US5838664A
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US
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Video teleconferencing system with digital transcoding
Assignee: Cisco Technology Inc
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Filing: 1997-07-17
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Granted: 1998-11-17
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Expires: 2017-07-17
Abstract
Abstract A video teleconferencing system uses digital transcoding to obtain algorithm transcoding, transmission rate matching, and spatial mixing. The video teleconferencing system comprises a multipoint control unit (MCU) for allowing multiple audiovisual terminals, which send and receive compressed digital data signals, to communicate with each other in a conference. The MCU has a video processing unit (VPU) that performs algorithm transcoding, rate matching, and spatial mixing among the terminals within a conference. The VPU includes a time division multiplex pixel bus and a plurality of processors. Each processor is assignable to an audiovisual terminal in the conference and is coupled to the pixel bus. In a receive mode, each processor receives and decodes compressed video signals from its assigned terminal and puts the decoded signal onto the pixel bus. In a transmit mode, each processor receives from the pixel bus uncompressed video signals from any terminal in the conference. The uncompressed video signals are processed and encoded for transmission to the respective assigned terminal. Video encoding time due to motion displacement search is reduced by passing displacement information from the compressed video signals to the encoder to be used directly or as a seed for further refinements of the motion displacement field.
Inventors
- 👤 Mark D. Polomski
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 07:30
CPC Classifications
H; H04; H04N; H04N7/00; H04N7/14; H04N7/15; H04N19/00; H04N19/40; H04N7/152
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
102 words
A multipoint control unit for receiving compressed video signals from terminals in a conference and for transmitting selected compressed video signals to the terminals, the multipoint control unit comprising: a plurality of decoders, each decoder for decoding the compressed video signals from respective terminals to uncompressed video signals in a pixel domain; a pixel bus receiving the uncompressed video signals at timeslots associated with respective terminals; a selector for selecting the uncompressed video signals from one or more timeslots of the pixel bus; and a plurality of encoders, each encoder for encoding the selected uncompressed video signals for transmission to respective terminals.
Claim 2
Dependent Claim
102 words
A multipoint control unit for receiving compressed video signals from terminals in a conference and for transmitting selected compressed video signals to the terminals, the multipoint control unit comprising: a plurality of decoders, each decoder for decoding the compressed video signals from respective terminals to uncompressed video signals in a pixel domain; a pixel bus receiving the uncompressed video signals at timeslots associated with respective terminals; a selector for selecting the uncompressed video signals from one or more timeslots of the pixel bus; and a plurality of encoders, each encoder for encoding the selected uncompressed video signals for transmission to respective terminals.
Claim 3
Dependent Claim
23 words
The multipoint control unit of claim 1 wherein the decoders and encoders each include different compression algorithms matching compression algorithms of respective terminals.
Claim 4
Dependent Claim
31 words
The multipoint control unit of claim 1 wherein the decoders and encoders operate at data rates matching respective terminals such that terminals having different data rates can intercommunicate in the conference.
Claim 5
Dependent Claim
25 words
The multipoint control unit of claim 1 wherein the encoders encode the selected uncompressed video signals from plural timeslots to form composite encoded video signals.
Claim 6
Dependent Claim
20 words
The multipoint control unit of claim 1 further comprising scaling means for scaling uncompressed video signals to a desirable resolution.
Claim 7
Dependent Claim
159 words
A multipoint control unit for receiving compressed video signals from terminals in a conference and for transmitting selected compressed video signals to the terminals, the multipoint control unit comprising: a first bus having timeslots for transporting compressed video signals and audio signals; at least one bridge processor coupled to the first bus for placing compressed video signals and audio signals from respective terminals into timeslots of the first bus; a decoder for decoding compressed video signals received from timeslots of the first bus; a second bus receiving the decoded video signals at timeslots associated with respective terminals; selector means for selecting the decoded video signals from one or more timeslots of the second bus; and an encoder for encoding the selected decoded video signals and for applying the encoded video signals to the first bus; at least one bridge processor receiving the selected encoded video signals and audio signals from the first bus for transmission to the respective terminals.
Claim 8
Dependent Claim
159 words
A multipoint control unit for receiving compressed video signals from terminals in a conference and for transmitting selected compressed video signals to the terminals, the multipoint control unit comprising: a first bus having timeslots for transporting compressed video signals and audio signals; at least one bridge processor coupled to the first bus for placing compressed video signals and audio signals from respective terminals into timeslots of the first bus; a decoder for decoding compressed video signals received from timeslots of the first bus; a second bus receiving the decoded video signals at timeslots associated with respective terminals; selector means for selecting the decoded video signals from one or more timeslots of the second bus; and an encoder for encoding the selected decoded video signals and for applying the encoded video signals to the first bus; at least one bridge processor receiving the selected encoded video signals and audio signals from the first bus for transmission to the respective terminals.
