JP2008151860A - Video display system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simultaneously display a thumbnail video and a user's desired video while suppressing video data to be transferred to a permissible value or below in a video display system using multi-screens. <P>SOLUTION: A video synthesis apparatus 1 has an input board 3 for converting a plurality of inputted video signals 100 to stream signals, a transfer bus 4 for transferring the stream signals, and an output board 5 which synthesizes the transfer bus 4 for transferring the stream signals and the plurality of the video signals and outputs the signals to a display apparatus 2. A display controller 10 lowers a frame rate relating to the video signals to be enumerated in a thumbnail window 210 of the multi-screen display apparatus 2 and transfers a transfer bus 4. Relating to the video signal to be displayed in enlargement on the display window 200, the controller returns the frame rate to the original one and transmits the video signal. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a video display system for displaying a plurality of videos on a multi-screen in which a plurality of displays are arranged in a grid pattern.

  When multiple people work while confirming the contents of the same display screen (for example, monitoring an infrastructure system, etc.), or when displaying video for the general public at various event venues, multiple displays are arranged. A video display system for outputting video to two large screen displays is used. In such a multi-screen display system, not only can the video to be displayed be enlarged and displayed on the entire multi-screen, it is advantageous when a plurality of videos are simultaneously displayed on the same screen, and can be used for various applications.

  In the multi-screen display system, the following technique is disclosed as a signal processing technique for displaying an enlarged image. For example, Patent Document 1 aims to select an arbitrary video signal from a plurality of input video signals and display it at an arbitrary position. The display system includes one master unit and other slave units. A configuration is described in which the control unit controls the master unit, and the master unit controls itself and the slave unit.

  Patent Document 2 discloses a video display device that can perform switching display of a plurality of videos on the same screen, such as equal magnification, enlargement, reduction, and composition. In this apparatus, an enlargement circuit board is inserted and enlargement processing is performed, and a plurality of video signals input by the screen composition circuit are composed on the screen.

  On the other hand, when searching for a desired video from a plurality of video sources or searching for a desired scene from a recorded video file, a search list display screen (so-called thumbnail screen) is displayed and the user selects from this. The method is known.

  Patent Document 3 discloses an information reproducing apparatus that can easily search for and select a desired video from video information recorded on a recording medium such as a disc. In this apparatus, as a selection screen, a symbol corresponding to a program recorded on the medium or an identifier for identifying the program is displayed on the screen, and a plurality of representative screens constituting the program of the selected symbol are reduced, enlarged, or cut out. Display on the screen. When one of a plurality of representative screens is selected, the scene on the representative screen is enlarged and displayed on the full screen.

  Patent Document 4 discloses a method for displaying a still image thumbnail and a moving image thumbnail together on a search screen in order to reliably search for a desired image in moving image data recorded on a recording medium.

JP-A-8-88820 Japanese Patent Laid-Open No. 7-154680 JP 2001-184842 A JP 2004-193695 A

  Even in the multi-screen display system, the operability for the user can be improved by adopting a display method in which a plurality of input videos are displayed as thumbnails on the multi-screen, and a desired video can be selected and enlarged from there. In that case, it is desirable that a large number of videos can be displayed on the thumbnail screen, and that the thumbnail display video includes a moving image. Furthermore, it is desirable that a large number of screens (windows) to be enlarged can be displayed.

  Recent video display systems are realized using dedicated image processing software in order to cope with an increase in the number of video inputs and to efficiently perform complicated processing such as video enlargement / reduction and composition. The plurality of input video signals are converted into digital signals by the input board and transferred to the output board via the transfer bus. Each video is enlarged / reduced and combined in the output board and sent to the multi-screen display device to display the composite video.

  Incidentally, since the capacity of the transfer bus for transferring input video data from the input board to the output board is limited, the number of videos that can be transferred simultaneously is limited. That is, even if the number of thumbnail screens to be displayed simultaneously on the multi-screen or the number of screens to be enlarged and selected is increased, the video can be displayed simultaneously only up to the allowable amount of the transfer bus. On the other hand, when the number of videos on the thumbnail screen is reduced, the operability when searching for a desired video is inferior, and when the number of screens to be enlarged and displayed is reduced, it is inconvenient to simultaneously refer to related videos. Thus, the transfer capability of the transfer bus is one factor that restricts the user's usability.

  In each of the above patent documents, no particular consideration is given to the transfer allowable amount of the transfer bus in the video display system.

  An object of the present invention is to simultaneously display a thumbnail video and a video desired by a user in a video display system using a multi-screen while keeping the video data to be transferred below an allowable value.

