JPH11249965A - Computer system and copy limiting method applied to its system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a video data copy preventing function by a kind of a protect function of a video memory. SOLUTION: An OS 32 sets CP information in the unit of windows on a window management table 33 as one of attribute information of picture information in accordance with an indication from an AP 30. When receiving a copy request for picture information in the unit of windows from another AP, the OS 32 invalidates this copy command based on CP information set on the window management table 33, thus realizing a copy protect function which inhibits read and copy of video data from a VRAM 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a computer system having a function of preventing copy of screen information (video data) displayed on a display screen.

[0002]

2. Description of the Related Art Conventionally, a personal computer has a display device such as a CRT display for displaying data on a screen. The CRT display device has a function of displaying characters and graphics in color on a display screen by a display method called a raster scan method. In recent years, personal computers have played back not only characters and graphics processed by a CPU but also digital image (video) information recorded on, for example, a DVD (digital video disk), and digital video information obtained by digital satellite broadcasting. Display devices are often used to receive and play back.

A display device has a video memory for storing video data (including color data) as display information (screen information), and a video controller sequentially reads out the video memory from the video memory and has a RAMDAC (having a color palette). D / A converter). The RAMDAC converts digital video data into an analog signal (RGB signal) and outputs it to a CRT display.

Here, the personal computer has C
The method is broadly classified into a method in which a PU directly accesses a video memory and writes video data, or a method in which a video controller writes video data to a video memory in accordance with a drawing command from a CPU. Some recent personal computers have a video controller connected to a dedicated video bus different from the CPU bus. The video controller inputs a video signal (digital video information) from a DVD playback device (decoder) or a TV (television) tuner via a video dedicated bus, and develops the video signal in a video memory.

[0005]

In a conventional personal computer, video data as screen information is stored in a video memory and displayed on a display screen of a CRT display. The video memory normally allows a CPU to freely read video data via a video controller. That is, another application program can read the video data stored in the video memory by the application program executed by the CPU.

Therefore, it is relatively easy for another user to copy screen information handled by one user as confidential information or screen information to be protected by copyright. In other words, the conventional method of handling video data in a personal computer has a problem that leakage of confidential information and infringement of copyright are likely to occur.

It is an object of the present invention to realize a copy protection function for video data by using a kind of protection function of a video memory. With this copy protection function, it is possible to prevent leakage of confidential information and copyright infringement.

[0008]

According to the present invention, in a computer system such as a personal computer, a video memory is associated with a screen display operation on a display screen, and screen information is displayed in units of windows to be displayed on the display screen. The window management table means for managing the window management table means and the window management table means are updated in response to a display instruction of screen information in window units, and copy protection information for instructing protection of the screen information copy processing is stored in the window management table. Setting means for setting the information on the screen information, and when receiving a copy request for screen information in window units displayed on the display screen, referencing the window management table means for the screen information of the copy request target. If copy protection information is set, A system comprising a control means for inhibiting copying of the video data corresponding to the screen information from the memory.

[0009] Specifically, the setting means and the control means are operating systems (OS) of the computer system.
Or window system (window system)
m). For example, the OS generates screen information to be displayed on the display screen of the display device according to an instruction from the application program (AP). At this time, the OS uses the window management table means to manage screen information to be displayed on the display screen in window units.

Here, in response to an instruction from the AP, the OS manages window-based copy protection information (CP information) as part of the attributes (window size, coordinates, etc.) of screen information in window units. Set in the table means. Then, when a copy command for reading video data corresponding to the screen information from the video memory and copying the video data from another AP is issued,
S refers to the window management table means to check whether or not CP information is set in the screen information of the copy request target, and invalidates the copy command if it is set. In other words, when the CP information is set for the screen information to be copied, the copy command becomes invalid unless the CP information is released (for example, password processing). Therefore, it is possible to prevent a situation in which video data corresponding to the screen information instructed to be generated is unlimitedly copied from the video memory from an AP whose copy processing is to be restricted.

As another aspect of the present invention, a system CP
Assume a system in which a video controller controlled by U sets a CP information set from an AP in an internal register, and has a function of restricting a video memory access request. Here, the video controller can set, in the internal register, CP information instructing to prohibit copying of video data corresponding to screen information in screen units, window units, address units, and area units consisting of addresses and coordinate information.

In such a system in which the video controller has a copy restriction function, the copy restriction function can be realized without depending on the function of the OS (including the window system). Can be.

