Arrangement and method for generating CP images

• US 20050195275A1
• Filed: 02/11/2005
• Published: 09/08/2005
• Est. Priority Date: 02/13/2004
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Tandberg Telecom AS (Cisco Systems, Inc.)
• Inventors: Lia, Tom Erik, Johansen, Tom-Ivar
• Granted Patent: US 7,720,157 B2
• Time in Patent Office: Days
• US Class Current: 348/14.13
• CPC Class Codes: H04N 7/152 Multipoint control units therefor
• CPC Class Codes: H04N 7/157 defining a virtual conference space and using avatars or agents computer conference optimisation or adaptation H04L12/1827

Abstract

The present invention relates to generating Continuous Presence (CP) images in a Multipoint Control Unit (MCU) managing a multisite videoconference. The invention utilises the bit structure of the ITU H.26* standards to reduce the processing time and requirements in an MCU for generating CP views without self-view. By rearranging macroblocks from coded CP images, regions in a CP image may be removed so as allow transmitting CP images without self view to the participating sites. The rearranging procedure significantly reduces the requirement of encoder resources in an MCU.

Claims

1. A method for creating a coded target Continuous Presence (CP) image according to a video coding standard from a number of coded video signals including defined orders of macroblocks, each comprising coded video signals corresponding to a respective endpoint video image, received from endpoints participating in a multipoint video conference,

said method comprising the step of

creating the coded target CP image by rearranging said orders of macroblocks in a predefined or controlled way.

2. A method according to claim 1, further comprising, prior to the step of creating the coded target CP image, the step of

requesting the endpoints to code the respective endpoint video images according to the video standard and a certain resolution, bit rate and scaling.

3. A method according to claim 1, further comprising, prior to the step of creating the coded target CP image, the steps of

decoding the video signals to the corresponding endpoint video images,

spatially mixing the endpoint video images to a number of CP images composed of regions respectively associated with each of the endpoint video images, and

coding said number of CP images to a number of coded CP images respectively,

resulting in the defined orders of macroblocks corresponding to the video coding standard and a merging of region boundaries and macroblock boundaries.

4. A method according to claim 3, wherein the coded CP images and the coded target CP image each are of a CIF format with 18 Group of Blocks (GOBs), each including 22 macroblocks, arranged in a stack formation so that the first 9 GOBs represent upper regions, and the last 9 GOBs represent lower regions.

5. A method according to claim 4, wherein the step of creating the coded target CP image includes:

replacing m numbers of macroblocks representing a region width in n numbers of succeeding GOBs representing a region height in a first of the number of coded CP images with m numbers of macroblocks in n numbers of succeeding GOBs from a second of the number of coded CP images.

6. A method according to claim 5, wherein m=11, n=9, and said regions each represents one quadrant of a CP image.

7. A method according to claim 5, wherein m=7 or m=8, n=6 and said regions each represents one eighth of a CP image.

8. An arrangement in a Multipoint Control Unit (MCU) for creating a coded target CP image according to a video coding standard from a number of coded video input signals, each corresponding to a respective endpoint video image, received from endpoints participating in a multipoint video conference, the arrangement comprising

one decoder for each coded video input signal configured to decoding the video signals to the corresponding endpoint video images,

a mixing and scaling unit configured to spatially mixing the endpoint video images to a number of CP images composed of regions respectively associated with each of the endpoint video images,

a number of encoders, configured to code said number of CP images to a number of coded CP images,

one data buffer for each of said encoders to which CP images respectively are inserted in orders of macroblocks corresponding to the video coding standard and a merging of region boundaries and macroblock boundaries, and

one re-packer for each MCU output configured to create the coded target CP image by fetching said macroblocks in a predefined or controlled order.

9. An arrangement according to claim 8, wherein the coded CP images and the coded target CP image each are of a CIF format with 18 Group of Blocks (GOBs), each including 22 macroblocks, arranged in a stack formation so that the first 9 GOBs represent upper regions, and the last 9 GOBs represent lower regions.

10. An arrangement according to claim 9, wherein the re-packer is further configured to replacing m numbers of macroblocks representing a region width in n numbers of succeeding GOBs representing a region height in a first of the number of coded CP images with m numbers of macroblocks in n numbers of succeeding GOBs from a second of the number of coded CP images.

11. An arrangement according to claim 10, wherein m=11, n=9, and said regions each represents one quadrant of a CP image.

12. An arrangement according to claim 10, wherein m=7 or m=8, n=6, and said regions each represents one eighth of a CP image.