Digital video storage
First Claim
1. Apparatus for digitally encoding an analog composite color NTSC video signal, and for subsequently displaying the color picture signal appearing in each horizontal scan line of the resulting encoded signal, comprisingan analog-to-digital converter for generating digital samples of the color burst signal appearing in each said horizontal scan line, andmeans for providing a reproduction of said color burst signal generated directly from and based solely on said digital samples of said color burst signal, said means for providing including means for storing a sequence of said samples, and means for repeatedly withdrawing said samples from said storing means for delivery at a rate and in an order such that said withdrawn samples represent a reproduction of said color burst signal having a predetermined phase relationship to said subsequently displayed color picture signal.
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Abstract
A simple, efficient technique for encoding NTSC video signals features sampling the signal at 8/3 the subcarrier frequency, generating no more than 256K samples for a full 525 line frame, generating as many samples per horizontal scan line as there are columns in a memory where the frame is to be stored, incrementing a row address counter for the memory once for each new horizontal scan line, and providing an analog reproduction of the color burst signal directly from and based solely on the digital samples of the color burst signal.
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Citations
25 Claims
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1. Apparatus for digitally encoding an analog composite color NTSC video signal, and for subsequently displaying the color picture signal appearing in each horizontal scan line of the resulting encoded signal, comprising
an analog-to-digital converter for generating digital samples of the color burst signal appearing in each said horizontal scan line, and means for providing a reproduction of said color burst signal generated directly from and based solely on said digital samples of said color burst signal, said means for providing including means for storing a sequence of said samples, and means for repeatedly withdrawing said samples from said storing means for delivery at a rate and in an order such that said withdrawn samples represent a reproduction of said color burst signal having a predetermined phase relationship to said subsequently displayed color picture signal.
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10. Apparatus for digitally encoding an analog composite color NTSC video signal, said apparatus comprising
an input port for receiving said signal, an analog-to-digital converter for generating digital samples of said signal at a predetermined sampling rate, and an output for delivering said digital samples at said rate, said delivered digital samples spanning less than all of said color video signal, said predetermined sampling rate being 8/3 times the subcarrier frequency of the NTSC signal, said samples including samples of some but less than all of the color burst signal.
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17. Apparatus for digitally encoding an analog composite color NTSC video signal representing a 525-line video frame, each line including a color burst signal portion, said apparatus comprising
an input port for receiving said signal, an analog-to-digital converter for generating digital samples of selected portions of each said line, and an output port for delivering said digital samples, said digital samples spanning less than all of said color video signal and including samples of said color burst signal, to capture an entire said frame in a set of said digital samples numbering no more than 256K samples.
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20. Apparatus for digitally encoding and storing the horizontal scan lines of an analog composite color NTSC video signal that includes a color picture signal portion and a burst signal portion, said apparatus comprising
an input port for receiving said composite color NTSC video signal, an analog-to-digital converter for generating digital samples of said video signal, a memory for storing said digital samples including samples of some but less than all of said color burst signal portion, said memory having a row address input for receiving a row address specifying a row in said memory, and a column address input for receiving a column address specifying a column in said memory, a row counter for delivering row addresses to said row address input, a horizontal synch detector for detecting the horizontal synch signal in each said horizontal scan line and for providing an increment signal in response to said horizontal synch signal to cause said row counter to increment by one for each succeeding said horizontal scan line in said NTSC video signal, a column counter for delivering column addresses to said column address input, said column counter being incremented by one for each successive digital sample generated from a given said scan line, the number of said samples generated for each said horizontal scan line being equal to the number of columns in said memory.
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22. A method for digitally encoding an analog composite color NTSC video signal and for subsequently demodulating the color picture signal appearing in each horizontal scan line of the resulting encoded signal, said method comprising the steps of:
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generating by analog-to-digital conversion digital samples of the color burst signal appearing in each horizontal sacn line, storing a sequence of said samples, and providing by digital-to-analog conversion an analog reproduction of said color burst signal based only on said digital samples of said color burst signal, by repeatedly withdrawing said stored samples for delivery at a rate and in an order such that said withdrawn samples represent a reproduction of said color burst signal having a predetermined phase relationship to said reproduction of said color picture signal.
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23. A method for digitally encoding an analog composite color NTSC video signal for a 525-line video frame, each line including a color burst signal portion, said method comprising the step of
generating, by analog-to-digital conversion, digital samples spanning less than all of the color video signal and including samples of said color burst signal, to capture an entire said frame, said generated samples numbering no more than 256K samples.
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24. A method for digitally encoding and storing the horizontal scan lines of an analog composite color NTSC video signal that includes a color picture signal portion and another signal portion, said method comprising the steps of
generating digital samples of said video signal, storing said samples including samples of some but less than all of said other signal portion in a memory having row and column address inputs, detecting the horizontal synch signal in each said horizontal scan line, incrementing the row address once for each succeeding horizontal scan line, and incrementing the column address once for each successive digital sample from a given scan line, the number of samples generated for each horizontal scan line being equal to the number of columns in the memory.
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25. Apparatus for digitally encoding an analog composite color NTSC video signal, and for subsequently displaying the color picture signal appearing in each horizontal scan line of the resulting encoded signal, comprising
an analog-to-digital converter for generating digital samples of the color burst signal appearing in each said horizontal scan line, said digital samples spanning some but less than all of said color burst signal, and means for providing a reproduction of said color burst signal generated directly from and based solely on said digital samples of said color burst signal, said means for providing including means for storing a sequence of said samples, and means for withdrawing said samples from said storing means for delivery at a rate and in an order such that said withdrawn samples represent a reproduction of said color burst signal having a predetermined phase relationship to said subsequently displayed color picture signal.
Specification