US5647048A — Trick mode VTR tracking for compressed video

Claim 1

Independent Claim 148 words

A method for tracking trick mode data areas of a tape during trick mode playback, the trick mode data areas including video data to be reproduced during trick mode playback, the method comprising the steps of: initially, accelerating a relative tape transport-drum rotation to an approximate speed that is appropriate for a particular trick mode, reproducing identification codes from said trick mode data areas of said tape, wherein certain of the identification codes correspond to the particular trick mode and thereby identify trick mode data areas which include video data to be reproduced during the particular trick mode, comparing a count of identification codes corresponding to the particular trick mode which are reproduced during a current interval to another count of identification codes corresponding to the particular trick mode which are reproduced during a previous interval, and depending on said comparison, adjusting said relative tape transport-drum rotation speed.

Claim 2

Independent Claim 148 words

A method for tracking trick mode data areas of a tape during trick mode playback, the trick mode data areas including video data to be reproduced during trick mode playback, the method comprising the steps of: initially, accelerating a relative tape transport-drum rotation to an approximate speed that is appropriate for a particular trick mode, reproducing identification codes from said trick mode data areas of said tape, wherein certain of the identification codes correspond to the particular trick mode and thereby identify trick mode data areas which include video data to be reproduced during the particular trick mode, comparing a count of identification codes corresponding to the particular trick mode which are reproduced during a current interval to another count of identification codes corresponding to the particular trick mode which are reproduced during a previous interval, and depending on said comparison, adjusting said relative tape transport-drum rotation speed.

Claim 3

Dependent Claim 39 words

The method of claim 1 wherein said step of comparing further comprises the steps of: attempting to match each reproduced identification code to said particular trick mode, and counting only said identification codes that match said particular trick mode.

Claim 4

Independent Claim 154 words

A method for tracking trick mode data areas of a tape during trick mode playback, the trick mode data areas including video data to be reproduced during the trick mode playback, the method comprising: initially, accelerating a relative tape transport-drum rotation to an approximate speed that is appropriate for a particular trick mode, during a searching stage, adjusting said relative tape transport-drum rotation speed to achieve a desired relative tape transport-drum rotation speed for said particular trick mode and to lock a head scan of said tape onto a desired scanning path, and during each of a plurality of intervals of a tracking stage, reproducing identification codes from said trick mode data areas of said tape, counting reproduced identification codes that match said particular trick mode and therefore identify trick mode data areas which include video data to be reproduced during the particular trick mode, and comparing a resulting count to a target count.

Claim 5

Independent Claim 154 words

A method for tracking trick mode data areas of a tape during trick mode playback, the trick mode data areas including video data to be reproduced during the trick mode playback, the method comprising: initially, accelerating a relative tape transport-drum rotation to an approximate speed that is appropriate for a particular trick mode, during a searching stage, adjusting said relative tape transport-drum rotation speed to achieve a desired relative tape transport-drum rotation speed for said particular trick mode and to lock a head scan of said tape onto a desired scanning path, and during each of a plurality of intervals of a tracking stage, reproducing identification codes from said trick mode data areas of said tape, counting reproduced identification codes that match said particular trick mode and therefore identify trick mode data areas which include video data to be reproduced during the particular trick mode, and comparing a resulting count to a target count.

Claim 6

Dependent Claim 40 words

The method of claim 3 further comprising the step of: leaving said searching stage and entering said tracking stage when said desired relative tape transport-drum rotation speed is achieved and said head scan is locked onto said desired scanning path.

Claim 7

Dependent Claim 34 words

The method of claim 3 further comprising the step of: leaving said tracking stage and returning to said searching stage if said resulting count of a current interval is different from said target count.

Claim 8

Dependent Claim 63 words

The method of claim 3 further comprising the steps of: during said searching stage, comparing a count of identification codes that match said particular trick mode, reproduced during a current interval, to a count of identification codes, that match said particular trick mode, reproduced during a previous interval, and depending on said comparison, adjusting said relative tape transport-drum rotation by a predetermined amount.

