JPH11327522A - Multi-display video display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To display plural video data over plural displays synchronized with each other. SOLUTION: A group decision means considers the positions of the video data 1, 2 displayed on respective displays to decide the groups of respective displays, and a video group decision means decides decodable video groups within a prescribed interval. Video transmitters transmit the video data 1, 2 to respective video display devices. Respective video display devices alternately write the transmitted video data 1, 2 in two series of frame buffers at the prescribed interval, and switch the written frame buffers to a display use to display them while holding synchronism between pictures.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-display video display device for displaying a video image by a plurality of video display devices connected to each other.

[0002]

2. Description of the Related Art Conventionally, when large projection displays are arranged in a matrix and video images are displayed on each of them, an image captured by a video input device is divided by an analog divider. In each case, video images must be input and displayed by analog input, and when displaying on multiple displays, the wiring is complicated, and it is difficult to input images from remote locations. .

[0003] Therefore, the inventors have filed a Japanese Patent Application No. Hei 9-1902.
In the specification of Japanese Patent No. 85, a video image is digitally encoded and converted, and transmitted to a plurality of video display devices through a communication channel. This not only realizes multi-display video display as a whole, but also facilitates video image input means when the number of screens increases, and also facilitates image input from a remote place.

[0004] However, in the above-mentioned conventional technique, since each video display device performs video display, means and a method for synchronizing video display timing between the video display devices are considered. Absent.

FIG. 24 is a block diagram showing a conventional multi-display video display device filed in Japanese Patent Application No. 9-190285. In the figure, 1 is video data to be displayed, 10 is video data encoding means for taking in and encoding (compressing) the video data 1, 11 is video data transmitting means for transmitting encoded video data by multicast, Reference numeral 20 denotes a video transmission device including a video data encoding unit 10 and a video data transmission unit 11.

Reference numerals 321 to 324 denote video data decoding means for decoding (expanding) the encoded video data, and reference numerals 331 to 334 denote video data 1 from the coordinate system of the entire multi-display to the coordinate system of the own screen. Coordinate conversion means 311 to 314 are video display means for writing the converted video data 1 into a frame memory (not shown); 301 to 304 are video data decoding means 321 to 324; 331 to 3
34, a video display device provided with video display means 311 to 314, and 171 to 174 are displays for actually displaying video data 1.

In this multi-display video display device, a screen is composed of 2 × 2 displays, and each of the displays 171 to 174 has a screen size of 1280 × 10.
Assuming 24 pixels, the size of the multi-display of the entire screen is 2560 × 2048 pixels. Also,
The upper left corner is (0,0) and the lower right corner is (1279,1023) as the coordinate system of each display 171 to 174. The upper left corner is (0,0) and the lower right corner as the coordinate system of the multi-display of the entire screen. Is (2559, 2047).

Accordingly, the display 171 changes from (0,1024) to (1279,20) of the entire multi-display.
47), the display 172 ranges from (0,0) to (1279,1023) of the entire multi-display, the display 173 ranges from (1280,0) to (2559,1023) of the entire multi-display,
The display 174 is the (12) of the entire multi-display.
80,1024) to (2559,2047).

Next, the operation will be described. FIG. 25 is a view for explaining display of video data on the multi-display. Here, as shown in FIG. 25, the video data 1 having the original image size of (640 × 480) is set on the multi-display by setting the coordinates of the starting point to (640, 240) and the image size to (1280 × 720). This will be described by taking an example of display.

FIG. 26 is a flowchart showing the processing of the video transmission device 20 and the video display devices 301 to 304. In step ST211 of FIG. 26, the video data encoding unit 10 of the video transmission device 20 encodes the video data 1, and in step ST212, the video data transmission unit 11 transmits the encoded video data 1 by multicast. Transmit to all video display devices 301-304.

In the video display devices 301 to 304, first, in step ST213, the video data decoding means 321 to 324 decode the encoded video data 1 respectively, and in the next step ST214, the video data decoding means 321 to 324 decode the coordinate data from the coordinate conversion means 331. 334 converts the transmitted video data 1 into the coordinate system of the displays 171 to 174.

Here, the coordinate conversion processing will be described.
When the coordinates (gx, gy) on the multi-display are converted into local coordinates (lx, ly) on each screen constituting the multi-display, the upper left corner of each screen in the multi-display coordinate system is converted. Coordinates to (of
fsetx, offset) can be expressed by the following equation. lx = gx-offsetx (1) ly = gy-offsety (2)

In step ST214, the coordinates of the start point on the multi-display are (640, 240) and the coordinates of the upper left corner of the screen of the display 171 corresponding to the coordinate conversion means 331 are (0, 1024). The coordinate transformation means 331 substitutes gx = 640, gy = 240, offsetx = 0, offsetset = 1024 into the above equations (1) and (2) to obtain lx = 640, ly = -784, Start point coordinates of video data 1 (64
0, 240) to (640, -784). In addition, the coordinate conversion unit 331 generates an image size (12 × 12) for displaying the image size (640 × 480) of the original video data 1.
80 × 720), the image is enlarged twice horizontally and 1.5 times vertically.

Similarly, in step ST214, since the coordinate of the upper left corner of the screen of the corresponding display 172 is (0, 0),
The start point coordinates (640, 240) of video data 1 are set to (64
0,240) and an image size (1280 × 720) for displaying the image size of the original video data 1
, It is enlarged by a factor of 2 horizontally and 1.5 times vertically.

In step ST214, since the coordinates of the upper left corner of the corresponding screen of the display 173 are (1280, 0), the coordinate conversion means 333 converts the start point coordinates to (-640, 240). , The image size is enlarged two times horizontally and 1.5 times vertically. Further, step ST
At 214, the coordinate conversion means 334 determines that the corresponding coordinates at the upper left corner of the screen of the display 174 are (128).
0,1024), the starting point coordinates are (−640, −
784), and enlarges the image size by 2 times horizontally and 1.5 times vertically.

Next, in step ST215, the video display means 311 converts the starting point coordinates (640, -784) converted by the coordinate conversion means 331, and the image size (1280 × 1280).
The video data 1 of 720) is to be displayed on the display 171. However, as shown in FIG. 25, the video data 1 is not displayed because it is outside the display area of the display 171.

In step ST215, the video display means 312 converts the starting point coordinates (640, 240) converted by the coordinate conversion means 332 and the image size (1280.times.1280).
720) is to be displayed on the display 172, but (1280, 24) of the video data 1 is to be displayed.
0), (1919, 240), (1919, 959),
Since the range of (1280, 959) is outside the display area, it is not displayed, and (640, 240), (1279,
240), (1279,959), (640,959)
Display only the range.

Similarly, in step ST215, the video display unit 313 displays the video data 1 of the starting point coordinates (−640, 240) and the image size (1280 × 720) converted by the coordinate conversion unit 333 on the display 173. Attempts to display the video data 1 (-
640, 240), (-1, 240), (-1, 95)
9) and (−640, 959) are outside the display area, and are not displayed, so that (0, 240), (639,
240), (639,959), and only the range of (0,959) are displayed.

In step ST215, the video display means 314 converts the start point coordinates (-640, -784) converted by the coordinate conversion means 334 and the image size (128).
0 × 720) video data 1
Is displayed outside the display area of the display 171, so that the video data 1 is not displayed.

In this way, as shown in FIG. 25, the video display means 312 and 313 display the video data 1 on the multi-display on the starting point coordinates (640, 240),
The image is displayed as a video image of an image size (1280 × 720).

[0021]

Since the conventional multi-display video display device is configured as described above, each video display device displays the video image on its own. However, when displaying an image straddling each display as described above, the processing speed may vary depending on the load of each video display device, and there has been a problem that the actual display timing is shifted.

The present invention has been made in order to solve the above-described problems. By synchronizing the video display devices, even when displaying an image over a display, the actual display timing is not changed. An object of the present invention is to provide a multi-display video display device that does not shift and does not cause a sense of incongruity.

As a prior art for solving the above problems, there is one disclosed in Japanese Patent Application Laid-Open No. Hei 6-214534. It includes a first frame memory and a second frame memory in which image data is written, and displays a display of the image data written in the first frame memory in response to a trigger signal from the system controller. The display is switched to the display of the image data written in the memory to synchronize a plurality of display units. However, this prior art does not simultaneously display a plurality of video data on a multi-display.

Further, as another prior art for solving the above-mentioned problem, there is one disclosed in Japanese Patent Application Laid-Open No. Hei. In this method, a time difference of display switching of each display device is added to a control signal given to each display device, and in each display device, a timer is set based on the time difference, and display is performed at the same timing. However, this prior art cannot adjust the time difference according to the actual display time.

[0025]

According to the present invention, there is provided a multi-display video display device, comprising: a video group determining means for determining a plurality of video data which can be decoded within a predetermined interval from video data to be displayed; A plurality of video transmission devices that encode and transmit the determined plurality of video data, respectively, and a plurality of video display devices that decode the transmitted plurality of video data and divide and display the plurality of displays, Each of the video display devices decodes a plurality of transmitted video data; first and second frame buffers into which the decoded video data is written; Writing position determining means for determining a writing position of the second frame buffer; and decoding the decoded video data with the first and second frames. A video writing means for writing in the writing position Mubaffa, for each of the predetermined intervals, the first
And a buffer switching means for alternately switching the second frame buffer between writing for the video writing means and display for displaying the written video data. The plurality of written video data are switched at predetermined intervals and displayed on the plurality of displays.

A multi-display video display apparatus according to the present invention includes group determining means for dividing a plurality of displays on which a plurality of video data are displayed into a predetermined group.
A plurality of video data that can be decoded within a predetermined interval among video data to be displayed is determined.

In the multi-display video display device according to the present invention, a video decoding time estimating means for estimating, as a decoding time, a time for each video display device to decode by the video data decoding means and a time to write by the video writing means. Comprising, for each video data, video decoding time determining means for determining the longest time among the decoding times notified by the video display devices, wherein the video group determining means comprises: Based on the longest time determined by the determining means, a plurality of video data that can be decoded within a predetermined interval among video data to be displayed are confirmed.

