 is a diagram illustrating the principle of the present invention, and FIG. 2 is a diagram showing a peak speed control circuit of a variable rate transmission device as an embodiment of the present invention. In fig. 1-Coding and transmission device 2-Communication device 3-User/network interface 11-Speech encoder 12.22--Buffer memory 13.23.33--FIFO buffer memory 14.
24--Fixed oscillator 15.25.35--Variable oscillator 21--Image encoder

Claims (1)

[Claims] A source (51) that generates data at a variable rate;
In a variable rate transmission device configured to change the amount of data to be transmitted according to the amount of data generated by the generation source, the first storage means (52) temporarily stores the data generated by the source (51). and a second storage means (53) that receives data transfer from the first storage means (52) and, when a predetermined amount of data is stored, sends the stored data to the transmission path as transmission data; from the first storage means (52) to the second storage means (53).
) control means (54) for variably controlling the data transfer speed to
A peak rate control circuit for a variable rate transmission device, comprising: a peak rate control circuit for a variable rate transmission device, comprising: a control means (54) configured to control a peak rate of transmitted data by changing the data transfer rate;