US6246701B1
Expired / Lapsed
US
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Reference time clock locking in a remultiplexer for video program bearing transport streams
Assignee: Ericsson Television Inc
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Filing: 1998-01-14
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Granted: 2001-06-12
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Expires: 2018-01-14
Abstract
Abstract A method and system are provided for remultiplexing program bearing data. The remultiplexing method and system are applicable to MPEG-2 compliant transport streams carrying video programs. A descriptor based system is used for scheduling the timely output of transport packets wherein each descriptor records a dispatch time as well as a receipt time for each transport packet. The receipt time is used for estimating program clock reference adjustments, but final program clock reference adjustment is performed in hardware in relation to the precise output timing of each transport packets. A descriptor and transport packet caching technique is used for decoupling the synchronous receipt and transmission of transport packets from any asynchronous processing performed thereon. The descriptors can also be used for managing scrambling and descrambling control words (encryption and decryption keys). Remultiplexing functions may be distributed across a network. The remultiplexer can furthermore optimize the bandwidth of transport streams by replacing null transport packets with transport packet data to be inserted into the output transport stream. Program data transmitted via asynchronous communication links is re-timed and assistance is provided for outputting program data on such asynchronous communication links to reduce a variation in end-to-end delay incurred by the program data. Remultiplexing and program specific information can be seamlessly dynamically varied without stopping, or introducing a discontinuity in, the flow of outputted transport packets. A technique is also provided for locking multiple internal reference clock generators.
Inventors
- 👤 William Slattery
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 17:22
CPC Classifications
H; H04; H04N; H04N21/00; H04N21/20; H04N21/23; H04N21/234; H04N21/23406; H04N21/23424; H04N21/2343; H04N21/234318; H04N21/236; H04N21/23608; H04N21/238; H04N21/2389; H04N21/40; H04N21/43; H04N21/4302; H04N21/4307; H04N21/43072; H04N21/80; H04N21/85; H04N21/854; H04N21/8547
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
295 words
A method for locking reference clocks at circuits that transmit and receive a transport stream formed from a sequence of transport packets containing compressed data for one or more programs, each of said programs having an independent bit rate and program clock reference time stamps of an independent encoder system time clock to which decoding and presentation of said program is synchronized, said method comprising the steps of: (a) maintaining a reference clock at each first circuit which receives transport packets and each second circuit which transmits transport packets, said reference clock at each first circuit for indicating a time at which each transport packet is received thereat and said reference clock at each second circuit for indicating when to transmit each transport packet therefrom; (b) designating a master reference clock to which each other one of said reference clocks is to be synchronized, wherein a reference clock at one of said first and second circuits is designated as said master reference clock; (c) periodically obtaining a current time of said master reference clock; (d) adjusting each other one of said reference clocks according to a difference between said time at each of said other reference clocks and said current time of said master reference clock so as to match a time of said respective reference clock to a corresponding time of said master reference clock; (e) simultaneously retrieving a current time of said reference clocks at each said first and second circuits; (f) forming a difference between said current times of said reference clocks at said one circuit and each of said first and second circuits other than said one circuit; and (g) adjusting said reference clock at each of said first and second circuits other than said one circuit to reduce said difference.
Claim 2
Independent Claim
295 words
A method for locking reference clocks at circuits that transmit and receive a transport stream formed from a sequence of transport packets containing compressed data for one or more programs, each of said programs having an independent bit rate and program clock reference time stamps of an independent encoder system time clock to which decoding and presentation of said program is synchronized, said method comprising the steps of: (a) maintaining a reference clock at each first circuit which receives transport packets and each second circuit which transmits transport packets, said reference clock at each first circuit for indicating a time at which each transport packet is received thereat and said reference clock at each second circuit for indicating when to transmit each transport packet therefrom; (b) designating a master reference clock to which each other one of said reference clocks is to be synchronized, wherein a reference clock at one of said first and second circuits is designated as said master reference clock; (c) periodically obtaining a current time of said master reference clock; (d) adjusting each other one of said reference clocks according to a difference between said time at each of said other reference clocks and said current time of said master reference clock so as to match a time of said respective reference clock to a corresponding time of said master reference clock; (e) simultaneously retrieving a current time of said reference clocks at each said first and second circuits; (f) forming a difference between said current times of said reference clocks at said one circuit and each of said first and second circuits other than said one circuit; and (g) adjusting said reference clock at each of said first and second circuits other than said one circuit to reduce said difference.
