JPH02257782A - Picture communication system - Google Patents

Abstract

PURPOSE:To receive normally high definition picture at all times by sending a fact of buffer overflow on picture control information and informing the result to an opposite terminal equipment even when buffer overflow takes place at a sender side. CONSTITUTION:When the data quantity of a compressed picture data exceeds the capacity of a transmission buffer memory 15, a specific number (m) except 0-n is given to a line number part and stored to inform the occurrence of overflow. The content of the transmission buffer memory 15 is sent to a data transmission section 2, converted into a serial data and sent to an I interface section 1 and sent to an opposite terminal equipment. Since it is recognized as an erroneous picture signal including a line number different from a conventional line number at the receiver side, a relevant picture signal is processed. Thus, the disturbance of the display screen is avoided and displeasure to a person watching the screen is avoided.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image communication system for transmitting image signals via an 15DN (integrated service digital network).

2. Description of the Related Art Devices that transmit audio information and image information via ISDN are generally called videophone devices.

FIG. 5 shows the configuration of a conventional videophone device.

(1) is an interface section for connecting with the 15DN, (2) is a data transmission section, (3) is a telephone, and (4) is a data processing control section that processes image information and various control information.

(5) is the operation unit, (6) is the display memory, (7) is the DA
converter, (8) a display unit for displaying the image in the image memory, (9) an imaging unit for capturing the image, 00
) is an AD converter, 00 is an acquisition memory, 0 is an integrated services digital network (ISDN), and Q is a line termination unit (DSU).

An image such as a human figure captured by the imaging unit (9) is converted into a digital video signal by an AD converter Gω, and then stored in a capture memory (11). The digital video signal stored in the capture memory 01) is sent to the data processing control unit (4).
) performs image compression processing, converts it into image data, and sends it to the data transmission section (2). The data transmission section (2) converts the image data into serial data, sends it to the I interface section (1), and sends it to the other party's terminal via DSUO and I5DN.

On the receiving side, image data from the DSUO bath is received by a data transmission unit (2) via an I interface unit (1). The data transmission section (2) extracts image data from the received serial data and sends it to the data processing control section (4). The data processing control section (4) performs decoding processing on the image data and converts it into a digital video signal. This digital video signal is stored in a display memory (6), converted into an analog video signal by a DA converter (7), and displayed on a display section (8).

Problems to be Solved by the Invention By the way, in a videophone device, on the transmitting side, after image data is compressed by a data processing control unit, it is stored in a transmission buffer memory, and the image data is read from this transmission buffer memory and transmitted. However, if the image data exceeds the capacity of the sending buffer memory and causes an overflow, there is no way to notify the receiving terminal, resulting in decoding errors and distorted displayed images. there were.

An object of the present invention is to provide a new image communication method that solves these problems.

In order to achieve the above-mentioned object of "i", the present invention provides an image processing system in which encoded image data is allocated for each predetermined period and an image signal to which a line number representing each period is attached is transmitted via ISDN. In the communication system, when the transmission buffer memory on the transmitting side overflows, an image signal is transmitted with a specific number added as the line number.

Further, in the image communication system of the present invention, when an image signal having a line number of a specific value is added when the transmission buffer memory on the transmitting side overflows, the receiving side transmits the line number of the specific value. A normal image signal that has been received before the image signal having the image signal and stored in the memory is read out and displayed on the display section in place of the image signal assigned the specific number.

1-Ri・ When the transmitting buffer memory on the transmitting side overflows like this, if a specific number is attached as the line number of the image signal, the receiving side will recognize this as an abnormal line number that contains a line number different from the normal line number. Since it can be recognized as an image signal, appropriate image signal processing can be performed.

As one of the processes on the receiving side, regarding abnormal image signals (image signals with line numbers of specific values),
If this is not displayed on the display and a normal image signal received before the abnormal image signal and stored in memory is read out and displayed, the display screen will not be disturbed and the screen will be displayed. Do not cause discomfort to those watching.

In FIG. 1, in which the present invention is implemented, the same parts as in FIG. In the figure, the side is a display control section that performs display control. σ■ is a transmission buffer memory provided in connection with the data transmission section (2), and 0ω is also a reception buffer memory. Although these buffer memories qω06) are not shown in FIG. 5, they are actually provided in FIG. 5 as well.

