FeatureSet: delta methods

Syntax: <feature set> <method> <feature> <source> [-delta <delta>]

Example: fs delta DELTA MEL -delta 2

Methods: When x(i) is the ith frame of the feature <source> then y(i) the ith frame of the destination feature <feature> is calclulated as:

delta

y(i) = x(i+delta) - x(i-delta)

shift

y(i) = x(i-delta)

adjacent

y(i) = x(i-delta), x(i-delta+1), .., x(i), .., x(i+delta-1), x(i+delta)
so y(i) has 2*delta+1 as many coefficients as x(i)

Optional flags:

-delta <delta>

The default for <delta> is 1.