JPH07123385A - Multi-spot video communications system - Google Patents

Abstract

PURPOSE:To provide a multi-spot video communications system enabling both display modes of a divided display mode and a full screen display mode by using an economical loop type connection system. CONSTITUTION:Each terminal connected in a loop form via a transmission line and arranged at plural spots has a display mode switch means switching two display modes of a division display mode and a full screen display mode and composed of an input/output image switch part 15, an encoding data switch part 19 and a control part 29, a control signal transmission and reception means performing the transmission and reception of control signals between each terminal and composed of a multiplex/separation part 13 and the control part 29 and a control means imparting the instruction of the switch of the display mode to the display mode switch means according to the contents of a received control signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multipoint video communication system in which a plurality of points are connected in a loop and video communication is performed.

[0002]

2. Description of the Related Art Conventional videophones can only perform one-to-one counter communication. Also, in a video conference system, which is a system that also performs image communication, multipoint connection is realized by connecting in a star shape via a center device.

In the star-type connection system using the center device, since images of all points are concentrated on the center device, switching control such as which image of each point is distributed to each point is easy.

However, the star-type multi-point video conference system has a drawback that a large-scale and expensive center device is necessarily required. Therefore, a method of connecting a plurality of terminals in a loop is conceivable as a method of realizing multipoint connection without requiring a center device.

This loop connection system also has an advantage that the number of channels required for connection may be smaller than that of the star connection system.

[0006]

In the loop type connection method, unlike the star type connection method, there is no node where the images of all points are concentrated, so it is difficult to edit and distribute images from each point. It is easy to think that the image of only one place is displayed.

[0007] However, depending on the usage scene, there are a scene in which split display in which a plurality of grounds can be viewed at the same time are suitable, and a scene in which full-screen display in which an image of the ground on a high resolution is displayed is suitable. For example, in the case of simultaneous monitoring of a plurality of points, a split screen display is suitable, but at a point where an abnormality is seen, it is necessary to monitor from a remote location up to the details of a high resolution image.

The present invention has been made in view of the above,
It is an object of the present invention to provide a multipoint video communication system which enables both a split display mode and a full screen display mode by using an economical loop type connection system.

[0009]

In order to achieve the above object, a multipoint video communication system of the present invention divides a screen into a plurality of areas, and an image using an encoding method for encoding each area. A multipoint video communication system in which a plurality of terminals capable of transmitting and receiving data and control signals are respectively arranged at a plurality of points, and the plurality of terminals are connected in a loop through a transmission path, The terminal is a display mode that switches between two display modes: a split display mode in which the display screen is divided and an image of a plurality of points is displayed on each split screen, and a full-screen display mode in which an image of one point is displayed on the entire display screen. A switching means, a control signal transmitting / receiving means for transmitting / receiving the control signal between the terminals, and an instruction for switching the display mode to the display mode switching means according to the content of the received control signal. And summarized in that and a obtaining control means.

[0010]

In the multipoint video communication system of the present invention, the control signal is transmitted and received between the terminals arranged at a plurality of points through the transmission lines connected in a loop, and the contents of the received control signal Two display modes, split display mode and full screen display mode, can be switched during communication, improving the man-machine interface of the display.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

In the embodiment of the present invention, CCITT Recommendation H.261 is used as a video coding system, CCITT Recommendations H.241 and H.242 are used as a multimedia multiplexing system, and an ISDN basic interface is used as a transmission line. The multipoint video communication system used will be described.

FIG. 1 shows the hierarchical structure of CCITT recommendation H.261 image data. According to CCITT Recommendation H.261, one screen is divided into 12 GOBs (Groups of Blocks), and each GOB is divided into 33 macroblocks, as shown in FIG. Encoding is performed in units of macroblocks. As described above, the H.261 coding method is an example of a coding method in which a screen is divided into a plurality of areas and coding is performed for each of the areas. In addition, JPEG (Joint Photographic Codin
g Experts Group), MPEG, etc. are also examples of methods for performing coding for each area.

Further, FIG. 1 shows a resolution called FCIF which is composed of 12 GOBs on the whole screen, but in H.261, the resolution of FCIF which is composed of 3 GOBs (GOB1,3,5) on the whole screen is shown. A format called QCIF having a resolution of 1/4 is also defined.

