Method for recording and reproducing a digital color video signal

• US 4,429,334 A
• Filed: 10/07/1980
• Issued: 01/31/1984
• Est. Priority Date: 10/12/1979
• Status: Expired due to Term

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Hashimoto, Yoshitaka, Yamamoto, Kaichi, Shirota, Norihisa
• Primary Examiner(s): Faber, Alan
• Application Number:
  US06/194,830
• Time in Patent Office: 1,211 Days
• Field of Search: 358/4, 358/13, 358/138, 358/31, 358/8, 358/310, 358/320, 358/324, 360/32, 360/22, 360/9, 360/38, 360/72.2, 360/10, 360/48, 360/9.1, 360/10.1, 360/10.3, 360/38.1
• US Class Current: 386/263
• CPC Class Codes: H04N 9/808 involving pulse code modulation of the composite colour video-signal
• CPC Class Codes: H04N 9/873 for restoring the colour component sequence of the reproduced chrominance signal
• CPC Class Codes: H04N 9/877 by assembling picture element blocks in an intermediate memory

Abstract

A method for recording a color video signal in a plurality of parallel tracks extending obliquely on a magnetic tape includes the steps of sampling the video signal at a frequency which is at least three times the color sub-carrier frequency of the color video signal, converting the sampled video signal into digital form, and recording respective pluralities of the digitized samples which are arranged in a predetermined sequence sequentially in the plurality of parallel tracks, by either recording respective pluralities of contiguous digitized samples sequentially in the tracks, in which each plurality corresponds to at least one cycle of the color sub-carrier, or by alternately separating contiguous ones of the digitized samples into first and second blocks and recording respective pluralities of successive digitized samples of the first and second blocks sequentially in the tracks with the sampling frequency being equal to four times the color sub-carrier frequency, such that the chrominance component of the digital color video signal can be separated during reproduction so as to correct any error in the phase of the color sub-carrier, and such that with the first embodiment of the last-mentioned step, a digital filter having a chrominance characteristic C=(1-Z.sup. -2)/2 can be used, and with the method according to the second embodiment, a fourth order digital filter having a chrominance characteristic C=(-1=2Z^-2 -Z^-4)/2 can be used to reproduce the chrominance component, where Z is a delay transfer characteristic of the respective filters.

Claims

1. A method of recording a color video signal in a plurality of parallel tracks extending obliquely on a magnetic tape, said method comprising the steps of:

sampling said color video signal at a frequency which is four times the color sub-carrier frequency of the color video signal;

converting the sampled color video signal into digitized form;

alternately separating consecutive ones of the digitized samples into a first odd block and a second even block; and

recording respective groupings of successive digitized samples from said first odd block in alternate ones of said plurality of parallel tracks and respective groupings of successive digitized samples from said second even block in the remaining alternate ones of said plurality of parallel tracks.

2. A method of recording and reproducing a color video signal in a plurality of parallel tracks extending obliquely on a magnetic tape, said color video signal including a chrominance component and a luminance component, said method comprising the steps of:

recording said color video signal in said plurality of parallel tracks, including the steps of;

sampling said color video signal at a frequency which is at least three times the color sub-carrier frequency of the color video signal;

converting the sampled color video signal into digitized form; and

recording respective pluralities of continguous ones of the digitized samples which are arranged in a predetermined sequence sequentially in said plurality of parallel tracks, with each plurality of contiguous ones of the digitized samples corresponding to at least one cycle of the color sub-carrier of said color video signal;

reproducing said color video signal from said plurality of parallel tracks, including the step of;

separating the chrominance component of the reproducing sampled digitized signal in each track by filter means having a chrominance filter characteristic C=(1-Z^-2)/2, where Z is a delay transfer characteristic of the filter means.

3. The method according to claim 2;

in which the step of reproducing said color video signal includes the step of correcting any error in the phase of the color subcarrier of the reproduced color video signal.

4. The method according to claim 3;

in which said step of correcting any error includes the steps of comparing the phase of the color sub-carrier of the separated chrominance component with a reference phase and producing an output in response to such comparison, and correcting any error in the phase of the color sub-carrier of the separated chrominance component in response to said output.