Claim 3
Independent Claim
257 words
A method for locking reference clocks at circuits that transmit and receive a transport stream formed from a sequence of transport packets containing compressed data for one or more programs, each of said programs having an independent bit rate and program clock reference time stamps of an independent encoder system time clock to which decoding and presentation of said program is synchronized, said method comprising the steps of: (a) maintaining a reference clock at each first circuit which receives transport packets and each second circuit which transmits transport packets, said reference clock at each first circuit for indicating a time at which each transport packet is received thereat and said reference clock at each second circuit for indicating when to transmit each transport packet therefrom, wherein said first and second circuits are distributed at multiple nodes; (b) designating a master reference clock to which each other one of said reference clocks is to be synchronized; (c) periodically obtaining a current time of said master reference clock; (d) adjusting each other one of said reference clocks according to a difference between said time at each of said other reference clocks and said current time of said master reference clock so as to match a time of said respective reference clock to a corresponding time of said master reference clock; (e) receiving said current time of said master reference clock at a first one of said nodes; and (f) transmitting said received current time from said first node to a second one of said nodes via a communication link.
Claim 4
Independent Claim
257 words
A method for locking reference clocks at circuits that transmit and receive a transport stream formed from a sequence of transport packets containing compressed data for one or more programs, each of said programs having an independent bit rate and program clock reference time stamps of an independent encoder system time clock to which decoding and presentation of said program is synchronized, said method comprising the steps of: (a) maintaining a reference clock at each first circuit which receives transport packets and each second circuit which transmits transport packets, said reference clock at each first circuit for indicating a time at which each transport packet is received thereat and said reference clock at each second circuit for indicating when to transmit each transport packet therefrom, wherein said first and second circuits are distributed at multiple nodes; (b) designating a master reference clock to which each other one of said reference clocks is to be synchronized; (c) periodically obtaining a current time of said master reference clock; (d) adjusting each other one of said reference clocks according to a difference between said time at each of said other reference clocks and said current time of said master reference clock so as to match a time of said respective reference clock to a corresponding time of said master reference clock; (e) receiving said current time of said master reference clock at a first one of said nodes; and (f) transmitting said received current time from said first node to a second one of said nodes via a communication link.
Claim 5
Independent Claim
251 words
A method for locking reference clocks at circuits that transmit and receive a transport stream formed from a sequence of transport packets containing compressed data for one or more programs, each of said programs having an independent bit rate and program clock reference time stamps of an independent encoder system time clock to which decoding and presentation of said program is synchronized, said method comprising the step of: (a) maintaining a reference clock at each first circuit which receives transport packets and each second circuit which transmits transport packets, said reference clock at each first circuit for indicating a time at which each transport packet is received thereat and said reference clock at each second circuit for indicating when to transit each transport packet therefrom; (b) designating a master reference clock to which each other one of said reference clocks is to be synchronized, wherein sad master reference clock is geographically remote from each of said first and second circuits; (c) periodically obtaining a current time of said master reference clock; (d) adjusting each other one of said reference clocks according to a difference between said time at each of said other reference clocks and said current time of said master reference clock so as to match a time of said respective reference clock to a corresponding time of said master reference clock; (e) periodically broadcasting said current time of said master reference clock; and (f) contemporaneously receiving said broadcasted current time at each of plural remote first and second circuits.
Claim 6
Independent Claim
251 words
A method for locking reference clocks at circuits that transmit and receive a transport stream formed from a sequence of transport packets containing compressed data for one or more programs, each of said programs having an independent bit rate and program clock reference time stamps of an independent encoder system time clock to which decoding and presentation of said program is synchronized, said method comprising the step of: (a) maintaining a reference clock at each first circuit which receives transport packets and each second circuit which transmits transport packets, said reference clock at each first circuit for indicating a time at which each transport packet is received thereat and said reference clock at each second circuit for indicating when to transit each transport packet therefrom; (b) designating a master reference clock to which each other one of said reference clocks is to be synchronized, wherein sad master reference clock is geographically remote from each of said first and second circuits; (c) periodically obtaining a current time of said master reference clock; (d) adjusting each other one of said reference clocks according to a difference between said time at each of said other reference clocks and said current time of said master reference clock so as to match a time of said respective reference clock to a corresponding time of said master reference clock; (e) periodically broadcasting said current time of said master reference clock; and (f) contemporaneously receiving said broadcasted current time at each of plural remote first and second circuits.
