Video signal dropout compensator

• US 4,250,521 A
• Filed: 07/19/1979
• Issued: 02/10/1981
• Est. Priority Date: 07/19/1979
• Status: Expired due to Term

• Current Assignee: RCA Corporation (General Electric Company)
• Original Assignee: RCA Corporation (General Electric Company)
• Inventors: Wright, David I.
• Primary Examiner(s): Konick, Bernard
• Assistant Examiner(s): Psitos, Aristotelis M.
• Application Number:
  US06/059,112
• Time in Patent Office: 572 Days
• Field of Search: 358/8, 358/21, 360/36, 360/38
• US Class Current: 348/616
• CPC Class Codes: H04N 9/888 for signals recorded by pulse code modulation

Abstract

A video signal dropout compensator stores information from at least one incoming television line which is represented by a plurality of samples of combined liminance and chrominance signal components. The samples occur at a rate equal to four times the chrominance subcarrier frequency. When a signal dropout is detected in one or more of the samples, a replacement sample is generated using samples from at least one adjacent television line. The value of the sample on the adjacent line at the horizontal location, corresponding to the dropout sample, is subtracted from the sum of the samples before and after this corresponding location sample. The resultant value gives a dropout replacement sample with proper chrominance phase having a close approximation of the correct luminance value.

Claims

1. A video signal dropout compensator for forming a replacement signal for a video signal dropout occurring in a television line, said dropout compensator comprising:

means for providing a video signal from at least one television line adjacent to the line in which said dropout occurred;

means for providing a first dropout replacement component comprising a signal value from said video signal at a horizontal position corresponding to the position of said dropout within a television line;

means for providing a second dropout replacement component comprising a signal value from said video signal at a horizontal position corresponding to one-quarter cycle of the chrominance subcarrier frequency immediately preceding said dropout;

means for providing a third dropout replacement component comprising a signal value from said video signal at a horizontal position corresponding to one-quarter cycle of the chrominance subcarrier frequency immediately following said dropout;

means for providing a dropout replacement signal comprising means for combining said first, second and third dropout replacement components; and

means for replacing said dropout with said dropout replacement signal.

2. The video signal dropout compensator defined in claim 1 wherein said means for providing a dropout replacement signal comprises means for adding said second and third dropout replacement components together and subtracting said first dropout replacement component therefrom.

3. A video signal dropout compensator for forming a replacement signal for a video signal dropout occurring in a television line, said dropout compensator comprising:

means for providing a plurality of video signal samples from two television lines adjacent to the line in which said signal dropout occurred, said samples occurring at a rate equal to an integer multiple of four times the color subcarrier frequency;

means for combining the samples at identical horizontal positions in said two adjacent television lines to provide a single combined television line comprising the average value of the signal samples in said two adjacent lines;

means for providing a first dropout replacement sample component comprising the sample from said combined television line occurring at the same horizontal position as said dropout;

means for providing a second dropout replacement sample component comprising the sample from said combined television line immediately preceding the sample occurring at the same horizontal position as said dropout;

means for providing a third dropout replacement sample component comprising the sample from said combined television line immediately following the sample at the same horizontal position as said dropout;

means for providing a dropout replacement signal comprising means for adding said second and third dropout replacement sample components together and subtracting said first dropout replacement sample component therefrom; and

means for replacing said dropout with said dropout replacement signal.

4. A video signal dropout compensator for forming a replacement signal for a video signal dropout occurring in a television line, said dropout compensator comprising:

means for providing a plurality of video signal samples in a television line adjacent to and preceding the line in which the signal dropout occurred, said samples occurring at a rate equal to an integer multiple of four times the color subcarrier frequency;

means for providing a first dropout replacement sample component comprising the sample from said adjacent television line at the same horizontal position as said dropout;

means for providing a second dropout replacement sample component comprising the sample from said adjacent line immediately preceding the sample at the same horizontal position as said dropout;

means for providing a third dropout replacement sample component comprising the sample from said adjacent television line immediately following the sample at the same horizontal position as said dropout;

means for providing a dropout replacement signal comprising means for adding said second and third dropout replacement sample components together and subtracting said first dropout replacement sample component therefrom; and

means for replacing said dropout with said dropout replacement signal.

5. A method for forming a replacement signal for a video signal dropout occurring in a television line, comprising:

providing a video signal from at least one television line adjacent to the line in which said signal dropout occurred;

providing a first dropout replacement component comprising a signal value from said video signal at a horizontal position corresponding to the position of said dropout within a television line;

providing a second dropout replacement component comprising a signal value from said video signal at a horizontal position corresponding to one-quarter cycle of the color subcarrier frequency immediately preceding said dropout;

providing a third dropout replacement component comprising a signal value from said video signal at a horizontal position corresponding to one-quarter cycle of the color subcarrier frequency immediately following said dropout;

providing a dropout replacement signal by combining said first and second and third dropout replacement components; and

replacing said dropout with said dropout replacement signal.

6. The method for forming a dropout replacement signal defined in claim 5 wherein the step of providing a dropout replacement signal comprises adding said second and third dropout replacement components together and subtracting said first dropout replacement component therefrom.

7. A method for forming a replacement signal for a video signal dropout occurring in a television line comprising:

providing a plurality of video signal samples from two television lines adjacent to the line in which said signal dropout occurred, said samples occurring at a rate equal to an integer multiple of four times the color subcarrier frequency;

combining the samples at the same horizontal position in said two adjacent television lines to provide a single combined television line comprising the average value of the signal samples in said two adjacent lines;

providing a first dropout replacement sample component comprising the sample from said combined television line occurring at the same horizontal position as said dropout;

providing a second dropout replacement sample component comprising the sample from said combined television line immediately preceding the sample occurring at the same horizontal position as said dropout;

providing a third dropout replacement sample component comprising the sample from said combined television line immediately following the sample occurring at the same horizontal position as dropout;

adding said second and third dropout replacement sample components together and subtracting said first dropout replacement sample component therefrom; and

replacing said dropout with said dropout replacement signal.

8. A method for forming a replacement signal for a video signal dropout occurring in a television line, comprising:

providing a plurality of video signal samples in a television line adjacent to and preceding the line in which the signal dropout occurred, said samples occurring at a rate equal to an integer multiple of four times the video subcarrier frequency;

providing a first dropout replacement sample component comprising the sample from said adjacent television line at the same horizontal position as said dropout;

providing a second dropout replacement sample component comprising the sample from said adjacent line immediately preceding the sample at the same horizontal position as said dropout;

providing a third dropout replacement sample component comprising the sample from said adjacent television line immediately following the sample at the same horizontal position as said dropout;

adding said second and third dropout replacement sample components together and subtracting said first dropout replacement sample component therefrom; and

replacing said dropout with said dropout replacement signal.