In the multi-display video display apparatus according to the present invention, the plurality of video data is determined by the video group determining means based on the priority of each video data.

[0029] The multi-display video display device according to the present invention includes video adjusting means for adjusting the resolution or the compression ratio for video data with low priority.

[0030] A multi-display video display apparatus according to the present invention comprises a plurality of video transmission apparatuses for encoding and transmitting a plurality of video data, and a plurality of displays for decoding the transmitted plurality of video data and dividing the plurality of displays into a plurality of displays. A plurality of video display devices for displaying, wherein each of the video display devices determines a decoding order based on a priority of the plurality of video data; and Video data decoding means for decoding data in the determined decoding order; and a first data writing means for writing the decoded video data.
And a second frame buffer, writing position determining means for determining a writing position of the first and second frame buffers, and a decoding of the decoded video data in the first and second frame buffers. Video writing means for writing to the writing position; and, at predetermined intervals, the first and second frame buffers for writing by the video writing means and for displaying the written video data. Buffer switching means for alternately switching the plurality of video data written in the first and second frame buffers at predetermined intervals and displaying the video data on the plurality of displays.

A multi-display video display device according to the present invention includes a plurality of video transmission devices for respectively encoding and transmitting a plurality of video data, and a plurality of displays for decoding the transmitted plurality of video data and dividing the data into a plurality of displays. In a device having a plurality of video display devices to be displayed, a load estimating means for estimating a load on the plurality of video display devices, and adjusting a frame rate of the plurality of video data based on the load estimated by the load estimating device And transmission control means.

In the multi-display video display device according to the present invention, the load estimating means estimates the load based on the total area of each piece of video data displayed on each display.

[0033] In the multi-display video display device according to the present invention, the load estimating means estimates the load based on the total amount of video data displayed on each display per unit time.

[0034] In the multi-display video display device according to the present invention, the load estimating means estimates the remaining amount of the reception buffer in the video display device that receives a plurality of transmitted video data.

According to the multi-display video display device of the present invention, based on the load estimated by the load estimating means,
Transmission control means adjusts the frame rate of the plurality of video data in consideration of the priority of the plurality of video data.

A multi-display video display device according to the present invention includes a plurality of video transmission devices for respectively encoding and transmitting a plurality of video data, a decoding device for decoding the transmitted plurality of video data, and dividing the plurality of video data into a plurality of displays. In a device having a plurality of video display devices for displaying, a load estimating means for estimating a load of the plurality of video display devices, and a communication band of the plurality of video data is controlled based on the load estimated by the load estimating device. And a transmission control means for controlling a transmission amount of the plurality of video data based on a communication band controlled by the communication band control means.

A multi-display video display device according to the present invention comprises a video transmission device for encoding and transmitting video data, and a plurality of video display devices for decoding the transmitted video data and dividing and displaying the divided video data on a plurality of displays. Wherein the video transmitting device comprises:
A time at which decoding is started by the plurality of video display devices, a time stamp adding unit that adds a time stamp to the video data, and a decoding start time changing unit that instructs to arbitrarily change the time stamp, A current time acquisition unit for examining the time at which each of the video display devices receives the video data; and a time for comparing the time examined by the current time acquisition unit with the time stamp added by the time stamp addition unit. Comparing means, time queuing means for performing queuing based on the time compared by the time comparing means, video data decoding means for performing queuing by the time queuing means, and then decoding the video data; A message notifying the result of comparison by the time comparing means to the decoding start time changing means. And a sending unit, the decoding start time changing means, based on the result notified by the message sending means is for instructing to change the time stamp to the time stamp adding unit.

[0038]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. Embodiment 1 FIG. FIG. 1 is a configuration diagram showing a multi-display video display device according to the first embodiment. In the figure, reference numerals 1 and 2 denote video data to be displayed on a multi-display, 21 and 22 video transmission devices for encoding (compressing) the video data 1 and 2 and transmitting them by multicast, and 141 to 144 denote video data 1 , 2 on the respective displays 171 to 174.

Reference numeral 31 denotes a group determining means for determining all the displays constituting the multi-display as a group, or determining an adjacent display in which the video window is straddled in the multi-display as a group.
Reference numeral 41 denotes a video group determining unit that determines a decodable combination within a predetermined interval from video data to be displayed on the display of each group determined by the group determining unit 31. 61 denotes video display devices 141 to 144; The video decoding time determining means 51 for determining the decoding time which takes the longest time in the decoding in
1, video group determining means 41, video decoding time determining means 6
1 is a video group determining device.

FIG. 2 shows the video display device 14 shown in FIG.
FIG. In FIG. 2, reference numeral 111 denotes video data decoding means for decoding (decompressing) the encoded video data, 121 denotes a writing position determining means for determining where to write the video data in the frame buffers 161 and 162, 131 is a video writing means for writing video data to one of the frame buffers, 15
1 is a two-frame buffer 161 at a predetermined interval.
Buffer switching means for switching 62, 161 and 162 two frame buffers for writing video data, and 181 a video decoding time estimating means for estimating the decoding time required for decoding and writing video data.

FIG. 2 shows the configuration of the video display device 141. The video display devices 142 to 144 have the same configuration, and the codes in the video display devices 142 to 144 are the same as those of the video data decoding means 112 to 114. ,
The writing position determining means is 122 to 124, the video writing means is 132 to 134, and the buffer switching means is 152 to 1
54, the video decoding time estimation means 182 to 184, and the frame buffer
2, 163, 164, video display device 143, 165,
166, 167 and 168 in the video display device 144.

The multi-display according to the present embodiment has a screen composed of 2 × 2 displays 171 to 174, and the screen size, coordinate system, and display range of each display 171 to 174 and the entire multi-display are conventional. It is the same as the technology.

Next, the operation will be described. FIG. 3 is a view for explaining display of video data on the multi-display. Here, as shown in FIG. 3, video data 1 having an original image size of (640 × 480) is displayed on a multi-display by setting the coordinates of the starting point to (960, 240) and the image size to (1280 × 720). An example in which video data 2 having an original image size of (320 × 240) is displayed on a multi-display on a multi-display by setting the coordinates of the starting point to (1600, 904) and the image size to (640 × 480). I will explain.

FIG. 4 is a flowchart showing the processing flow of the video group determining device, the video transmitting device, and the video display device. In step ST111 in FIG. 4, the group determining means 31 of the video group determining device 51 in FIG.
In consideration of the positions of the video data 1 and 2 displayed on each of the displays 171 to 174 in FIG.
Decide as one group.

FIG. 5 shows step ST1 based on the position of the video data displayed on each of the displays 171 to 174.
FIG. 11 is a diagram for explaining the determination of the group of each display at 11. As shown in FIG. 5A, when video data 1 and 2 are displayed across displays 172 to 174 and video data 3 and 4 are displayed only on display 171, display 172 to 174 is displayed in group 1. The display 171 can be divided into two groups as the group 2.

On the other hand, as shown in FIG. 5B, video data 1, 2, 3, and 4 are displayed on the displays 171 to 174.
Are displayed on the displays 171 to 174
Cannot be divided and are determined as one group.

Then, in step ST112 of FIG. 4, the video group determining means 41 determines, for each group, a video group which can be decoded within a predetermined interval among video data to be displayed on the display. In this case, there is one group, and the video data 1 and 2 are determined as video groups that can be decoded within a certain interval.

Next, in step ST113, the video transmitters 21 and 22 encode (compress) the video data 1 and 2 respectively and transmit them to all the video display devices 141 to 144 by multicast. In this case, the video data 1 and 2 are the video transmission devices 21 and 22
Is transmitted asynchronously due to

In step ST114, the video data decoding means 111 to 114 in the video display devices 141 to 144 decode (decompress) the coded (compressed) video data 1 respectively. The deciding means 121 to 124 respectively convert the decoded video data 1 into the coordinate system of its own display, and convert the frame data into frame buffers 161, 163, 165,
167 is determined.

Here, the coordinates on the multi-display are (gx, gy), the local coordinates on each screen constituting the multi-display are (lx, ly), and the upper left corner of each screen in the multi-display coordinate system. Assuming that the coordinates of the end are (offsetx, offsetset), coordinate conversion is performed using Expressions (1) and (2) as in the related art.

Since the coordinates of the upper left corner of the screen of the display 171 corresponding to the writing position determining means 121 of the video display device 141 are (0,1024), the writing position determining means 121 performs coordinate conversion to obtain the video data 1. Start point coordinates (960,
240) is converted to (960, -784), and the image size (640 × 480) is enlarged by 2 times in width and 1.5 times in height to make it (1280 × 720).

Since the coordinates of the upper left corner of the screen of the display 172 are (0, 0), the writing position determining means 122 of the video display device 142 sets the starting point coordinates of the video data 1 to (960, 240). After the conversion, the image size is similarly enlarged by a factor of 2 horizontally and 1.5 times vertically. Further, the writing position determining means 123 of the video display device 143
Since the coordinates of the upper left corner of the screen 73 are (1280, 0), the starting point coordinates of the video data 1 are (−320, 240).
And enlarge the image size by 2 times in width and 1.5 times in height.

Since the coordinates of the upper left corner of the screen of the display 174 are (1280, 1024), the writing position determining means 124 of the video display device 144 sets the starting point coordinates of the video data 1 to (−320, −784). ),
The image size is enlarged twice horizontally and 1.5 times vertically. Thus, in step ST115, the writing position determination means 121 to 124 determine the writing position of the video data 1 in the frame buffers 161, 163, 165, 167.

Next, in step ST116, the video writing means 131 to 134 make the writing position determination means 121
, 163, 165, and 167, respectively, based on the determination of
Write to.

Here, writing to the frame buffer will be described. The video data 1 whose coordinates have been converted by the writing position determining means 121 have start point coordinates (960, -78).
4), the image size is (1280 × 720). However, since the display area of the display 171 is (1280 × 1024) with the upper left end set to (0,0),
The display 171 is the entire video image (96
0, -784), (2239, -784), (223
9, -65) and (960, -65) cannot be actually displayed. Therefore, the video writing unit 131 does not write anything into the frame buffer 161 because there is no video data in the range that can be actually displayed.

