Video compression noise immunity

• US 8,805,096 B2
• Filed: 08/14/2007
• Issued: 08/12/2014
• Est. Priority Date: 06/25/2004
• Status: Active Grant

• Current Assignee: Vertiv IT Systems, Inc. (Vertiv Holdings Co.)
• Original Assignee: Avocent Corporation (Vertiv Holdings Co.)
• Inventors: Gilgen, Robert L.
• Primary Examiner(s): Dang, Duy M
• Application Number:
  US11/889,525
• Publication Number:
  US 20080019441A1
• Time in Patent Office: 2,555 Days
• Field of Search: 382/100, 382/162, 382/163, 382/166, 382/232, 382/240, 382244-248, 382/274, 382/275, 375/240.19, 348/398.1, 348/408.1
• US Class Current: 382/232
• CPC Class Codes: H04N 19/105 Selection of the reference unit for prediction within a chosen coding or prediction mode, e.g. adaptive choice of position and number of pixels used for prediction
• CPC Class Codes: H04N 19/172 the region being a picture, frame or field
• CPC Class Codes: H04N 19/182 the unit being a pixel
• CPC Class Codes: H04N 19/186 the unit being a colour or a chrominance component
• CPC Class Codes: H04N 19/507 using conditional replenishment
• CPC Class Codes: H04N 19/593 involving spatial prediction techniques
• CPC Class Codes: H04N 19/93 Run-length coding

Abstract

A method of improving run length video encoding commands is described in which all compression commands that require a current pixel value to be compared to a previously sent pixel value to determine whether compression can take place in a longer run is adjusted to relieve stringent match conditions. Instead of requiring an exact match, the compression engine subtracts one pixel value from another, and compares the absolute value of the result to a threshold value. In this way, run lengths can be lengthened for purposes of compression and compression efficiency can be increased.

Claims

1. A video system having an encoder to compress a video stream using run length encoding, the video system comprising:

a system in the encoder configured to;

initiate run length encoding;

compare an absolute value of the difference between a previous pixel and a current pixel with a predetermined threshold value to determine whether to continue the run-length encoding;

continue the run length encoding if the absolute value is less than the predetermined threshold value; and

end the run length encoding if the absolute value is above the predetermined threshold value.

2. A video system according to claim 1, wherein the system further varies the predetermined threshold based on a run-length encoding type.

3. A video system according to claim 2, wherein the run length encoding type includes a copy command comparing current pixel values in the video stream with known pixel values to the left of the current pixel values.

4. A video system according to claim 3, wherein the system further renders a color match condition when the comparing the absolute value indicates a color difference within the predetermined threshold.

5. A video system according to claim 2, wherein the run length encoding type includes at least a copy command comparing current pixel values in the video stream with known pixel values above the current pixel values.

6. A video system according to claim 5, wherein the system further renders a color match condition when the comparing the absolute value indicates a color difference within the predetermined threshold.

7. A video system according to claim 2, wherein the run length encoding type includes a copy command comparing current pixel values in the video stream with known pixel values at corresponding pixel locations of a different pixel frame in the video stream.

8. A video system according to claim 7, wherein the system further renders a color match condition when the comparing the absolute value indicates a color difference within the predetermined threshold.

9. A video system according to claim 1, wherein the system further varies the predetermined threshold based on a run-length encoding type including a two-color series command type.

10. A video system according to claim 9, wherein two-color series command type includes at least a copy command comparing current pixel values in the video stream with two known pixel values wherein the two known pixel values are taken from the video stream as the first two unique pixel values immediately preceding the current pixel values in the video stream.

11. A video system according to claim 10, wherein renders a color match condition when the comparing the absolute value indicates a color difference between the current pixel values and at least one of the two known pixel values within the predetermined threshold.

12. A method in a data processing system of compressing a video stream using run length encoding, the method comprising:

initiating run length encoding;

comparing an absolute value of the difference between a previous pixel and a current pixel with a predetermined threshold value to determine whether to continue the run-length encoding;

continuing the run length encoding if the absolute value is less than the predetermined threshold value; and

ending the run length encoding if the absolute value is above the predetermined threshold value.

13. A method according to claim 12, further including the step of:

comparing current pixel values in the video stream with known pixel values to the left of the current pixel values, and rendering a color match condition when the comparing an absolute value indicates a color difference within the predetermined threshold.

14. A method according to claim 12, further including the step of:

comparing current pixel values in the video stream with known pixel values above the current pixel values, and rendering a color match condition when the comparing an absolute value indicates a color difference within the predetermined threshold.

15. A method according to claim 12, further including the step of:

comparing current pixel values in the video stream with known pixel values at corresponding pixel locations of a different pixel frame in the video stream, and rendering a color match condition when the comparing an absolute value indicates a color difference within the predetermined threshold.

16. A method according to claim 12, further including the step of:

comparing current pixel values in the video stream with two known pixel values wherein the two known pixel values are taken from the video stream as the first two unique pixel values immediately preceding the current pixel values in the video stream, and rendering a color match condition when the comparing an absolute value indicates a color difference within the predetermined threshold.