As another aspect of the present invention, in a system in which a video playback device and a video controller are connected by a video dedicated line, the video controller inputs video data from the video dedicated line and outputs the video data ( It has a function of inputting a copy protection control signal for instructing protection of a copy process of (screen information). The video controller prohibits a copy process for video data stored in, for example, an off-screen area (non-display area) of the video memory based on the copy protection control signal. Therefore, even if a certain AP issues a copy command instructing a copy process of video data stored in the off-screen area of the video memory via the OS,
The video controller inhibits the read operation from the video memory, thereby invalidating the copy command.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a block diagram showing a hardware configuration of a system related to the present embodiment.
3 and 4 are conceptual diagrams for explaining the operation of the system, and FIG. 5 is a flowchart for explaining the operation of the system. (System Configuration) In the present embodiment, the CRT display 2
This is a computer system assuming a personal computer equipped with a display device having the standard. As shown in FIG. 2, the present system is roughly divided into a CRT display 2
A graphics control device 1 for outputting display data to a display screen, a CPU 3, and a video reproducing device 4 as an optional peripheral device. Here, the CPU 3
A data processing unit including a microprocessor, a bus, and a main memory storing an OS (window system). The video reproducing device 4 means a DVD reproducing device (decoder), a digital TV tuner, or a digital VTR.

The graphics controller 1 includes a video controller 10 as a display control element and a video memory (V
(RAM) 11 and a RAMDAC 12. The video controller 10 has a graphics accelerator and a video accelerator, and has a function of receiving a drawing command and display data from the CPU 3 and developing display data in the video memory 11 according to the drawing command. Further, the video controller 10 sequentially reads out data (hereinafter collectively referred to as video data) stored in the VRAM 11 and transfers the data to the RAMDAC 12. RAMDAC1
2 converts digital video data into an analog signal (RG
B signal) and outputs it to the CRT display 2.
When outputting video data from the video reproducing device 4 to be described later to the CRT display 2, the video accelerator functions to execute processing different from the processing by the graphics accelerator. (Copy Protection Process of the Present Embodiment) Hereinafter, the copy protection process of the present embodiment in the system of FIG. 2 will be described with reference to FIGS. In the present embodiment, FIG.
As shown in the application program (AP)
This is a method of setting copy protection information (CP information) in window units from an OS (or window system) 32 through an API (application program interface) 31 from an API 30. The CP information is control information for instructing prohibition of a copy process of the designated screen information (video data). Also, the CP information is copy processing restriction information including a password, and may be information including a function of releasing copy prohibition when the passwords match.

Here, the drawing control unit included in the OS 32 generates screen information in accordance with an instruction from the AP 30,
When storing in the VRAM 11, the window management table 33 manages screen information for each window. The window management table 33 holds attribute information (size, coordinates, etc.) 40A and 40B for each window in associating the VRAM 11 with a screen display operation on the display screen of the display 2. In this embodiment,
As one of the attribute information, the CP information 50A, 50B for each window is set in the window management table 33.

When the AP 30 performs copy processing of video data corresponding to screen information on the display screen, the OS 32
Issue a copy command to The OS 32 reads the video data of the copy request target from the VRAM 11 and executes a copy process. That is, as shown in FIG.
U3 (via video controller 10)
From 11, the video data to be copied is transferred to a free access area called a clipboard 60 </ b> A on the main memory 60. The CPU 3 can transfer the data from the clipboard 60A to, for example, an external storage device in accordance with an instruction from the AP 30.

Hereinafter, the procedure of the copy protection process will be specifically described with reference to the flowchart of FIG. First,
When the AP 30 is activated, the CPU 3 reads the source data and the CP information from, for example, the video playback device 4 and stores them in the main memory 60. The CPU 3 transfers the data to the video reproduction device 4 having a software decoder corresponding to each source data, decodes the data into video data as necessary, and the video controller 1 via the main memory 60.
Transfer to 0. The video controller 10 expands the transferred video data in the VRAM 11 (see FIG. 1).

Here, the AP 30 communicates via the API 31
The CP information is set in the OS (window system) (step S1). At this time, the CP information may include a password set in advance by the user. O
In S32, the set C information is set on the window management table 33 together with the attribute information 40A and 40B for each window.
The P information 50A, 50B is set (step S2).

Here, it is assumed that a copy command for each window (for example, screen information 100A) is issued from another AP (YES in step S3). OS32
Corresponds to the window management table 3 according to the copy command.
3, the CP information (here, 50A) included in the attribute information corresponding to the screen information 100A to be copied.
Is checked (step S4). At this time, C
When P information is not set, as described above,
The CPU 3 (via the video controller 10)
The video data of the copy request is transferred from the AM 11 to the clipboard 60A on the main memory 60 (step S7).