The video data 1 whose coordinates have been converted by the writing position determining means 122 have start point coordinates (960, 24).
0), and the image size is (1280 × 720). However, since the display area of the display 172 connected to the video display processing device 142 is (1280 × 1024) with the upper left end set to (0,0), the display 172 displays (1280,240), (22
39, 240), (2239, 959), (1280,
959) cannot be displayed and the video writing unit 132
Are actually displayable (960, 240), (127
9,240), (1279,959), (960,95)
Only the range of 9) is written to the frame buffer 163.

The video data 1 having undergone the coordinate conversion by the writing position determining means 123 has a starting point coordinate of (−320,
240), and the image size is (1280 × 720). However, since the display area of the display 173 is (1280 × 1024) with the upper left end set to (0, 0), the display 173 displays (−320,
240), (-1,240), (-1,959), (-
320, 959), the video writing means 133 cannot display the range (0, 240), (95).
9, 240), (959, 959), and only the range of (0, 959) are written to the frame buffer 165.

Further, the starting point coordinates of the video data 1 converted by the writing position determining means 124 are (-32).
0, -784) and the image size is (1280 × 720). However, since the display area of the display 174 is (1280 × 1024) with the upper left end at (0,0), the display 174 is the entire video image (−320, −784), (959, −784). , (9
59, -65) and (-320, -65) cannot be displayed, and the video writing unit 134 does not write anything into the frame buffer 167 because there is no video data in the actually displayable range. As described above, step ST
At 116, the video writing means 131 to 134
Each of the video data 1 is stored in its own frame buffer 161,
163, 165, 167 are written.

Next, in step ST117, the video decoding time estimating means 181 to 184 estimate the decoding time required for decoding and writing the video data 1, respectively, and notify the video decoding time determining means 61 of the result. For example, in the video display device 141, although the video data 1 is decoded but not written, the video decoding time estimating means 181 sets the decoding time to 10
Since the video display device 142 has both decoded and written the video data 1, the video decoding time estimating means 182 estimates the decoding time as 15 msec.

Similarly, video decoding time estimation means 183
Has a decoding time of 1
The 5 msec video decoding time estimating means 184 estimates the decoding time to be 10 msec since only decoding is performed. Therefore, the video decoding time estimation means 181 to 1
Numeral 84 informs the video decoding time determining means 61 of the decoding time estimated to be 10 msec or 15 msec, respectively.

Then, in step ST118, the video decoding time determining means 61 determines the estimated decoding time of the video data 1 to be the longer processing time of 15 msec, and notifies the video group determining means 41.

Next, in step ST119, the coded video data 2 is also decoded by the video data decoding means 111 to 114 in the same manner as the video data 1, and in step ST120, the write position determination means 121 124 converts the video data 2 into the coordinate system of the own display and determines the writing position.

Next, in step ST121, the video writing means 131 to 134
The video data 2 is stored in the own frame buffer 161, 163, 165, 1 based on the write position determined by
Write to 67 respectively. Actually, as shown in FIG.
The video data 2 is written to the frame buffers 165 and 167 so as to be displayed on the displays 173 and 174.

Then, in step ST122, the video decoding time estimating means 181 to 184 estimate the decoding time required for decoding and writing the video data 2, and inform the video decoding time determining means 61 of the result. For example, since the video decoding time estimating means 181 and 182 only decode the video data 2,
c, video decoding time estimation means 183, 184
Has been decoded and written, so that it is estimated to be 10 msec and the video decoding time determining means 61 is notified.

Further, in step ST123, the video decoding time determining means 61 determines the estimated decoding time of the video data 2 to be 10 msec, which is the longer processing time, and notifies the video group determining means 41.

Next, in step ST124, the video group determining means 41 determines that the estimated decoding time of the video data 1 is one.
5 msec, estimated decoding time of video data 2 is 10 ms
ec, the total of the video data 1 and 2 as a video group does not exceed 30 msec (30 frames per second, more precisely 33 msec) required for full-rate decoding and writing according to the NTSC system. After confirmation, the switching timing of the buffer switching units 151 to 154 is set to 30 msec, and a frame buffer switching instruction is issued to the buffer switching units 151 to 154 every 30 msec.

In step ST125, the buffer switching units 151 to 154
61, 163, 165 and 167 are switched for display, and the frame buffers 162, 164, 166 and 168 are switched for writing. Frame buffers 161, 163, 165, 16
7 is switched for display, the video data 1 and 2 written by the video writing means 131 to 134 are displayed on the displays 171 to 174 in step ST126. Subsequent video data is stored in frame buffers 162, 164, 166, and 168.
, And the buffer is switched and displayed.

In this embodiment, the group determining means 3
Although 1 determines all displays as one group, it may be determined as a plurality of groups. For example,
When displaying video data as shown in FIG. 5A, in step ST111 of FIG. 4, two groups are determined. Next, in step ST112, video data 1 and 2 in group 1 are determined as a video group, and video data 3 and 4 in group 2 are determined as a video group. Then, in step ST113, the video data 1 and 2 are encoded and the video display devices 142 to 14 are encoded.
4 and encodes the video data 3 and 4 to transmit to the video display device 141.

The video data 1 and 2 are group 1
Are displayed on the displays 172 to 174, the video display devices 142 to 144 perform the processing from steps ST114 to ST123, and
Is displayed on the display 171 of the group 2, so that the video device 141
The processing up to 23 is performed.

In this case, assuming that the decoding time of video data 1 + video data 2 is 25 msec and the decoding time of video data 3 + video data 4 is 20 msec, the video data 1 and video data 1 are processed by being divided into two groups.
Full rate decoding and writing can be performed within 30 msec for all of 2, 3, and 4. Thus, each time the video data to be displayed changes, the group determining means 31 changes the group of the displays 171 to 174.

FIG. 6 is a diagram for explaining writing of video data to the frame buffer and switching of display. in this way,
By displaying the already written video data by switching the buffer every 30 msec, the synchronization of the video images displayed on the displays 171 to 174 is maintained.

As described above, in this embodiment, the video transmitting apparatus encodes a plurality of video data, transmits the encoded data to a plurality of video display apparatuses by multicasting, and each video display apparatus encodes the video data. The decoded video data is decoded, the writing position to the frame buffer is determined in accordance with the white screen position on the multi-display, and the decoded data is written to the frame buffer. A plurality of video data are displayed on a plurality of displays while switching the frame buffer of the system and maintaining synchronization between screens.

In this embodiment, video data 1 is decoded and written, and then video data 2 is decoded and written, and serial processing is performed. However, a series of processing is performed by software. Thus, separate processing may be performed instead of serial processing.

In this embodiment, the switching timing of the frame buffers of the buffer switching units 151 to 154 is determined by the video decoding time estimating units 181 to 184. By synchronizing to a fixed reference interval,
The frame buffer may be switched. in this case,
The video decoding time determining means 61 in FIG. 1 and the video decoding time estimating means 181 in FIG. 2 are omitted, and the processes of steps ST117, 118, 122, and 123 in FIG. 4 are also omitted.

As described above, according to the first embodiment, a plurality of video data are written in the frame buffer corresponding to each display, and the video data written in the frame buffer is displayed at a predetermined timing. Also in the case of displaying an image straddling each display, it is possible to obtain an effect that a display without a sense of incongruity can be performed without a shift in actual display timing.

According to the first embodiment, the groups on the displays 171 to 174 are determined, and the video groups that can be decoded within a predetermined interval are determined for each of the determined groups. When displaying video data, full-rate processing can be performed for each group, and a display without discomfort can be achieved. In addition, by transmitting video data only to the video display device that displays each group, communication can be performed. The effect that efficiency can also be obtained is obtained.

Further, according to the first embodiment, the decoding time of the actual video data is estimated, and the longest time among the decoding times notified from the video display devices is determined for each video data. Thereby, there is an effect that a plurality of video data that can be decoded can be confirmed within a predetermined interval based on the longest time.

Embodiment 2 FIG. 7 is a configuration diagram showing a multi-display video display device according to the second embodiment. In FIG. 7, reference numerals 1, 2, and 3 denote video data to be displayed on a multi-display, 21, 22, and 23 video transmission devices for encoding (compressing) video data and transmitting the video data by multicast, and 141 to 144 denote video display devices. , 171 to 174 are displays for displaying video data 1, 2, and 3.

A group determining means 31 groups all the displays constituting the multi-display and groups adjacent displays in the multi-display where a video window is straddled. Reference numeral 41 denotes a video group determining unit that determines a combination that can be decoded (decompressed) within a predetermined interval from the video data in the group determined by the group determining unit 31, and 51 denotes a group determining unit 31, a video group. This is a video group determination device including a determination unit 41.

FIG. 8 is a block diagram showing the video display devices 141 to 144, which is obtained by removing the video decoding time estimating means 181 from FIG. 2 of the first embodiment.

Next, the operation will be described. Here, an example will be described in which video data 1, 2, and 3 are displayed on three screens as shown on the displays 171 to 174 in FIG. In FIG. 7, the group determination means 31 of the video group determination device 51 determines all displays as one group by considering the positions of the video data 1, 2, and 3 displayed on the displays 171 to 174.

Next, the video group determination means 41 determines a combination of video data that can be decoded at full rate from the priorities of the video data 1, 2, 3, and the resolution, compression ratio, and the like. Here, it is assumed that the priority of the video data 1 is the highest, and the time required for video decoding and writing is 15 msec. Also, the priority of the video data 2 is normal, and video decoding,
It is assumed that the time required for writing is 10 msec. Further, it is assumed that the priority of the video data 3 is low, and the time required for video decoding and writing is 10 msec. here,
The priority is specified by the application or the user.