  The video display system of the present invention includes a video synthesis device that synthesizes a plurality of input video signals, and a multi-screen display device that displays the synthesized video signals. The video composition device includes a video input unit that converts a plurality of input video signals into a digitized stream signal, a video transfer unit that transfers the stream signal converted by the video input unit, and a video transfer unit that transfers the video signal. A video output unit that receives the stream signal, combines a plurality of video signals, and outputs the combined video signal to a multi-screen display device; and a display control unit that controls the video input unit and the video output unit. The multi-screen display device has a thumbnail window that displays a list of input videos that are reduced and a display window that displays an enlarged image selected from the thumbnail window. The display control unit controls the video input unit to change the video signal displayed in the thumbnail window to a stream signal with reduced image quality and transfer the stream signal to the video transfer unit.

  Further, the display control unit controls the video input unit to transfer the video signal to be enlarged and displayed on the display window to the video transfer unit as a stream signal whose image quality is restored.

  In addition, the display control unit calculates the data amount of the stream signal to be transferred to the video transfer unit, and if the calculated data amount exceeds the allowable value of the video transfer unit, the image quality is reduced for a part of the video displayed in the display window. Control to change to a stream signal and transfer.

  Here, the display control unit controls the video input unit to lower at least one of the frame rate and resolution of the video when the video quality is lowered.

  According to the present invention, there is provided a video display system that comfortably performs thumbnail display of video input on a multi-screen and enlarged display of a video selected by a user.

  FIG. 1 is a block diagram showing an embodiment of a video display system according to the present invention. The video synthesizer 1 synthesizes a plurality of input video signals 100 and displays them as a single synthesized video on the multi-screen display device 2. The multi-screen display device 2 forms a large screen by arranging, for example, eight rear projection displays 2a, 2b, 2c,... In a 2 × 4 matrix, and displays an image on the large screen. The input video signal 100 can be various video sources such as a computer signal (RGB signal), a TV broadcast signal (NTSC, HD signal), a playback video signal from a recording medium (DVD), and the resolution thereof is SXGA, It supports various formats such as XGA and VGA. The captured video signal can be displayed as a display window 200 having a desired size at a desired position on the multi-screen.

  The video synthesizing device 1 is a device that synthesizes a plurality of input video signals 100 into one screen. For example, by performing video processing with software using a computer, the video synthesizer 1 is easy to operate for users and performs complex video processing. Can be done comfortably. In addition, the multi-screen display device 2 can be handled as a high-resolution desktop screen. The input board 3 converts a plurality of input video signals into digitized stream signals, and changes the image quality (frame rate, resolution, etc.) of the video signals as necessary. The stream signal is transferred to the output board 5 via the transfer bus 4. The output board 5 combines a plurality of input videos into a video signal of one screen according to a layout designated by the user. The synthesized video signal is separated into signals for each of the eight displays 2a, 2b, 2c... And sent to the multi-screen display device 2. A plurality of input boards 3 and output boards 5 may be mounted when the number of handled videos increases.

  The display control unit 10 controls the video signal processing in the input board 3 and the output board 5 to realize the display screen layout specified by the user, as well as the video data (stream signal) to be displayed in the transfer bus 4. It has a function of controlling the amount of video data to be transferred to be less than or equal to an allowable value so as to transmit without trouble. Such a function is realized by installing an application 6 and operation system (OS) 7 which are dedicated software and providing them to the input board 3 and the output board 5 via the input driver 8 and the output driver 9. That is, the function of the application 6 obtains information (video type, stream ID, frame rate, resolution, etc.) of the input video signal, and calculates and controls (changes the frame rate, etc.) the amount of stream data transmitted on the transfer bus. To display the specified video in the specified display window.

  FIG. 2 is a diagram illustrating an example of video display on the multi-screen display device 2. In FIG. 2A, two input videos are displayed on the display windows 200a and 200b, respectively, and all input videos are reduced and displayed in a list on the thumbnail window 210 (hereinafter referred to as thumbnail display). . When the user selects a desired video from the thumbnail window 210, the selected video is enlarged and displayed on the display windows 200a and 200b. The number of display windows, window size, and display position can be set freely. These video selections and window settings can be performed by operating the mouse on the large screen using the operation terminal. If the input video is a moving image, the video displayed as a thumbnail is also displayed as a moving image. However, since the thumbnail window 210 is used for video confirmation / search, it is displayed with a lower image quality (for example, frame rate) as will be described later. As for the display window 200, when the number of windows to be displayed is increased, the image quality of some windows is lowered.

