Lossless video data compressor with very high data rate

A video signal processor for processing a video signal, said video signal consisting of a stream of pixel bytes representing the pixels of successive video frames, each of said video frames corresponding to a two-dimensional array of pixel bytes, said video processor comprising:

• a subtractor for converting said stream of pixel bytes into a stream of difference bytes by performing a subtraction between each pixel byte and a preceding pixel byte in said stream;
• the number of bits of said subtractor being equal to the number of bits of said pixel bytes, whereby to discard any carry bit produced by said subtraction;
• means for grouping together in a single group the difference bytes corresponding to a current one of said video frames;
• and
• a minimum length encoder comprising:
• means for ranking the difference bytes occurring in said group in accordance with the population of the difference bytes of the same value in said group, and generating a code table for the current video frame correlating each of said difference bytes with one of a set of minimum length characters, wherein higher ranking difference bytes are assigned to shorter length characters;
• means for replacing each difference byte with the corresponding character in accordance with said code table, so as to produce a stream of minimum length characters, said stream comprising a compressed version of said video signal.

A method of recording in real time onto a storage device video data from a camera or recorder by compensating for a difference in data rate of said video data and a write speed of said storage device, said video data consisting of a stream of pixel bytes representing the pixels of successive video frames, each of said video frames corresponding to a two-dimensional array of pixel bytes, said method comprising:

• converting, by the processor, said stream of pixel bytes into a stream of difference bytes by performing a subtraction between each pixel byte and a preceding pixel byte in said stream;
• discarding, by the processor, any carry bit produced by said subtraction;
• grouping together, by the processor, in a single group the difference bytes corresponding to a current one of said video frames;
• ranking, by the processor, the difference bytes occurring in said group in accordance with the population of the difference bytes of the same value in said group, and generating a code table for the current video frame correlating each of said difference bytes with one of a set of minimum length characters, wherein higher ranking difference bytes are assigned to shorter length characters;
• replacing, by the processor, each difference byte with the corresponding character in accordance with said code table, so as to produce a stream of minimum length characters, said stream comprising a compressed version of said video data;
• and writing the stream of minimum length characters and the code table to a storage device.

A real time video recording system comprising:

• an input port for receiving incoming high speed video camera data in real time at a high data rate nR;
• an output port for providing compressed video data to a digital storage medium at a low data rate R at which the digital storage medium is capable of writing;
• a video signal processor for compressing a video signal comprising the incoming high speed video camera data received at said input port to produce compressed video data at said output port with a compression ratio of at least n, said video signal consisting of a stream of pixel bytes representing the pixels of successive video frames, each of said video frames corresponding to a two-dimensional array of pixel bytes, said video processor comprising:
• a subtractor for converting said stream of pixel bytes into a stream of difference bytes by performing a subtraction between each pixel byte and a preceding pixel byte in said stream;
• the number of bits of said subtractor being equal to the number of bits of said pixel bytes, whereby to discard any carry bit produced by said subtraction;
• means for grouping together in a single group the difference bytes corresponding to a current one of said video frames;
• and
• a minimum length encoder comprising:
• means for ranking the difference bytes occurring in said group in accordance with the population of the difference bytes of the same value in said group, and generating a code table for the current video frame correlating each of said difference bytes with one of a set of minimum length characters, wherein higher ranking difference bytes are assigned to shorter length characters;
• means for replacing each difference byte with the corresponding character in accordance with said code table, so as to produce a stream of minimum length characters, said stream comprising a compressed version of said video signal.