FIG. 2 shows a format of a transmission frame of CCITT recommendation H.261 encoded data. The encoded data is framed in units of GOB in FIG.

FIG. 3 shows a connection example of the multipoint video communication system of this embodiment. The ISDN basic interface allows two B channels to be used simultaneously on one line, and each terminal is connected to both adjacent terminals by one B channel respectively, and a loop of one B channel is formed as a whole. There is. FIG. 3 shows an example of a multipoint video communication system including four terminals A, B, C, and D.

CCITT Recommendation H.242 stipulates how the above video data and user data (LSD) are multiplexed on the B channel of ISDN. In this embodiment, the video data and LSD are multiplexed on one B channel accordingly.

FIG. 4 is a block diagram showing the structure of a terminal used in a multipoint video communication system according to an embodiment of the present invention.

The terminal shown in FIG. 4 is connected to a partner terminal via ISDN, receives data and call control information sent from the partner terminal via ISDN, and receives data on the B channel and D channel. It has a network interface unit 11 for separating a call control signal. The network interface unit 11 has multiple
The screen synthesizing unit 1 is connected to the image decoding unit 21 via the separating unit 13 and further via the input / output image switching unit 15.
Connected to 7. The image decoding unit 21 is the image display unit 2.
3, the screen synthesis unit 17 is connected to the image coding unit 25 via the coded data switching unit 19, and the image input unit 27 is connected to the image coding unit 25. Further, the network interface unit 11, the multiplexing / demultiplexing unit 13, the input / output image switching unit 15, the screen synthesizing unit 17, the encoded data switching unit 19, and the image encoding unit 25 are connected to the control unit 29 via the bus 31, respectively. ing.

The multiplexing / separating unit 13 separates the data on the B channel into image data and user data, sends the image data to the screen synthesizing unit 17 via the input / output image switching unit 15, and also the image decoding unit. Send to 21. The user data is transferred to the control unit 29 via the bus 31. Since the multipoint video communication system has a loop-shaped connection form as shown in FIG. 3, the flow of video data is unidirectional. In this example, for convenience, in FIG. 3, A → B → C →
The direction is D → A. Therefore, the multiplexer / demultiplexer 13 of the terminal A uses the data from the channel connected to the terminal D as the reception data, and the transmission data is sent to the channel connected to the terminal B.

The image decoding unit 21 decodes the image data from the multiplexing / demultiplexing unit 13 according to CCITT Recommendation H.261.

The image coding unit 25 uses the CCITT recommendation for the input image.
Encode according to H.261. As for the encoding, full-screen display is performed as a system according to an instruction from the control unit 29, and when the terminal itself is an image transmission terminal, the encoding is performed by FCIF,
If split screen display is used as the system, QCIF encoding is performed. The encoded data has the format shown in FIG.

In response to an instruction from the control unit 29, the input / output image switching unit 15 transfers the received data from the multiplexing / demultiplexing unit 13 to the screen synthesizing unit 17 when the system is in the split screen display, and vice versa. The received data from the synthesizer 17 is transferred to the multiplexer / demultiplexer 13. When the system is performing full-screen display and is displaying the image of the terminal itself, the received data from the multiplexing / separating unit 13 is not sent to the screen synthesizing unit 17, and the encoded data switching unit 19 sends the received data. The data is transferred to the multiplexing / separating unit 13. When the image of another terminal is displayed on the full screen, the received data from the multiplexing / separating unit 13 is returned to the multiplexing / separating unit 13 as it is.

In response to an instruction from the control unit 29, the encoded data switching unit 19 transfers the QCIF data from the image encoding unit 25 to the screen compositing unit 17 when the system is in split screen display. When the system is performing full-screen display and is displaying the image of the terminal itself, the FCIF data from the image encoding unit 25 is transferred to the input / output image switching unit 15. When an image of another terminal is displayed in full screen display, the input / output image switching unit 1 is also included in the screen combining unit 17.
No data is transferred to 5.