  FIG. 2B shows a case where a plurality of tabs 220 are provided in the thumbnail window 210 and the thumbnail display screen is switched and displayed by designating the tabs. Thereby, it is possible to prevent the amount of video data to be transferred from becoming excessive by limiting the number of videos to be displayed simultaneously on the thumbnail display screen. Further, when the number of input videos increases, searchability can be improved by classifying the input videos using tabs and displaying them in a list.

  As described above, in the video display system of the present embodiment, all the input videos are displayed as thumbnails in the multi-screen display device 2, and a desired video is selected from the thumbnails and displayed in an enlarged display window. At this time, if the number of images to be displayed increases, the amount of data passing through the transfer bus 4 may exceed the allowable value. Therefore, the display control unit 10 is characterized in that the amount of data passing through the transfer bus 4 is calculated, and the image quality of each video is changed so as to be less than the allowable value. Hereinafter, some control examples of the display control employed in this embodiment will be described.

<Comparative example>
FIG. 3 is a diagram showing a case where an input video is transferred with the same image quality when a plurality of videos are displayed on a multi-screen for comparison. The plurality of input video signals 100 are converted into digitized stream signals by the video control unit 32 of the input board 3 and sent from the transmission unit 31 to the reception unit 51 of the output board 5 through the transfer bus 4. In the graphic processor unit (GPU) 52, each video is enlarged / reduced / combined according to a designated layout, and is displayed on the multi-screen 2 as one synthesized video. In FIG. 3, a thumbnail display 210 of a plurality of videos and an enlarged window display 200 of one video are displayed.

  In this case, the video data necessary for the thumbnail display 210 is transmitted to the transfer bus 4, but since all the videos are transmitted with the image quality at the time of input, the amount of data passing through the transfer bus 4 is Increase. However, since the transmission capacity of the transfer bus 4 is finite, even if an attempt is made to display the input video as a thumbnail, the allowable value is quickly exceeded. For example, if an attempt is made to transmit SXGA RGB video (resolution = 1280x1024, 32bit color, refresh rate 60Hz) to the PCI-X bus (transfer rate = 1.06GB / s) with the same image quality, the transmission amount per video Is 1280 × 1024 × 4 × 60 = 300 MB / s. That is, when the four input videos are transmitted simultaneously, the allowable transfer capacity is exceeded.

<Control example 1>
On the other hand, FIG. 4 is a diagram showing a control method in which the image quality of the input video is lowered when a plurality of videos are displayed on the multi-screen. Here, all the input videos 100 displayed as thumbnails are transferred at a reduced frame rate. For this purpose, the display control unit 10 controls the input board 3 so as to change the frame rate of each input video signal 100 from, for example, 60 Hz to 30 Hz using an API (Application Program Interface) function provided from the application 6. To do. By reducing the frame rate, the total amount of data sent to the transfer bus is reduced so that it is less than or equal to the transmission allowable value of the transfer bus. The frame rate to be changed in this case may be the same frame rate for all input videos, or may be switched to a different frame rate (for example, 30 Hz or 10 Hz) depending on the type of input video.

<Control example 2>
Further, FIG. 5 is a diagram showing a control method in which when a plurality of videos are displayed on a multi-screen, the picture quality of the display window is restored and transferred. As described in the above <Control Example 1>, thumbnail-displayed video is transferred at a reduced frame rate, but video that is enlarged and displayed on the display window 200 is transferred with its frame rate restored. In FIG. 5, the frame rate of the input video signal 100a is returned from, for example, 30 Hz to 60 Hz and displayed on the display window 200a. This control is also performed by the display control unit 10 on the input board 3 using an API function. In this way, the display window 200 displays the video selected by the user with the image quality at the time of input, so there is no dissatisfaction for the user. Similarly, when there are a plurality of display windows 200, the frame rate of each video is restored and transferred. However, if the number of windows to be displayed at the same time increases and the amount of data on the transfer bus is expected to exceed the allowable value, some images are displayed with reduced image quality. This will be described later in <Control Example 3>.

FIG. 6 is a flowchart illustrating a case where an input video is newly displayed by applying <Control Example 1> and <Control Example 2>.
First, input video information is acquired (S601), and it is checked whether there is a change (addition of a new input video, etc.) in the input video (S602). If there is a new input video, the display rate (frame rate) is reduced on the input board in accordance with the above <Control Example 1> (S603). Then, the thumbnail window is displayed in a state where the display rate of all input videos is lowered (S604).

