Oscillating video refresh

Abstract

A system and a method are disclosed describing a mechanism for preventing recording of security sensitive media content when that content is displayed on a screen. The mechanism includes selecting two refresh rates for a display and oscillating between those two refresh rates thereby preventing a recording device's recording frame rate from synchronizing with the display device's refresh rate. As a result, anything recorded by the recording device will be distorted.

What is claimed is: 
     
         1 . A method for preventing recording of a display screen, the method comprising:
 determining a request to display security sensitive media content;   responsive to the request, determining a plurality of different refresh rates for displaying the security sensitive media content; and   transmitting at least one command to a display device to change a previously set refresh rate to a first refresh rate from the plurality of different refresh rates, and to change from the first refresh rate to a second refresh rate from the plurality of different refresh rate responsive to a time interval elapsing.   
     
     
         2 . The method of  claim 1 , wherein transmitting the at least one command comprises:
 transmitting a single command including the first refresh rate, the second refresh rate, and the time interval.   
     
     
         3 . The method of  claim 1 , further comprising:
 transmitting a command to the display device to change from one of the first refresh rate or the second refresh rate to the previously set refresh rate responsive to determining that non-security sensitive media content is requested to be displayed on the display device.   
     
     
         4 . The method of  claim 1 , further comprising:
 determining a refresh rate range for the display device; and   generating the first refresh rate that is in the refresh rate range.   
     
     
         5 . The method of  claim 4 , wherein generating the first refresh rate in the refresh rate range comprises inputting a subrange of the refresh rate range into a random number generator, the random number generator generating a value for the first refresh rate that is between a minimum and a maximum of the subrange. 
     
     
         6 . The method of  claim 3 , further comprising:
 selecting an offset number based on the previously set refresh rate; and   offsetting the previously set refresh rate by the offset number to generate the first refresh rate.   
     
     
         7 . The method of  claim 6 , further comprising:
 offsetting the previously set refresh rate by an additive inverse of the offset number to generate the second refresh rate.   
     
     
         8 . The method of  claim 1 , wherein determining the request to display security sensitive media content comprises:
 receiving a request to display media content;   retrieving, from metadata associated with the media content, an indication of a security level associated with the media content; and   determining that the media content is security sensitive based on the indication.   
     
     
         9 . The method of  claim 1 , further comprising:
 comparing the first refresh rate with each of a plurality of recording frame rates, wherein each of the plurality of recording frame rates is associated with a known recording device;   determining whether the first refresh rate is a multiple of a recording frame rate of the plurality of recording frame rates based on the comparison; and   responsive to determining that the first refresh rate is the multiple of the recording frame rate of the plurality of recording frame rates, modifying the first refresh rate.   
     
     
         10 . The method of  claim 1 , wherein the previously set refresh rate is the second refresh rate. 
     
     
         11 . A non-transitory computer-readable medium comprising memory with instructions encoded thereon for preventing recording of a display screen, the instructions causing one or more processors to perform operations when executed, the instructions comprising instructions to:
 determine a request to display security sensitive media content;   responsive to the request, determine a plurality of different refresh rates for displaying the security sensitive media content; and   transmit at least one command to a display device to change a previously set refresh rate to a first refresh rate from the plurality of different refresh rates, and to change from the first refresh rate to a second refresh rate from the plurality of different refresh rate responsive to a time interval elapsing   
     
     
         12 . The non-transitory computer-readable medium  claim 11 , wherein the instructions to transmit the at least one command further comprise instructions to:
 transmit a single command including the first refresh rate, the second refresh rate, and the time interval.   
     
     
         13 . The non-transitory computer-readable medium  claim 11 , wherein the instructions further comprise instructions to:
 transmit a command to the display device to change from one of the first refresh rate or the second refresh rate to the previously set refresh rate responsive to determining that non-security sensitive media content is requested to be displayed on the display device.   
     
     
         14 . The non-transitory computer-readable medium  claim 11 , wherein the instructions further comprise instructions to:
 determine a refresh rate range for the display device; and   generate the first refresh rate that is in the refresh rate range.   
     
     
         15 . The non-transitory computer-readable medium  claim 14 , wherein the instructions to generating the first refresh rate in the refresh rate range further comprises instructions to:
 input a subrange of the refresh rate range into a random number generator, the random number generator generating a value for the first refresh rate that is between a minimum and a maximum of the subrange.   
     
     
         16 . The non-transitory computer-readable medium  claim 13 , wherein the instructions further comprise instructions to:
 select an offset number based on the previously set refresh rate; and   offset the previously set refresh rate by the offset number to generate the first refresh rate.   
     
     
         17 . The non-transitory computer-readable medium  claim 16 , wherein the instructions further comprise instructions to:
 offset the previously set refresh rate by an additive inverse of the offset number to generate the second refresh rate.   
     
     
         18 . The non-transitory computer-readable medium  claim 11 , wherein the instructions to determine the request to display security sensitive media content further comprises instructions to:
 receive a request to display media content;   retrieve, from metadata associated with the media content, an indication of a security level associated with the media content; and   determine that the media content is security sensitive based on the indication.   
     
     
         19 . The non-transitory computer-readable medium  claim 11 , wherein the instructions further comprise instructions to:
 compare the first refresh rate with each of a plurality of recording frame rates, wherein each of the plurality of recording frame rates is associated with a known recording device;   determining whether the first refresh rate is a multiple of a recording frame rate of the plurality of recording frame rates based on the comparison; and   responsive to determining that the first refresh rate is the multiple of the recording frame rate of the plurality of recording frame rates, modifying the first refresh rate.   
     
     
         20 . A method of a display system for preventing recording of a display screen of the display system, the method comprising:
 displaying, by the display system, non-security sensitive media content at a previously set refresh rate;   receiving, by the display system, a first command to change from the previously set refresh rate to a first refresh rate for displaying security sensitive media comment;   displaying, by the display system, the security sensitive media content at the first refresh rate;   responsive to a threshold amount of time elapsing since receiving the first command, receiving, by the display system, a second command to change the first refresh rate to the second refresh rate; and   displaying, by the display system, the security sensitive media content at the second refresh rate.