The screen synthesizing unit 17 synthesizes images from each ground. The composition of the screen depends on any suitable known method. For example,
If four terminals on the ring transmit images of QCIF resolution and synthesize four FCQC images to form one FCIF image, the screen synthesis unit 17
Deletes the portion other than the GOB data from the data of the format shown in FIG. 2 received from the encoded data switching unit 19 and rewrites the GOB number with the number corresponding to the display position.
By replacing it with the corresponding GOB data of the data received by the input / output image switching unit 15, a FCIF composite image in which a new self-terminal image is composited is created.

As shown in FIG. 12, the control unit 29 instructs the screen synthesizing unit 17 to display the display position (GOB number) of its own terminal image, or uses a signal from the screen synthesizing unit 17 as a trigger, and the image coding unit A switching control unit 3 for instructing 25 to perform encoding, or for instructing switching to the input / output image switching unit 15 or the encoded data switching unit 19 depending on the display state of the system.
9. User data receiving / recognizing unit 37 that switches the display state according to the content of the user data received from the multiplexing / demultiplexing unit 13, call control unit 33 that performs ISDN call control, capability exchange specified in H.242, etc. From the H.242 / H.230 control unit 35, the man / machine interface control unit 31, and the user data reception / recognition unit 37 that control user data, and the user data transmission unit 41 that transmits user data from the man / machine interface. It is composed of a man-machine interface control unit 31 for activating display switching and the like.

If the received user data is not addressed to its own terminal, the user data receiving / recognizing unit 37 sends it to the user data sending unit 41 as it is, and the user data sending unit 41 sends it to the next terminal. In this way, each terminal is sent to the target terminal via the relay system.

Returning to FIG. 4, the image display unit 23 is a monitor for displaying the image decoded by the image decoding unit 21. The image input unit 27 is a camera that inputs an image to the image encoding unit 25.

The input / output image switching unit 15, the coded data switching unit 19, and the switching control unit 39 of the control unit 29 constitute display mode switching means. Multiplexing / separating unit 13, control unit 2
The user data receiving / recognizing unit 37 and the user data transmitting unit 41 of 9 constitute a control signal transmitting / receiving unit. The screen synthesizing unit 17 and the image encoding unit 25 constitute a division display mode realizing means. The image coding unit 25 constitutes a means for realizing the full screen display mode.

Next, as shown in FIG.
The operation of each unit will be specifically described in the case of shifting from the state in which the full screen is displayed to the split screen display as shown in FIG.

The flow of the image signal of each terminal in the display state shown in FIG. 5 is as follows.

The flow of the image data in the terminal A at the time of transmitting the full screen is, as indicated by the arrow in FIG. 9, ISDN → network interface 11 → demultiplexer 13 → image decoder 21 → image display 23. Further, the image is sent to the route of the image input unit 27 → image coding unit (FCIF) 25 → coded data switching unit 19 → input / output image switching unit 15 → multiplex / separation unit 13 → network interface unit 11 → ISDN.

The flow of image data when the terminals B, C and D receive the full screen sent from the terminal A is as shown by the arrow in FIG. Separation unit 13 → image decoding unit 21
→ image display unit 23, simultaneously demultiplexing unit 13 → input / output image switching unit 15 → demultiplexing unit 13 → network interface unit 11
→ Becomes the ISDN route.

In the loop shown in FIG. 3, shown in FIG.
Only one H.261 frame orbits (Fig. 7 and 2 are the same).

When the terminal A is the starting source, the control unit 29 of the terminal A instructs the multiplexing / demultiplexing unit 13 to send a screen switching command to the LSD area (man / machine interface control unit 31 → user data). Sending unit 41 →
Multiplexing / separating unit 13). The screen switching command may be uniquely determined by the system. The information includes destination terminal information, screen type information, screen type information (whether divided into four screens or all screens), and display position information (any of four divided screens). LS
Area D is defined in CCITT Recommendation H.221.

