US5473385A
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US
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Clock correction in a video data decoder using video synchronization signals
Assignee: TV/COM TECHNOLOGIES Inc
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Filing: 1994-06-07
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Granted: 1995-12-05
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Expires: 2014-06-07
Abstract
Abstract In a system which encodes video data in response to an encoding clock, transmits the encoded video data with an encoder clock signal representing the encoding clock frequency, and decodes the video data in response to a decoding clock, system clock accuracy is maintained by adjusting the decoding clock frequency. In order to reduce buffer requirements and to prevent deterioration of video program presentation, the decoding clock frequency is adjusted by slewing only during composite video synchronization periods when composite video decoded from the encoded video stream is not being presented. The preferred video synchronization periods are the vertical blanking interval and the front porch period. Restriction of decoding clock rate adjustment to these periods ensures that decoding clock slew rate limits may be unrestricted, thereby avoiding noticeable effects in the video program presentations.
Inventors
- 👤 Lawrence A. Leske
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 11:37
CPC Classifications
H; H04; H04N; H04N21/00; H04N21/40; H04N21/43; H04N21/4302; H04N21/4305; H04N21/41; H04N21/426; H04N5/00; H04N5/44; H04N5/445; H04N5/45; H04N21/434; H04N21/4341
Claims Analysis
Total Claims: 32
Claim 1
Independent Claim
132 words
A method for alignment of a decoding clock in a video data decoder with an encoding clock, comprising the steps of: receiving a video data stream with encoded video data at the video data decoder, the video data stream including an encoder clock signal representing a frequency of the encoding clock with which the video data is encoded; providing the decoding clock at the video data decoder; decoding the video data from the video data stream at the video data decoder in response to the decoding clock; producing composite video data from the decoded video data at the video data decoder; and in response to the encoder clock signal and to video synchronization signals in the composite video data, adjusting the decoding clock to match the decoding clock with the encoding clock.
Claim 2
Independent Claim
132 words
A method for alignment of a decoding clock in a video data decoder with an encoding clock, comprising the steps of: receiving a video data stream with encoded video data at the video data decoder, the video data stream including an encoder clock signal representing a frequency of the encoding clock with which the video data is encoded; providing the decoding clock at the video data decoder; decoding the video data from the video data stream at the video data decoder in response to the decoding clock; producing composite video data from the decoded video data at the video data decoder; and in response to the encoder clock signal and to video synchronization signals in the composite video data, adjusting the decoding clock to match the decoding clock with the encoding clock.
Claim 3
Dependent Claim
23 words
The method of claim 1, wherein the adjusting step is performed in response to a vertical blanking signal in the composite video data.
Claim 4
Dependent Claim
30 words
The method of claim 2, wherein the decoding clock has a decoding clock frequency, the adjusting step including changing the frequency of the decoding clock during the vertical blanking signal.
Claim 5
Dependent Claim
35 words
The method of claim 1, wherein the decoding clock has a decoding clock frequency, the adjusting step including slewing the frequency of the decoding clock during a vertical blanking interval in the composite video data.
Claim 6
Dependent Claim
23 words
The method of claim 1, wherein the adjusting step is performed in response to a front porch signal in the composite video data.
Claim 7
Dependent Claim
30 words
The method of claim 5, wherein the decoding clock has a decoding clock frequency, the adjusting step including changing the frequency of the decoding clock during the front porch signal.
Claim 8
Dependent Claim
35 words
The method of claim 1, wherein the decoding clock has a decoding clock frequency, the adjusting step including slewing the frequency of the decoding clock during a front porch period in the composite video data.
Claim 9
Independent Claim
156 words
A method for alignment of a decoding clock in a video data decoder with an encoding clock, comprising the steps of: receiving a video data stream with encoded video data at the video data decoder, the video data stream including an encoder clock signal representing a frequency of the encoding clock with which the video data is encoded; providing the decoding clock at the video data decoder, the decoding clock having a frequency that is substantially equal to the encoding clock frequency; decoding the video data from the video data stream at the video data decoder in response to the decoding clock; producing composite video data from the decoded video data at the video data decoder; and slewing the decoding clock frequency to reduce a frequency difference between the encoding clock and the decoding clock, the slewing being performed in response to the encoder clock signal and to video synchronization signals in the composite video data.
