Video data scaling for video teleconferencing workstations communicating by digital data network

• US 5,475,421 A
• Filed: 07/16/1992
• Issued: 12/12/1995
• Est. Priority Date: 06/03/1992
• Status: Expired due to Term

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Digital Equipment Corporation (HP Inc.)
• Inventors: Palmer, Larry G., Palmer, Ricky S.
• Primary Examiner(s): Harvey, David E.
• Application Number:
  US07/915,087
• Time in Patent Office: 1,244 Days
• Field of Search: 358/133, 358/135, 358/138, 358/140, 358/141, 358/142, 358/146, 358/11, 358/12, 358/13, 358/134, 379/53, 395/200, 370/60, 370/118, 370/62, 348/13-19, 348/424, 348/425, 348/427, 348/581, 348/582, 364/514
• US Class Current: 348/14.1
• CPC Class Codes: G06F 3/04847 Interaction techniques to control parameter settings, e.g. interaction with sliders or dials
• CPC Class Codes: H04N 21/4135 external recorder interface circuits between an apparatus for recording television signals and a television receiver H04N5/775
• CPC Class Codes: H04N 21/42203 sound input device, e.g. microphone
• CPC Class Codes: H04N 21/4223 Cameras H04N23/00 takes precedence
• CPC Class Codes: H04N 21/43076 of the same content streams on multiple devices, e.g. when family members are watching the same movie on different devices
• CPC Class Codes: H04N 21/4621 Controlling the complexity of the content stream or additional data, e.g. lowering the resolution or bit-rate of the video stream for a mobile client with a small screen arrangements for using the results of monitoring on user's side in broadcast systems H04H60/65; flow control in packet networks H04L47/10
• CPC Class Codes: H04N 21/4788 communicating with other users, e.g. chatting arrangements for providing for computer conferences, e.g. chat rooms, to substation in data switching networks H04L12/1813; distributed application using peer-to-peer [P2P] networks H04L67/104
• CPC Class Codes: H04N 21/485 End-user interface for client configuration
• CPC Class Codes: H04N 21/6118 involving cable transmission, e.g. using a cable modem
• CPC Class Codes: H04N 21/6168 involving cable transmission, e.g. using a cable modem
• CPC Class Codes: H04N 21/632 using a connection between clients on a wide area network, e.g. setting up a peer-to-peer communication via Internet for retrieving video segments from the hard-disk of other client devices broadcast-related systems characterised by transmission among terminal devices H04H60/80; distributed application using peer-to-peer [P2P] networks H04L67/104
• CPC Class Codes: H04N 21/643 Communication protocols network streaming protocols, e.g. real-time transport protocol [RTP] or real-time control protocol [RTCP], H04L65/65
• CPC Class Codes: H04N 21/64322 IP
• CPC Class Codes: H04N 7/147 Communication arrangements, e.g. identifying the communication as a video-communication, intermediate storage of the signals selecting H04Q
• CPC Class Codes: H04N 7/15 Conference systems

Abstract

A video scaling apparatus and technique for compressing and reconstructing video data sent between multimedia workstations during a video teleconference includes a video data scaling device which scale unscaled video data, having V horizontal lines of H pixels each, to reduce the quantity of horizontal lines and the quantity of pixels along each line. A pixel replication device replicates the received scaled pixels to increase the quantity of horizontal lines to V and the quantity of pixels along each of the horizontal lines to H. The scaling device reduces the quantity of horizontal lines to about V/2, and the quantity of pixels along each horizontal line to about H/2. A received pixel is replicated to replace an adjacent pixel along a line-to reconstruct the line. The reconstructed line is replicated to replace an adjacent line. The replicated line is shifted by one pixel relative to the adjacent line from which it was replicated to reduce sharp edges and blockiness.

Claims

1. Video teleconferencing apparatus for a distributed data processing System having a plurality of computer workstations connected by a digital data network, the computer workstations comprising:

a) source means for a local workstation to send scaled video data across the digital data network to a remote workstation, the unscaled video data having V horizontal lines of H pixels each, the source means comprising video data scaling means for scaling the unscaled video data to reduce the quantity of horizontal lines to about V/2 and the quantity of pixels along each of the horizontal lines to about H/2;

b) receiver means for the local workstation to receive scaled video data from across the digital data network sent from source means of the remote workstation, the receiver means comprising pixel replication means for replicating the pixels of the received scaled video data to increase the quantity of horizontal lines to V and the quantity of pixels along each of the horizontal lines to H by replicating received pixels to replace adjacent pixels along a horizontal line to reconstruct the horizontal line, by replicating the reconstructed horizontal line to replace an adjacent horizontal line, and by shifting the replicated horizontal line in the horizontal direction relative to the adjacent horizontal line from which it was replicated.

2. The video teleconferencing apparatus of claim 1, wherein the replicated horizontal line is shifted by one pixel relative to the adjacent horizontal line from which it was replicated.

