Motion video signal processing for recording or reproducing – Local trick play processing – With randomly accessible medium
Reexamination Certificate
2000-04-18
2004-01-20
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
06681076
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a magnetic recording and reproducing apparatus in which digitized picture signals and digitized information signals are recorded on a magnetic tape through a rotational head while forming a series of inclined video tracks on the magnetic tape and are reproduced from the tracks of the magnetic tape, and more particularly to a magnetic recording and reproducing apparatus in which any of groups of digitized signals transmitted at different data rates is recorded and reproduced.
2. Description of the Related Art
As a magnetic recording and reproducing apparatus in which digitized signals are recorded and reproduced in/from a magnetic recording medium such as a magnetic tape through a rotational head, a video tape recorder, a digital tape recorder or the like are conventionally known. In the above conventional apparatus, picture signals and audio signals converted into digital signals are recorded at a high recording density and are reproduced.
However, digital signals are recorded and reproduced at a fixed recording data rate in the conventional magnetic recording and reproducing apparatus. Therefore, in cases where digital signals transmitted at a data rate lower than the fixed recording data rate are recorded in the conventional apparatus, a remaining data region between data regions for the digital signals is filled with zero data “0” to change the digital signals to processed digital signals having the fixed recording data rate, and the processed digital signals are recorded and reproduced at the fixed recording data rate in the conventional apparatus. Therefore, even though the digital signals transmitted at the data rate lower than the fixed recording data rate are input to the conventional apparatus, an allowable recording time in the conventional apparatus for digital signals transmitted at a data rate lower than the fixed recording data rate cannot be lengthened. In other words, there is a drawback that a recording capacity for the digital signals transmitted at the data rate lower than the fixed recording data rate is lower than that for the digital signals transmitted at the fixed recording data rate.
2.1. Previously Proposed Art:
To solve the above drawback, For example, the digital signals are modulated to PCM signals according to a pulse code modulation (PCM), and the PCM signals are recorded and reproduced through a rotational head in a PCM signal recording and reproducing apparatus (the Published Unexamined Japanese Patent Application No.S59-195306 (195306/1984)). Also, an audio digital tape recorder operated with a rotational head is proposed (the Published Unexamined Japanese Patent Application No.S61-139906 (139906/1986)).
In the Application No.S61-139906, the audio digital tape recorder has a rotational cylinder on which a magnetic tape is wound, a pair of rotational heads which are attached to the rotational cylinder and have different azimuth angles, and a tape driving means for driving the magnetic tape at a prescribed speed. In the above configuration, the magnetic tape travels at a first tape traveling speed by the function of the tape driving means in cases where digital signals transmitted at a standard data rate are input. Also, the magnetic tape travels at a second tape traveling speed equal to ⅓ the first tape traveling speed by the function of the tape driving means in cases where digital signals transmitted at a low data rate equal to ⅓ the standard data rate are input, and the digital signals are recorded or reproduced each time one of the rotational heads traces the magnetic tape three times. Therefore, regardless of whether digital signals transmitted at the standard data rate or at the low data rate are input to the audio digital tape recorder, the digital signals can be recorded and reproduced at the same data rate.
2.2. Problems to be Solved by the Invention:
However, the data rate in the above audio digital tape recorder is limited to the standard data rate and the low data rate (⅓ standard data rate) because of the relationship between the different azimuth angles in a recording operation, and a digital data recording and reproducing apparatus in which picture signals, audio signals and other information signals in a moving picture experts group 1 (MPEG1), a moving picture experts group 2 (MPEG2), a digital video broadcasting (DVD), an advanced television (ATV) and the like are converted into digital signals transmitted at various data rates and the digital signals are efficiently recorded and reproduced has been recently required. Therefore, digital signals cannot be efficiently recorded or reproduced in cases where the digital signals transmitted at one of other data rates are input, and there is a drawback that a utilization efficiency of a recording medium for digital signals cannot be enhanced.
That is, in cases where a recording and reproducing technique in the above audio digital tape recorder is simply extended to be applied for digital signals transmitted at an arbitrary data rate equal to 1/(2N) (N is an integer) the standard data rate, a pair of video tracks adjacent to each other on the magnetic tape have the same azimuth, and there is a drawback that a guard bandless azimuth recording cannot be performed in the above audio digital tape recorder.
Also, in cases where the rotational speed of the rotational cylinder is changed to read out digital signals recorded at a fixed data rate, even though the digital signals are recorded on the magnetic tape in equal magnetic inversion intervals, the inversion frequency of the digital signals reproduced changes according to the rotational speed of the rotational cylinder. Therefore, it is required to prepare a waveform equalization circuit for each rotational speed of the rotational cylinder, and there is a drawback that the configuration of the above audio digital tape recorder is complicated.
Also, in the PCM signal recording and reproducing apparatus disclosed in the Application No.S59-195306, the PCM signals time-compressed are recorded and reproduced in an attaching period in which the rotational head is attached to the magnetic tape. In this case, it is required to stop the driving of the magnetic tape three times in the attaching period each time the rotational head is rotated at a prescribed rotational speed, and it is required to move the magnetic tape at a high speed during the traveling of the magnetic tape. Therefore, there is a drawback that the control of the magnetic tape is complicated.
SUMMARY OF THE INVENTION
A first object of the present invention is to provide, with due consideration to the drawbacks of such a conventional magnetic recording and reproducing apparatus, a magnetic recording and reproducing apparatus in which digital signals are efficiently recorded in a magnetic recording medium regardless of a data rate of the digital signals and digital signals recorded at any of various data rates are reproduced without complicating the configuration of a reproducing circuit.
A second object of the present invention is to provide a magnetic recording and reproducing apparatus in which digital signals transmitted at a first data rate or at an arbitrary data rate equal to 1/N the first data rate are recorded and reproduced without changing the rotational speed of a rotational cylinder in a reproducing operation according to the data rate of the recorded digital signals and without using any additional rotational head.
The first object is achieved by the provision of a magnetic recording and reproducing apparatus for recording and reproducing digital signals on/from a magnetic recording medium, comprising:
signal processing means for processing a plurality of input digital signals transmitted at a first data rate, a second data rate equal to 1/N (N is a natural number) the first data rate or a third data rate equal to N times the first data rate and producing a plurality of blocks of digital recording signals; control means for generating an information si
Fujita Mitsuo
Ohishi Takeo
Chevalier Robert
Israel Gopstein Clark & Brody
Victor Company of Japan Ltd.
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