Time division multiplexing of video redundancy reduction data compressors

Claim 2

In combination, a plurality of data compressors each one of which has a buffer memory means for storing selected video samples taken from successive frames of a video signal, and a counting means for registering the number of video frames corresponding to the samples stored in said buffer memory means, means for transmitting samples, and a time division multiplex switching means responsive to said counting means in each of said plurality of data compressors for selectively connecting to said transmitting means the data compressor having stored samples corresponding to the largest number of video frames.

Claim 3

The combination as defined in claim 1 wherein each of said plurality of data compressors also includes a second counting means for registering the number of samples stored in its corresponding buffer memory means, and said time division multiplex switching means in response to said second counting means selectively connects the data compressor having the largest number of samples in storage to said transmitting means when said first-mentioned counting means indicates that all of said data compressors have samples stored in their buffer memory means which correspond to the same number of video frames.

Claim 4

Asynchronous time division multiplexing apparatus in combination with a plurality of data compressors each of which reduces the redundancy in the samples transmitted from a video signal, frame memory means within each of said plurality of data compressors for storing an entire frame of video samples, means within each of said plurality of data compressors for comparing each new video sample with a previously stored video sample from said frame memory means to produce an energizing signal if the difference between the new sample and stored sample exceeds a threshold level, buffer memory means within each of said plurality of data compressors for storing said new sample in response to said energizing signal, a counting means within each of said plurality of data compressors for registering the number of video frames corresponding to the samples stored in its corresponding buffer memory means, means for transmitting video samples, a time division multiplex switching means for selectively connecting the samples stored in the buffer memory means of said plurality of data compressors to said transmitting means in response to a control signal, control means responsive to the counting means in each of said plurality of data compressors for providing a control signal to said multiplex switching meaNs which causes the data compressor having samples stored in its buffer memory means which correspond to the largest number of video frames to be connected to said transmitting means.

Claim 5

Asynchronous time division multiplexing apparatus in combination with a plurality of data compressors each of which reduces the redundancy in the samples transmitted from a video signal, frame memory means within each of said plurality of data compressors for storing an entire frame of video samples, means within each of said plurality of data compressors for comparing each new video sample with a previously stored video sample from said frame memory means to produce an energizing signal if the difference between the new sample and stored sample exceeds a threshold level, buffer memory means within each of said plurality of data compressors for storing said new sample in response to said energizing signal, a counting means within each of said plurality of data compressors for registering the number of video frames corresponding to the samples stored in its corresponding buffer memory means, means for transmitting video samples, a time division multiplex switching means for selectively connecting the samples stored in the buffer memory means of said plurality of data compressors to said transmitting means in response to a control signal, control means responsive to the counting means in each of said plurality of data compressors for providing a control signal to said multiplex switching meaNs which causes the data compressor having samples stored in its buffer memory means which correspond to the largest number of video frames to be connected to said transmitting means.

Claim 6

Apparatus as defined in claim 3 wherein the combination further includes a second counting means within each of said plurality of data compressors for registering the number of samples stored in its corresponding buffer memory means, and said control means responds to said second counting means in each of said plurality of data compressors for providing a control signal to said multiplex switching means which causes the data compressor having the largest number of samples in storage in its buffer memory means to be connected to said transmitting means when said first-mentioned counting means indicates that all data compressors of said plurality of data compressors have samples stored in their buffer memory means which correspond to the same number of video frames.

Claim 7

Apparatus as defined in claim 3 wherein said control means includes means for counting the number of samples transmitted from each of said plurality of data compressors within a predetermined interval, and means for changing said threshold level in response to said means for counting the number of samples transmitted.

Claim 8

Apparatus as defined in claim 4 wherein said control means includes means for counting the number of samples transmitted from each of said plurality of data compressors within a predetermined interval, and means for changing said threshold level in response to both said means for counting the number of samples transmitted and said second counting means for registering the number of samples stored.

Claim 9

Apparatus as defined in claim 6 wherein said means for changing said threshold level includes means for deriving a figure of use for each buffer memory means, the figure of use being equal during any given instant to a decay factor times the sum of the number of samples transmitted from its corresponding buffer memory means during the last predetermined interval and the figure of use value during the last predetermined interval.

Claim 10

Apparatus as defined in claim 7 wherein said means for changing said threshold level further includes means for deriving an average figure of use and means for comparing each figure of use to the average figure use, a change in threshold level being indicated only when a figure of use differs by more than a predetermined amount from the average figure of use.

Claim 11

Asynchronous time division multiplexing apparatus in combination with a plurality of data compressors each of which reduces the redundancy in the samples transmitted from a video signal, frame memory means within each of said plurality of data compressors for storing an entire frame of video samples, means within each of said plurality of data compressors for comparing each new video sample with a previously stored video sample from said frame memory means to produce a difference signal, buffer memory means within each of said plurality of data compressors for storing samples to be transmitted, a counting means within each of said plurality of data compressors for registering the number of samples stored in said buffer memory means and for further registering the number of video frames to which these stored samples correspond, a threshold circuit means within each of said plurality of data compressors for writing said new video sample into its corresponding buffer memory means if said difference signal is determined to exceed a threshold level, said threshold level being a function of the number of samples stored in its corresponding buffer memory means, means for transmitting video samples, a time division multiplex switching means responsive to said counting means for selectively connecting the samples in the buffer memory means of said plurality of data compressors to said transmitting means, means for counting the number of samples transmitted from each of said plurality of data compressors within a predetermined inTerval, and means for changing said threshold level in response to said means for counting the number of samples transmitted.

Claim 12

Asynchronous time division multiplexing apparatus in combination with a plurality of data compressors each of which reduces the redundancy in the samples transmitted from a video signal, frame memory means within each of said plurality of data compressors for storing an entire frame of video samples, means within each of said plurality of data compressors for comparing each new video sample with a previously stored video sample from said frame memory means to produce a difference signal, buffer memory means within each of said plurality of data compressors for storing samples to be transmitted, a counting means within each of said plurality of data compressors for registering the number of samples stored in said buffer memory means and for further registering the number of video frames to which these stored samples correspond, a threshold circuit means within each of said plurality of data compressors for writing said new video sample into its corresponding buffer memory means if said difference signal is determined to exceed a threshold level, said threshold level being a function of the number of samples stored in its corresponding buffer memory means, means for transmitting video samples, a time division multiplex switching means responsive to said counting means for selectively connecting the samples in the buffer memory means of said plurality of data compressors to said transmitting means, means for counting the number of samples transmitted from each of said plurality of data compressors within a predetermined inTerval, and means for changing said threshold level in response to said means for counting the number of samples transmitted.

Claim 13

Apparatus as defined in claim 9 wherein said means for changing said threshold level includes means for deriving a figure of use for each buffer memory means, the figure of use being equal during any given instant to a decay factor times the sum of the number of samples transmitted from its corresponding buffer memory means during the last predetermined interval and the figure of use value during the last predetermined interval.

Claim 14

Apparatus as defined in claim 10 wherein said means for changing said threshold level further includes means for deriving an average figure of use and means for comparing each figure of use to the average figure of use, a change in threshold level being indicated only when a figure of use differs by more than a predetermined amount from the average figure of use.