On the other hand, if the CP information is set, the OS 32 invalidates the copy command from the AP (step S6). In this command invalidation processing, specifically, the memory management unit of the CPU 3 is operated to
The reading operation of AM11 is prohibited. If an API for reading screen information is called, error processing is performed. Further, the video data read from the VRAM 11 is painted in a predetermined pattern, for example, to invalidate the video data itself to be copied. Or VRAM
The mosaic processing or the like is performed on the video data read from the data 11 to reduce the amount of information. In addition, noise is added to the video data read from the VRAM 11 to falsify a part of the data or to add a visible mark or digital watermark information that is an illegal copy but can be recognized.

As described above, according to this embodiment, the CRT
The AP including the process of displaying the confidential screen information on the display screen of the display 2 transmits the prepared CP information to the OS.
By setting to, the copy protection function can be realized. That is, even if another AP issues a copy command,
Based on the set CP information, it is possible to execute copy prohibition processing such as prohibiting the operation of reading video data from the video memory 11. Furthermore, if the method uses the window management table 33 as in the present embodiment, FIG.
As shown in (A), on the display screen of the display 2, copy protection can be set for the designated window 200A, and the restriction on the copy processing can be removed especially for the other window 200B. Further, as shown in FIG. 3B, all windows A-1 to A-3 can be copy-protected for the window 201 having a hierarchical structure. (First Modification of the Present Embodiment) The conceptual diagram of FIG. 6 and the flowchart of FIG. 7 are diagrams relating to the first modification of the present embodiment.

The first modification is a system in which the video controller 10 executes copy protection processing instead of the OS (window system). Specifically, as shown in FIG. 6, the video controller 10
0A, and sets CP information in this internal register 10A. The CP information is set in the internal register 10A of the video controller 10 by the OS, that is, the CPU 3, in response to an instruction from the AP.

Here, it is assumed that the CP information is information which can set copy prohibition for each screen, each window, each address, and each area including address and coordinate information. As the copy protection process, it is effective in an actual system to copy protect video data stored in an off-screen area (non-display area) of the VRAM 11. As shown in FIG. 7, the VRAM 11 has an on-screen area (display area) 11A and an off-screen area (non-display area) 11B. RAMDAC1
2 converts the data developed in the on-screen area 11A into an analog signal and outputs it to a display. The off-screen area (non-display area) 11B includes a buffer area for video data to be displayed next, an area for storing frequently displayed data, and the video controller 1.
0 is used as an area for calculation processing.

The operation of the first modification will be described below with reference to the flowchart of FIG. First, as described above, the video controller 10 stores the CP information corresponding to the instruction from the AP via the OS (that is, the CPU 3) in the internal register 1.
It is set to 0A (step S10). This CP information
Copy prohibition is set for each screen, each window, each address, and each area including address and coordinate information.

Here, when there is a copy request from the CPU 3 to the video controller 10 in response to a copy command from another AP, the video controller 10 checks the set contents of the CP information with reference to the internal register 10A. (Steps S11 and S12). If the CP information is not set, the video controller 10
Read video data for copy request from M11
Transfer to PU3. The CPU 3 causes the data to be transferred to the clipboard 60A on the main memory 60 (step S16).

On the other hand, when the CP information is set, the video controller 10 compares the copy prohibition range defined by the CP information with the copy request range, and specifies the copy protection range (step). S1
4). Specifically, when the CP information sets the entire screen as the copy protection range, the video controller 10 invalidates all the copy requests included in the range (step S15). Here, as described above,
In practice, the video controller 10 has a VRAM 11
Of the video data stored in the off-screen area (non-display area) 11B. In this case, as the invalidation processing of the copy request, various processings such as prohibition of the reading operation to the VRAM 11 can be assumed as in the present embodiment.

As described above, according to the first modification, the video controller 10 sets the CP information in the internal register 10A, and executes the copy protection processing if necessary. Therefore, the video controller 10 needs a function for executing the copy protection process, but the OS and the window system do not require a special function for the copy protection process as in the present embodiment. In addition, by setting a copy protection range in the CP information such as a screen unit, a window unit, an address unit, and an area unit including address and coordinate information, only a specific range of screen information is prohibited from being copied. Can be. In other words, no copy protection is required,
Information that requires normal handling, including copy processing, can be excluded from the copy protection range. (Modification 2 of this embodiment) FIGS. 9 and 10 are diagrams related to Modification 2 of this embodiment. The second modification is a copy protection method assuming a video controller 10 that can process digital video data from the video reproducing apparatus 4 described above.

