In many contexts, it is necessary to compute the output of a delay line at fractional delay-line lengths.
While signal values in a delay line are stored at integer multiples of the sample period , it is possible to apply interpolation techniques to approximate values between those in memory.
The most common interpolation techniques used in conjunction with delay lines are linear, allpass and cubic spline interpolation.
The Pd delread~ object does not interpolate values in a delwrite~ buffer. Fractional delay lengths that result after a delay argument in milliseconds is converted to samples are either rounded or truncated (the documentation does not say exactly).
When delay line interpolation is needed in Pd, the delread4~ object, which provides 4-point interpolation, should be used.
, it is possible to apply interpolation techniques to approximate values between those in memory.