FIG. 9 is a diagram for explaining switching between writing of video data to the frame buffer and display. Here, the combination of the processing time of each video data and the video group when three video data are written to the frame buffer and displayed are shown on the time axis. Displaying the three video data of video data 1, 2, and 3 requires 35 msec. However, as shown in FIG. 9, if the switching timing of the buffer switching units 151 to 154 is 30 msec, the writing of video data 3 is performed. The switching of the frame buffer occurs during the transfer, and a normal image is not displayed. Therefore, the video group determining means 41 gives up the display of the video data 3 having the lowest priority and transmits and displays only the video data 1 and 2.

In the video display devices 141 to 144, two video windows of video data 1 and 2 are:
As in the first embodiment, the displays 171 to 174
Is displayed while keeping the screen synchronized.

As described above, according to the second embodiment, a plurality of video data are written in the frame buffer corresponding to each display, and the video data written in the frame buffer is displayed at a predetermined timing. Even when displaying images straddling each display, it is possible to display without discomfort without the actual display timing being shifted, and to select a group of videos that can be decoded at regular intervals, the selection of each video data Since the priority is determined based on the priority, an effect that a video image with a high priority can be preferentially displayed can be obtained.

Embodiment 3 FIG. 10 is a configuration diagram showing a multi-display video display device according to the third embodiment. In the figure, reference numerals 71, 72, 73 denote video data 1,
Video adjustment means for adjusting the compression ratio and resolution of a few, 4
Reference numeral 1 denotes a video group determining means for determining a combination of video data that can be subjected to full-rate decoding (expansion) from the priority of each video data, resolution, compression ratio, and the like. Is the same.

Next, the operation will be described. Here, an example in which three screens of video data 1, 2, and 3 are displayed will be described. In FIG. 10, the group determining means 31 determines all the displays as one group by considering the positions of the video data 1, 2, and 3 displayed on the displays 171 to 174. Next, the video group determination means 41 determines a combination of video data that can be decoded at full rate from the priorities of the video data 1, 2, 3, and the resolution, compression ratio, and the like. Here, the priority of the video data 1 is the highest, and the time required for video decoding and writing is 15 ms.
ec. The priority of video data 2 is normal,
The time required for video decoding and writing is 10 msec. The priority of the video data 3 is low, and the time required for video decoding and writing is 10 msec.

FIG. 11 is a diagram for explaining switching between writing of video data into the frame buffer and display. Here, three video images are written to the frame buffer,
The time axis indicates the combination of the processing time of each video data and the video group in the case of displaying. If three video images of video data 1, 2, 3 are to be displayed, 3
However, as shown in FIG. 11, the switching timing of the buffer switching units 151 to 154 is set to 3 ms.
If the time is 0 msec, the buffer is switched during the writing of the video data 3, and a normal image is not displayed. Therefore, the video group determining means 41 determines that the video data 1 and 2 can be decoded at the full rate, but the video data 3 having the lowest priority cannot be decoded at the full rate. Notify.

The video adjusting means 73 having received the notification sets the time required for video decoding and writing of the video data 3 to 5 ms.
ec so that the resolution is (320 × 24
0) to (200 × 150). By changing the resolution, as shown in FIG. 11, three pieces of video data of video data 1, 2, and 3 can be displayed within 30 msec of the buffer switching timing.

Although the resolution is changed in this embodiment, the compression ratio may be changed. Also, three video windows of video data 1, 2, 3 are described in the first embodiment.
Similarly to the above, the images are displayed on the displays 171 to 174 while maintaining synchronization between the screens.

As described above, according to the third embodiment, a plurality of video data are written in the frame buffer corresponding to each display, and the video data written in the frame buffer is displayed at a predetermined timing. Even when displaying images across each display, it is possible to display without discomfort without delaying the actual display timing, and by adjusting the resolution and compression ratio of low priority video data Thus, an effect is obtained in which as many high-priority video images as possible can be included in a video group capable of full-rate decoding.

Embodiment 4 FIG. FIG. 12 is a block diagram showing a multi-display video display device according to the fourth embodiment.
1 is deleted.

FIG. 13 is a block diagram showing the video display devices 141 to 144 in FIG. In the figure, 1
Reference numeral 91 denotes a decoding order determining means for determining the order of decoding (expanding) the video data sent from the video transmission devices 21 to 23, and the other configuration is the same as that of FIG. 8 of the second embodiment. .

Next, the operation will be described. FIG. 14 is a diagram illustrating the display of video data on the multi-display. Here, as shown in FIG. 14, video data 1 having an original size of (640 × 480) is displayed on a multi-display by setting the coordinates of the starting point to (960, 240) and the image size to (1280 × 720). The original size is (32
0 × 240) video data 2 on the multi-display, the coordinates of the starting point are (1600, 904), the image size is (640 × 480), and the original size is (320 × 2).
40) The video data 3 of
The coordinates of the starting point are (900, 1200) and the image size is (1
280 × 480) and a three-screen display will be described.

FIG. 15 is a flowchart showing the processing flow of the video transmission device and the video display device. In step ST131, the video transmission devices 21, 22, 23
Encodes (compresses) video data 1, 2, and 3, respectively,
It is transmitted to all the video display devices 141 to 144 by multicast.

Next, the video display devices 141 to 144
Upon receiving the video data 1, 2 and 3, respectively, in step ST132, the decoding order determining means 191 to 194 decode and display the respective video data, and in this order, the next video data decoding means 11
Output from 1 to 114.

Here, the decoding order determining means 191 to 1
The determination of the decoding order performed by the 94 will be described. here,
The display priorities of the video data 1, 2, 3 are set to low,
Medium and high. That is, where three pieces of video data overlap, the pieces of video data 3, 2, and 1 are overlapped in order from the top. Therefore, the decoding order of the video data is the order of the video data 1, 2, 3,. Here, regarding the display priority of the video data 1, 2, 3,
It is assumed that the decoding order determining units 191 to 194 have been notified in advance.

In step ST133, first, the video data decoding units 111 to 114 decode the video data 1 according to the order determined by the decoding order determination units 191 to 194. Then, in step ST134, the writing position determining means 121 to 124 determine the writing position, and in step ST135, the video writing means 131 to 134 transfer the video data 1 to the own frame buffers 161, 163, 165, 167. Write. These processes are as described in the first embodiment.

Next, video data 2 is similarly decoded in steps ST136, 137, and 138.
The writing position is determined and the video writing process is performed. Further, regarding video data 3, steps ST139, 140, 1
At 41, decoding, writing position determination, and video writing processing are similarly performed. Frame buffers 161, 163, 1
65, 167, where the three video data overlap, the video data 3, video data 2,
The video data 1 is written in an overlapping order.

Then, in step ST142, the buffer switching means 151 to 154 switch the frame buffer 16 when the writing processing of the three video data is completed.
1, 163, 165, and 167 are switched for display, and the frame buffers 162, 164, 166, and 168 are switched for writing.

Frame buffers 161, 163, 16
5, 167 are switched for display, and in step ST143, video writing means 131
34, the video data 1, 2, 3 written by
As shown in FIG. 14, each of the displays 171 to 174
Is displayed in. In addition, since decoding and writing are performed starting from the lower video display, it is not necessary to perform clip processing or the like, and superimposition of a plurality of video windows can be realized.

As described above, according to the fourth embodiment, a plurality of video data are written in the frame buffer corresponding to each display, and the video data written in the frame buffer is displayed at a predetermined timing. Even when displaying images across each display, it is possible to perform a display without a sense of incongruity without shifting the actual display timing, and to display a plurality of video windows of two or more video data without clip processing. The effect that superposition can be realized is obtained.

Embodiment 5 FIG. FIG. 16 is a configuration diagram showing a multi-display video display device according to the fifth embodiment. In the figure, reference numerals 1 and 2 denote video data to be displayed on the multi-display, and 91 denotes video data from the video display devices 141 to 1.
The load estimating means for estimating the load of 44, the transmission control means 81 and 82 for adjusting the frame rate of the video data according to the one with the highest load, and the encoding means 11 and 12 which are encoded (compressed) by multicast The video data transmission units 21 and 22 for transmitting video data are video transmission devices including transmission control units 81 and 82 and video data transmission units 11 and 12.

Further, reference numerals 111 to 114 denote video data decoding means for decoding encoded video data,
61, 163, 165 and 167 are video data 1 and 2
Is a frame buffer to be written.
24 is a frame buffer 161, 163, 165, 1
It is a writing position determining means for determining a writing position of video data to 67.

Reference numerals 131 to 134 denote the frame buffer 16
1, 163, 165, 167, video writing means 141 to 144, video data decoding means 111 to 114, writing position determining means 121 to 124, video writing means 131 to 134, frame buffer Video display devices provided with 161, 163, 164, 165, and 171 to 174 are displays for displaying video images written in the frame buffers 161, 163, 165, 167, respectively.

In the first to fourth embodiments, two systems of frame buffers are provided to switch between writing and display. However, in this embodiment, one system of frame buffers is used. That is, each frame buffer 161, 16
3, 165, 167, video data is not displayed in synchronization with each frame buffer 16
1, 163, 165, 167 and video data 1 and 2 are displayed each time. However, as in the first to fourth embodiments, the display can be performed without a sense of incongruity without strict synchronization. In addition, the frame rate is adjusted.

Next, the operation will be described. Here, as in FIG. 3 of the first embodiment, the original image size is (640).
× 480) video data 1 on the multi-display, the coordinates of the starting point are (960, 240), the image size is (1280 × 720), and the original image size is (320, 240).
A description will be given of an example in which the video data 2 of (× 240) is displayed on a multi-display on a multi-display by setting the coordinates of the starting point to (1600, 904) and the image size to (640 × 480).

FIG. 17 is a flowchart showing the processing flow of the load estimating means, the video transmitting device, and the video display device. In step ST151, the load estimating means 9
1 estimates the load on the video display devices 141 to 144 in consideration of the coordinate positions and sizes of the video data 1 and 2 displayed on the video display devices 141 to 144. Next, in step ST152, the video transmission devices 21 and 22
The transmission control means 81 and 82 adjust the frame rate of video data to be transmitted by reducing the frame rate when the load is high. In step ST153, the video data transmitting units 11 and 12 encode the video data 1 and 2, and transmit the encoded data to all the video display devices 141 to 144 by multicast.