Claim 7
Dependent Claim
298 words
A remultiplexer for remultiplexing a transport stream formed from a sequence of transport packets containing compressed data for one or more programs, each of said programs having a independent bit rate and program clock reference time stamps of an independent encoder system time clock to which decoding and presentation of said program is synchronized, said remultiplexer comprising: one or more first circuits that receive transport packets, each first circuit comprising a first reference clock for indicating a time at which each transport packet is received; one or more second circuits that transmit transport packets, each second circuit comprising a second reference clock for indicating when to transmit each transport packet; a master reference clock to which each of said first and second reference clocks is to be synchronized, for periodically obtaining a current time of said master reference clock, wherein a reference clock at one of said first and second circuits is designated as said master reference clock; and a processor for adjusting each of said first and second reference clocks according to a difference between said time at each of said first and second reference clocks and said current time of said master reference clock so as to match a time of said respective first and second reference clock to a corresponding time of said master reference clock, wherein said processor simultaneously retrieves a current time of said first and second reference clocks at each of said first and second circuits, forms a difference between said current times of said first and second reference clocks at said one circuit and each of said first and second circuits other than said one circuit, and adjusts each first and second reference clock at each of said first and second circuits other than said one circuit to reduce said difference.
Claim 8
Dependent Claim
298 words
A remultiplexer for remultiplexing a transport stream formed from a sequence of transport packets containing compressed data for one or more programs, each of said programs having a independent bit rate and program clock reference time stamps of an independent encoder system time clock to which decoding and presentation of said program is synchronized, said remultiplexer comprising: one or more first circuits that receive transport packets, each first circuit comprising a first reference clock for indicating a time at which each transport packet is received; one or more second circuits that transmit transport packets, each second circuit comprising a second reference clock for indicating when to transmit each transport packet; a master reference clock to which each of said first and second reference clocks is to be synchronized, for periodically obtaining a current time of said master reference clock, wherein a reference clock at one of said first and second circuits is designated as said master reference clock; and a processor for adjusting each of said first and second reference clocks according to a difference between said time at each of said first and second reference clocks and said current time of said master reference clock so as to match a time of said respective first and second reference clock to a corresponding time of said master reference clock, wherein said processor simultaneously retrieves a current time of said first and second reference clocks at each of said first and second circuits, forms a difference between said current times of said first and second reference clocks at said one circuit and each of said first and second circuits other than said one circuit, and adjusts each first and second reference clock at each of said first and second circuits other than said one circuit to reduce said difference.
Claim 9
Dependent Claim
255 words
A remultiplexer for remultiplexing a transport stream formed from a sequence of transport packets containing compressed data for one or more programs, each of said programs having an independent bit rate and program clock reference time stamps of an independent encoder system time clock to which decoding and presentation of said program is synchronized, said remultiplexer comprising: one or more first circuits that receive transport packets, each first circuit comprising a first reference clock for indicating a time at which each transport packet is received; one or more second circuits that transmit transport packets, each second circuit comprising a second reference clock for indicating when to transmit each transport packet, wherein said first and second circuits are distributed at multiple nodes; a master reference clock to which each of said first and second reference clocks is to be synchronized, for periodically obtaining a current time of said master reference clock; a processor for adjusting each of said first and second reference clocks according to a difference between said time at each of said first and second reference clocks and said current time of said master reference clock so as to match a time of said respective first and second reference clock to a corresponding time of said master reference clock; and a communication link connecting first and second ones of said nodes, said first node receiving said current time of said master reference clock and transmitting said received current time from said first node to a second one of said nodes via a communication link.
Claim 10
Dependent Claim
255 words
A remultiplexer for remultiplexing a transport stream formed from a sequence of transport packets containing compressed data for one or more programs, each of said programs having an independent bit rate and program clock reference time stamps of an independent encoder system time clock to which decoding and presentation of said program is synchronized, said remultiplexer comprising: one or more first circuits that receive transport packets, each first circuit comprising a first reference clock for indicating a time at which each transport packet is received; one or more second circuits that transmit transport packets, each second circuit comprising a second reference clock for indicating when to transmit each transport packet, wherein said first and second circuits are distributed at multiple nodes; a master reference clock to which each of said first and second reference clocks is to be synchronized, for periodically obtaining a current time of said master reference clock; a processor for adjusting each of said first and second reference clocks according to a difference between said time at each of said first and second reference clocks and said current time of said master reference clock so as to match a time of said respective first and second reference clock to a corresponding time of said master reference clock; and a communication link connecting first and second ones of said nodes, said first node receiving said current time of said master reference clock and transmitting said received current time from said first node to a second one of said nodes via a communication link.
