Motion video signal processing for recording or reproducing – Local trick play processing – With randomly accessible medium
Reexamination Certificate
1998-03-25
2001-04-24
Chevalier, Robert (Department: 2615)
Motion video signal processing for recording or reproducing
Local trick play processing
With randomly accessible medium
C386S349000, C386S349000
Reexamination Certificate
active
06222980
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an apparatus for generating a time code signal such as a longitudinal time code (LTC) signal in a recording and reproducing system using a tape-like recording medium. Also, this invention relates to an apparatus for reading out a time code signal. Furthermore, this invention relates to an apparatus for rearranging a time code signal.
2. Description of the Related Art
A typical helical-scan video tape recorder (VTR) includes a rotary drum on which magnetic heads are mounted. The magnetic heads rotate together with the rotary drum. A magnetic tape is wrapped on the rotary drum along a helix in a predetermined angular range. During a recording mode of operation of the VTR, an information signal containing a video signal is recorded on the magnetic tape via the magnetic heads while the rotary drum is rotated and the magnetic tape is fed in a given direction relative to the rotary drum. Specifically, the information signal is recorded on an array of slant tracks which are sequentially formed on the magnetic tape by the magnetic heads. The slant tracks extend along directions oblique with respect to the magnetic tape. During a playback mode of operation of the VTR, the slant tracks are sequentially scanned by the magnetic heads and hence the information signal is reproduced from the magnetic tape via the magnetic heads while the rotary drum is rotated and the magnetic tape is fed in the given direction relative to the rotary drum.
In general, the VTR also includes a fixed control head. During the recording mode of operation of the VTR, a control pulse signal having a constant period is recorded on the magnetic tape via the control head. Specifically, the control pulse signal is recorded on a control track which is formed by the control head on the magnetic tape along a longitudinal direction thereof During the playback mode of operation of the VTR, the control track is scanned by the control head and hence the control pulse signal is reproduced from the magnetic tape via the control head.
In a known business-use helical-scan VTR, a fixed head records a longitudinal time code (LTC) signal on a magnetic tape while forming a dedicated track for the LTC signal which extends along a longitudinal direction of the magnetic tape. The LTC signal represents an absolute position on the magnetic tape. During playback, the LTC signal track is scanned by the fixed head so that the LTC signal is reproduced from the magnetic tape.
The LTC signal has a sequence of 80-bit segments synchronized with frames represented by a video signal recorded on slant tracks on the magnetic tape. The 80-bit segments of the LTC signal are also referred to as the 1-frame-corresponding segments of the LTC signal. During reverse-direction playback, the 1-frame-corresponding segments of the reproduced LTC signal are arranged along a time base in the order opposite to the arrangement order in the original LTC signal. Also, the 80 bits of every 1-frame-corresponding segment of the reproduced LTC signal are arranged along a time base in the order opposite to the arrangement order in the original LTC signal. Such opposite arrangement orders of 1-frame-corresponding segments of an LTC signal and 80 bits of every 1-frame-corresponding segment are inconvenient to certain signal processing.
SUMMARY OF THE INVENTION
It is a first object of this invention to provide an improved apparatus for generating a time code signal.
It is a second object of this invention to provide an improved apparatus for reading out a time code signal.
It is a third object of this invention to provide an apparatus for rearranging a time code signal.
A first aspect of this invention provides a time code signal generating apparatus comprising a direction detector for detecting a direction of feed of a recording tape; a timer for counting pulses of a clock signal, and outputting a signal representing a first count value corresponding to a number of counted pulses; first means for generating a second count value corresponding to a pulse width related to a first bit represented by an input time code signal reproduced from the recording tape; second means for adding the first count value represented by the output signal of the timer at a first time point and the second count value generated by the first means into a first addition-result value; third means for comparing the first addition-result value generated by the second means and the first count value currently represented by the output signal of the timer to detect that the first count value currently represented by the output signal of the timer comes equal to the first addition-result value generated by the second means; fourth means for generating an output time code signal; fifth means for inverting the output time code signal generated by the fourth means when the third means detects that the first count value currently represented by the output signal of the timer comes equal to the first addition-result value generated by the second means; sixth means for selecting a second bit from among bits represented by the input time code signal in response to the direction detected by the direction detector, wherein the second bit to be selected neighbors the first bit in a normal time direction when the direction detected by the direction detector agrees with a forward direction, and the second bit to be selected neighbors the first bit in a reverse time direction when the direction detected by the direction detector agrees with a reverse direction; seventh means for generating a third count value corresponding to a pulse width related to the second bit selected by the sixth means; eighth means for adding the first count value represented by the output signal of the timer at a second time point after the first time point and the third count value generated by the seventh means into a second addition-result value; and ninth means for updating the first addition-result value used by the third means into the second addition-result value generated by the eighth means.
A second aspect of this invention is based on the first aspect thereof, and provides a time code signal generating apparatus wherein the input time code signal is recorded on the recording tape in synchronism with every frame represented by a video signal recorded on the recording tape.
A third aspect of this invention provides a time code signal reading apparatus comprising an edge detector for detecting every rising edge and every falling edge in an input time code signal, and generating an edge detection signal representative thereof; first means for detecting pulse widths of the input time code signal in response to the edge detection signal generated by the edge detector; second means for deciding logic states of bits in response to the pulse widths detected by the first means; third means for generating an active error flag when the pulse widths detected by the first means are arranged in an abnormal order; fourth means for detecting a sync word represented by the bits in the logic states decided by the second means; fifth means for deciding whether or not the sync word detected by the fourth means has a predetermined pattern, and generating a pattern decision signal representative thereof; sixth means for recovers a first time value from the bits in the logic states decided by the second means; and seventh means for correcting the first time value recovered by the sixth means into a second time value in response to the active error flag generated by the third means and the pattern decision signal generated by the fifth means.
A fourth aspect of this invention is based on the third aspect thereof, and provides a time code signal reading apparatus wherein the seventh means comprises eighth means for changing the first time value by a given value to convert the first time value to a third time value; ninth means for setting a seriality comparison value equal to the third time value generated by the eighth means; tenth means for changing the second time value by a
Asai Hiroshi
Ishiwata Masaki
Chevalier Robert
Gopstein Israel
Victor Company of Japan Ltd.
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