Digital video processing

A method of digital video processing in which an output compressed video signal is derived from an input compressed video signal;

• (i) said input compressed video signal representing successive input pictures, in which subsets of said pictures are derived from other input pictures in accordance with a repetitive group of pictures (GOP) structure, using input picture motion vectors;
• (ii) said output video signal representing successive output pictures, in which subsets of said pictures are derived from other pictures in accordance with a repetitive GOP structure different to or not picture-aligned with that of said input compressed video signal, using output picture motion vectors;
• said method comprising deriving said output picture motion vectors from said input picture motion vectors and comparing magnitudes of respective output picture motion vectors with a test magnitude;
• whereby said test magnitude is an average magnitude of a plurality of motion vectors associated with surrounding picture areas;
• and
• whereby said comparing includes determining whether the magnitudes of said output picture motion vectors differ from said average magnitude by more than a predetermined percentage.

Digital video processing apparatus in which an output compressed video signal is derived from an input compressed video signal;

• (i) said input compressed video signal representing successive input pictures, in which subsets of the pictures are derived from other input pictures in accordance with a repetitive group of pictures (GOP) structure, using input picture motion vectors;
• (ii) said output video signal representing successive output pictures, in which subsets of said pictures are derived from other pictures in accordance with a repetitive GOP structure different to or not picture-aligned with that of said input compressed video signal, using output picture motion vectors;
• said apparatus comprising a motion vector processor for deriving said output picture motion vectors from said input picture motion vectors, a correlation detector for detecting correlation of blocks of pixels pointed to by a motion vector generated by said motion vector processor and for altering said motion vector in response to said detection, and a motion vector tester for comparing magnitudes of respective motion vectors output by said motion vector processor with a test magnitude;
• whereby said test magnitude is an average magnitude of a plurality of motion vectors associated with surrounding picture areas;
• and
• whereby said comparing includes determining whether the magnitudes of said output picture motion vectors differ from said average magnitude by more than a predetermined percentage.

A method of digital video processing in which an output compressed video signal is derived from an input compressed video signal;

• (i) said input compressed video signal representing successive input pictures, in which subsets of the pictures are derived from other input pictures in accordance with a repetitive group of pictures (GOP) structure, using input picture motion vectors;
• (ii) said output video signal representing successive output pictures, in which subsets of said pictures are derived from other pictures in accordance with a repetitive GOP structure different to or not picture-aligned with that of said input compressed video signal, using output picture motion vectors;
• said method comprising the steps of deriving said output picture motion vectors from said input picture motion vectors, detecting correlation of blocks of pixels pointed to by a motion vector generated in said step of deriving, altering said motion vector according to said step of detecting, and comparing magnitudes of respective output picture motion vectors with a test magnitude;
• whereby said test magnitude is an average magnitude of a plurality of motion vectors associated with surrounding picture areas;
• and
• whereby said comparing includes determining whether the magnitudes of said output picture motion vectors differ from said average magnitude by more than a predetermined percentage.