Next, in step ST154, the video data decoding means 1 of the video display devices 141 to 144
11 to 114 decode the video data 1 respectively. In step ST155, the write position determining means 121 to 124 determine whether the frame buffer 161, 163, 16
5,167 write positions are determined. Step ST156
, The video writing means 131 to 134 transmit the video data 1 to the own frame buffers 161, 163, 16 based on the determination by the writing position determining means 121 to 124.
Write to 5,167. These processes are as described in the first embodiment.

In step ST157, the video data 1 written in the frame buffers 161, 163, 165, and 167 is output from the respective displays 171 to 1
74, the start point coordinates (960, 240) and the image size (1280 × 72) as shown in FIG.
0) Video data 1 is displayed.

For video data 2 also, step ST
From 158 to step ST161, the same processing is performed. That is, as shown in FIG.
0,904), and video data 2 of an image size (640 × 480) are displayed.

Here, the load estimation processing and the transmission control processing will be described. The load estimating means 91 is a video display device 1
The load is estimated by the sum of the total area of the video images on each display from 41 to 144. In the video display device 141, since the video image is not displayed on the display 171, the total area per second for decoding and displaying at the full rate is 0. In addition, the video display device 1
In 42, since the video image on the display 172 is only the video data 1, the total area per second for decoding and displaying at full rate is 1280 × 720 × 30 = 276488000 (dots or pixels).

In the video display device 143, the video image displayed on the display 173 is both the video data 1 and the video data 2. Therefore, the total area per second for decoding and displaying at the full rate is (1280) × 720 + 640 × 480) × 30 = 368
64000 (dots).

Further, since the video image on the display 174 is only the video data 2 in the video display device 144, the total area per second for decoding and displaying at full rate is 640 × 480 × 30 = 9216000 ( Dot). Therefore, when the video display devices 143, 142, and 1 are arranged in descending order of load.
44, and the video display device 141.

Each of the video display devices 141 to 144 converts a video image having an area of 1280 × 800 into 30 fr.
Assuming the ability to decode and display in ame / sec,
The total area per second of the video data written to the frame buffer is 1280 × 800 × 30 = 30720000 (dots).

Therefore, in the video display device 142, since 27648000 ≦ 30720000, the full-rate decoded display is performed. In the video display device 144, since 9216000 ≦ 30720000, the full-rate decoded display is performed. Further, since the video display device 141 does not originally perform display, it is irrelevant here.

However, in the video display device 143 having the highest load, (1280 × 720 + 640 × 480) × 30 = 368
64000 ≧ 30720000 (dots), which exceeds the capability, so that two video images cannot be decoded and displayed at full rate. For this reason, the video display devices 142 and 144 perform the decoding display at the full rate, but the video display device 143 cannot perform the decoding display at the full rate, and the synchronization between the screens is disrupted.

Accordingly, the transmission control means 81 and 82 adjust the frame rate of each video data according to the load of the video display device 143. That is, when the frame rates of the respective video data are suppressed to 15 frame / sec by the transmission control means 81 and 82, the video display device 143 having the highest load has (1280 × 720 + 640 × 480) × 15 = 184.
32000 (dots). Since this does not exceed the capability of the video display device 143 of 1280 × 800 × 30 = 30720000 (dots), the video display device 143 can decode and display each video data at 15 frames / sec.

It is clear that the video display devices 142 and 144 can decode and display each video data at 15 frames / sec. Therefore, all the video display devices can decode and display each video data at the same frame rate.

By controlling the communication amount by adjusting the frame rate by the transmission control means 81 to 82, the multi-display video display apparatus has a certain degree of synchronization between the screens for two or more video data. Is displayed while maintaining.

In this embodiment, the load estimating means estimates based on the area. However, the load estimating means is not limited to the area. Similar display is possible by estimating the load.

As described above, according to the fifth embodiment, the load of each video display device is estimated based on the total area of video data displayed on each display, and is adjusted to the video display device with the highest load. By adjusting the frame rate of the video data to be transmitted, it is possible to display the video window over the screen without any dislocation between the video display devices without any discomfort.

Embodiment 6 FIG. FIG. 18 is a configuration diagram showing a multi-display video display device according to the sixth embodiment. In the figure, reference numerals 1 and 2 denote video data to be displayed on the multi-display, 81 and 82 denote transmission control means for adjusting the frame rate of the video data 1 and 2 in accordance with the data having the highest load, , Video data 1,
Video data transmitting means for encoding (compressing) the video data 2 and transmitting the video data encoded by the multicast;
Reference numerals 1 and 22 denote video transmission devices provided with transmission control means 81 and 82 and video data transmission means 11 and 12, respectively. 141 to 144 are video display devices, and 171 to 1
A display 74 displays the video data 1 and 2.

FIG. 19 is a configuration diagram showing the video display device 141 in FIG. In the figure, reference numeral 241 denotes a load estimating means for estimating the load of the video display device, and the other configuration is the same as that of the video display device 141 in FIG. Also in this embodiment, as in the fifth embodiment, the frame buffer is a single system, and a display without a sense of incongruity is performed without strict synchronization between the video display devices. Further, in the fifth embodiment, the load estimating means 91 is provided on the video data transmitting side. However, in this embodiment, the load estimating means 91 is provided on the video data displaying side to perform more accurate estimation.

In FIG. 19, the configuration of the video display device 141 is shown. However, the video display devices 142 to 144 have the same configuration, and the signs in the video display devices 142 to 144 indicate that the load estimating means are 242 to 244, The video data decoding means is 112 to 114, the writing position determining means is 122 to 124, and the video writing means is 132 to 13
4. The frame buffers are 163, 165 and 167.

Next, the operation will be described. Here, as in FIG. 3 in the first embodiment, the original size is (64).
0 × 480) video data 1 on the multi-display, the starting point coordinates are (960, 240), the image size is (1280 × 720), and the original size is (320 × 2).
40) The video data 2 of
The coordinates of the starting point are (1600, 904), and the image size is (6, 904).
40 × 480) and an example of a two-screen display will be described.

In FIG. 18, first, the video transmission device 2
The transmission control means 81 and 82 in 1 and 22 respectively apply the load estimating means 241 to 2 to the previously transmitted frame.
In consideration of the load estimated by 44, adjustment is made so as to reduce the frame rate in accordance with the video display device having the highest load. Then, the video data transmitting means 11 and 12 encode the video data, and transmit it to all the video display devices 141 to 144 by multicast.

Next, the video data decoding means 111 to 114 decode (decompress) the video data 1 respectively, and the writing position determination means 121 to 124 determine the writing position.
The video writing means 131 to 134 write the video data 1 to the own frame buffers 161, 163, 165, 167. These processes are as described in the first embodiment.

In this manner, the video data 1 written by the video writing means 131 to 134 is passed to the respective displays 171 to 174, and as shown in FIG. , Video data 1 of a video image size (1280 × 720) is displayed.

The video data 2 is processed in a similar manner, and the video data 2 written by the video writing means 131 to 134 is displayed on each display 171 to 17.
3, the start point coordinates (1600, 904) and the video image size (640 × 4) as shown in FIG.
80) Video data 2 is displayed.

Here, the estimation of the load will be described. The load estimation means 241 to 244
The load is estimated based on the total amount of data per unit time of the video image applied to each of the displays 41 to 144. The data amount of video data 1 is 1/5
If it is transmitted at 0,30 frame / sec and one dot (pixel) is composed of 32 bits, 640 × 480 × (32/8) × (1/50) × 30 =
737280 (bytes / sec).

Assuming that the video data 2 is transmitted at a compression rate of 1/20, 30 frame / sec, the data amount is 320 × 240 × (32/8) × (1/20) × 30 =
460800 (bytes / sec).

In the estimation by the load estimating means 241, since the video data is not applied to the display 171 in the video display device 141, the total data amount is zero. Further, in the estimation by the load estimating means 242, in the video display processing device 142, the video image on the display 172 is only the video data 1, so that the data amount is 737,280 (bytes / sec).

In the estimation by the load estimating means 243, in the video display device 143, since the video data on the display 173 is both the video data 1 and the video data 2, the total data amount is 737280 + 460800 = 1198080 (byt
e / sec). In the estimation by the load estimating means 244, the video amount on the video display device 144 is 460800 (bytes / sec) because the video image on the display 174 is only the video data 2.
Therefore, when the video display devices 14 are arranged in descending order of load,
3, video display device 142, video display device 144, and video display device 141.

Here, for example, the video display devices 141 to 144 have an input image size of 640 × 480 and a compression ratio of 1/240.
It is assumed that there is an ability to decode 50 at 30 frames / sec, and when this is represented by a data amount, 640 × 480 × (32/8) × (1/50) × 30 =
737,280 (bytes / sec).

Accordingly, in the video display device 142, since 737280 = 737280, the full-rate decoded display is performed. In the video display device 144, since 460800 ≦ 737280, full-rate decoded display is performed.

In the video display device 141, since the display is not originally performed, it is irrelevant here. However, in the video display device 143 with the highest load, 737280 + 460800 = 1119080 ≧ 737
280, which exceeds the capability and cannot decode and display two video data at full rate.

Accordingly, the video display devices 142 and 14
4 performs the decoding display at the full rate, but the video display device 143 cannot perform the decoding display at the full rate, and the synchronization between the screens is disturbed. Therefore, the transmission control means 81
And 82, in accordance with the video display device 143,
The frame rate of the video data 1 and 2 is controlled.

Now, transmission control will be described. When the frame rates of the video data 1 and 2 are suppressed to 15 frame / sec by the transmission control means 81 and 82, the video display device 143 having the highest load has 640 × 480 × (32/8) × (1/50). × 15 =
368640 (byte / sec) 320 × 240 × (32/8) × (1/20) × 15 =
230400 (bytes / sec) 368640 + 230400 = 599040.

This is the capacity of the video display device 143, 640 × 480 × (32/8) × (1/50) × 30 =
Since it does not exceed 737280 (bytes / sec), the video display device 143 can decode and display the video data 1 and 2 at 15 frames / sec.

