JPH04192838A - Atm cell generating system and method and device for synthesizing tv conference image in atm exchange - Google Patents

Abstract

PURPOSE:To take the syhchronization in an ATM cell level, and also, to curtail the number of ATM cells by converting a synchronizing signal in an image signal, etc., to the ATM cell separately from other image signal. CONSTITUTION:A TV conference image synthetizing device in ATM exchange is constituted by providing an ATM cell accumulating part 2, an image synchronization cell detecting part 4, a cell switch 6, an image synchronization control part 8, a switch control part 10, and a cell distributor 12. In such a state, at the time of transmitting a signal from an ATM terminal equipment to an ATM switching network in order to offer an information signal containing a synchronizing signal outputted from a TV camera, etc., for synthesizing a signal in a TV conference, etc., the synchronizing signal in the information signal is generated as a synchronization cell being independent from other signal part in its ATM terminal equipment. In such a way, image synchronization is taken in an ATM cell level, and also, the number of ATM cells are curtailed.

Description

[Detailed description of the invention] [Table of contents] Overview Industrial field of application Prior art (Figures 6 to 9) Means for solving the problem to be solved by the invention (Figure 1) Operation implementation Examples (Figures 2 to 5) Effects of the invention (Summary) Regarding an ATM cell generation method using a synchronization signal as an independent cell, and a method and device for synthesizing TV conference images in ATM exchange, images, etc. at the ATM cell level are provided. In an ATM switching network that exchanges ATM cells, the aim is to achieve synthesis and synchronization of ATM cells.
An invention for generating a synchronization signal in an information signal in an M terminal device as a synchronization cell independent of other signal parts, and an ATM
In an ATM switching network that performs cell exchange, when cells for image synchronization from each subscriber participating in a TV conference are not detected simultaneously, cells for image signals are accumulated, and cells for image synchronization from all subscribers are detected. ATM
In an ATM switching network for exchanging cells, an ATM cell storage section, an image synchronization cell detection section, a cell switch,
An invention comprising an image synchronization control section, a switch control section, and a cell distribution section is disclosed.

[Industrial application field]

The present invention relates to an ATM cell generation system using a synchronization signal as an independent synchronization cell, and a method and apparatus for synthesizing TV conference images in ATM exchange.

Integrated service digital networks (Integrat
ed 5service Digital Netw
ATM switching system is one of the switching systems that is considered promising for constructing a network (hereinafter referred to as 15DN). This ATM exchange system allows for unified exchange of various information data. One of the information data is image data. Also, in the ATM switching network, construction of a TV conference system within the ATM switching network is also being considered.

[Conventional technology]

As a possible TV conference image synthesis method for providing a TV conference system within a conventional ATM switching network, there is one that is constructed by applying the TV conference image synthesis method in the conventional circuit switching system to the ATM switching network. be. A shown in Figure 6
The TM switch 30 is included in a known ATM exchange, and uses the ATM bridge 32 and the ATM switch 30 to combine ATM cells from subscribers participating in the TV conference. The ATM cell of the TV conference image synthesized by the ATM bridge 32 is transmitted via the ATM switch 30 to the subscribers participating in the TV conference, and the image is broadcast on the screen of the subscriber's monitor device. This TV conference image synthesis method will be described in detail with reference to the ATM subscriber device shown in FIG. 7 and the ATM bridge 32 shown in FIG.

From the ATM subscriber device shown in FIG.
M cells are generated and sent to the ATM switch. Analog image signals from a camera or the like 70 are encoded by an encoding circuit 72, assembled into cells by a cell assembly section 74, and transmitted from a transmission termination device 76 to an ATM switch. Cell assembly section 7
4 consists of a buffer 74A, a cell assembly control section 74B, and a header adding section 74C. As shown in (1) in FIG. 9, the cell assembling section 74 reads the image signal data and the image synchronization signal data from the buffer 74A under the control of the cell assembly control section 74B. In this method, the image data consisting of the output image signal data and image synchronization signal data is attached with a header by the header attaching section 74C, and is assembled into an image data cell string as shown in (2) of FIG. .