Claim 9
Dependent Claim
20 words
The multipoint control unit of claim 6 further comprising scaling means for scaling decoded video signals to a desirable resolution.
Claim 10
Dependent Claim
31 words
The multipoint control unit of claim 6 wherein audio signals received by at least one bridge processor are delayed a sufficient amount to compensate for encoding and decoding of video signals.
Claim 11
Dependent Claim
24 words
The multipoint control unit of claim 6 wherein the encoder receives motion displacement vectors associated with the selected decoded video signals for motion estimation.
Claim 12
Dependent Claim
204 words
In a video teleconferencing system in which a plurality of audiovisual terminals operable to send and receive compressed digital video signals communicate with each other through a multipoint control unit having a video processing unit, the video processing unit comprising: a pixel bus having a plurality of timeslots for transporting uncompressed digital video signals; a pixel bus controller for controlling access to the pixel bus; and a plurality of processors, each processor coupled to the pixel bus and associated with at least one timeslot; each processor comprising: a decoder for decoding first compressed digital video signals from one of the plurality of audiovisual terminals to first uncompressed digital video signals; means for inserting the first uncompressed digital video signals into the at least one associated timeslot on the pixel bus when an output control signal is received from the pixel bus controller; means for receiving second uncompressed digital video signals from any timeslot associated with any processor when an input control signal is received from the pixel bus controller; a encoder for encoding the second uncompressed digital video signals to second compressed digital video signals; and means for transmitting the second compressed digital video signals to the one of the plurality of audiovisual terminals.
Claim 13
Dependent Claim
204 words
In a video teleconferencing system in which a plurality of audiovisual terminals operable to send and receive compressed digital video signals communicate with each other through a multipoint control unit having a video processing unit, the video processing unit comprising: a pixel bus having a plurality of timeslots for transporting uncompressed digital video signals; a pixel bus controller for controlling access to the pixel bus; and a plurality of processors, each processor coupled to the pixel bus and associated with at least one timeslot; each processor comprising: a decoder for decoding first compressed digital video signals from one of the plurality of audiovisual terminals to first uncompressed digital video signals; means for inserting the first uncompressed digital video signals into the at least one associated timeslot on the pixel bus when an output control signal is received from the pixel bus controller; means for receiving second uncompressed digital video signals from any timeslot associated with any processor when an input control signal is received from the pixel bus controller; a encoder for encoding the second uncompressed digital video signals to second compressed digital video signals; and means for transmitting the second compressed digital video signals to the one of the plurality of audiovisual terminals.
Claim 14
Dependent Claim
61 words
The video processing unit of claim 10 wherein the decoder and the encoder comprise a coding algorithm, the coding algorithm for a respective processor matching a terminal coding algorithm for a respective assigned audiovisual terminal and optionally differing from the coding algorithms of other processors in the conference, such that the conference comprises audiovisual terminals having optionally different terminal coding algorithms.
Claim 15
Dependent Claim
52 words
The video processing unit of claim 10 wherein a respective processor further comprises means for spatially mixing a plurality of second uncompressed digital video signals received from the pixel bus to form a composite uncompressed digital video signal for encoding and transmission by the encoder and transmitting means of the respective processor.
Claim 16
Dependent Claim
193 words
A video teleconferencing system comprising: a plurality of audiovisual terminals, each audiovisual terminal operable to send and receive compressed digital video signals; and a multipoint control unit for allowing the plurality of audiovisual terminals to communicate with each other in a conference, having a video processing unit, the video processing unit comprising: a plurality of processors, each processor comprising: a decoder for decoding first compressed digital video signals received from one of the plurality of audiovisual terminals to first uncompressed digital video signals; means for sending the first uncompressed digital video signals to any other processor; means for receiving second uncompressed digital video signals from any processor; an encoder for encoding the second uncompressed digital video signals to second compressed digital video signals; and means for transmitting the second compressed digital video signals to the one of the plurality of audiovisual terminals; wherein the decoder and the encoder comprise a coding algorithm, the coding algorithm for a respective processor matching a terminal coding algorithm for a respective audiovisual terminal and differing from the coding algorithms of other processors in the conference, such that the conference comprises audiovisual terminals having different terminal coding algorithms.
