Method and apparatus for digitizing and compressing remote video signals

• US 20040042547A1
• Filed: 08/29/2002
• Published: 03/04/2004
• Est. Priority Date: 08/29/2002
• Status: Active Grant

• Current Assignee: Raritan Americas Incorporated (Legrand SA)
• Original Assignee: Raritan Americas Incorporated (Legrand SA)
• Inventors: Coleman, Scott
• Granted Patent: US 7,684,483 B2
• Time in Patent Office: Days
• US Class Current: 375/240.01
• CPC Class Codes: H04N 19/507 using conditional replenishment
• CPC Class Codes: H04N 21/4143 embedded in a Personal Computer [PC]

Abstract

A method and apparatus for digitizing and compressing video signals for transmitting the signals between a remotely located computer and a host or local computer. The digitization and compression method and apparatus is capable of dividing frame buffers into cells and comparing image data from previously captured frame buffers to create synchronized video signals and transmit the video signals over an extended range by limiting the portions of the transmission bandwidth of pixel data transferred between the remote computer and the local computer. In an alternate embodiment of the present invention, a keyboard video mouse switch is disposed between the remotely located computer and the local computer.

Claims

1. A method of coding video signals comprising the steps of:

(i) capturing a first frame buffer from a remotely located computer;

(ii) capturing a second frame compare buffer from said remotely located computer;

(iii) comparing said first frame buffer to said second frame compare buffer; and

(iv) transmitting portions of the image that have changed from the first frame image to the second frame image,

wherein a video display of said remotely located computer is provided on a local computer reflecting changes of the video display based on local input.

2. A method according to claim 1 wherein said frame buffers are divided into cells.

3. A method according to claim 1 wherein a switch device is connected between said remotely located computer and said local computer.

4. A method according to claim 1 wherein said comparing said first frame buffer and said second compare frame buffer further include a first threshold stage and a second threshold stage wherein said first threshold stage includes a pixel threshold technique for filtering small Red, Green and Blue color gradation changes and said second threshold stage includes a cell threshold value for determining the sum of changes in the frame for retransmitting a block.

5. A method according to claim 1 wherein said comparing said first frame buffer and said second compare frame buffer further include a cache of a series of the previous versions of the cells of previous frame buffers for determining cell matches and transmitting only said cell matches.

6. A method of coding video signals comprising the steps of:

(v) capturing a first frame buffer from a remotely located computer;

(vi) capturing a second frame compare buffer from said remotely located computer;

(vii) comparing said first frame buffer to said second frame compare buffer by utilizing a first threshold stage and a second threshold stage wherein said first threshold stage includes a pixel threshold technique for filtering small Red, Green and Blue color gradation changes and said second threshold stage includes a cell threshold value for determining the sum of changes in the frame; and

(viii) transmitting portions of the image that have changed from the first frame image to the second compare frame image based on the summation of the pixel threshold as compared to the cell threshold value,

wherein a video display of said remotely located computer is provided on a local computer reflecting changes of the video display based on local input.

7. A method according to claim 6 wherein said frame buffers are divided into cells.

8. A method according to claim 6 wherein a switch device is connected between said remotely located computer and said local computer.

9. A method according to claim 6 wherein said method of coding video signals further includes the step of compensating for various analog to digital converters by adjusting the offset and the gain of the video transmission.

10. A keyboard, video, mouse device for operating a remotely located computer from a local computer comprising:

at least one local computer;

at least one remote computer;

a compression device for analyzing and converting a video signal from said remote computer;

a first frame buffer captured from said at least one remote computer;

a second frame compare buffer captured from said at least one local computer; and

a cache of a stored series of the previous versions of the cells of previous frame buffers,

wherein said compression device compares said first frame buffer to said second compare frame buffer by utilizing a first threshold stage and a second threshold stage wherein said first threshold stage includes a pixel threshold and a cell threshold value and further includes a comparison of said cache of said stored series of cells of a frame buffer to determine cell matches and transmit only said cell matches.

11. An apparatus according to claim 10 wherein said remote computer and said local computer are connected via a switch device.