Claim 11
Dependent Claim
235 words
A remultiplexer for remultiplexing a transport stream formed from a sequence of transport packets containing compressed data for one or more programs, each of said programs having an independent bit rate and program clock reference time stamps of an independent encoder system time clock to which decoding and presentation of said program is synchronized, said remultiplexer comprising: one or more first circuits that receive transport packets, each first circuit comprising a first reference clock for indicating a time at which each transport packet is received; one or more second circuits that transmit transport packets, each second circuit comprising a second reference clock for indicating when to transmit each transport packet; a master reference clock to which each of said first and second reference clocks is to be synchronized, for periodically obtaining a current time of said master reference clock, wherein said master reference clock is geographically remote from each of said first and second circuits; a processor for adjusting each of said first and second reference clocks according to a difference between said time at each of said first and second reference clocks and said current time of said master reference clock so as to match a time of said respective first and second reference clock to a corresponding time of said master reference clock; and one or more receivers for contemporaneously receiving a periodic broadcast of said current time of said master reference clock.
Claim 12
Dependent Claim
235 words
A remultiplexer for remultiplexing a transport stream formed from a sequence of transport packets containing compressed data for one or more programs, each of said programs having an independent bit rate and program clock reference time stamps of an independent encoder system time clock to which decoding and presentation of said program is synchronized, said remultiplexer comprising: one or more first circuits that receive transport packets, each first circuit comprising a first reference clock for indicating a time at which each transport packet is received; one or more second circuits that transmit transport packets, each second circuit comprising a second reference clock for indicating when to transmit each transport packet; a master reference clock to which each of said first and second reference clocks is to be synchronized, for periodically obtaining a current time of said master reference clock, wherein said master reference clock is geographically remote from each of said first and second circuits; a processor for adjusting each of said first and second reference clocks according to a difference between said time at each of said first and second reference clocks and said current time of said master reference clock so as to match a time of said respective first and second reference clock to a corresponding time of said master reference clock; and one or more receivers for contemporaneously receiving a periodic broadcast of said current time of said master reference clock.
Claim 13
Dependent Claim
301 words
A remultiplexed transport stream formed by reference clock locked circuits that transmit and receive a transport stream formed from a sequence of transport packets containing compressed data for one or more programs, each of said programs having an independent bit rate and program clock reference time stamps of an independent encoder system time clock to which decoding and presentation of said program is synchronized, said remultiplexed transport stream being produced by the steps of: (a) maintaining a reference clock at each first circuit which receives transport packets and each second circuit which transmits transport packets, said reference clock at each first circuit for indicating a time at which each transport packet is received thereat and said reference clock at each second circuit for indicating when to transmit each transport packet therefrom; (b) designating a master reference clock to which each other one of said reference clocks is to be synchronized, wherein a reference clock at one of said first and second circuits is designated as said master reference clock; (c) periodically obtaining a current time of said master reference clock; (d) adjusting each other one of said reference clocks according to a difference between said time at each of said other reference clocks and said current time of said master reference clock so as to match a time of said respective reference clock to a corresponding time of said master reference clock; (e) simultaneously retrieving a current time of said reference clocks at each said first and second circuits; (f) forming a difference between said current times of said reference clocks at said one circuit and each of said first and second circuits other than said one circuit; and (g) adjusting said reference clock at each of said first and second circuits other than said one circuit to reduce said difference.
Claim 14
Dependent Claim
301 words
A remultiplexed transport stream formed by reference clock locked circuits that transmit and receive a transport stream formed from a sequence of transport packets containing compressed data for one or more programs, each of said programs having an independent bit rate and program clock reference time stamps of an independent encoder system time clock to which decoding and presentation of said program is synchronized, said remultiplexed transport stream being produced by the steps of: (a) maintaining a reference clock at each first circuit which receives transport packets and each second circuit which transmits transport packets, said reference clock at each first circuit for indicating a time at which each transport packet is received thereat and said reference clock at each second circuit for indicating when to transmit each transport packet therefrom; (b) designating a master reference clock to which each other one of said reference clocks is to be synchronized, wherein a reference clock at one of said first and second circuits is designated as said master reference clock; (c) periodically obtaining a current time of said master reference clock; (d) adjusting each other one of said reference clocks according to a difference between said time at each of said other reference clocks and said current time of said master reference clock so as to match a time of said respective reference clock to a corresponding time of said master reference clock; (e) simultaneously retrieving a current time of said reference clocks at each said first and second circuits; (f) forming a difference between said current times of said reference clocks at said one circuit and each of said first and second circuits other than said one circuit; and (g) adjusting said reference clock at each of said first and second circuits other than said one circuit to reduce said difference.