That is, in the second modification, as shown in FIG. 9, the video controller 10 has a video accelerator, and the video controller 20
And the copy protection control signal line 21 are connected. The video dedicated bus 20 is a dedicated bus for transferring digital video data from the video playback device 4. The copy protection control signal line 21 is a signal line for transferring a copy protection control signal corresponding to the protection information from the video playback device 4. The copy prevention control signal line 21 is, for example, a bidirectional serial interface signal line, and desirably can realize a bidirectional communication function capable of exchanging information such as a password.

Here, as described above, the video playback device 4 is specifically a DVD playback device (decoder), a digital TV tuner, or a digital VTR. The copy protection control signal is a signal that is reproduced based on copy protection information (corresponding to protection information) recorded in advance on a disk as a recording medium in the case of a DVD reproducing device. In the case of a digital TV tuner or a digital VTR, the signal is reproduced based on copy protection information included in a digital video signal broadcast from, for example, digital satellite broadcasting.

Hereinafter, the copy protection processing of the second modification will be described with reference to the flowchart of FIG. The video controller 10 inputs the copy protection control signal via the copy protection control signal line 21 together with the video data (digital video signal) transferred from the video playback device 4 via the video dedicated bus 20 (step S20). Here, as shown in FIG. 9, the video controller 10 sets, for example, a copy protection flag in the internal register 10B according to the input of the copy protection control signal.

Here, when there is a copy request from the CPU 3 to the video controller 10 in response to a copy command from another AP, the video controller 10 checks the copy prevention flag with reference to the internal register 10B. (Steps S21, S22). If the copy protection flag is not set, the video controller 1
0 reads out the video data of the copy request target from the VRAM 11 and transfers it to the CPU 3. The CPU 3 causes the data to be transferred to the clipboard 60A on the main memory 60 (step S25).

On the other hand, if the copy protection flag is set, the video controller 10 executes a copy protection process (YES in step S23, S2).
4). That is, in response to a read request from the CPU 3, the video controller 10 executes a process of invalidating a copy command such as prohibiting an operation of reading video data from the video memory 11. Here, as described above, in practice, the video controller 10 prohibits copying of video data stored in the off-screen area (non-display area) 11B of the VRAM 11.

As described above, according to the second modification, similarly to the first modification, the video controller 10 needs a function for executing the copy protection processing. In addition, the OS and the window system do not require a special function for the copy protection processing. Also, unlike the above-described first modification, a system in which the video dedicated bus 20 and the copy protection control signal line 21 are connected between the video controller 10 and the video playback device 4 is assumed. Since the copy protection function can be set without requiring the intervention of the system, a stable copy protection function can be realized as a system.

[0035]

As described in detail above, according to the present invention, a copy protection function for a video memory used in a display device is used to prevent a video data stored in a video memory from being read and copied. The prevention function can be realized. Therefore, it is possible to prevent the leakage of confidential information and the occurrence of copyright infringement of information handled as confidential information and information that is subject to copyright protection in the screen information displayed on the display screen. Become.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing a configuration of a system related to an embodiment of the present invention.

FIG. 2 is a block diagram for explaining a hardware configuration of the system.

FIG. 3 is a conceptual diagram for explaining the operation of the system.

FIG. 4 is a conceptual diagram showing an example of a display screen of the system.

FIG. 5 is a flowchart for explaining the operation of the system.

FIG. 6 is a conceptual diagram related to a first modification of the present embodiment.

FIG. 7 is a conceptual diagram related to Modification Examples 1 and 2 of the embodiment.

FIG. 8 is a flowchart relating to the first modification.

FIG. 9 is a conceptual diagram related to the second modification.

FIG. 10 is a flowchart relating to the second modification.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Graphics control device 2 ... CRT display (display screen) 3 ... CPU (including OS and window system) 4 ... Video playback device 10 ... Video controller 11 ... Video memory (VRAM) 12 ... RAMDAC 20 ... Video dedicated bus 21 ... Copy protection control signal line

Claims (11)

