OPTIMIZED KEY FRAME CACHING FOR REMOTE INTERFACE RENDERING

• US 20090100125A1
• Filed: 10/11/2007
• Published: 04/16/2009
• Est. Priority Date: 10/11/2007
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: McDowell, Brian
• Granted Patent: US 8,619,877 B2
• Time in Patent Office: Days
• US Class Current: 709/203
• CPC Class Codes: G06F 16/9574 of access to content, e.g. by caching
• CPC Class Codes: H04L 65/70 Media network packetisation
• CPC Class Codes: H04L 67/568 Storing data temporarily at an intermediate stage, e.g. caching
• CPC Class Codes: H04L 67/75 Indicating network or usage conditions on the user display

Abstract

Frames of user interface (UI) graphical data can be remotely rendered more efficiently at a client during a remote session with a server by utilizing graphical data cached at the client to prevent re-sending data to the client that was sent in previous payloads. By using cache memory to remember recurring frames of similar UI data and delta encoding to correct areas that are not similar, encoded payload sizes are greatly reduced. When a cached frame is closer to a new frame than the current frame, the cached frame is selected and delta commands are derived from differences between the selected cache frame and the new frame. The differences between the cached frame and the new frame are then encoded as delta commands and the cache commands and delta commands are sent to the client which receives and applies the commands to render the new frame.

Claims

1. A method for managing a cache, comprising:

providing current graphical frame data for a current frame to a client by a server over a network;

identifying a new frame by the server to be rendered at the client;

selecting a cached frame by the server, the selected cache frame corresponding to a frame cached at the client;

determining a set of difference data associated with the difference between the new frame and the selected cached frame; and

transmitting an identifier for the selected cached frame and difference data information to the client by the server.

2. The method of claim 1, wherein said step of selecting a cached frame by the server includes:

determining if a first difference between the new frame and any of one or more cached frames at a client satisfies a threshold.

3. The method of claim 1, wherein said step of selecting a cached frame by the server includes:

determining if the new frame is associated with a full frame update.

4. The method of claim 1, further comprising:

detecting a constant color frame;

generating a constant color fill command; and

transmitting the constant color fill command to the client.

5. The method of claim 1, wherein said step of selecting a cached frame by the server includes:

determining the amount of memory available at the client for caching frames.

6. The method of claim 1, wherein said step of selecting a cached frame by the server includes:

incrementing a relevance value for the current cached frame

7. The method of claim 1, wherein said step of selecting a cached frame by the server includes:

selecting a least relevant cache frame as a new cache frame; and

overwriting the least relevant cache frame with data associated with the new frame.

8. The method of claim 7, resetting a relevance value for a current cached frame.

9. The method of claim 1, wherein said step of determining a set of difference data includes:

comparing pixel data values between for pixels in the selected cache frame and the new frame.

10. The method of claim 9 wherein said step of determining a set of difference data includes:

generating instructions to set raster segments in the selected cache frame to a set of pixel data values associated with the new frame.

11. One or more processor readable storage devices having processor readable code embodied on said processor readable storage devices, said processor readable code for programming one or more processors to perform a method comprising:

receiving a set of instructions by a client from a server, the set of instructions including a cache instruction and difference data instructions;

setting a first pointer to a cache slot at the client in response to executing the cache instruction;

modifying graphical frame data associated with the cache slot in response to executing the difference data instructions; and

presenting a frame associated with the modified graphical frame data through a display device by the client.

12. The one or more processor readable storage devices of claim 11, wherein the cache instruction identifies the cache slot at the client to which the first pointer is set.

13. The one or more processor readable storage devices of claim 11, wherein the first pointer may be set to an address associated with client cache memory or a client frame buffer.

14. The one or more processor readable storage devices of claim 13, wherein only one copy of two or more graphical frames of data is stored in a client memory, the client memory including the client cache and client frame buffer.

15. The one or more processor readable storage devices of claim 11, wherein the set of instructions include an instruction to fill the cached frame with a color.

16. The one or more processor readable storage devices of claim 11, wherein the set of instructions includes difference data instructions in two different data formats used to present graphical information.

17. The one or more processor readable storage devices of claim 11, wherein said step of modifying includes:

applying updates to raster segments in the selected cache slot frame with raster segment data contained in the difference data instructions.

18. A method for managing a cache, comprising:

providing current graphical frame data for a current frame to a client by a server over a network;

identifying a new frame by the server to be rendered at the client;

determining whether the changes between the new frame and the current frame are associated with a full frame update;

determining that the difference in pixel data values between the new frame and the current frame does not satisfy a threshold;

determining whether the new frame is similar to a frame that is cached at the client;

selecting a cached frame by the server, the selected cache frame corresponding to a frame cached at the client;

generating a cache instruction to select the selected cache frame;

encoding a set of difference data instructions associated with the difference between the new frame and the selected cached frame; and

transmitting a payload that includes the cache instruction and the set of difference data instructions to the client by the server.

19. The method of claim 18, wherein said step of generating a cache instruction includes an instruction to set a client pointer to the selected cache frame.

20. The method of claim 18, wherein said step of generating a cache instruction to select the selected cache frame includes generating a constant fill data command.