Claim 9

Dependent Claim 112 words

The method of claim 3 wherein said searching stage comprises the steps of: determining a first polarity of a difference between a count of identification codes, reproduced from said tape during a previous interval, from a count of identification codes, reproduced from said tape during a current interval, determining a second polarity of a speed difference currently being used to adjust said relative tape transport-drum rotation speed, and determining a speed difference for adjusting said relative tape transport-drum rotation speed during a following interval from said first and second polarities and from a difference between said count of identification codes, reproduced from said tape during said current interval, and a target count.

Claim 10

Dependent Claim 31 words

The method of claim 7 further comprising the step of: scaling said speed difference for said following interval with a feedback scaling constant so as to prevent de-stabilizing said head scan.

Claim 11

Dependent Claim 95 words

The method of claim 8 wherein said speed difference for said following interval is determined by: ΔV.sub.m+1 =k·f(C.sub.m -C.sub.m-1)·(C-C.sub.m)·f(ΔV.sub.m)·f(.DELTA.V.sub.m)·V.sub.1 ( 2) where: ##EQU8## ΔV m is said speed difference currently being used, ΔV m+1 is said speed difference for said following interval, C m is said count of identification codes reproduced in said current interval m, C m-1 is said count of identification codes reproduced in said previous interval m--1, C is said target count, V 1 is a relative tape transport-drum rotation speed during normal speed playback, and k is said feedback scaling constant.

Claim 12

Dependent Claim 174 words

A video tape transport playback apparatus for tracking trick mode data areas of a tape during trick mode playback., the trick mode data areas including video data to be reproduced during the trick mode playback, the apparatus comprising: a capstan servo for transporting said tape at a tape transport speed, a scanner assembly for rotating magnetic heads over said tape at a speed relative to said tape transport speed, to reproduce identification codes recorded on trick mode data areas of said tape, wherein certain of the identification codes correspond to a particular trick mode and thereby identify trick mode data areas which include video data to be reproduced during the particular trick mode, a servo speed controller for initially accelerating a relative tape transport-drum rotation to an approximate speed that is appropriate for said particular trick mode, and a two stage tracking circuit for comparing a count of identification codes reproduced during a current interval to another count, and depending on said comparison, transmitting a signal for adjusting said relative tape transport-drum rotation speed.

Claim 13

Dependent Claim 174 words

A video tape transport playback apparatus for tracking trick mode data areas of a tape during trick mode playback., the trick mode data areas including video data to be reproduced during the trick mode playback, the apparatus comprising: a capstan servo for transporting said tape at a tape transport speed, a scanner assembly for rotating magnetic heads over said tape at a speed relative to said tape transport speed, to reproduce identification codes recorded on trick mode data areas of said tape, wherein certain of the identification codes correspond to a particular trick mode and thereby identify trick mode data areas which include video data to be reproduced during the particular trick mode, a servo speed controller for initially accelerating a relative tape transport-drum rotation to an approximate speed that is appropriate for said particular trick mode, and a two stage tracking circuit for comparing a count of identification codes reproduced during a current interval to another count, and depending on said comparison, transmitting a signal for adjusting said relative tape transport-drum rotation speed.

Claim 14

Dependent Claim 55 words

The video tape transport and playback apparatus of claim 10 further comprising: a counter circuit for matching each identification code reproduced by said scanner assembly to said particular trick mode, and for outputting a signal to said two stage tracking circuit indicative of a count of only said identification codes which match said trick mode.

Claim 15

Independent Claim 181 words

An apparatus for tracking trick mode data areas of a tape during a particular trick mode playback, the trick mode data areas including video data to be reproduced during the trick mode playback, the apparatus comprising: a video tape transport and playback apparatus for, initially, accelerating a relative tape transport-drum rotation to an approximate speed that is appropriate for a particular trick mode, and a two stage tracking circuit responsive to said video tape transport and playback apparatus for, during a searching stage, adjusting said relative tape transport-drum rotation speed to achieve a desired relative tape transport-drum rotation speed for said particular trick mode and to lock a head scan of said tape onto a desired scanning path, and for, during each of a plurality of intervals of a tracking stage, reproducing identification codes from said trick mode data areas of said tape, counting reproduced identification codes that match said particular trick mode and therefore identify trick mode data areas which include video data to be reproduced during the particular trick mode, and comparing a resulting count to a target count.