3. Video teleconferencing apparatus for a distributed data processing system having a plurality of computer workstations connected by a digital data networks, the computer workstations comprising:

a) source means for a local workstation to send scaled video data across the digital data network to a remote workstation, the unscaled video data having V horizontal lines of H pixels each, the source means comprising video data scaling means for scaling the unscaled video data to reduce the quantity of horizontal lines to about V/2 and the quantity of pixels along each of the horizontal lines to about H/2;

b) receiver means for the local workstation to receive scaled video data from across the digital data network sent from source means of the remote workstation, the receiver means comprising pixel replication means for replicating the pixels of the received scaled video data to increase the quantity of horizontal lines to V and the quantity of pixels along each of the horizontal lines to H by replicating received pixels to replace adjacent pixels along a vertical column to reconstruct the vertical column, by replicating the reconstructed vertical column to replace an adjacent vertical column, and by shifting the replicated vertical column in the vertical direction relative to the adjacent vertical column from which it was replicated.

4. The video teleconferencing apparatus of claim 3, wherein the replicated vertical column is shifted by one pixel relative to the adjacent vertical column from which it was replicated.

5. Video teleconferencing apparatus for a distributed data processing system having a plurality of computer workstations connected by a digital data network, the computer workstations comprising:

a) source means for a local workstation to send scaled video data across the digital data network to a remote workstation, the unscaled video data having V horizontal lines of H pixels each, the source means comprising video data scaling means for scaling the unscaled video data to reduce the quantity of horizontal lines to about V/2 and the quantity of pixels along each of the horizontal lines to about H/2;

b) receiver means for the local workstation to receive scaled video data from across the digital data network sent from source means of the remote workstation, the receiver means comprising pixel replication means for replicating a pixel of the received scaled video data to replace an adjacent pixel along a horizontal line to reconstruct the quantity of pixels along the horizontal line to H pixels, for replicating the reconstructed horizontal line to replace an adjacent horizontal line to restore the quantity of horizontal lines to V lines, and for shifting the replicated horizontal line in the horizontal direction relative to the adjacent horizontal line from which it was replicated.

6. The video teleconferencing apparatus of claim 5, wherein the replicated horizontal line is shifted by one pixel relative to the adjacent horizontal line from which it was replicated.

7. A method for compressing video teleconferencing data for a distributed data processing system having a plurality of computer workstations connected by a digital data network, comprising the steps of:

a) the source workstation scaling a frame of video data having V horizontal lines of H pixels each to reduce the quantity of horizontal lines to about V/2 and the quantity of pixels along each of the horizontal lines to about H/2 in the frame;

b) the source workstation sending the scaled video data across the digital data network to a remote workstation;

c) the remote workstation receiving the scaled video data from across the digital data network; and

d) the remote workstation replicating the pixels of the received scaled video data to increase the quantity of horizontal lines to V and the quantity of pixels along each of the horizontal lines to H by replacing an adjacent pixel with a received pixel along a horizontal line to reconstruct the horizontal line, replacing an adjacent horizontal line with the reconstructed horizontal line, and shifting the replicated horizontal line in the horizontal direction relative to the adjacent horizontal line from which it was replicated.

8. The method of claim 7, wherein the reducing step comprises eliminating every other pixel along a horizontal line, and eliminating every other horizontal line.

9. The method of claim 7, wherein the reducing step comprises replacing a plurality of pixels of the unscaled video data with a scaled pixel determined as a function of the plurality of pixels it replaces.

10. The method of claim 7, wherein the replicated horizontal line is shifted by one pixel relative to the adjacent horizontal line from which it was replicated.

11. Video teleconferencing apparatus for a distributed data processing system having a plurality of computer workstations connected by a digital data network, the computer workstations comprising:

a) source means for a local workstation to send scaled video data across the digital data network to a remote workstation, the unscaled video data having V horizontal lines of H pixels each, the source means comprising video data scaling means for scaling the unscaled video data to reduce the quantity of horizontal lines and the quantity of pixels along each of the horizontal lines;

b) receiver means for the local workstation to receive scaled video data from across the digital data network sent from source means of the remote workstation, the receiver means comprising pixel replication means for replicating the pixels of the received scaled video data to increase the quantity of pixels along a first and second orthogonal directions by replicating a received pixel to replace an adjacent pixel along the first direction to reconstruct a line along the first direction, by replicating the reconstructed line along the second direction to replace an adjacent parallel line, and then by shifting the replicated line along the first direction relative to the adjacent parallel line from which it was replicated.

12. The video teleconferencing apparatus of claim 11, wherein the scaling means provides a scaled pixel to replace a plurality of pixels of the unscaled video data, wherein each scaled pixel is determined as a function of the plurality of pixels it replaces.

13. The video teleconferencing apparatus of claim 11, wherein the replicated line is shifted by one pixel relative to the adjacent line from which it was replicated.