The control unit 29 (man / machine interface unit 31 → switching control unit 39) of the terminal A instructs the input / output image switching unit 15 to the encoded data switching unit 19 to switch the input / output image switching unit. The data from the image coding unit 25 is input / output to / from the coded data switching unit 19 so that the image data is sent to the screen synthesizing unit 17 to 15 and the data from the screen synthesizing unit 17 to the multiplexing / dividing unit 13. The screen compositing unit 17 is instructed not to switch to the image switching unit 15 (FIG. 11). Further, the screen synthesizing unit 17 is instructed of the display position of its own terminal. As shown in FIG. 6, since the display position of the terminal A is the upper left, it is instructed that the position corresponds to GOB 1, 3, 5 as compared with FIG.

When the screen synthesizing unit 17 detects the PSC of the H.261 frame shown in FIG. 2 that has looped around the loop, it notifies the control unit 29 of it.

When the control unit 29 (switching control unit 39) receives the notification from the screen synthesizing unit 17, the image coding unit 25 receives the QCIF
To instruct encoding. The data sent from the image coding unit 25 to the coded data switching unit 19 has the format shown in FIG.

In the screen synthesizing unit 17, the input / output image switching unit 1
Of the data of FIG. 7 received from FIG. 5, the data of GOB 1, 3, 5 (corresponding to the upper left of the screen) is deleted, and GOB 1, 3, of the data of FIG. 8 received from the encoded data switching unit 19 is deleted.
5 Insert the data. Then, the format of FIG. 7 is reconstructed and sent to the input / output image switching unit 15.

Next, the operation of the terminal B will be described.

Control unit 29 (user data reception / recognition unit 3
7) analyzes the screen switching command received through the multiplexing / demultiplexing unit 13, switches from the full screen to the 4-split screen, and understands that the display area of the own terminal is the upper right (see FIG. 6).

Then, the user data receiving / recognizing unit 37 notifies the switching control unit 39, and the switching control unit 39 instructs the input / output image switching unit 15 and the encoded data switching unit 19 to perform switching. The input / output image switching unit 15 has been
Although the data from the demultiplexing unit 13 is folded back, it is sent to the screen synthesizing unit 17 and the data from the screen synthesizing unit 17 is sent to the multiplexing / separating unit 13. The encoded data switching unit 19 instructs the screen synthesis unit 17 to pass the data from the image encoding unit 25 (FIG. 11). Further, the screen synthesizing unit 17 is instructed of the display position of its own terminal. As shown in FIG. 6, since the display position of the terminal B is at the upper right, it is instructed that the position corresponds to GOB 2, 4, 6 as compared with FIG.

When the screen synthesizing unit 17 detects the PSC of the H.261 frame of FIG. 2 that has looped around the loop, it notifies the control unit 29 of it.

When the control unit 29 (switch control unit 39) receives the notification from the screen synthesizing unit 17, the image coding unit 25 receives the QC.
Instruct to perform encoding at IF. The data sent from the image coding unit 25 to the coded data switching unit 19 has the format shown in FIG.

In the screen synthesizing unit 17, the input / output image switching unit 1
Of the data of FIG. 7 received from FIG. 5, the data of GOB 2, 4, 6 (corresponding to the upper right of the screen) is deleted. Also, the GOB of the data of FIG. 8 received from the encoded data switching unit 19
Rewrite GOB numbers (GN in Fig. 2) of 1, 3 and 5 data to 2, 4 and 6, respectively. Insert the rewritten GOB data into the deleted data. Then, the format of FIG. 7 is reconstructed and sent to the input / output image switching unit 15.

The operations of the terminals C and D are the same as those of the terminal B, except that the GO is deleted / inserted by the screen compositing unit 17.
Only B number. Delete / insert the GOB number corresponding to the position shown in FIG. 6, respectively.

As described above, the 4-split screen of FIG. 6 is completed through the transitional state while the format of FIG. 7 goes around the loop after the terminal A is activated.

On the contrary, the case of changing from the 4-split screen of FIG. 6 to the full-screen display of FIG. 5 will be described.

When the terminal A is the activation source, the control unit 29 (man / machine interface control unit 31 → user data transmission unit 41) of the terminal A instructs the multiplexing / demultiplexing unit 13 to switch the screen to the LSD area. Instruct to issue.

