A signal modification technique facilitates compact voice coding by
employing a continuous, rather than piece-wise continuous, time warp
contour to modify an original residual signal to match an idealized
contour, avoiding edge effects caused by prior art techniques. Warping is
executed using a continuous warp contour lacking spatial discontinuities
which does not invert or overly distend the positions of adjacent end
points in adjacent frames. The linear shift implemented by the warp
contour is derived via quadratic approximation or other method, to reduce
the complexity of coding to allow for practical and economical
implementation. In particular, the algorithm for determining the warp
contour uses only a subset of possible contours contained within a
sub-range of the range of possible contours. The relative correlation
strengths from these contours are modeled as points on a polynomial trace
and the optimum warp contour is calculated by maximizing the modeling
function.