[Claims] 1. A computer system having means for performing display processing on a display screen of a display device in accordance with video data stored in a video memory, wherein the computer system manages screen information in window units displayed on the display screen. Window management table means, and updating the window management table means in response to the display instruction of the screen information in window units, and copying the copy protection information for instructing protection of the screen information copy processing to the window management table means. Setting means for setting, when receiving a copy request for screen information in window units which have been displayed and processed on the display screen, referring to the window management table means for the screen information of the copy request target If the copy protection information is set Control means for prohibiting a copy process of video data corresponding to the screen information from the video memory. 2. The system according to claim 1, wherein the control unit and the setting unit have a function of generating the screen information and control information necessary for the screen display operation, and manage the window management table unit in response to an instruction from an application program. 2. A computer system according to claim 1, wherein said computer executes prohibition control of said copy processing. 3. The copy processing prohibition process includes a prohibition process of a read operation of the video memory, an error process with respect to a command instructing the copy request, and a processing process with respect to the video data of the copy request target. The computer system according to claim 1, wherein: 4. A computer system having means for performing display processing on a display screen of a display device in accordance with video data stored in a video memory, the video control controlling a write operation and a read operation of video data in the video memory. Register means for storing copy protection information for instructing protection of copy processing in predetermined units of screen information to be displayed on the display screen; and When a copy request for the screen information subjected to the display processing is received, if the copy protection information is set for the screen information of the copy request target with reference to the register means, the relevant screen is read from the video memory. Means for inhibiting a read operation of video data corresponding to the information. Computer system. 5. The video control means sets copy protection information for instructing copy protection in the register means in a screen unit, a window unit, an address unit, and an area unit including address and coordinate information of the screen information. The computer system according to claim 4, wherein 6. A computer system having means for performing display processing on a display screen of a display device in accordance with video data stored in a video memory, comprising: a video controller for controlling a write operation and a read operation of video data in the video memory. Means for inputting the video data corresponding to screen information to be displayed on the display screen and a copy protection control signal for instructing protection of a copy process of the screen information from outside. Means for reading out video data corresponding to the screen information of the copy request target from the video memory based on the copy protection control signal when receiving a copy request for the screen information displayed on the display screen. A computer system comprising: a prohibition unit. 7. The computer system according to claim 4, wherein said video control means sets copy protection for said video data stored in an off-screen area of said video memory. 8. A copy for applying to a computer system having means for performing display processing on a display screen of a display device in accordance with video data stored in a video memory, and restricting copying of screen information displayed on the display screen. A limitation method, comprising: a window management table unit for managing screen information in window units to be displayed on the display screen, and updating the window management table unit in accordance with a display instruction of the screen information in window units. Setting copy protection information for instructing protection of the copy processing of the screen information in the window management table means; and receiving a copy request for screen information in window units which has been displayed on the display screen. Refer to the window management table means Prohibiting a copy process of video data corresponding to the screen information from the video memory when the copy protection information is set for the screen information of the copy request target. A copy restriction method characterized by the following. 9. A copy for applying to a computer system having means for performing display processing on a display screen of a display device in accordance with video data stored in a video memory, and restricting copying of screen information displayed on the display screen. A video control unit for controlling a write operation and a read operation of video data to and from the video memory, wherein the video control unit performs copy processing of screen information to be displayed on the display screen in a predetermined unit. Storing copy protection information for instructing protection in a built-in register; and when receiving a copy request for screen information displayed and processed on the display screen, referring to the register to perform a copy request target screen. If the copy protection information is set for the information, Copy restriction method characterized by performing a process comprising the step of prohibiting the reading operation of the video data corresponding to said screen information. 10. A copy for applying to a computer system having means for performing display processing on a display screen of a display device in accordance with video data stored in a video memory, and restricting copying of screen information displayed on the display screen. A video control means for controlling a write operation and a read operation of video data in the video memory, wherein the video control means externally controls the video data corresponding to screen information to be displayed on the display screen. Inputting a copy protection control signal instructing protection of data and the copy processing of the screen information; and, upon receiving a copy request for screen information displayed and processed on the display screen, based on the copy protection control signal. To read video data corresponding to the screen information of the copy request target from the video memory. Copy restriction method characterized by performing a process comprising the step of prohibiting the work. 11. A storage medium readable by a computer system having means for performing display processing on a display screen of a display device in accordance with video data stored in a video memory, wherein the screen is a window unit displayed on the display screen. In order to prepare a window management table for managing information in the system, update the window management table in accordance with the display instruction of the screen information in window units, and instruct protection of a copy process of the screen information. A function of setting copy protection information of the window management table in the window management table; and when receiving a copy request for screen information of a window displayed and processed on the display screen, referring to the window management table to determine a copy request target. The copy protection for screen information A storage medium storing a program including a function of prohibiting a copy process of video data corresponding to the screen information from the video memory when the port information is set.