Further, the input / output image switching unit 15 and the encoded data switching unit 19 are instructed to perform switching (man / machine interface control unit 31 → switch control unit 39). In the input / output image switching unit 15, the output to the screen compositing unit 17 is stopped,
The data from the encoded data switching unit 19 is multiplexed / demultiplexed 1
In order that the data from the image encoding unit 25 be supplied to the input / output image switching unit 15, the encoded data switching unit 19 is instructed to flow to the input / output image switching unit 15 (FIG. 9).

When the screen synthesizing unit 17 detects the PSC of the H.261 frame in FIG. 2 that has looped around the loop, it notifies the control unit 29 of it.

When the control unit 29 (switching control unit 39) receives the notification from the screen synthesizing unit, it instructs the image coding unit 25 to perform FCIF coding. The format of the data from the image encoding unit 25 to the encoded data switching unit 19 is shown in FIG.

The operations of the terminals B, C and D are as follows.

The user data receiving / recognizing unit 37 of the control unit 29, which has received the screen switching command for switching to the full-screen display from the multiplexing / demultiplexing unit 13, notifies the switching control unit 39, and the switching control unit 39 switches the input / output image. A switching instruction is issued to the unit 15 and the encoded data switching unit 19. The input / output image switching unit 15 is instructed to return the data output to the screen synthesis unit 17 to the multiplexing / separation unit 13, and the encoded data switching unit 19 is stopped to output to the screen synthesis unit 17. (Fig. 10).

In the above embodiment, an example in which the control signal is transmitted and received using the LSD area has been described, but an area other than that, for example, a BAS area may be used. The configuration in that case is the same as that in FIG.

[0056]

As described above, according to the present invention,
Control signals are transmitted and received between terminals arranged at multiple points via a loop-connected transmission path, and two display modes, split display mode and full screen display mode, are used depending on the content of the received control signal. It is possible to switch between the two during communication, so normally you can watch multiple low resolution ground images at the same time in split screen mode, and switch to high resolution one ground images when necessary. In this case, the switching of the display modes, which is effective in the case of, can be achieved by an economical loop type connection method, and a large-scale and expensive center device as in the related art is not required, and the economy can be achieved.

[Brief description of drawings]

FIG. 1 is a diagram showing a hierarchical structure of image data of CCITT recommendation H.261.

FIG. 2 is a diagram showing a format of a transmission frame of CCITT recommendation H.261 encoded data.

FIG. 3 is a diagram illustrating a control example of the multipoint video communication system according to the present embodiment.

FIG. 4 is a block diagram showing a configuration of a terminal used in a multipoint video communication system according to an embodiment of the present invention.

5 is a diagram showing a full-screen display example in which each terminal displays the screen of terminal A. FIG.

FIG. 6 is a diagram showing a split display example in which each terminal displays a screen of each terminal.

FIG. 7 is a diagram showing a format of FCIF which is a transmission frame of CCITT recommendation H.261 encoded data.

FIG. 8 is a diagram showing a format of QCIF which is a transmission frame of CCITT recommendation H.261 encoded data.

9 is a diagram showing a flow of image data when a full screen is sent from the terminal A. FIG.

FIG. 10 is a diagram showing a flow of image data when terminals B, C, and D receive a full screen.

FIG. 11 is a diagram showing a flow of image data when transmitting a split screen.

12 is a block diagram showing a configuration of a control unit used in the configuration of the terminal shown in FIG.

[Explanation of symbols]

 11 network interface unit 13 multiplexing / demultiplexing unit 15 input / output image switching unit 17 screen combining unit 19 encoded data switching unit 21 image decoding unit 23 image display unit 25 image encoding unit 27 image input unit 29 control unit 31 bus

Claims (1)

[Claims] 1. A screen is divided into a plurality of areas, and a plurality of terminals capable of transmitting and receiving video data and a control signal using an encoding method for encoding each area are arranged at a plurality of points, respectively. And a multipoint video communication system in which the plurality of terminals are connected in a loop through a transmission path,
Each terminal has a split display mode in which the display screen is divided and an image of a plurality of points is displayed on each split screen, and a full screen display mode in which an image of one point is displayed on the entire display screen
Display mode switching means for switching between two display modes, control signal transmitting / receiving means for transmitting / receiving the control signal between the terminals, and control for giving an instruction for switching the display mode to the display mode switching means according to the content of the received control signal A multipoint video communication system comprising: