US 5,570,131 AGranted

Pseudo-digital compression of video signals

OwnerH. George Piresinventor

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Abstract

A system for transmitting multiple video signals via a single video channel, each video signal having a luminance component in respective sequential horizontal line periods. Luminance components of the video signals are separated and compressed. An output video signal having sequential output horizontal line periods is formed and the compressed luminance components are inserted in the output horizontal line periods. Chroma components are compressed by a higher compression factor and inserted in the blanking intervals. The two color video signals are compressed into one standard 4.2 MHz channel, permitting the system to replace directly any existing 6 MHz audio/video transmission system. An encoder aspect of the invention combines plural video source channels to form an output video channel for transmission, using first and second decoders for separating the input video signal into respective luminance and chroma signals. A compressor compresses the luminance and chroma signals, and a multiplexer selects alternately between the decoders. A decoder system extracts the video channels from the encoded video signal. An analog-to-digital converter issues luminance digital data corresponding to a luminance component of the encoded video signal. A luminance expander expands the luminance digital data, and a demultiplexer alternately produces portions of the time-expanded luminance digital data corresponding to respective ones of the video channels. Sync information is regenerated at the decoders from the vertical sync pulses which are left intact in the transmitted signal. Interpolated chroma information is provided to reconstructed video channels.

Claims25

Dependent claims

A method of combining first and second video signals for transmission via a single video channel, each of said first and second video signals being of the type having a luminance component within each of a plurality of sequentially recurring horizontal line periods, the method comprising the steps of:

first separating a luminance component of the first video signal during a respective first horizontal line period;
second separating a luminance component of the second video signal during a respective first horizontal line period;
first time compressing the luminance component of the first video signal by a predetermined compression factor;
second time compressing the luminance component of the second video signal by a predetermined compression factor;
forming an output video signal having a plurality of sequential output horizontal line periods;
first inserting the time-compressed luminance component of the first video signal in a selected one of the output horizontal line periods;
second inserting the time-compressed luminance component of the second video signal in a selected one of the output horizontal line periods;
digitizing said luminance component of the first video signal to produce first digital data corresponding to said first video signal;
writing said first digital data in a first memory location;
digitizing said luminance component of the second video signal to produce second digital data corresponding to said second video signal;
writing said second digital data in a second memory location;
third separating a first chroma component of the first video signal during a respective first horizontal line period;
fourth separating a first chroma component of the second video signal during a respective first horizontal line period;
third time compressing the first chroma component of the first video signal by a predetermined compression factor;
fourth time compressing the first chroma component of the second video signal by a predetermined compression factor;
third inserting the time-compressed first chroma component of the first video signal in said selected one of the output horizontal line periods;
and
fourth inserting the time-compressed first chroma component of the second video signal in said selected one of the output horizontal line periods;
wherein:
said step of third inserting is performed into a synchronization data portion of said selected one of the output horizontal line periods;
and
said step of fourth inserting is performed into a synchronization data portion of said selected one of the output horizontal line periods.

19 more elements

A method of decoding a source video signal to produce a plurality of video channels therefrom, the method comprising the step of forming a first video channel signal having a plurality of sequential horizontal intervals, said step of forming comprising the steps of:

extracting from the source video signal a first luminance component signal related to a first one of the plurality of video channels;
inserting said first luminance component signal in a first one of said horizontal intervals of said first video channel;
extracting from the source video signal a second luminance component signal related to the first video channel;
inserting said second luminance component signal in a second one of said horizontal intervals of said first video channel;
extracting from the source video signal a first chroma component signal related to the first one of the plurality of video channels;
inserting said first chroma component signal in said first one of said horizontal intervals of said first video channel;
and
inserting said first chroma component signal in said second one of said horizontal intervals of said first video channel, whereby said first chroma component signal is repeated in said second one of said horizontal intervals.

5 more elements

An encoding system for combining a plurality of video source channels to form an output video channel for transmission, the encoding system comprising:

first and second decoder means, each having a video input for receiving a respectively associated input video signal corresponding to one of the video source channels, for separating said input video signal into respective luminance and chroma signals at respective luminance and chroma outputs, said luminance signal comprising luminance information corresponding to respective horizontal periods, and said chroma comprising chroma information associated with luminance information corresponding to a respectively associated predetermined horizontal period, said chroma information being repeated over a subsequent horizontal period;
compressor means for compressing in time said luminance and chroma signals, said compressor means being further provided with;
a first compressor coupled to said first decoder means for compressing in time said luminance signal issued by said first decoder means;
a second compressor coupled to said second decoder means for compressing in time said luminance signal issued by said second decoder means;
a third compressor coupled to said first decoder means for compressing in time said chroma signal issued by said first decoder means;
and
a fourth compressor coupled to said second decoder means for compressing in time said chroma signal issued by said second decoder means;
and
multiplexer means coupled to said compressor means for selecting alternately between said first and second decoder means.

6 more elements

A method of scrambling first and second video signals for transmission via a single video channel, each of said first and second video signals being of the type having a luminance component within each of a plurality of sequentially recurring horizontal line periods, the method comprising the steps of:

first separating a luminance component of the first video signal during a respective first horizontal line period;
second separating a luminance component of the second video signal during a respective first horizontal line period;
first time compressing the luminance component of the first video signal by a predetermined compression factor;
second time compressing the luminance component of the second video signal by a predetermined compression factor;
forming an output video signal having a plurality of sequential output horizontal line periods;
determining a predetermined scrambling pattern related to said sequential output horizontal line periods;
first inserting the time-compressed luminance component of the first video signal in a one of the output horizontal line periods selected in response to said predetermined scrambling pattern;
and
second inserting the time-compressed luminance component of the second video signal in a one of the output horizontal line periods selected in response to said predetermined scrambling pattern.

6 more elements

A method of decoding a source video signal to produce a plurality of video channels therefrom, the method comprising the steps of:

forming first and second video channel signals each having a respective plurality of sequential horizontal intervals, said step of forming further comprising the steps of:
extracting from the source video signal a first luminance component signal related to a first one of the plurality of video channels;
inserting said first luminance component signal in a first one of said horizontal intervals of said first video channel;
extracting from the source video signal a second luminance component signal related to the first video channel;
inserting said second luminance component signal in a second one of said horizontal intervals of said first video channel;
extracting from the source video signal a first luminance component signal related to a second one of the plurality of video channels;
inserting said first luminance component signal in a first one of said horizontal intervals of said second video channel;
extracting from the source video signal a second luminance component signal related to the second video channel;
and
inserting said second luminance component signal in a second one of said horizontal intervals of said second video channel;
and
adding chroma information to said first video channel, said step of adding chroma information comprising the steps of:
extracting from the source video signal a first chroma component signal related to said first one of the plurality of video channels;
inserting said first chroma component signal in said first one of said horizontal intervals of said first video channel;
interpolating said first chroma component signal with a further chroma component signal associated with said first one of the plurality of video channels to form an interpolated chroma component signal;
and
inserting said interpolated chroma component signal in said second one of said horizontal intervals of said first video channel.

14 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/328,672Filed 25 Oct 1994
Granted: 29 Oct 1996
Term ends: Not estimatedThe source records don’t support an estimate.

Classification5 codes

H04N 7/0806
Systems for the simultaneous or sequential transmission of more than one television signal, e.g. additional information signals, the signals…: the…
H04N 7/0855
The inserted signal being digital: the signal being time-compressed before its insertion and subsequently decompressed at reception
H04N 11/02
Colour television systems: with bandwidth reduction
H04N 11/08
Transmission systems characterised by the manner in which the individual colour picture signal components are combined: using sequential signals only