It is obvious that the video display devices 142 and 144 can decode and display each video data at 15 frames / sec. Therefore, all the video display devices can decode and display each video data at the same frame rate.

By controlling the amount of transmission by such transmission control means, the multi-display video display device displays two or more video data while maintaining a certain degree of synchronization between the screens.

As described above, according to the sixth embodiment, the load on the video display device is estimated from the amount of video data displayed on each display per unit time, and the video display device having the highest load is estimated. By adjusting the frame rate of the video data in accordance with the above, it is possible to obtain the effect that the video window can be displayed across the screen without any dislocation between the video display devices without any discomfort.

Embodiment 7 FIG. The configuration of this embodiment is as follows.
As in the sixth embodiment, the configuration is the same as that shown in FIGS. In the sixth embodiment, the load of the video display device is estimated based on the total amount of data per unit time of the video image. However, in the sixth embodiment, the video display is performed based on the remaining amount of the reception buffer of each video display device. This is for estimating the load on the device. Although not shown in FIG. 19, this reception buffer is provided before the video data decoding means 111.

Here, the estimation of the load will be described. The load estimating means 241 to 244
To 144 are estimated based on the remaining capacity of each reception buffer. The data amount of video data 1 is 1/5
If it is transmitted at 0,30 frame / sec and one dot (pixel) is composed of 32 bits, 640 × 480 × (32/8) × (1/50) × 30 =
737280 (bytes / sec).

Assuming that the data amount of video data 2 is transmitted at a compression rate of 1/20, 30 frame / sec, 320 × 240 × 32/8 × 1/20 × 30 = 4608
00 (bytes / sec), and 737,280 + 460,800 = 1119,080 (bytes)
e / sec) of video data is transmitted from the video transmission devices 21 and 22.

In the load estimating means 241, the decoding and writing processing capacity of the video display device 141 is 2 Mbytes.
/ Sec, then 11998080 (byte / sec) ≦ 200000
(Byte / sec), the data does not accumulate in the reception buffer.

In the load estimating means 242 and 244, the video display device 142 and the video display device 144 are used.
Assuming that the decoding and writing capabilities of the data are 1.5 Mbytes / sec, 11998080 (bytes / sec) ≦ 1500000
(Byte / sec), the data does not accumulate in the reception buffer.

In the load estimating means 243, the decoding capability of the video display device 143 is 1 Mbyte.
/ Sec, 11998080 (byte / sec) ≧ 1,000,000
(Byte / sec), the data accumulates in the reception buffer, the remaining amount of the reception buffer gradually decreases, and eventually the reception buffer overflows, causing a delay in communication.

As described above, the video display devices 141 and 14
2 and 144 perform normal communication, but communication is delayed in the video display device 143, and as a result, synchronization between screens is disrupted. Therefore, the transmission control means 81 and 82 adjust the frame rate of each video data according to the video display device 143.

Here, transmission control will be described. When the transmission control means 81 and 82 control the frame rate of the video data 1 and 2 to 15 frame / sec,
In the video display device 143 having the highest load, 640 × 480 × (32/8) × (1/50) × 15 =
368640 (byte / sec) 320 × 240 × (32/8) × (1/20) × 15 =
230400 (bytes / sec) 368640 + 230400 = 599040. This is the capability of the video display device 143.
Mbyte / sec, the video display device 1
At 43, each video data can be decoded and displayed at 15 frames / sec.

It is clear that the video display devices 142 and 144 can decode and display each video data at 15 frames / sec. Therefore, all video data can be decoded and displayed at the same frame rate in all video display devices.

By controlling the amount of transmission by such transmission control means, the multi-display video display device displays two or more video data while maintaining a certain degree of synchronization between the screens.

As described above, according to the seventh embodiment, the load on the video display device is estimated based on the remaining capacity of each receiving buffer, and the frame rate of the video data is adjusted according to the video display device having the highest load. By performing the adjustment, it is possible to obtain an effect that the video window can be displayed across the screens without any dislocation between the video display devices without any discomfort.

Embodiment 8 FIG. The configuration of this embodiment is as follows.
As in the fifth embodiment, the configuration is the same as that shown in FIG.

Next, the operation will be described. The original image sizes of the video data 1 and 2, the coordinates of the starting point on the multi-display, and the image size are described in the first and fifth embodiments.
Is the same as FIG. However, in the fifth embodiment, the load estimating means 91 is
4, the transmission control means 81 and 82 adjust the frame rates of the video data 1 and 2 uniformly.
In this embodiment, the load estimating means 91 obtains the load of the video display devices 141 to 144 and determines the frame rate of the video data 1 and 2 based on the priorities of the video data 1 and 2 which have been determined in advance. Are adjusted separately.

The flow of the processing for displaying video data 1 and 2 is basically the same as the flow chart shown in FIG. 17 of the fifth embodiment, but in step ST152,
Transmission control means 81, 82 of video transmission devices 21, 22
Adjusts the frame rate of each video data to be transmitted based on the priorities of the video data 1 and 2 when the load on the video display devices 141 to 144 is high.

As described in the fifth embodiment, the video display device 143 has the highest load among the video display devices 141 to 144. Video display device 14
Assuming that there is a capability of decoding and displaying a video image having an area of 1280 × 800 at 30 frames / sec, the total area of video data written to the frame buffer is 1280 × 800 × 30 = 30720,000. Become.

However, in the video display device 143 having the highest load, (1280 × 720 + 640 × 480) × 30 = 368
64000 ≧ 30720000, which exceeds the capability and cannot decode and display two video images at the full rate.

It is assumed that the priority of the video data 1 is high and the priority of the video data 2 is low. The ratio of each priority is 10 for high priority and 2 for low priority. Video display device 14
3, the total area of the video data to be displayed is 30720000
3070000 / (1280 × 720 + 640 × 48
0) = 25, and the adjustment may be made so that the sum of the frame rates of the two video data becomes 25 frames.

Here, since the priority ratio of the two video data is 10 and 2, the frame rate of the video data 1 is 25 × 10/12 = 20, and the frame rate of the video data 2 is 25 × 2/12 = 5.

As a result, the transmission control means 81 and 82 set the frame rate of the video data 1 to 20 frame.
/ Sec, the frame rate of video data 2 is 5 fra
By suppressing the speed to me / sec, decoding and display can be performed at the same frame rate in all video display devices.

By controlling the transmission amount of each piece of video data based on the priority of each piece of video data, in a multi-display video display device, a certain degree of synchronization between screens is maintained for two or more pieces of video data. While displaying. In this embodiment, the frame rate of video data 1 is set to 20 frame / sec.
Although the frame rate of the video data 2 is set to 5 frame / sec separately,
There is no particular problem.

As described above, by adjusting the frame rate of each video data based on the priority of each video data, the display of the video window over the screen is prevented from being extremely shifted between the video display devices. The effect that it can be performed without discomfort is obtained.

Embodiment 9 FIG. FIG. 20 is a configuration diagram showing a multi-display video display device according to the ninth embodiment. In the figure, reference numeral 91 denotes a video display device 141 to 14
4 is a load estimating means for estimating the load, 1011 is a communication band control means for determining a communication band of video data based on information from the load estimating means 91, 1001 is a load estimating means 91,
This is a communication band management device including a communication band control unit 1011, and the other configuration is the same as that of FIG. 16 of the fifth embodiment.

Next, the operation will be described. Embodiment 5
Then, the video display device 1 estimated by the load estimating means 91
Transmission control means 81, 8 based on the loads of 41 to 144
2 adjusts the frame rates of the video data 1 and 2, but in this embodiment, the video data 1 and 2 are adjusted based on the estimated loads of the video display devices 141 to 144.
The second communication band is controlled. First, the load estimating unit 91 estimates the load status of the video display devices 141 to 144, and notifies the communication band control unit 1011.

Here, the load estimation will be described. Assuming that the receiving capabilities of the video display devices 141 to 144 are 1M
It is assumed to be byte / sec. Assuming that video data 1 is received at a compression rate of 1/50, 30 frame / sec, and one dot (pixel) is composed of 32 bits, the data amount of video data 1 is 640 × 480 × (32/8) × (1/50) × 30 =
737280 (bytes / sec).

The video data 2 is compressed at a compression ratio of 1/2.
If it is received at 0,30 frame / sec, the data amount of the video data 2 is 320 × 240 × (32/8) × (1/20) × 30 =
460800 (bytes / sec), and the total data amount of the video data 1 and the video data 2 is 737280 + 460800 = 1119080 (byte)
e / sec) ≧ 1,000,000 (byte / sec), and it is determined that the load is higher than the reception capability, and the communication band controller 1011 is notified that the transmission load is high.

Next, the communication band control means 1011 determines the communication band of the video data 1 and 2 and notifies the transmission control means 81 and 82 of the video transmission devices 21 and 22 of the determination.

Here, distribution of the communication band will be described. If video data 1 is compressed at a compression ratio of 1/50, the data amount per frame is 640 × 480 × (32/8) × (1/50) = 245
If the video data 2 is compressed at a compression ratio of 1/20 at 76 (bytes), the data amount per frame is 320 × 240 × (32/8) × (1/20) = 153
60 (bytes).

If the transmission amount is to be evenly distributed while maintaining the entire transmission amount, the transmission amount of video data 1 is 1,000,000 × 24576 / (24576 + 1536).
0) = 615384, and the transmission amount of the video data 2 is 1,000,000 × 15360 / (24576 + 1536)
0) = 384615. The communication band of the video data 1 is determined to be 610 Kbyte / sec and the communication band of the video data 2 is determined to be 380 Kbyte / sec by rounding down fractions.

Next, the video transmission devices 21 and 22 transmit video data 1 and 2 by transmission control means 81 and 82, respectively.
, The video data is encoded by the video data transmitting means 11 and 12, and transmitted to all the video display devices 141 to 144 by multicast.

