Boots – shoes – and leggings
Patent
1994-08-19
1997-04-22
Mai, Tan V.
Boots, shoes, and leggings
G06J 100
Patent
active
056234317
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a method of detecting a segment of a given signal which corresponds to a reference segment, the method comprising rectifying the reference segment, deriving a first auxiliary reference segment from the rectified reference segment by anti-alias filtering and sampling at a first rate, storing said first auxiliary reference segment, rectifying the given signal, deriving a first signal from the rectified given signal by anti-alias filtering and sampling at said first rate, and performing a sliding correlation between said first signal and the stored first auxiliary reference segment to determine which segment of said first signal has at least a predetermined degree of correlation with said first auxiliary reference segment.
A method of this general kind is disclosed in U.S. Pat. No. 3,919,479. This known method is used for automatically recognising and identifying programmes and commercial advertisements broadcast on television and radio.
A method of aligning a segment of a given signal with a corresponding reference segment is disclosed, for example, in published European patent application EP-A-0309639. This known method is used inter alia in the evaluation of the quality of recording on a magnetic tape containing audio and video programme material. Characteristics of a selected segment of the audio material recorded are measured both upon recording and upon playback, and are compared one with the other, thereby indicating the quality of the recording. Obviously for this process to be successful it is necessary that the segment of played back material corresponds substantially exactly to the segment whose characteristics were measured upon recording. In order to ensure such correspondence in the known method, a picture frame number forming part of the video material recorded is used as a marker indicating the start of the audio segment to be evaluated upon playback.
Such picture frame numbers or an equivalent timecode track may not be available in some applications. It is, in theory, possible to record dedicated markers within the audio track(s). However, it is difficult to make such markers imperceptible to the end user of the tape. It is an object of the present invention to make the provision of markers unnecessary.
The invention provides a method as defined in the first paragraph hereof which is characterized in that the method further comprises deriving a second auxiliary reference segment from the rectified reference segment by anti-alias filtering and sampling at a second rate, the second rate being greater than the first rate, storing said second auxiliary reference segment, deriving a second signal from the rectified given signal by anti-alias filtering and sampling at said second rate, and performing a sliding correlation between at least a subsegment of the stored second auxiliary reference segment and at least a subsegment of that segment of said second signal which corresponds to said segment of said first signal to determine the position of the peak correlation therebetween and thereby align the segment of the given signal with the reference segment.
An embodiment of the invention will now be described, by way of example, with reference to the accompanying diagrammatic drawing in which
FIG. 1 is a block diagram of an apparatus in accordance with the invention and
FIG. 2 is a flow diagram of various operations performed by the apparatus of FIG. 1.
FIG. 1 is a block diagram of apparatus in accordance with the invention which, in the present example, is intended to facilitate evaluation of the quality of prerecorded audio tapes. To this end a segment of the signal recorded on each tape to be evaluated is played back and, after suitable processing, is compared with a corresponding segment, also suitably processed, played back from a master tape.
In the apparatus of the Figure reference numeral 1 denotes a playback machine for the master tape and reference numeral 2 denotes a playback machine for each prerecorded tape to be evaluated. The machines 1 and 2 are independently
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patent: 4813006 (1989-03-01), Burns et al.
patent: 4823293 (1989-04-01), Oda
patent: 5040081 (1991-08-01), McCutchen
Komiyama, "Tape-Lock Systems without Time Code", NHK Lab. Note, No. 305, Sep. 1984, Tokyo Japan, pp. 2-7.
Central Research Laboratories Limited
Mai Tan V.
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