KR0121062Y1 - A controlling device for transmitting data of video telephone - Google Patents

Abstract

The present invention relates to a data transmission control apparatus of a video telephone that maintains a variable ratio of video data at a constant rate, which is a non-uniform screen state caused by video data irregularly changing with time. It is to solve the problem.

Therefore, the present invention temporarily stores the variable output video data and transmits the stored data sequentially, and outputs the video data at a constant ratio to the channel, and checks the data amount stored in the buffer and sends the detected data to the video encoder. By controlling the supply, it is possible to prevent and control the over flow and under flow of video data.

Description

Data transmission control device of video telephone

1 is a block diagram of a data transmission control device according to the present invention

2 is a time chart for explaining the operation of the device

* Explanation of symbols for main parts of the drawings

10: video encoder 20: transmitter

30: Transmission buffer 40: Up / down counter

50: clock generator

The present invention temporarily stores variable video data transmitted from a video encoder and controls to transmit first-in first-out data to a channel to output video data of a constant ratio at all times. It is about.

In general, since video data output from a video encoder of a video telephone is formed in a variable length coding form, the amount of data varies irregularly with time.

Conventional video telephones for such variable video data do not have the same function as the present invention for maintaining output at a constant rate and controlling the output. Thus, a screen according to the overflow or underflow of video data transmitted through a channel. The state was not uniform.

Therefore, the purpose of this paper is to solve the above-mentioned problems of the prior art, and to temporarily store variable video data so as to transmit a constant ratio of video data, and to temporarily check the amount of stored data to check the stored data state. An object of the present invention is to provide a data transmission control apparatus of a video telephone, which is transmitted to a video encoding unit so as to prevent excessive or insufficient output video data.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. As shown in FIG. 1, the device of the present invention records the recording state according to the tissue state of the plurality of input blocks CK ₁ and CK ₂ . And an increase UUP) control signal and a video encoder 10 for outputting variable-length encoding video data, and temporarily storing the video data output from the video encoder 10, Read according to the logic state of the transfer buffer 30 and the plurality of input clocks CK ₁ and CK _{2 that first} input and output the data preferentially inputted by And a transmission unit 20 for generating a down control signal and transferring the video data preferentially output from the buffer 30 to a channel, and the recording signal ( ) And readout signal ( The up / down counter 40 and the recording signal for transmitting the number data to the video encoder 10 by increasing or decreasing the input / output data amount of the buffer 30 according to ) And readout signal ( In order to prevent the collision of the ()) is configured by interconnecting the clock generator 50 to generate a plurality of different clocks (CK ₁ ) (CK ₂ ).

If described in the embodiment with reference to Figure 2 the effect of the present invention configured as described as follows.

That is, when the operation of the video telephone starts, the clock generator 50 divides the clock of 2 MHz oscillated from the crystal oscillator (CM), so that the first clock CK ₁ and the second clock of 1 MHz as shown in FIG. The second clock CK _{2 at} 0.5 MHz as shown in (b) is supplied to the video encoder 10 and the transmitter 20.

In addition, the first clock CK _{1 of} 1 MHz, as shown in (a) of FIG. 2, has a clock terminal ( ₁ ) of the up / down counter 40. Is also applied. In such a state, the video encoder 10 only records a write control signal such as (d) of FIG. 2 only in the high state of the second clock CK ₂ supplied from the clock generator 50. ) And record the output data of the video encoder 10 at the input (Data in) of the buffer 30. At the same time, the low level write signal ( ) Is also applied to the increasing terminal UP of the up / down counter 40 so that the up / down counter 40 when the first clock CK ₁ as shown in FIG. Incremental coefficient operation is performed.

In addition, since the plurality of clocks CK ₁ and CK ₂ of the clock generator 50 are applied to the transmission unit 20 as described above,

Only in the low state of the second clock Ck ₂ , the read control signal shown in FIG. ) Is stored and the stored video data is read through the output terminal (Data out) of the buffer 30 and transmitted to the channel not shown.

At this time, the low level read control signal ( ) Is also applied to the down terminal of the up / down counter 40 so that the up / down counter 40 is turned on when the first clock CK _{1 as} shown in FIG. Decrease coefficient operation is performed.

In this way, the up / down counter 40 which increases or decreases the input / output data of the buffer according to the logic states of the first and second clocks CK ₁ and CK ₂ receives the input and output data of the buffer 30. The video encoder 10 controls the video data to be counted and stored in the inspection data regarding the amount of stored data.

As described above, the present invention outputs a constant ratio of video data to the channel by temporarily storing the variable output video data and controlling the transmission of the stored data sequentially, and inspects the detection data by checking the amount of data stored in the buffer. It is a very useful design that can prevent and control the output flow (Dver Flow) and underflow (Under Flow) of video data by controlling the supply to the video encoder.

Claims (1)

In the transmission of video data through a channel having a video encoder 10 and a transmitter 20, a buffer 30 for temporarily storing the video data and outputting the pre-input data preferentially, An up / down counter 40 for monitoring the amount of input / output data and transmitting the increase or decrease coefficient data to the video encoder 10, and a recording control signal ( ) And read control signal ( And a clock generator (50) for generating a plurality of clocks (CK ₁ ) (CK ₂ ), each of which has a different value for generating a).