14. A method for compressing video teleconferencing data for a distributed data processing system having a plurality of computer workstations connected by a digital data network, comprising the steps of:

a) the source workstation scaling a frame of video data having V horizontal lines of H pixels each to reduce the quantity of horizontal lines to about V/2 and the quantity of pixels along each of the horizontal lines to about H/2 in the frame;

b) the source workstation sending the scaled video data across the digital data network to a remote workstation;

c) the remote workstation receiving the scaled video data from across the digital data network; and

d) the remote workstation replicating the pixels of the received scaled video data to increase the quantity of horizontal lines to V and the quantity of pixels along each of the horizontal lines to H by replacing an adjacent pixel with a received pixel along a horizontal line to reconstruct the horizontal line, replacing an adjacent horizontal line with the reconstructed horizontal line., and shifting the replicated vertical column in the vertical direction relative to the adjacent vertical column from which it was replicated.

15. The method of claim 14, wherein the replicated vertical column is shifted by one pixel relative to the adjacent vertical column from which it was replicated.

16. A video teleconferencing device comprising:

a video frame grabber for capturing and storing video frames from a video source;

a video scaler for generating scaled video frames from the stored video frames in the video frame grabber by decimating pixels of the stored video frames;

a network controller for converting the scaled video frames into data packets in accordance with a network protocol of a digital network., for transmitting the data packets via a first one-way variable bandwidth digital data connection across the digital network to a different network transmission controller of a remote video teleconferencing device, and for receiving and converting data packets from the remote teleconferencing device into remote video frames, the data packets from the remote teleconferencing device being received via a second one-way variable bandwidth digital data connection across the digital network;

a video descaler for descaling the remote video frames to generate descaled video frames by regenerating pixels decimated at the remote video teleconferencing device in response to pixels of the remote video frames; and

a video buffer for storing the descaled video frames prior to display;

wherein the video descaler regenerates pixels for the descaled video frames by replicating pixels of the remote video frames along the horizontal and vertical axes of the frames, and shifts one of horizontal and vertical rows of the descaled video frames by a pixel to reduce blockiness.

17. A video teleconferencing device as claimed in claim 16, wherein the video scaler decimates alternating rows of the pixels of the stored video frames along horizontal and vertical axes of the stored video frames.

18. A video teleconferencing device as claimed in claim 16, wherein the video descaler regenerates pixels for the descaled video frames by replicating pixels of the remote video frames along the horizontal and vertical axes of the frames.

19. A video teleconferencing device, comprising:

a video frame grabber for capturing and storing video frames from a video source;

a video scaler for generating scaled video frames from the stored video frames in the video frame grabber by decimating pixels of the stored video frames;

a network controller for converting the scaled video frames into data packets in accordance with a network protocol of a digital network, for transmitting the data packets via a first one-way variable bandwidth digital data connection across the digital network to a different network transmission controller of a remote video teleconferencing device, and for receiving and converting data packets from the remote teleconferencing device into remote video frames, the data packets from the remote teleconferencing device being received via a second one-way variable bandwidth digital data connection across the digital network;

a video descaler for descaling the remote video frames to generate descaled video frames by regenerating pixels decimated at the remote video teleconferencing device in response to pixels of the remote video frames; and

a video buffer for storing the descaled video frames prior to display;

wherein the video descaler replicates each pixel of the remote video frames into an adjacent pixel along one of the horizontal and vertical axes to form complete rows, and then replicates the complete rows into adjacent rows along the other one of the horizontal and vertical axes, and shifts one of horizontal and vertical rows of the descaled video frames by a pixel to reduce blockiness.

20. A video teleconferencing device, comprising:

a network controller for receiving data packets from a remote teleconferencing device via a one-way variable bandwidth digital data connection across a digital network and for converting the data packets into remote video frames;

a video descaler for descaling the remote video frames to generate descaled video frames by regenerating pixels decimated at the remote video teleconferencing device in response to pixels of the remote video frames; and

a video buffer for storing the descaled video frames prior to display;

wherein the video descaler regenerates pixels for the descaled video frames by replicating pixels of the remote video frames along the horizontal and vertical axes of the frames, and shifts one of horizontal and vertical rows of the descaled video frames by a pixel to reduce blockiness.

21. A video teleconferencing device as claimed in claim 20, wherein the video descaler regenerates pixels for the descaled video frames by replicating pixels of the remote video frames along the horizontal and vertical axes of the frames.

22. A video teleconferencing device as claimed in claim 20, wherein the video descaler replicates each pixel of the remote video frames into an adjacent pixel along one of the horizontal and vertical axes to form complete rows, and then replicates the complete rows into adjacent rows along the other one of the horizontal and vertical axes.

23. A video teleconferencing device, comprising:

a network controller for receiving data packets from a remote teleconferencing device via a one-way variable bandwidth digital data connection across a digital network and for converting the data packets into remote video frames;

a video descaler for descaling the remote video frames to generate descaled video frames by regenerating pixels decimated at the remote video teleconferencing device in response to pixels of the remote video frames; and

a video buffer for storing the descaled video frames prior to display;

wherein the video descaler replicates each pixel of the remote video frames into an adjacent pixel along one of the horizontal and vertical axes to form complete rows, then replicates the complete rows into adjacent rows along the other one of the horizontal and vertical axes, and shifts one of horizontal and vertical rows of the descaled video frames by a pixel to reduce blockiness.