As described above, the ATM cells transmitted from each ATM subscriber device are sent to the ATM of the ATM switch.
It is exchanged at the M switch 30 and sent manually to the ATM bridge 32. The ATM cell is decomposed into digital image data by a cell decomposition unit 88 corresponding to each subscriber (no code is given to distinguish between subscribers; the same applies hereinafter in this section), and then the digital image data of each subscriber is decomposed into digital image data. For each image synchronization detection section 90 detects image synchronization for the digital image data in a manner similar to the conventional circuit switching method, and in response to the image synchronization detection, writing to and reading from the frame memory 92 is performed by the readout control section 94. The read digital image data is assembled into an ATM cell in the cell assembly section 96, and the ATM cell is transferred to the ATM switch 3.
Transfer to 0.

In this way, the combined ATM cells are exchanged at the ATM switch 30 and transmitted to each subscriber participating in the aforementioned TV conference. Each ATM terminal device receives the ATM cell transmitted by the transmission termination device 76,
The ATM cell is removed by a cell disassembly device (header deletion unit 78).
A, and a buffer 78B. ) is decomposed into digital image data, and the digital image data is decoded into an analog image signal by a decoding circuit 80 and sent to a monitor, etc.
A TV conference system is formed within the above-mentioned ATM switching network by broadcasting from the screen of the subscriber display device No. 2.

[Problems to be Solved by the Invention] As mentioned above, in the TV conference image synthesis method in the conventional TV conference system, the image synthesis method used in the ATM bridge 32 is different from the image synthesis method in the conventional circuit switching system. Therefore, decomposition of ATM cells into digital image data, image synthesis at the digital image data level,
Then, the combined digital image data is transferred to ATM again.
Assembly into cells is essential. Therefore, the complexity of the processing, the increase in hardware, the increase in delay time, etc. arise as technical problems to be solved. In addition to these problems, in the process of assembling digital image data into cells in an ATM terminal device, the image synchronization signal data included in the digital image data is separated from the image signal data as described above, and As shown in (2) in the figure, since the image synchronization signal data is included in the previous and subsequent image data cells and assembled into cells continuously, it is possible to synchronize the digital image signal data at the cell level. There are also technical challenges that will become more difficult.

The present invention was created in view of such technical problems, and provides an ATM cell generation method and a TV conference image synthesis method in ATM exchange that contribute to the synthesis and synchronization of images at the ATM cell level. and its equipment.

[Means to solve the problem]

The invention according to claim 1 is configured such that, in an ATM switching network that exchanges ATM cells, a synchronization signal within an information signal in an ATM terminal device is generated as a synchronization cell independent of other signal parts. .

The invention according to claim 2 is an A for exchanging ATM cells.
In the TM switching network, when the image synchronization cells input from the communication channels corresponding to each subscriber are detected, and the image synchronization cells from each subscriber participating in the TV conference are not detected at the same time, causing an accumulation of image signal cells,
When the image synchronization cells from all the subscribers participating in the TV conference are detected and synchronization is established from all the subscribers, after outputting the image synchronization cells, the image synchronization cells from each subscriber participating in the TV conference are detected. Exchanging switching corresponding to a predetermined image synthesis pattern by sequentially outputting the image signal cells from the beginning, and applying the outputted image synchronization cells and the sequential image signal cells corresponding to each subscriber to each other in accordance with a predetermined image synthesis pattern. It is constructed by giving exchanges in patterns and composing them.

The invention according to claim 3 is an ATM, as shown in FIG.
In an ATM switching network that exchanges cells, an ATM cell storage section 2 is provided for the subscribers participating in the TV conference, and an ATM cell storage section 2 is provided for the subscribers participating in the TV conference, and is used for detecting cells for image synchronization and for image signals. An image synchronization cell detection section 4 that outputs cells, a cell switch 6 connected to the output of the image synchronization cell detection section 4, and a cell switch 6 connected to the detection output of the image synchronization cell detection section 4, In response to each detection output before the detection of cells for image synchronization from all participating subscribers, the corresponding ATM cells are stored in the storage storage, and in response to the detection of cells for image synchronization from all subscribers participating in the TV conference. an image synchronization control section 8 that causes simultaneous reading from each ATM cell storage section 2;
In response to the detection of image synchronization cells from all subscribers participating in the conference, image signals at the same timing are simultaneously read out from the image synchronization cells and subsequently from the ATM cell storage section 2 to be image synthesized. a switch control unit IO for switching and outputting cells for use from the cell switch 6; and a cell distribution unit 12 for distributing ATM image cells synthesized by switching in the cell switch 6 to subscribers participating in the TV conference. configured.

[For production]

For example, an AT
When the information signal is transmitted from the M terminal device to the ATM switching network, the synchronization signal within the information signal is generated in the ATM terminal device as a synchronization cell independent of other signal parts.

