Motion video signal processing for recording or reproducing – Local trick play processing – With randomly accessible medium
Reexamination Certificate
1998-10-26
2001-09-11
Garber, Wendy R. (Department: 2715)
Motion video signal processing for recording or reproducing
Local trick play processing
With randomly accessible medium
C386S349000, C386S349000
Reexamination Certificate
active
06289162
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to high-speed reproduction or playback of an image signal recorded on a video tape recorder (VTR) tape through conversion of an image produced at twenty-four (24) frames per second to an image of sixty (60) fields/second. More particularly, but not exclusively, this invention relates to a high-speed image reproduction method and apparatus for reproducing only a specific predefined image or images at an increased speed 2.5 times greater than the standard playback speed, which images are selected from among those of two fields and three fields recording therein a single video frame, respectively.
It should be noted that although in the currently available NTSC standard scheme, the number of successive fields per second in televisions is precisely set at 59.94 (59.94 fields/second) and in a high definition television (HDTV) environment—such as the “High-Vision” system in Japan—the number could be a mixture of 59.94 and 60, these are collectively called the “60 fields/second”. Accordingly, it is to be understood that the term “60 fields/second” as will be used herein refers to either 59.94 fields/second or 60 fields/second.
2. Description of the Related Art
Currently, component signals for use in broadcasting and composite signals such as NTSC, PAL or the like are typically subject to interlace (interlaced scanning) processing. In the NTSC system, video frame images are at the rate of 30 pieces per second whereas field images are at 60 pieces/second. Animations and motion pictures are generally photographed and filmed at the rate of 24 frames/second. Accordingly, one prior known approach to record such original images on a VTR tape is to first convert the initial one picture frame into two video fields while converting the next frame to three fields, repeat this procedure consecutively, thereby perform conversion to video images of 60 fields/second by what is called the “two-to-three (2-3) pull-down” technique, and then record them on the VTR tape.
As digital VTRs including “D-2” or “D-3” VTRs, currently available VTRs come with a function of thinning out video fields at constant intervals in conformity with a playback speed when reproducing a video signal from N recording tracks (where “N” is a predetermined natural number) that have been recorded on a tape in a manner corresponding to field images by use of an auto-tracking (AT) head movable in the track width direction in units of N tracks corresponding to the field images, thereby outputting the reproduced video signal.
Considering one exemplary case of high-speed reproduction at an increased speed that is, for example, 2.5 times the standard playback speed—say, 2.5×quick playback—as implemented in the present invention, the above function of the conventional VTRs is achieved by setting the tape feed speed at a value 2.5 times greater than the standard feed speed, and sequentially repeating a playback procedure which includes playing back a field image that essentially consists of N tracks recorded on a tape while thinning out a single field and then thinning out two fields. However, a problem may occur in that one or more picture frames fail to be played back or “skipped” during the high-speed reproduction unless a deeper appreciation is given to the exact relation between one “frame” or “picture” of the original image (i.e. a one-scene picture on motion picture films) and a plurality of video fields of the image signal thus converted.
As noted above, in the conventional VTRs' high-speed or quick playback function, achievability of the 2.5×quick playback does not come without accompanying a penalty—it has been impossible to intentionally select any desired fields. Thus, during reproduction of VTR tapes which record thereon video images through conversion from 24-frames/second images to 60-fields/second ones, it has been impossible, or at least greatly difficult, to select a single field from a group of two successive fields with one picture recorded therein and also one field from a group of three fields recording therein one picture, and then play back only images of such selected fields at high speeds.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a high-speed image reproduction method and apparatus capable of reconstructing or reproducing, from a VTR tape on which an original image produced at the rate of 24 frames per second has been recorded by conversion using the aforementioned 2-3 pull-down technique into an image of 60 fields/second, only those images of selected fields at a high speed 2.5 times greater than the standard playback speed, the fields including one predefined field selected from a group of two successive fields storing therein a single picture and another specific field as selected from a group of three fields recording a single picture.
To attain the foregoing object the present invention provides a high-speed image reproduction method for reproducing or playing back, from a tape recording thereon an image signal of 60 fields/second as converted from an original image of 24 frames/second, said image signal by use of at least one rotary head, wherein said image signal is generated by combining in a predefined layout a first group including two fields obtained from a single frame of said original image, and a second group including three fields obtained from a single frame of said original image, the method including the steps of: (a) reproducing said image signal in a standard playback mode to detect a frame change of said original image corresponding to said image signal from the magnitude of a change in luminance level and/or chromaticity level between those fields contained in said image signal; (b) detecting, based on the detected frame change, an exact correspondence relationship of the recording tracks on said tape versus the layout of said first and second groups to thereby store the correspondence relationship detected; and (c) performing, while simultaneously letting said tape travel at an increased speed 2.5 times greater than that in the standard playback mode, position-control of said at least one rotary head on the basis of the stored correspondence relation in such a way as to play back only one field image from each of said first and second groups.
The instant invention also provides a high-speed image reproduction apparatus for reproducing from a tape recording thereon an image signal of 60 fields/second recorded thereon through conversion from an original image of 24 frames/second, wherein said image signal is generated by combining in a predefined layout a first group including two fields obtained from a single frame of said original image and a second group including three fields obtained from a single frame of said original image, the apparatus including: first detection means for detecting a change of frames of said original image corresponding to said image signal from the significance of a change in luminance level and/or chromaticity level between fields contained in said image signal as reproduced in the standard playback mode; second detection means for detecting, based on the frame change detected by said first detection means, a correspondence relation between recording tracks on said tape and the layout of said first and second groups; and storage means for storing therein said correspondence relation as detected by said second detection means.
REFERENCES:
patent: 5808664 (1998-09-01), Yamashita et al.
patent: 5835163 (1998-11-01), Liou et al.
patent: 5929902 (1999-07-01), Kwok
Majima Keigo
Uehara Toshihiro
Antonelli Terry Stout & Kraus LLP
Garber Wendy R.
Nippon Hoso Kyokai
Onuaku Christopher
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