Video compression noise immunity

• US 20080019441A1
• Filed: 08/14/2007
• Published: 01/24/2008
• 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
• Granted Patent: US 8,805,096 B2
• Time in Patent Office: Days
• US Class Current: 375/240.01
• 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 a plurality of different compression command types at least some of which are comparative command types that employ comparative analysis of current pixel values in the video stream with known prior pixel values in the video stream, the improvement comprising:

a system in the encoder to selectively add predetermined hysteresis functions to corresponding ones of the comparative command types such that the hysteresis functions will provide customized sensitivity reductions in the respective comparative analyses associated with the different compression command types.

2. A video system according to claim 1, wherein the different comparative compression command types include at least one run length encoding type, the encoder providing different hysteresis functions for the run length encoding.

3. A video system according to claim 2, wherein the run length encoding type command type includes at least a copy command employing the comparative analysis of 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 predetermined hysteresis functions are added to the comparative analysis of the current pixel values in the video stream with the known pixel values to the left of the current pixel values to render a color match condition when the comparative analysis yields a color difference within a threshold.

5. A video system according to claim 2, wherein the run length encoding type command type includes at least a copy command employing the comparative analysis of 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 predetermined hysteresis functions are added to the comparative analysis of current pixel values in the video stream with known pixel values above the current pixel values to render a color match condition when the comparative analysis yields a color difference within a threshold.

7. A video system according to claim 2, wherein the run length encoding type command type includes at least a copy command employing the comparative analysis of 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 predetermined hysteresis functions are added to the comparative analysis of current pixel values in the video stream with known pixel values at corresponding pixel locations of a different pixel frame in the video stream to render a color match condition when the comparative analysis yields a color difference within a threshold.

9. A video system according to claim 1, wherein the different comparative compression command types include at least one two-color series command type, the encoder providing different hysteresis functions to the 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 employing the comparative analysis of 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 the predetermined hysteresis functions are added to the comparative analysis of the current pixel values in the video stream with the two known pixel values to render a color match condition when the comparative analysis yields a color difference between the current pixel values and at least one of the two known pixel values within a threshold.

12. A method of compressing a video stream using a plurality of different compression command types at least some of which are comparative command types that employ comparative analysis of current pixel values in the video stream with known prior pixel values in the video stream, the improvement comprising:

selectively adding predetermined hysteresis functions to corresponding ones of the comparative command types such that the hysteresis functions will provide customized sensitivity reductions in the respective comparative analyses associated with the different compression command types.

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, with a hysteresis function modifying the comparison to render a color match condition when the comparing step yields a color difference within a 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, with a hysteresis function modifying the comparison to render a color match condition when the comparing step yields a color difference within a 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, with a hysteresis function modifying the comparison to render a color match condition when the comparing step yields a color difference within a 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, with a hysteresis function modifying the comparison to render a color match condition when the comparing step yields a color difference within a threshold.