Claim 17
Dependent Claim
193 words
A video teleconferencing system comprising: a plurality of audiovisual terminals, each audiovisual terminal operable to send and receive compressed digital video signals; and a multipoint control unit for allowing the plurality of audiovisual terminals to communicate with each other in a conference, having a video processing unit, the video processing unit comprising: a plurality of processors, each processor comprising: a decoder for decoding first compressed digital video signals received from one of the plurality of audiovisual terminals to first uncompressed digital video signals; means for sending the first uncompressed digital video signals to any other processor; means for receiving second uncompressed digital video signals from any processor; an encoder for encoding the second uncompressed digital video signals to second compressed digital video signals; and means for transmitting the second compressed digital video signals to the one of the plurality of audiovisual terminals; wherein the decoder and the encoder comprise a coding algorithm, the coding algorithm for a respective processor matching a terminal coding algorithm for a respective audiovisual terminal and differing from the coding algorithms of other processors in the conference, such that the conference comprises audiovisual terminals having different terminal coding algorithms.
Claim 18
Dependent Claim
47 words
The video teleconferencing system of claim 13 wherein a respective processor further comprises means for spatially mixing a plurality of second uncompressed digital video signals to form a composite uncompressed digital video signal for encoding and transmission by the encoder and transmitting means of the respective processor.
Claim 19
Dependent Claim
119 words
In a multipoint control unit for receiving compressed video signals from terminals in a conference and for transmitting selected compressed video signals to the terminals, the method comprising the steps of: decoding the compressed video signals from respective terminals to uncompressed video signals; making the uncompressed video signals available at the respective maximum data rate of each uncompressed signal on a bus; selecting plural uncompressed video signals from the bus for a receiving terminal; and encoding the selected plural uncompressed video signals in a composite image for transmission to the receiving terminal at a data rate determined by the receiving terminal such that the receiving terminal receives each video signal in the composite image at maximum available image resolution.
Claim 20
Dependent Claim
119 words
In a multipoint control unit for receiving compressed video signals from terminals in a conference and for transmitting selected compressed video signals to the terminals, the method comprising the steps of: decoding the compressed video signals from respective terminals to uncompressed video signals; making the uncompressed video signals available at the respective maximum data rate of each uncompressed signal on a bus; selecting plural uncompressed video signals from the bus for a receiving terminal; and encoding the selected plural uncompressed video signals in a composite image for transmission to the receiving terminal at a data rate determined by the receiving terminal such that the receiving terminal receives each video signal in the composite image at maximum available image resolution.
Claim 21
Dependent Claim
87 words
In a multipoint control unit for receiving compressed video signals from terminals in a conference and for transmitting selected compressed video signals to the terminals, the method comprising the steps of: decoding the compressed video signals from respective terminals to uncompressed video signals in a pixel domain; receiving the uncompressed video signals on a pixel bus having timeslots associated with respective terminals; selecting uncompressed video signals from one or more timeslots of the pixel bus; and encoding the selected uncompressed video signals for transmission to respective terminals.
Claim 22
Dependent Claim
87 words
In a multipoint control unit for receiving compressed video signals from terminals in a conference and for transmitting selected compressed video signals to the terminals, the method comprising the steps of: decoding the compressed video signals from respective terminals to uncompressed video signals in a pixel domain; receiving the uncompressed video signals on a pixel bus having timeslots associated with respective terminals; selecting uncompressed video signals from one or more timeslots of the pixel bus; and encoding the selected uncompressed video signals for transmission to respective terminals.
Claim 23
Dependent Claim
23 words
The method of claim 16 wherein the steps of decoding and encoding include using different compression algorithms matching compression algorithms of respective terminals.
Claim 24
Dependent Claim
33 words
The method of claim 16 wherein the steps of decoding and encoding further include operating at data rates matching respective terminals such that terminals having different data rates can intercommunicate in the conference.
Claim 25
Dependent Claim
25 words
The method of claim 16 wherein the step of encoding further includes selecting uncompressed video signals from plural timeslots to form composite encoded video signals.
Claim 26
Dependent Claim
18 words
The method of claim 16 further comprising the step of scaling uncompressed video signals to a desirable resolution.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2001-11-16 | 2002-05-18 | 2002-11-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-11-16 | 2006-05-18 | 2006-11-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-11-16 | 2010-05-18 | 2010-11-17 | $7700.00 | Window Closed / Lapsed |