  Next, it is checked whether or not an image to be enlarged is selected by the user (S605). Also, it is checked whether there is another window displaying the selected video (S606). Otherwise, the video being displayed has already been displayed at the display rate at the time of input. In that case, a new window is created and enlarged and displayed on the window (S611). If there is no other, it is calculated how much the total data amount (transfer amount) of the transfer bus increases when the selected video is returned to the original display rate (S607). It is determined whether or not the calculated transfer amount is less than or equal to the allowable value of the transfer bus (S608). If it is equal to or smaller than the allowable value, the process of returning the display rate of the selected video is performed according to the above <Control Example 2> (S609). If it exceeds the allowable value, the display rate of each input video is changed to the optimal value so that the transfer amount is less than the allowable value (S610). The optimization of the display rate will be described later in <Control Example 3>. Then, the selected video is enlarged and displayed in a new window (S612).

  FIG. 7 is a diagram showing a flowchart in the case where the video of the display window is switched and displayed by applying <Control Example 1> and <Control Example 2>. Here, it is assumed that the input video A is displayed in the display window, and this is switched to the input video B.

  First, the original video A is deleted from the display window (S701). It is checked whether there is another window displaying the original video A (S702). Otherwise, since the original video A is only a thumbnail display, it is transferred at a lower display rate on the input board in accordance with <Control Example 1> (S703). Next, it is checked whether there is another window displaying the new video B (S704). If there are others, the video B has already been displayed at the display rate at the time of input, and a new video B is displayed using the window that displayed the original video A (S709). If there is nothing else, it is calculated how much the total data amount (transfer amount) of the transfer bus increases when the new video B is returned to the original display rate (S705). It is determined whether the calculated transfer amount is equal to or less than the allowable value of the transfer bus (S706). If it is equal to or less than the allowable value, processing for returning the display rate of the new video B is performed in accordance with <Control Example 2> (S707). If it exceeds the allowable value, the display rate of each input video is changed to the optimal value so that the transfer amount is less than the allowable value (S708). The optimization of the display rate will be described later in <Control Example 3>. Then, the new video B is enlarged and displayed in the window where the original video A was displayed (S710).

<Control example 3>
FIG. 8 is a diagram showing a control method when there are a plurality of display windows on the multi-screen and the windows are displayed overlapping on the screen. FIG. 8A shows a case where two display windows 200a and 200b are displayed without overlapping on the screen. In this case, the display priority of both windows is made equal, and both videos are displayed with the image quality at the time of input. On the other hand, FIG. 8B shows a case where two display windows are displayed overlapping each other. In this case, the display priority of the front display window 200c is increased, and the display priority of the rear display window 200d is decreased. That is, a weighting index indicating the priority is assigned to each display window. Then, when it is desired to lower the image quality of the video displayed in the plurality of display windows, control is performed so as to lower the image quality (display rate) from the rear-side window 200d with a small weight.

  FIG. 9 is a diagram showing a flowchart for optimizing the display rate for a plurality of display windows by applying <Control Example 3>. Here, how to optimize the display rate (frame rate) of each window when the number of display windows increases and the transfer amount of the transfer bus exceeds an allowable value will be described.

  First, it is checked whether or not the display windows overlap on the screen. If they overlap, the priority (weighting) of the video displayed in each window is determined according to <Control Example 3>. If there is a window that is completely hidden behind, the image is excluded from the display target (weighting = zero) (S901). When the same video is displayed in a plurality of windows, the value of the window to which the maximum weight is given is set as the weight of the video (S902).

  Next, although the image quality is lowered from a video with a small weight, in this embodiment, a difference is provided in the priority depending on the type of the input video. First, a display rate is lowered from a video with a small weight in RGB video. For example, the frame rate is changed from 60 Hz to 30 Hz (S903). It is calculated how much the total data amount (transfer amount) of the transfer bus after the frame rate change is reduced, and it is determined whether or not the calculated transfer amount is less than or equal to the allowable value of the transfer bus (S904). If it is less than the allowable value, the condition is determined as the optimum value (S907). If the allowable value is exceeded, the display rate is lowered from the video with the smallest weight in the NTSC video. For example, the frame rate is changed from 30 Hz to 15 Hz (S905). The transfer amount of the transfer bus after the frame rate change is calculated, and it is determined whether or not it is less than the allowable value (S906). If it is less than the allowable value, the condition is determined as the optimum value (S907). If it still exceeds the allowable value, the process returns to S903, and the frame rate is lowered for the video with the next lowest weight in the RGB video. Alternatively, the rate is further lowered (for example, changed from 30 Hz to 15 Hz) for the video whose frame rate was previously lowered. If the allowable value is still exceeded, the NTSC video is performed in S905. In this way, the RGB video and the NTSC video are alternately reduced from a video with a small weighting, and the frame rate is reduced, and the transfer is repeated until the transfer amount of the transfer bus becomes less than the allowable value.