Claim 10
Independent Claim
156 words
A method for alignment of a decoding clock in a video data decoder with an encoding clock, comprising the steps of: receiving a video data stream with encoded video data at the video data decoder, the video data stream including an encoder clock signal representing a frequency of the encoding clock with which the video data is encoded; providing the decoding clock at the video data decoder, the decoding clock having a frequency that is substantially equal to the encoding clock frequency; decoding the video data from the video data stream at the video data decoder in response to the decoding clock; producing composite video data from the decoded video data at the video data decoder; and slewing the decoding clock frequency to reduce a frequency difference between the encoding clock and the decoding clock, the slewing being performed in response to the encoder clock signal and to video synchronization signals in the composite video data.
Claim 11
Dependent Claim
23 words
The method of claim 8, wherein the slewing step is performed in response to a vertical blanking signal in the composite video data.
Claim 12
Dependent Claim
23 words
The method of claim 8, wherein the slewing step is performed in response to a front porch signal in the composite video data.
Claim 13
Independent Claim
159 words
A method for alignment of a decoding clock in a video data decoder with an encoding clock, comprising the steps of: receiving a video data steam with encoded video data at the video data decoder, the video data stream including an encoder clock signal representing a frequency of the encoding clock with which the video data is encoded; providing the decoding clock at the video data decoder, the decoding clock having a clock frequency that is substantially equal to the encoding clock frequency; decoding the video data from the video data stream at the video data decoder in response to the decoding clock; producing composite video data from the decoded video data at the video data decoder; and changing the frequency of the decoding clock to reduce a frequency difference between the encoding clock and the decoding clock, the changing being performed in response to the encoder clock signal and to video synchronization signals in the composite video data.
Claim 14
Independent Claim
159 words
A method for alignment of a decoding clock in a video data decoder with an encoding clock, comprising the steps of: receiving a video data steam with encoded video data at the video data decoder, the video data stream including an encoder clock signal representing a frequency of the encoding clock with which the video data is encoded; providing the decoding clock at the video data decoder, the decoding clock having a clock frequency that is substantially equal to the encoding clock frequency; decoding the video data from the video data stream at the video data decoder in response to the decoding clock; producing composite video data from the decoded video data at the video data decoder; and changing the frequency of the decoding clock to reduce a frequency difference between the encoding clock and the decoding clock, the changing being performed in response to the encoder clock signal and to video synchronization signals in the composite video data.
Claim 15
Dependent Claim
23 words
The method of claim 11, wherein the changing step is performed in response to a vertical blanking signal in the composite video data.
Claim 16
Dependent Claim
23 words
The method of claim 11, wherein the changing step is performed in response to a front porch signal in the composite video data.
Claim 17
Dependent Claim
183 words
A combination for adjustment of a decoding clock in a video data decoder, the decoding clock having a decoding clock frequency that is substantially equal to an encoding clock frequency, the combination comprising: means for receiving a video data stream with encoded video data, the video data stream including an encoder clock signal representing the frequency of the encoding clock with which the video data is encoded; a decoding clock circuit for providing the decoding clock; a video data decoder coupled to the decoding clock circuit and to the means for receiving for decoding the video data from the video data stream in response to the decoding clock; a composite video generator coupled to the video data decoder for generating composite video data from the decoded video data in response to the decoding clock; and a clock rate alignment circuit coupled to the composite video generator and to the decoding clock circuit for adjusting the decoding clock to match the decoding clock with the encoding clock in response to the encoder clock signal and to video synchronization signals in the composite video data.
Claim 18
Dependent Claim
183 words
A combination for adjustment of a decoding clock in a video data decoder, the decoding clock having a decoding clock frequency that is substantially equal to an encoding clock frequency, the combination comprising: means for receiving a video data stream with encoded video data, the video data stream including an encoder clock signal representing the frequency of the encoding clock with which the video data is encoded; a decoding clock circuit for providing the decoding clock; a video data decoder coupled to the decoding clock circuit and to the means for receiving for decoding the video data from the video data stream in response to the decoding clock; a composite video generator coupled to the video data decoder for generating composite video data from the decoded video data in response to the decoding clock; and a clock rate alignment circuit coupled to the composite video generator and to the decoding clock circuit for adjusting the decoding clock to match the decoding clock with the encoding clock in response to the encoder clock signal and to video synchronization signals in the composite video data.
Claim 19
Dependent Claim
27 words
The combination of claim 14, wherein the clock rate alignment circuit adjusts the decoding clock in response to a vertical blanking signal in the composite video data.
Claim 20
Dependent Claim
28 words
The combination of claim 15, wherein the clock rate alignment circuit adjusts the decoding clock by changing the frequency of the decoding clock during the vertical blanking signal.
Claim 21
Dependent Claim
33 words
The combination of claim 14, wherein the clock rate alignment circuit adjusts the decoding clock by slewing the frequency of the decoding clock during a vertical blanking interval in the composite video data.
