Methods and apparatus for encoding a digital video signal

• US 7,822,278 B1
• Filed: 09/18/2006
• Issued: 10/26/2010
• Est. Priority Date: 09/20/2005
• Status: Active Grant

• Current Assignee: Teradici Corporation (HP Inc.)
• Original Assignee: Teradici Corporation (HP Inc.)
• Inventors: Hobbs, David Victor, Ratto, Patrick
• Primary Examiner(s): Alavi; Amir
• Application Number:
  US11/532,865
• Time in Patent Office: 1,499 Days
• Field of Search: 382/232, 382/233, 375/240.01, 375/E7.264, 348/14.01, 348/14.13, 348/420, 345/2.1, 345/3.1, 345/329, 341/63, 341/65, 341/106, 709/247, 709/250, 713/171, 714/E11.173
• US Class Current: 382/232
• CPC Class Codes: H04N 19/12 Selection from among a plurality of transforms or standards, e.g. selection between discrete cosine transform [DCT] and sub-band transform or selection between H.263 and H.264
• CPC Class Codes: H04N 19/124 Quantisation
• CPC Class Codes: H04N 19/149 by estimating the code amount by means of a model, e.g. mathematical model or statistical model
• CPC Class Codes: H04N 19/166 concerning the amount of transmission errors, e.g. bit error rate [BER]
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/196 being specially adapted for the computation of encoding parameters, e.g. by averaging previously computed encoding parameters processing of motion vectors H04N19/513
• CPC Class Codes: H04N 19/34 Scalability techniques involving progressive bit-plane based encoding of the enhancement layer, e.g. fine granular scalability [FGS]
• CPC Class Codes: H04N 19/507 using conditional replenishment

Abstract

The invention provides a non-intrusive method and apparatus for encoding a digitized raster display signal which may then be transmitted from a host computer system to a remote display across a communications link. Hash codes are used to detect persistent blocks of pixels in a real-time digital raster signal generated by the host computer. A progressive encoding and transmission sequence is then initiated, using parameters such as bandwidth availability and build quality requirements to determine suitable encoding methods and build levels.

Claims

1. A method for transmitting an update to an image, the method executed under the control of a processor configured with computer executable instructions, the method comprising:

a) determining, by a host system having one or more processors, a state of a section of the image as being unchanged from a previous transmission of a previous encoding of the section,

b) in response to the state being unchanged, identifying, by the host system having the one or more processors, a requirement for transmitting an update encoding of the section;

c) determining, by the host system having the one or more processors, an availability of network bandwidth to transmit the update encoding of the section; and

d) responsive to the requirement to transmit and the availability of network bandwidth, transmitting, by the host system having the one or more processors, the update encoding of the section.

2. The method of claim 1 wherein the section comprises a scan block comprising pixel data.

3. The method of claim 1 wherein the image comprises a time sequence of a previous image frame and a current image frame, and determining the state being unchanged comprises:

calculating a current hash code from current pixel data of a section of the current image frame; and

comparing the current hash code to a previous hash code, the previous hash code associated using pixel data from the section of the previous image frame.

4. The method of claim 1 wherein identifying the requirement for transmitting the update encoding comprises determining that a previous encoding of the section is transmitted less than a lossless quality or at less than a defined quality.

5. The method of claim 1 wherein transmitting the update encoding of the section comprises transmitting at least one additional encoding associated with the section and a current build state.

6. The method of claim 5 wherein the at least one additional encoding comprises a quality increment, the quality increment comprising at least one transformed bit plane.

7. The method of claim 5 wherein the at least one additional encoding is associated with current build states of other sections of the image.

8. The method of claim 5, wherein the at least one additional encoding is responsive to a second update encoding of at least one other section.

9. The method of claim 1, wherein transmitting the update encoding of the section comprises encoding the section according to the availability of network bandwidth.

10. The method of claim 1, wherein the transmitting the update encoding of the section comprises determining a bandwidth requirement for a region of the image.

11. The method claim of 1, wherein the image comprises a plurality of sections.

12. The method of claim 11, wherein each section of the plurality of sections comprises an independent state.

13. The method claim of 1, further comprising obtaining the section from a raster video signal.

14. The method claim of 1, wherein the image comprises a computer display image.

15. The method of claim 1 further comprising repeating steps a), b), c) and d) until an update to the image is transmitted.

16. The method of claim 1 further comprising:

e) if the state identifies the section as being changed, identifying a requirement to transmit an update encoding of the section comprising an initial quality encoding of the section.

17. A method for transmitting an image, the method executed under the control of a processor configured with computer executable instructions, the method comprising:

determining, by a host system having one or more processors, a requirement to transmit an encoding of a scan block in response to the scan block having changed from a previous transmission of a previous encoding of the scan block, the scan block comprising a plurality of pixels of the image, the scan block being one of a plurality of scan blocks of the image;

determining, by the host system having the one or more processors, an availability of bandwidth to transmit the encoding of the scan block; and

responsive to the requirement to transmit and the availability of network bandwidth, transmitting, by the host system having the one or more processors, the encoding of the scan block.

18. The method of claim 17 wherein the plurality of scan blocks of the image comprise at least one changed scan block and at least one unchanged scan block.

19. The method of claim 18 wherein the availability of bandwidth is associated with the quantity of changed scan blocks.

20. The method of claim 17 wherein the bandwidth to transmit comprises at least one of network bandwidth, memory bandwidth or processing bandwidth.

21. The method of claim 17 further comprising determining the scan block being changed comprises:

calculating a current hash code from current pixel data of the scan block; and

comparing the current hash code to a previous hash code, the previous hash code associated with previous pixel data from the scan block.

22. The method of claim 17 wherein the transmitting the encoding of the scan block comprises encoding at least one layer of quality of current pixel data of the scan block.

23. The method of claim 22 wherein the encoding at least one layer of quality of current pixel data comprises encoding the current pixel data to a defined quality level.

24. The method of claim 23 wherein the encoding the at least one layer of quality of current pixel data comprises encoding according to current build states for other scan blocks from the image.

25. The method of claim 23, wherein the encoding the at least one layer of quality of the current pixel data is responsive to a state change of at least one other scan block.

26. The method of claim 23, wherein the encoding the at least one layer of quality of current pixel data comprises encoding according to the availability of network bandwidth.

27. The method of claim 23, wherein the encoding at least one layer of quality of the current pixel data comprises determining a bandwidth requirement for a region of the image.

28. The method of claim 17 wherein the transmitting the encoding of the scan block comprises updating a current build state of the scan block in association with the encoding of the scan block.