The operation shown in FIG. 1 will be explained first from the transmitting side. Imaging unit (9
) is converted into a digital video signal by an AD converter αω, and is stored in the capture memory 01). The digital video signal stored in the capture memory 00 is subjected to image compression processing in the data processing control section (4), and then stored in the transmission buffer memory 05). At that time, if the capacity of the compressed image data is within the capacity of the transmission buffer memory 05), one line of image data is stored with a line number from O to n at the beginning, as shown in Figure 3. However, if the amount of compressed image data overflows the capacity of the transmission buffer memory 05), the number from 0 to n is displayed in the line number part as shown in Figure 4 to notify that the overflow has occurred.
It is stored with a specific number m other than m. The contents of these transmission buffer memories are sent to the data transmission section (2), converted to 64 kb/s serial data, and sent to the ■interface section (1), and sent to the DSU side and l5DNO2.
) to the other party's terminal.

Note that the line number insertion section (LN) is provided following the screen synchronization signal (S) in the image signal packet shown in FIG. Coded image encoded data is assigned after the line number insertion part (LN),
Finally, end of frame
me) period is provided, and data indicating a parity check and the end of the frame is inserted. In FIGS. 3 and 4, the line numbers are 0, 1, 2, . . . for convenience. ...-9n, but these line numbers are also actually coded. The specific value m of the line number is 0, 1.2. -, any value other than n may be used, but it is preferable to set it in advance.

Next, the operation on the receiving side will be explained. Furthermore, l5DNO2
) The other devices connected to the terminal have the same configuration as in FIG. Since these devices can become a transmitter or a receiver depending on the operation of the operating section (5), a case will be described in which the device shown in FIG. 1 is operated as a receiver.

First, image data from DSUQ3) is received by the data transmission unit (2) via the I interface unit (1).

The data transmission section (2) extracts the image data from the 64kb/s serial data and once transfers it to the reception buffer memory 00.
is stored in If the line numbers are assigned in the correct order on the transmitting side, the received image data is sequentially sent to the data processing control unit (4), but the compressed image data is taken into the transmitting buffer on the transmitting side. If an overflow occurs and as a result, a packet with line number m exists, the display control unit Q41 does not clear the display memory (6) even after receiving one screen worth of image data. Therefore, the screen that was previously received and currently displayed is kept as it is without changing the display. That is, when an abnormal image signal with line number m is received, it is not displayed on the display section (8), but a normal image signal received previously and stored in the display memory (6) is displayed. Read and display. Then, data is continuously received from the first packet (line number is 0) of the next screen, and image data for one screen is received from the first packet (line number is 0).
The display control unit 04) switches the display only when the information from n to n is received correctly.

By doing this, even if an abnormal image signal with overflow is received on the transmitting side, the display screen will not be disturbed and a normal image will be displayed. In the embodiment shown in FIG. 1, the data processing control section (4) can be composed of a microcomputer, and this microcomputer can control the above-mentioned operations on the transmitting side and receiving side.

As explained above, according to the present invention, even if a buffer overflow occurs on the transmitting side, it can be reported to the other party's terminal by putting it in the image control information, so the receiving side cannot decode it and the error occurs. This has the effect of always receiving a normal, high-quality image without displaying the screen and causing no discomfort to the viewer.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, and FIG. 2 is a diagram schematically showing the frame structure of encoded data transmitted according to the present invention. FIG. 3 is a diagram showing a data format when encoding is performed normally, and FIG. 4 is a diagram showing a data format when a buffer overflow occurs. FIG. 5 is a block diagram of a conventional example. (0,1,2,・-,n) -Line number (m)
・-Specific value line number (6)・-Display memory, (8)・-Display section, 02)・
...l5DN. 05) - Transmit buffer memory. 0ω-...Reception buffer memory.

Claims (2)

[Claims] (1) When the transmission buffer memory on the transmitting side overflows in an image communication system in which encoded image data is allocated every predetermined period and an image signal with a line number representing each period is transmitted via ISDN. An image communication system characterized in that an image signal is transmitted with a specific number attached as the line number. (2) When receiving an image signal with a line number of a specific value that is added when the transmission buffer memory on the transmitting side overflows, the receiving side receives the image signal before the image signal with the line number of the specific value. An image communication system characterized in that a normal image signal previously stored in a memory is read out and displayed on a display section in place of the image signal assigned the specific number.