5. A method of recording and reproducing a color video signal in a plurality of parallel tracks extending obliquely on a magnetic tape, said color video signal including a chrominance component and a luminance component, said method comprising the steps of:

recording said color video signal in said plurality of parallel tracks, including the steps of;

sampling said color video signal at a frequency which is four times the color sub-carrier frequency of the color video signal;

converting the sampled color video signal into digitized form;

alternately separating contiguous ones of the digitized samples into first and second blocks; and

recording respective pluralities of successive digitized samples of said first and second blocks sequentially in said plurality of parallel tracks; and

reproducing said color video signal from said plurality of parallel tracks, including the step of;

separating the chrominance component of the reproduced sampled digitized signal in each track by filter means having a chrominance filter characteristic C=1/4(-1+2Z^-2 -Z⁴), where Z is a delay transfer characteristic of the filter means.

6. Apparatus for recording a color video signal in a plurality of parallel tracks extending obliquely on a magnetic tape, comprising:

means for sampling said color video signal at a frequency which is four times the color sub-carrier frequency of the color video signal and for converting the sampled color video signal into digitized form; and

means for alternately separating consecutive ones of the digitized samples into a first odd block and a second even block and for recording respective groupings of successive digitized samples from said first odd block in alternate ones of said plurality of parallel tracks and respective groupings of successive digitized samples from said second even block in the remaining alternate ones of said plurality of parallel tracks.

7. Apparatus for recording and reproducing a color video signal in a plurality of parallel tracks extending obliquely on a magnetic tape, said color video signal including a chrominance component and a luminance component, said apparatus comprising:

a recording section for recording said color video signal in said plurality of parallel tracks, including;

means for sampling said color video signal at a frequency which is at least three times the color sub-carrier frequency of the color video signal and for converting the sampled color video signal into digital form; and

means for recording respective pluralities of the digitized samples which are arranged in a predetermined sequence sequentially in said plurality of parallel tracks, in which said digitized samples in each plurality of digitized samples are arranged in a contiguous manner, with each plurality of contiguous digitized samples corresponding to at least one cycle of the color sub-carrier of said color video signal; and

a reproducing section for reproducing said color video signal from said plurality of parallel tracks, including;

filter means for separating the chrominance component of the reproduced sampled digital signal in each track and having a delay transfer characteristic;

in which said filter means has a chrominance filter characteristic C=(1-Z^-2)/2, where Z is the delay transfer characteristic of the filter means.

8. Apparatus according to claim 7;

in which said filter means includes an input receiving said contiguous digitized samples of each plurality from said plurality of tracks;

sample delay means for delaying the contiguous samples from said input by a period of two samples;

means for subtracting the contiguous samples at the input from said delayed contiguous samples from the sample delay means and producing an output therefrom; and

dividing means for dividing said output by two so as to produce the separated chrominance component.

9. Apparatus according to claim 7;

in which said reproducing section further includes phase correcting means for correcting any error in the phase of the color sub-carrier of the separated chrominance component.

10. Apparatus according to claim 9;

in which said phase correcting means includes phase comparator means for comparing the phase of the color sub-carrier of the separated chrominance component with a reference phase and for producing an output in response thereto, and phase compensating means for correcting any error in the phase of the color sub-carrier of the separated chrominance component in response to the output from said phase comparator means.

11. Apparatus for recording and reproducing a color video signal in a plurality of parallel tracks extending obliquely on a magnetic tape, said color video signal including a chrominance component and a luminance component, said apparatus comprising:

a recording section for recording said color video signal in said plurality of parallel tracks, including;

means for sampling said color video signal at a frequency which is four times the color sub-carrier frequency of the color video signal and for converting the sampled color video signal into digital form; and

means for alternately separating contiguous ones of the digitized samples into first and second blocks and for recording respective pluralities of successive digitized samples of said first and second blocks sequentially in said plurality of parallel tracks; and

a reproducing section for reproducing said color video signal from said plurality of parallel tracks, including;

filter means for separating the chrominance component of the reproduced sampled digital signal in each track and having a chrominance filter characteristic C=1/4(-1+2Z^-2 -Z^-4), where Z is a delay transfer characteristic of the filter means.

12. Apparatus according to claim 11;

in which said filter means includes an input receiving said contiguous digitized samples of said plurality from said plurality of tracks;

first sample delay means for delaying the contiguous samples from said input by a period of two samples;

second sample delay means for further delaying by a period of two samples the delayed contiguous samples from said first sample delay means;

multiplier means for multiplying the delayed contiguous samples from said first sample delay means by two;

means for subtracting the contiguous samples from said input and the delayed samples from said second sample delay means from the delayed samples from said multiplier means; and

dividing means for dividing the output of the means for subtracting by four to produce the separated chrominance component.