Claim 16

Independent Claim 181 words

An apparatus for tracking trick mode data areas of a tape during a particular trick mode playback, the trick mode data areas including video data to be reproduced during the trick mode playback, the apparatus comprising: a video tape transport and playback apparatus for, initially, accelerating a relative tape transport-drum rotation to an approximate speed that is appropriate for a particular trick mode, and a two stage tracking circuit responsive to said video tape transport and playback apparatus for, during a searching stage, adjusting said relative tape transport-drum rotation speed to achieve a desired relative tape transport-drum rotation speed for said particular trick mode and to lock a head scan of said tape onto a desired scanning path, and for, during each of a plurality of intervals of a tracking stage, reproducing identification codes from said trick mode data areas of said tape, counting reproduced identification codes that match said particular trick mode and therefore identify trick mode data areas which include video data to be reproduced during the particular trick mode, and comparing a resulting count to a target count.

Claim 17

Dependent Claim 41 words

The apparatus of claim 12 wherein said two stage tracking circuit leaves said searching stage and enters said tracking stage when said desired relative tape transport-drum rotation speed is achieved and said head scan is locked onto said desired scanning path.

Claim 18

Dependent Claim 34 words

The apparatus of claim 12 wherein said two stage circuit leaves said tracking stage and returns to said searching stage if said resulting count of a current interval is different from said target count.

Claim 19

Dependent Claim 109 words

The apparatus of claim 12 further comprising: a counter circuit for matching each reproduced identification code to said particular trick mode, and for outputting a signal to said two stage tracking circuit indicative of a count of only said identification codes which match said trick mode, wherein, during said searching stage, said two stage tracking circuit compares a count of identification codes that match said particular trick mode, reproduced during a current interval, to a count of identification codes, that match said particular trick mode, reproduced during a previous interval, and depending on said comparison, said two stage circuit adjusts said relative tape transport-drum rotation by a predetermined amount.

Claim 20

Dependent Claim 41 words

The apparatus of claim 15 wherein said two stage tracking circuit compares a count of identification codes that match said particular trick mode, reproduced during a current interval, to a target count and leaves said tracking stage depending on said comparison.

Claim 21

Dependent Claim 44 words

The apparatus of claim 12 wherein said two stage tracking circuit further comprises a zero crossing rate phase locked loop receiving a count of identification codes reproduced during a current interval, and outputting a speed difference for adjusting said relative tape transport-drum rotation speed.

Claim 22

Dependent Claim 133 words

The apparatus of claim 17 wherein said zero crossing rate phase locked loop comprises: a first polarity determination circuit for determining a first polarity of a difference between a count of identification codes reproduced from said tape during a previous interval, from said received count of identification codes reproduced from said tape during a current interval, a second polarity determination circuit for determining a second polarity of a speed difference currently being used to adjust said relative tape transport-drum rotation speed, and a speed difference determination circuit for determining a speed difference for adjusting said relative tape transport-drum rotation speed during a following interval from said first and second polarities and from a difference between said received count of identification codes, reproduced from said tape during said current interval, and a target count.

Claim 23

Dependent Claim 32 words

The apparatus of claim 18 wherein said speed difference determination circuit scales said speed difference for said following interval with a feedback scaling constant so as to prevent de-stabilizing said head scan.

Claim 24

Dependent Claim 97 words

The apparatus of claim 19 wherein said zero crossing rate phase locked loop determines said speed difference from: ΔV.sub.m+1 =k·f(C.sub.m -C.sub.m-1)·(C-C.sub.m)·f(ΔV.sub.m)·V.sub.1 ( 2) where: ##EQU9## ΔV m is said speed difference currently being used. ΔV m+1 is said speed difference for said following interval, C m is said count of identification codes reproduced in said current interval m, C m-1 is said count of identification codes reproduced in said previous interval m-1, C is said target count, V 1 is a relative tape transport-drum rotation speed during normal speed playback, and k is said feedback scaling constant.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	2000-07-07	2001-01-06	2001-07-08	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2004-07-07	2005-01-06	2005-07-08	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2008-07-07	2009-01-06	2009-07-08	$7700.00	Window Closed / Lapsed

Trick mode VTR tracking for compressed video

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