The information signal is an image signal, and multiple AT
Image synthesis of image signals output from the M terminal device is performed in the following manner according to the invention according to claims 2 and 3.

For ATM cells from each subscriber participating in the TV conference, it is first detected in the ATM switching network whether or not a cell for image synchronization has arrived. In the invention according to claim 3, this is performed by the image synchronization cell detection section 4.

In this detection, when it is found that the image synchronization cells have not arrived from all the subscribers, the image signal cells that are input are accumulated in response to the detection of the image synchronization cells. This is performed by the image synchronization control section 6 in the invention according to claim 3.

As each of the operations described above progresses and when image synchronization cells from all subscribers are detected, the image synchronization cells are first output. In the invention according to claim 3, the switch control section 10, the cell switch 8, and the cell distribution section 12
It will be held in The image signal cells from each subscriber participating in the TV conference are exchanged and combined using an exchange switching pattern corresponding to a predetermined image combination pattern. In the invention according to claim 3, this is performed by the switch control section 10, the cell switch 8, and the cell distribution section 12.

As mentioned above, since the synchronization signal in the image signal etc. is made into an ATM cell separately from other image signal parts, the ATM
Image synchronization can be achieved at the M cell level, and ATM
The number of cells may also be reduced. In addition, by using this synchronization method in ATM cell exchange for TV conference image synthesis, AT
The need to disassemble and synthesize M cells is eliminated, and AT
Images can be synthesized using the M cell itself. Therefore, the amount of hardware can be reduced and the delay in signal propagation time can be reduced. It is possible to perform TV conference image synthesis with excellent real-time performance.

〔Example〕

FIG. 2 and FIG. 3 each show an ATM implementing the present invention.
The configuration of a terminal device and an ATM bridge is shown, and claims 1,
An embodiment corresponding to the invention according to claim 2.3 is shown.

In FIG. 2, the encoding circuit 33 and the cell assembly section 37
The components are the same as those of the conventional ATM terminal device shown in FIG. 7 except for the following. Therefore, those conventional components are given the same numbers as those given to the same components as in FIG. 7, and the explanation thereof will be omitted. The encoding circuit 33 separately outputs image signal data and image synchronization signal data. The image data consists of image synchronization signal data shown in (1) of FIG. 4 and image signal data shown in (2) of FIG. The cell assembly unit 37 includes a buffer 74A and a synchronization information creation unit 37.
A, a cell assembly control section 37B, and a header 37C. The synchronization cell creation section 37A creates one piece of image synchronization cell information under the control of the cell assembly control section 37B in response to the image synchronization signal data output from the encoding circuit 33, as shown in FIG. . The cell assembly control unit 37B controls calling of the buffer 74A to call the image signal cell information. The cell assembly control section 37B has a header adding section 37C.
A header is added to the beginning of each of the image synchronization cell information from the synchronization cell creation unit 37A and the image signal cell information from the buffer 74A, thereby creating an image synchronization cell and an image signal cell. .

The cell assembling section 37 sends out an image signal cell for each predetermined image signal data from the encoding circuit 33, but the sending out of the image signal cell corresponding to the image signal data from the cell assembling section 37 is based on the encoding circuit 33. Under the control of the cell assembly control unit 37B which receives the image synchronization signal data from the circuit 33, it is sent out after sending out the image synchronization cells described later (see (3) in FIG. 4).

Therefore, unlike the prior art, the image signal cell does not contain any component of the image synchronization signal data.

As shown in FIG. 3, the ATM bridge 36 has a cell buffer 40 and a synchronization detection circuit 42 for each subscriber. The image synchronization control section 44 controls storage and readout of the cell buffer 40 in response to a detection signal from the synchronization detection circuit 42. The cell buffer 40 is composed of, for example, a FIFO, and writes the ATM cells transmitted in response to the accumulation command signal in the order in which they were received. A cell switch 46 is connected to the output of each synchronization detection circuit 42.
switches and outputs ATM cells, and the switching control is performed by a switch control section 48 that receives a switching control signal from an image synchronization control section 44. The ATM cells outputted from the cell switch 46 are duplicated in the cell copy circuit 50 and then outputted.

The duplicate output (ATM cells of the composite image) of the TV conference joining frame from this ATM bridge 36 is input to the ATM switch 30 described in the above-mentioned [Prior Art] section, and there sent to each person.

In FIGS. 2 and 3, the cell buffer 4° is
This corresponds to the ATM cell storage section 2 in the figure. Synchronization detection circuit 42
corresponds to the image synchronization cell detection section 4 in FIG. The cell switch 46 corresponds to the cell switch 6 in FIG. 1, and the switch control section 48 corresponds to the switch control section 8 in FIG. The cell copy section 50 corresponds to the cell distribution section 10 in FIG.

The operation of the embodiment of the present invention having the above-described configuration will be described below.

Each ATM terminal device takes an image of a subscriber participating in a TV conference using a camera or the like, and encodes the image in an encoding circuit 33. The image signal data of the image data is assembled into an image signal cell in substantially the same manner as the conventional method under the control of the buffer 37A and header adding section 37C by the cell assembly control section 37B in response to the image synchronization signal data. The image synchronization signal data is sent to the buffer 37A and the header adding section 37 by the cell assembly control section 37B in response to the image synchronization signal data.
Under the control of C, the signals are assembled into image synchronization cells and transmitted from the transmission termination device 76 via the subscriber line 77 to the ATM switch. The image synchronization cell indicates that the image signal cell for one image follows the image synchronization cell.

In the ATM switch, the first ATM cell input to the corresponding cell buffer 40 for each subscriber participating in the TV conference, that is, the image synchronization cell, passes through the cell buffer 40 and is input to the synchronization detection circuit 42. be done. The synchronization detection circuit 4
Step 2 determines whether the input ATM cell is an image synchronization cell. When each synchronization detection circuit 42 detects an image synchronization cell, it sends the detection information (including synchronization detection circuit information) to the image synchronization control unit 44, and the image synchronization control unit 44 transmits the image of the subscriber participating in the TV conference. Determine whether synchronization is achieved. When the synchronization is not achieved, the image synchronization control section 44 sends an accumulation command signal to the cell buffer 40 corresponding to the synchronization detection circuit information, and sequentially accumulates the input ATM cells. When all the image synchronization cells have been detected through this accumulation, that is, when the images of the subscribers participating in the TV conference have been synchronized, the image signal cells from all the cell buffers 40 are simultaneously read out. Start from the beginning.

In response to synchronization of the synchronization detection circuit information that last notified the detection of the image synchronization cell and the images of the subscribers participating in the TV conference, the image synchronization control unit 44 first starts the simultaneous reading. Switching is performed to output the last image synchronization cell from the cell switch 46.

Subsequently, the image signal cells read from each cell buffer 40 cause the cell switch 46 to switch according to a switching pattern preset in the switch control section 48 to synthesize an image. The preset switching pattern may be fixed, or may be variable and transferred from a control means that determines the image composition mode. The setting control of the switching pattern itself is not an object of the present invention.

An example of image composition in the cell switch 46 will be explained with reference to FIG.

As shown in FIG. 5, the ATM cells input from each subscriber to the input of the cell switch 46 correspond to all images captured by a camera or the like. At the timing corresponding to the upper left quarter of the raster that constitutes the screen of a monitor, etc. (from ■ to ■ in Figure 5), the upper left quarter of the raster that constitutes the screen of the monitor, etc. Each of the ATM cells to the subscriber corresponding to subscriber B is switched and output, and at the timing corresponding to the upper right quarter in the first raster (from ■ to ■ in FIG. 5), the ATM cells of subscriber B Each of subscriber B's ATM cells corresponding to the upper right-hand quarter of the first raster in the subroutine are switched and output. This switching continues from each raster following the first raster to each raster forming the upper half of a screen such as a monitor.

The switching process then proceeds to the switching of the ATM cells for the next raster, ie the bottom half of the screen, which is the same as described for the top half of the screen. However, the timing corresponding to the lower left quarter and lower right quarter (from ■ to ■ in Figure 5)
The ATM cells that are switched by the cell switch 46 in the steps up to and from ■ to ■) are each of the ATM cells corresponding to the lower left quarter of subscriber C, and the ATM cells corresponding to the lower right quarter of subscriber C. each of them.

The ATM cells switched by the cell switch 46 in this manner are duplicated by the number of participants in the TV conference by the cell copy circuit 50, and transferred to the ATM switch 30, where the ATM cells are copied by the cell copy circuit 50 and transferred to the ATM switch 30.
It is distributed to each of the V-conference participants. In each ATM terminal device, the synthesized image is displayed on the screen of a monitor 82 in the same manner as in the past. The display state is shown in FIG.

For subscriber A, as shown at 200 in FIG.
For subscriber B, the upper right quarter half B2 is displayed; for subscriber R, the lower left quarter D-; and for subscriber C, the lower right quarter C1 is displayed.

In the embodiment described above, the cell assembly control unit 37B receives the synchronization signal data from the encoding circuit 33, but it is also possible that the encoding circuit separates the image signal data and the synchronization signal data and outputs them. If the synchronizing signal data is not available, the same processing as described above will be performed after separating the synchronizing signal data from the image signal data. Furthermore, although a case has been described in which a cell switch and a part of a cell copy are provided, even if the hardware configuration is such that the ATM cells of each subscriber can be exchange-switched corresponding to each time period as described above, good.

〔Effect of the invention〕

As described above, according to the present invention, since the synchronization signal in the image signal etc. is converted into an ATM cell separately from other image signal parts, it is possible to provide a means for synchronizing at the ATM cell level. The number of ATM cells can also be reduced. During the ATM cell exchange process for synthesizing TV conference images, the ATM
By using cell-level synchronization means, the need for disassembling and recombining ATM cells is eliminated;
Image composition can be performed within the cell itself.

Therefore, the amount of hardware can be reduced and the delay in signal propagation time can be reduced. Excellent real-time performance in combining TV conference images.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of the principle of the present invention, Fig. 2 is a block diagram of an ATM terminal device implementing the present invention, Fig. 3 is a block diagram of an ATM bridge implementing the present invention, and Fig. 4 is a block diagram of the ATM terminal device implementing the present invention. A diagram showing the relationship between the image data output from the decoding circuit of the ATM terminal device and its image data cell string, Figure 5 is a diagram explaining image synthesis, and Figure 6 is a diagram of the TV conference image synthesis method. Fig. 7 is a block diagram of a conventional ATM terminal device, Fig. 8 is a block diagram of a conventional ATM bridge, and Fig. 9 shows image data input to the cell assembly section of the ATM terminal device in Fig. 7. , and the image data cell string. 1 to 3, 2 is an ATM cell storage unit (cell buffer 40), 4 is an image synchronization cell detection unit (synchronization detection circuit 42), 6 is a cell switch (cell switch 46), and 8 is a switch control unit. section (switch control section 48); 10 is a cell distribution section (cell copy section 5);
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Claims (3)

[Claims] (1) In an ATM switching network that exchanges ATM cells, an ATM cell generation method is characterized in that a synchronization signal in an information signal in an ATM terminal device is generated as a synchronization cell independent of other signal parts. (2) In the ATM switching network that exchanges ATM cells, the image synchronization cells input from the communication channels corresponding to each subscriber are detected, and the image synchronization cells from each subscriber participating in the TV conference are simultaneously transmitted. When not detected, cells for image signals from detection-compatible subscribers are accumulated, and when cells for image synchronization from all subscribers participating in the TV conference are detected and synchronization from all the subscribers is achieved, After outputting the image synchronization cells, the image signal cells from each subscriber participating in the TV conference are sequentially output all at once from the beginning, and the outputted image synchronization cells and each of the above sequentially T in an ATM exchange characterized in that image signal cells corresponding to subscribers are given an exchange in an exchange switching pattern corresponding to a predetermined image synthesis pattern and synthesized.
V conference image synthesis method. (3) In an ATM switching network that exchanges ATM cells, there is an ATM cell storage unit (2) provided for subscribers participating in the TV conference, and an ATM cell storage unit (2) provided for supporting subscribers participating in the TV conference, and an image synchronization cell storage unit (2) provided for supporting subscribers participating in the TV conference. an image synchronization cell detection unit (4) that detects and outputs an image signal cell; a cell switch (6) connected to the output of the image synchronization cell detection unit (4); and the image synchronization cell detection unit (4). The corresponding ATM cell accumulating unit (
2) and in response to the detection of image synchronization cells from all subscribers participating in the TV conference, each ATM cell storage unit (
2) Image synchronization control unit (
8), and in response to the image synchronization control unit (8) detecting the image synchronization cells from all the subscribers participating in the TV conference, the image synchronization cells, and subsequently the image synthesis target A.
a switch control unit (10) that causes the cell switch (6) to switch and output image signal cells read out at the same time from the TM cell storage unit (2) at the same time; A characterized in that it is provided with a cell distribution unit (12) that distributes the combined ATM image cells to the subscribers participating in the TV conference.
TV conference image synthesis device in TM exchange.