  Alternatively, S903 to S906 may be changed to the following procedure. First, the frame rate is lowered from a video with a small weight in the RGB video. If the allowable value is exceeded even if the rate is lowered for all of the RGB images, the rate is lowered from the image with the smaller weight in the NTSC image. If the allowable value is still exceeded, the rate rate to be decreased is increased and the above is repeated.

  In either case, if the display window increases and it is not possible to restore each image to the image quality at the time of input, the image quality is reduced from the RGB image on the back side on the display screen, and the total transfer bus To be less than the allowable amount. If the image cannot be achieved with only RGB video, the image quality of the NTSC video is lowered so that the total is less than the allowable transfer bus capacity.

  Note that the image of the display window operated last and the image of the display window in the foreground are often important for the user. An emergency video displayed in an emergency such as an incident or accident is also a video that should be displayed with priority over others. Therefore, it is desirable to display these priority videos without reducing the image quality. That is, in the optimum value calculation in <Control Example 3>, these priority videos are returned to the original image quality, and changes in the display rate are examined for other videos except these.

  In the above embodiment, the case where the frame rate is changed when changing the image quality to be displayed has been described as an example, but the changing method is not limited to this. For example, the amount of transfer data can be similarly reduced by lowering the display resolution, and further reduction of the data amount and finer control can be achieved by combining the frame rate and the resolution.

  According to the present embodiment, a video display system capable of simultaneously enlarging and displaying a thumbnail display and a plurality of videos desired by a user on a multi-screen within the range of transmission capability of a transfer bus for transferring an input video. Can be provided.

1 is a block configuration diagram showing an embodiment of a video display system according to the present invention. The figure which shows an example of the video display with the multiscreen display apparatus. The figure which shows the case where an input image | video is transferred with the image quality as it is for comparison description. The figure which shows the control method which lowers | hangs the image quality of an input image, and transfers. The figure which shows the control method which returns and restores the image quality of the image | video of a display window. The figure which shows the flowchart in the case of displaying an input image newly. The figure which shows the flowchart in the case of switching and displaying the image | video of a display window. The figure which shows the control method in case a window overlaps and is displayed on a screen. The figure which shows the flowchart of the optimization of the display rate with respect to several display windows.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Video composition apparatus 2 ... Multi-screen display apparatus 3 ... Input board 4 ... Transfer bus 5 ... Output board 10 ... Display control part 100 ... Input video signal 200 ... Display window 210 ... Thumbnail window.

Claims (6)

In a video display system comprising a video synthesizer that synthesizes a plurality of input video signals and a multi-screen display device that displays the synthesized video signals,
The video composition device
A video input unit for converting a plurality of input video signals into digitized stream signals;
A video transfer unit for transferring the stream signal converted by the video input unit;
A video output unit that receives the stream signal transferred from the video transfer unit, combines the plurality of video signals, and outputs the combined video signal to the multi-screen display device;
A display control unit for controlling the video input unit and the video output unit;
The multi-screen display device is
A thumbnail window that displays a list of the video that has been reduced,
A display window for displaying an enlarged image selected from the thumbnail window;
The display control unit controls the video input unit to control the video signal to be displayed on the thumbnail window to be changed to a stream signal with reduced image quality and to be transferred to the video transfer unit. system. The video display system according to claim 1,
The display control unit controls the video input unit to transfer a video signal to be enlarged and displayed on the display window to the video transfer unit as a stream signal whose image quality has been restored. Video display system. The video display system according to claim 2,
The display control unit calculates the data amount of the stream signal transferred to the video transfer unit, and when the calculated data amount exceeds the allowable value of the video transfer unit, the image quality of a part of the video displayed on the display window is determined. A video display system, wherein the video input unit is controlled so that the stream signal is changed to a lower stream signal and transferred. The video display system according to claim 3,
The display control unit, when the display window is displayed so as to overlap the screen, changes the video displayed on the display window on the back side to a stream signal with reduced image quality and transfers the video. Display system. The video display system according to claim 3,
The display control unit, when an RGB system video and an NTSC system video are displayed in the display window, changes the RGB system video to a stream signal with a lower image quality and transfers the video stream. system. The video display system according to any one of claims 1 to 5,
The display control unit controls the video input unit to lower at least one of a frame rate and a resolution of the video when the video image quality is lowered.

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