Here, control of the transmission amount will be described.
The communication band of the video data 1 is 610 Kbytes / se
c, so that 610000 ÷ (640 × 480 × 32/8 × 1/5
0) = 24.82. The communication band of the video data 2 is 380 Kb.
yte / sec, 380000 ÷ (320 × 240 × 32/8 × 1/2
0) = 24.73, and by limiting the transmission amount to 24 frames / sec or less, respectively, the designated communication band (610 Kb
(te / sec, 380 Kbyte / sec) or less. In this way, the video data 1 and 2 whose transmission amounts are limited are respectively transmitted to the video display device 141.
To 144.

The processing of the video display devices 141 to 144 is performed in the same manner as in the fifth embodiment. In this way,
Start point coordinates (960, 240), video image size (12
80 × 720) video data 1 is 24 frame / s
ec or less, and the starting point coordinates (1600, 90
4), video data 2 of a video image size (640 × 480) is displayed at a speed of 24 frame / sec or less.

Thus, the transmission amount is controlled,
By maintaining a communicable band, the multi-display video display device displays two or more pieces of video data while maintaining a certain degree of synchronization between screens.

As described above, according to the ninth embodiment, the communication band control means controls the communication band on the basis of the load of the video display device to control the transmission amount, so that the video over the screen can be controlled. The effect is obtained that the display of the window can be performed without discomfort in each video display device without extreme displacement.

Embodiment 10 FIG. FIG. 21 shows Embodiment 10
1 is a configuration diagram showing a multi-display video display device according to the present invention. In the figure, 1 is video data to be displayed on the multi-display, 1021 is a time stamp adding means for adding a decoding start time to the video data 1 as a time stamp, and 1031 is a time stamp when the decoding start time is inappropriately determined. Decryption start time change means for instructing change,
Reference numeral 11 denotes video data transmitting means for transmitting video data 1 encoded (compressed) by multicast, and 2
Reference numeral 1 denotes a video transmitting apparatus including a time stamp adding unit 1021, a decoding start time changing unit 1031, and a video data transmitting unit 11. Further, 141 to 144 are video display devices, and 171 to 174 are displays for displaying video data 1 and 2.

FIG. 22 is a configuration diagram showing the video display device 141 in FIG. In the figure, reference numeral 201 denotes current time acquisition means for examining the arrival time of video data;
11 is a time comparing means for comparing the time obtained by the current time capturing means 201 with the time added to the video data to obtain a time difference, 221 is a time waiting means for performing a waiting for the compared time, and 231 is Time comparison means 21
1 is a message sending means for notifying the video transmission device 21 of the time difference determined.

A video data decoding unit 111 decodes (decompresses) the encoded video data.
Is a frame buffer in which video data 1 is written, 1
21 is a writing position determining means for determining a writing position of the video data 1 in the frame buffer 161, and 131 is a video writing means for writing the video data 1 in the frame buffer 161.

FIG. 21 shows the configuration of the video display device 141. The video display devices 142 to 144 have the same configuration. 204, the time comparison means is 212 to 214, and the time waiting means is 2
22 to 224, message sending means 232 to 23
4, video data decoding means 112 to 114, writing position determination means 122 to 124, video writing means 1
32 to 134, frame buffer 163, 165
167.

Next, the operation will be described. Here, the video data having the original image size of (640 × 480) is
On the multi-display, set the coordinates of the starting point to (960, 24
0), and an example in which the image size is set to (1280 × 720) and displayed.

FIG. 23 is a flowchart showing the processing flow of the video transmission device and the video display device. Step S
At T171, the time stamp adding unit 1021
Is the sum of the absolute time of the time at which the video data 1 was fetched and the arbitrary time required for transmission as the time to start decoding, and adds this to the first frame of the video data 1 as a time stamp. Here, the video data capture time is set to 102120, and the transmission time is set to 100
As a timestamp, 10222
Set to 0. In this case, the unit is msec.
Then, in step ST172, the video data transmitting means 11 encodes the first frame of the video data 1, and transmits all the video display devices 14 by multicast.
1 to 144.

On the video display devices 141 to 144,
In step ST173, the current time capturing means 201
To 204 investigate the arrival time of the first frame of the encoded video data. Here, the current time capturing means 2
The arrival times examined by 01 to 204 are respectively 102
200, 102210, 102225, and 102210, and notify the time comparing means 211 to 214.

Next, in step ST174, the time comparing means 211 to 214 compare the arrival time of the first frame with the added time stamp, and obtain the time difference. The time differences obtained by the time comparing means 211 to 214 are 20, 10, -5, and 10, respectively.

Next, in step ST175, the time waiting means 221 to 224 wait for the first frame if the obtained time difference is a positive value. That is, in the time waiting means 221, 222, and 224,
Waiting is performed for 20, 10, and 10 (msec), respectively. Then, in step ST176, the video data decoding units 111 to 114 each decode the first frame of the encoded video data. If the obtained time difference is a negative value, decoding is not performed.

In step ST177, write position determining means 121, 122, and 124 determine the write position, but write position determining means 123 does not perform the write position determining process. Next, in step ST178, the video writing means 131, 132, 134 writes the first frame into the own frame buffers 161, 163, 167.
However, the video writing means 133 does not perform video writing processing.

In this way, the video data 1 written by the video writing means 131, 132, 134 almost simultaneously is transferred to the respective displays 171, 172, 174 in step ST179, so that the start point coordinates (960, 240), video image size (128
The first frame of video data 1 (0 × 720) is displayed. However, regarding the display 173, the display of the first frame is not performed.

[0188] In step ST180, the message sending means 231 to 234 transmits the message to the above-mentioned step ST174.
, The time differences 20, 10, -5, and 10 obtained by the time comparison means 211 to 214 are notified to the video transmission device 21.

[0189] Next, in step ST181, the decoding start time changing means 1031 sends the message sending means 231.
234 are determined to be impossible to display on the video display device 143, and the time stamp adding means 1021 is instructed to change the decoding start time. For example, an instruction is issued to change the arbitrary time required for transmission added to the second frame of video data 1 from 100 to 110.

In step ST182, the time stamp adding means 1021 sets, as a time stamp, a decoding start time obtained by adding an arbitrary time 110 for transmission to the absolute time of the time at which the second frame is fetched to the second frame of the video data 1. Add. Here, the capture time of the second frame of video data is set to 102220, the time required for transmission is added as 110, and this is set to 102330 as a time stamp. The unit is msec. Then, in step ST183, the video data transmitting means 11 encodes the second frame and transmits it to all the video display devices 141 to 144 by multicast.

In step ST184, the current time capturing means 201 to 204 examine the arrival time of the second frame. Here, the current time capturing means 201, 202,
The time when 203 and 204 investigated are each 10230
0, 102310, 102325, and 102310.

Next, in step ST185, the time comparing means 211 to 214 compare the arrival time of the second frame with the added time stamp, and obtain the time difference. Here, the time differences obtained by the time comparing means 211 to 214 are 30, 20, 5, 20, respectively.
The determined time difference is notified to the video transmitting device 21 by the message transmitting units 231 to 234 as in step ST180.

In step ST186, the time waiting means 221 to 224 determine that the time difference is a positive value, so that the time difference
(Msec). And step ST
At 187, the video data decoding means 111
14 decodes the second frame simultaneously. here,
Since all of the second frame is normally decoded, processing is performed in the subsequent steps ST188 to ST190, and the start coordinates (960, 240) and the video image size (1280 × 720) are displayed on the displays 171 to 174 almost simultaneously. ) Is displayed. Regarding the frame captured next to the video data 1,
The same processing is repeated.

In this way, the display is performed while maintaining the synchronization between the screens while changing the time added as the transmission time. In this embodiment, one video data is processed, but two or more video data can be processed similarly.

Also, in this embodiment, the decryption start time changing means 1031 and the message sending means 231 to 23
However, if the time stamp adding means 1021 appropriately sets the time required for transmission when adding a time stamp, even if the decoding start time changing means 1031 and the message sending means 231 to 234 are not provided, it is almost possible Obviously, a similar operation is performed.

Further, when the time difference between the time of the time stamp and the arrival time of the video data is longer than necessary, it is apparent that the waiting time can be shortened by changing the time to be added by the time stamp adding means to a shorter time. It is.

As described above, according to the tenth embodiment, the video display device waits for the time difference obtained from the time stamp added to the video data and the arrival time of the video data. The effect is obtained that the display of the video window over the screen can be simultaneously displayed on each video display device.

Further, according to the tenth embodiment, if there is a video display device whose arrival time of video data does not meet the time of the time stamp, the time of the time stamp added to the video data by the video transmission device Has the effect of being able to be displayed simultaneously on all video display devices.

Further, according to the tenth embodiment, if the arrival time of video data has a considerable margin in all video display devices as compared with the time of the time stamp, the video display device converts the arrival time to video data. By changing the time of the time stamp to be added earlier, it is possible to obtain an effect that all the video display devices can simultaneously display the images at the wait time without waste.

[0200]

As described above, according to the present invention, a plurality of video data are written to the frame buffer corresponding to each display, and the video data written to the frame buffer at a predetermined timing is displayed.
Also in the case of displaying an image straddling each display, there is an effect that a display without a sense of incongruity can be performed without shifting the actual display timing.

According to the present invention, a group on the display is determined, and a group of videos that can be decoded is determined for each determined group within a predetermined interval. Therefore, when displaying a plurality of video data, Processing at the full rate can be performed for each group, and display without discomfort can be performed. In addition, by transmitting video data only to the video display device that displays for each group, communication efficiency can be improved. .

According to the present invention, the decoding time of the actual video data is estimated, and the longest time among the decoding times notified from each video display device is determined for each video data, thereby obtaining the longest decoding time. Based on the time, a plurality of video data that can be decoded within a predetermined interval can be confirmed.

According to the present invention, a plurality of video data is written to the frame buffer corresponding to each display, and the video data written to the frame buffer is displayed at a predetermined timing, thereby displaying an image extending over each display. In this case, it is possible to provide a display that does not cause a sense of incongruity without shifting the actually displayed timing, and to select a group of videos that can be decoded at regular intervals, based on the priority of each video data. Therefore, there is an effect that a video image with high priority can be displayed with priority.