Claim 15
Dependent Claim
263 words
A remultiplexed transport stream formed by reference clock locked circuits that transmit and receive a transport stream formed from a sequence of transport packets containing compressed data for one or more programs, each of said programs having an independent bit rate and program clock reference time stamps of an independent encoder system time clock to which decoding and presentation of said program is synchronized, said remultiplexed transport stream being produced by the steps of: (a) maintaining a reference clock at each first circuit which receives transport packets and each second circuit which transmits transport packets, said reference clock at each first circuit for indicating a time at which each transport packet is received thereat and said reference clock at each second circuit for indicating when to transmit each transport packet therefrom, wherein said first and second circuits are distributed at multiple nodes; (b) designating a master reference clock to which each other one of said reference clocks is to be synchronized; (c) periodically obtaining a current time of said master reference clock; (d) adjusting each other one of said reference clocks according to a difference between said time at each of said other reference clocks and said current time of said master reference clock so as to match a time of said respective reference clock to a corresponding time of said master reference clock; (e) receiving said current time of said master reference clock at a first one of said nodes; and (f) transmitting said received current time from said first node to a second one of said nodes via a communication link.
Claim 16
Dependent Claim
263 words
A remultiplexed transport stream formed by reference clock locked circuits that transmit and receive a transport stream formed from a sequence of transport packets containing compressed data for one or more programs, each of said programs having an independent bit rate and program clock reference time stamps of an independent encoder system time clock to which decoding and presentation of said program is synchronized, said remultiplexed transport stream being produced by the steps of: (a) maintaining a reference clock at each first circuit which receives transport packets and each second circuit which transmits transport packets, said reference clock at each first circuit for indicating a time at which each transport packet is received thereat and said reference clock at each second circuit for indicating when to transmit each transport packet therefrom, wherein said first and second circuits are distributed at multiple nodes; (b) designating a master reference clock to which each other one of said reference clocks is to be synchronized; (c) periodically obtaining a current time of said master reference clock; (d) adjusting each other one of said reference clocks according to a difference between said time at each of said other reference clocks and said current time of said master reference clock so as to match a time of said respective reference clock to a corresponding time of said master reference clock; (e) receiving said current time of said master reference clock at a first one of said nodes; and (f) transmitting said received current time from said first node to a second one of said nodes via a communication link.
Claim 17
Dependent Claim
256 words
A remultiplexed transport stream formed by reference clock locked circuits that transmit and receive a transport stream formed from a sequence of transport packets containing compressed data for one or more programs, each of said programs having an independent bit rate and program clock reference time stamps of an independent encoder system time clock to which decoding and presentation of said program is synchronized, said remultiplexed stream being produced by the steps of: (a) maintaining a reference clock at each first circuit which receives transport packets and each second circuit which transmits transport packets, said reference clock at each first circuit for indicating a time at which each transport packet is received thereat and said reference clock at each second circuit for indicating when to transmit each transport packet therefrom; (b) designating a master reference clock to which each other one of said reference clocks is to be synchronized, wherein said master reference clock is geographically remote from each of said first and second circuits; (c) periodically obtaining a current time of said master reference clock; (d) adjusting each other one of said reference clocks according to a difference between said time at each of said other reference clocks and said current time of said master reference clock so as to match a time of said respective reference clock to a corresponding time of said master reference clock; (e) periodically broadcasting said current time of said master reference clock; and (f) contemporaneously receiving said broadcasted current time at each of plural remote first and second circuits.
Claim 18
Dependent Claim
256 words
A remultiplexed transport stream formed by reference clock locked circuits that transmit and receive a transport stream formed from a sequence of transport packets containing compressed data for one or more programs, each of said programs having an independent bit rate and program clock reference time stamps of an independent encoder system time clock to which decoding and presentation of said program is synchronized, said remultiplexed stream being produced by the steps of: (a) maintaining a reference clock at each first circuit which receives transport packets and each second circuit which transmits transport packets, said reference clock at each first circuit for indicating a time at which each transport packet is received thereat and said reference clock at each second circuit for indicating when to transmit each transport packet therefrom; (b) designating a master reference clock to which each other one of said reference clocks is to be synchronized, wherein said master reference clock is geographically remote from each of said first and second circuits; (c) periodically obtaining a current time of said master reference clock; (d) adjusting each other one of said reference clocks according to a difference between said time at each of said other reference clocks and said current time of said master reference clock so as to match a time of said respective reference clock to a corresponding time of said master reference clock; (e) periodically broadcasting said current time of said master reference clock; and (f) contemporaneously receiving said broadcasted current time at each of plural remote first and second circuits.
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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) | 2004-06-11 | 2004-12-11 | 2005-06-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2008-06-11 | 2008-12-11 | 2009-06-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2012-06-11 | 2012-12-11 | 2013-06-12 | $7700.00 | Window Closed / Lapsed |