Claim 22
Dependent Claim
28 words
The combination of claim 14, wherein the clock rate alignment rate circuit adjusts the decoding clock in response to a front porch signal in the composite video data.
Claim 23
Dependent Claim
28 words
The combination of claim 18, wherein the clock rate alignment circuit adjusts the decoding clock by changing the frequency of the decoding clock during the front porch signal.
Claim 24
Dependent Claim
33 words
The combination of claim 14, wherein the clock rate alignment circuit adjusts the decoding clock by slewing the frequency of the decoding clock during a front porch period in the composite video data.
Claim 25
Dependent Claim
181 words
A combination for alignment of a decoding clock with an encoding clock, the combination comprising: means for receiving a video data stream with encoded video data, the video data stream including an encoder clock signal representing a frequency of the encoding clock with which the video data is encoded; a decoding clock circuit for providing the decoding clock having a frequency that is substantially equal to the encoding clock frequency; a video data decoder coupled to the means for receiving and to the decoding clock circuit for providing the video data in response to the video data stream and the decoding clock; a composite video generator coupled to the decoding clock circuit and the video data decoder for generating composite video data from the provided video data in response to the decoding clock; and a clock rate alignment circuit coupled to the composite video generator, to the means for receiving, and to the decoding clock circuit for slewing the frequency of the decoding clock in response to the encoder clock signal and to video synchronization signals in the composite video data.
Claim 26
Dependent Claim
181 words
A combination for alignment of a decoding clock with an encoding clock, the combination comprising: means for receiving a video data stream with encoded video data, the video data stream including an encoder clock signal representing a frequency of the encoding clock with which the video data is encoded; a decoding clock circuit for providing the decoding clock having a frequency that is substantially equal to the encoding clock frequency; a video data decoder coupled to the means for receiving and to the decoding clock circuit for providing the video data in response to the video data stream and the decoding clock; a composite video generator coupled to the decoding clock circuit and the video data decoder for generating composite video data from the provided video data in response to the decoding clock; and a clock rate alignment circuit coupled to the composite video generator, to the means for receiving, and to the decoding clock circuit for slewing the frequency of the decoding clock in response to the encoder clock signal and to video synchronization signals in the composite video data.
Claim 27
Dependent Claim
15 words
The combination of claim 21, wherein the video synchronization signals include, a vertical blanking signal.
Claim 28
Dependent Claim
15 words
The combination of claim 21, wherein the video synchronization signals include a front porch signal.
Claim 29
Dependent Claim
181 words
A combination for alignment of a decoding clock with an encoding clock, the combination comprising: means for receiving a video data stream with encoded video data, the video data stream including an encoder clock signal representing a frequency of the encoding clock with which the video data is encoded; a decoding clock circuit for providing the decoding clock having a frequency that is substantially equal to the encoding clock frequency; a video data decoder coupled to the means for receiving and to the decoding clock circuit for providing the video data in response to the video data stream and the decoding clock; a composite video generator coupled to the decoding clock circuit and the video data decoder for generating composite video data from the provided video data in response to the decoding clock; and a clock rate alignment circuit coupled to the composite video generator, to the means for receiving, and to the decoding clock circuit for changing the frequency of the decoding clock in response to the encoder clock signal and to video synchronization signals in the composite video data.
Claim 30
Dependent Claim
181 words
A combination for alignment of a decoding clock with an encoding clock, the combination comprising: means for receiving a video data stream with encoded video data, the video data stream including an encoder clock signal representing a frequency of the encoding clock with which the video data is encoded; a decoding clock circuit for providing the decoding clock having a frequency that is substantially equal to the encoding clock frequency; a video data decoder coupled to the means for receiving and to the decoding clock circuit for providing the video data in response to the video data stream and the decoding clock; a composite video generator coupled to the decoding clock circuit and the video data decoder for generating composite video data from the provided video data in response to the decoding clock; and a clock rate alignment circuit coupled to the composite video generator, to the means for receiving, and to the decoding clock circuit for changing the frequency of the decoding clock in response to the encoder clock signal and to video synchronization signals in the composite video data.
Claim 31
Dependent Claim
15 words
The combination of claim 24, wherein the video synchronization signals include a vertical blanking signal.
Claim 32
Dependent Claim
15 words
The combination of claim 24, wherein the video synchronization signals include a front porch signal.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1998-12-04 | 1999-06-05 | 1999-12-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-12-04 | 2003-06-05 | 2003-12-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-12-04 | 2007-06-05 | 2007-12-05 | $7700.00 | Window Closed / Lapsed |