According to the present invention, a plurality of video data is written to the frame buffer corresponding to each display, and the video data written to the frame buffer is displayed at a predetermined timing, thereby displaying an image extending over each display. In this case, it is possible to display without discomfort without actually shifting the displayed timing, and to adjust the resolution and compression ratio of the low-priority video data to create a video group that can be decoded at full rate. There is an effect that as many high priority video images as possible can be inserted.

According to the present invention, a plurality of video data is written to the frame buffer corresponding to each display, and the video data written to the frame buffer is displayed at a predetermined timing, thereby displaying an image extending over each display. Also in this case, it is possible to perform display without a sense of incongruity without shifting the actually displayed timing, and it is possible to superimpose a plurality of video windows on two or more video data without clip processing. This has the effect.

According to the present invention, the load on the video display device is estimated, and the frame rate of the video data to be transmitted is adjusted in accordance with the video display device having the highest load, thereby displaying the video window over the screen. To
In each video display device, there is an effect that the video display can be performed without any discomfort without extreme displacement.

According to the present invention, by controlling the communication band based on the load of the video display device and controlling the transmission amount, the video window over the screen can be extremely displayed by each video display device. There is an effect that the operation can be performed without any discomfort without shifting.

According to the present invention, queuing is performed by the time difference obtained from the time stamp added to the video data and the arrival time of the video data.
There is an effect that the display of the video window over the screen can be simultaneously displayed on each video display device, and the time stamp can be changed to an appropriate time stamp by checking the actual decoding start time.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a multi-display video display device according to Embodiment 1 of the present invention.

FIG. 2 is a configuration diagram showing a video display device according to Embodiment 1 of the present invention.

FIG. 3 is a diagram for explaining display of video data on a multi-display according to the first embodiment of the present invention.

FIG. 4 is a flowchart showing a processing flow of a video group determining device, a video transmitting device, and a video display device according to the first embodiment of the present invention.

FIG. 5 is a diagram for explaining determination of a group of each display according to the first embodiment of the present invention.

FIG. 6 is a diagram for explaining switching between writing of video data into a frame buffer and display according to the first embodiment of the present invention;

FIG. 7 is a configuration diagram showing a multi-display video display device according to a second embodiment of the present invention.

FIG. 8 is a configuration diagram showing a video display device according to a second embodiment of the present invention.

FIG. 9 is a diagram for explaining switching between writing of video data into a frame buffer and display according to the second embodiment of the present invention.

FIG. 10 is a configuration diagram showing a multi-display video display device according to Embodiment 3 of the present invention.

FIG. 11 is a diagram illustrating switching between writing of video data to a frame buffer and display according to the third embodiment of the present invention.

FIG. 12 is a configuration diagram showing a multi-display video display device according to Embodiment 4 of the present invention.

FIG. 13 is a configuration diagram showing a video display device according to a fourth embodiment of the present invention.

FIG. 14 is a diagram illustrating display of video data on a multi-display according to a fourth embodiment of the present invention.

FIG. 15 is a flowchart showing a flow of processing of a video transmission device and a video display device according to Embodiment 4 of the present invention.

FIG. 16 is a configuration diagram showing a video display device according to Embodiments 5 and 8 of the present invention.

FIG. 17 is a flowchart illustrating a flow of processing of a load estimating unit, a video transmitting device, and a video display device according to Embodiments 5 and 8 of the present invention.

FIG. 18 is a configuration diagram showing a multi-display video display device according to Embodiments 6 and 7 of the present invention.

FIG. 19 is a configuration diagram showing a video display device according to Embodiments 6 and 7 of the present invention.

FIG. 20 is a configuration diagram showing a multi-display video display device according to Embodiment 9 of the present invention.

FIG. 21 is a configuration diagram showing a multi-display video display device according to Embodiment 10 of the present invention.

FIG. 22 is a configuration diagram showing a video display device according to Embodiment 10 of the present invention.

FIG. 23 is a flowchart showing a processing flow of the video transmission device and the video display device according to the tenth embodiment of the present invention.

FIG. 24 is a configuration diagram showing a conventional multi-display video display device.

FIG. 25 is a diagram illustrating display of video data on a conventional multi-display.

FIG. 26 is a flowchart showing the flow of processing of a conventional video transmitting device and video display device.

[Explanation of symbols]

1, 2, 3 video data, 21, 22, 23 video transmitting device, 31 group determining means, 41 video group determining means, 61 video decoding time determining means, 71, 72,
73 video adjustment means, 81, 82 transmission control means, 9
1 load estimation means, 111, 112, 113, 114
Video data decoding means, 121, 122, 123, 1
24 writing position determining means, 131, 132, 133, 1
34 video writing means, 141, 142, 143, 14
4 video display device, 151 buffer switching means, 16
1,162 frame buffer, 171,172,17
3,174 display, 181 video decoding time estimation means, 191 decoding order determination means, 201 current time acquisition means, 211 time comparison means, 221 time waiting means, 231 message sending means, 1011
Communication band control means, 1021 time stamp adding means, 1031 decoding start time changing means.

Claims (13)

[Claims] 1. A video group determining means for determining a plurality of video data that can be decoded within a predetermined interval from video data to be displayed, and a plurality of video data respectively encoding and transmitting the determined plurality of video data. A video transmitting device, and a plurality of video display devices for decoding the plurality of transmitted video data and displaying the divided video data on a plurality of displays, wherein each of the video display devices transmits the plurality of transmitted video data. Video data decoding means for decoding; first and second frame buffers in which the decoded video data is written; and write position determination for determining write positions in the first and second frame buffers. Means for writing the decoded video data to the write position of the first and second frame buffers; Buffer switching means for alternately switching the first and second frame buffers between writing for the video writing means and display for displaying the written video data at intervals of A multi-display video display device, wherein a plurality of video data written in the first and second frame buffers are switched at predetermined intervals and displayed on the plurality of displays. 2. A group determining means for dividing a plurality of displays on which a plurality of video data are displayed into a predetermined group, and for each of the groups, the video group determining device determines a predetermined interval of video data to be displayed. The multi-display video display device according to claim 1, wherein a plurality of video data that can be decoded are determined. 3. Each video display device has video decoding time estimating means for estimating a decoding time by a video data decoding means and a writing time by a video writing means as a decoding time. Video decoding time determining means for determining the longest time among the decoding times notified by the video display devices, wherein the video group determining means determines the longest time determined by the video decoding time determining means. 2. The multi-display video display device according to claim 1, wherein a plurality of video data that can be decoded within a predetermined interval is confirmed from the video data to be displayed based on the video data. 4. The multi-display video display device according to claim 1, wherein the determination of the plurality of video data by the video group determination means is performed based on the priority of each video data. 5. The multi-display video display device according to claim 4, further comprising video adjusting means for adjusting resolution or compression ratio for video data having a low priority. 6. A plurality of video transmission devices for encoding and transmitting a plurality of video data, respectively, and a plurality of video display devices for decoding the transmitted plurality of video data and dividing and displaying the plurality of video data on a plurality of displays. A multi-display video display device, wherein each of the video display devices determines a decoding order based on a priority of the plurality of video data; and Video data decoding means for decoding in the decoded decoding order, first and second frame buffers in which the decoded video data is written, and writing positions of the first and second frame buffers. Writing position determining means for determining; and the writing position of the decoded video data in the first and second frame buffers. Video writing means for writing; and a buffer for alternately switching the first and second frame buffers between writing for the video writing means and display for displaying written video data at predetermined intervals. Switching means for switching the plurality of video data written in the first and second frame buffers at predetermined intervals and displaying the video data on the plurality of displays. . 7. A plurality of video transmission devices for encoding and transmitting a plurality of video data, respectively, and a plurality of video display devices for decoding the transmitted plurality of video data and dividing and displaying the plurality of displays on a plurality of displays. A multi-display video display device, comprising: load estimating means for estimating the load of the plurality of video display devices; and transmission control means for adjusting a frame rate of the plurality of video data based on the load estimated by the load estimating means. A multi-display video display device comprising: 8. The multi-display video display device according to claim 7, wherein the load estimating means estimates the load based on the total area of each piece of video data displayed on each display. 9. The multi-display video display device according to claim 7, wherein the load estimating means estimates the load based on a total data amount per unit time of each video data displayed on each display. 10. A load estimating means for estimating a load based on a remaining amount of a reception buffer in a video display device receiving a plurality of transmitted video data.
A multi-display video display device as described. 11. The transmission control means, based on the load estimated by the load estimating means, adjusts the frame rates of the plurality of video data in consideration of the priorities of the plurality of video data. A multi-display video display device as described. 12. A plurality of video transmission devices for encoding and transmitting a plurality of video data, respectively, and a plurality of video display devices for decoding the transmitted plurality of video data and dividing and displaying the plurality of video data on a plurality of displays. A load estimating means for estimating a load of the plurality of video display devices, and a communication band control means for controlling a communication band of the plurality of video data based on the load estimated by the load estimating means. And a transmission control means for controlling a transmission amount of the plurality of video data based on a communication band controlled by the communication band control means. 13. A multi-display video display device, comprising: a video transmission device for encoding and transmitting video data; and a plurality of video display devices for decoding the transmitted video data and displaying the divided video data on a plurality of displays. In the above, the video transmitting apparatus may include: a time stamp adding unit that adds a time at which decoding is started by the plurality of video display apparatuses to the video data as a time stamp; and a decoding instruction that arbitrarily changes the time stamp. Starting time changing means, wherein each of the video display devices is provided with a current time capturing means for checking the time at which the video data is received, and a time determined by the current time capturing means and added by the time stamp adding means. Time comparing means for comparing the time stamp with Time queuing means for performing queuing based on time, video data decoding means for performing queuing by the time queuing means, and then decoding the video data; and decoding the result of comparison by the time comparing means. Message sending means for notifying the time changing means, wherein the decoding start time changing means instructs the time stamp adding means to change the time stamp based on a result notified by the message sending means. Characteristic multi-display video display device.