Method and apparatus for spline parameter transitions in sound synthesis
AssigneeChromatic Research, Inc.
InventorAvery L. Wang
Life of this patent
Estimating the term…
Abstract
In a sound (music) synthesis system, a transition between levels of a sound parameter (e.g. volume) is synthesized by fitting a cubic (third degree) spline function between two discontinuous parameter levels. This advantageously eliminates any sound artifacts (pops or clicks) which would otherwise be present due to abrupt changes in the parameter. The cubic spline is fitted (interpolated) to match both the parameter value and its derivative with respect to time at each of the adjacent parameter levels on either side of the transition. The transition thus is advantageously kept brief and in addition it is possible to deal with the situation when the parameter dynamically changes during the transition period, again without causing undesirable sound artifacts.
Claims33
A method of controlling a transition in a parameter of a sound with respect to time, comprising the steps of:
- determining a first level of the sound parameter at an initial time, and a second level of the sound parameter at a target time following the initial time;
- and
- fitting a spline function between the first level and the second level over a time increment between the initial time and the target time, wherein the spline function is a smoothly changing value of the sound parameter.
An apparatus for controlling a transition in a sound parameter with respect to time, comprising:
- means for determining a first level of the sound parameter at an initial time, and a second level of the sound parameter at a target time following the initial time;
- and
- means for fitting a spline function between the first level and the second level over a time increment between the initial time and the target time, wherein the spline function is a smoothly changing value of the sound parameter.
An apparatus for controlling a sound parameter during a transition in the sound parameter, the transition being from a first level to a second level of the sound parameter, comprising:
- a timer for timing a duration of the transition;
- and
- a cubic spline calculator operatively coupled to the timer and operating during the timed duration, wherein the cubic spline calculator fits a cubic spline between the first level and the second level.
A method for note stealing to synthesize music, comprising the steps of:
- generating a first note using an oscillator;
- stopping the generation of the first note by reducing its volume to zero;
- generating a second note using the oscillator;
- and
- during a transition from the stopping generation of the first note to the generating of the second note, fitting a spline function between the volume of zero of the first note to a volume of the second note, wherein the spline function is a smoothly changing value of the volume.
A method for note stealing by turning off a quieter note in favor of another note to synthesize music, comprising the steps of:
- generating a first note using an oscillator;
- stopping the generation of the first note by reducing its volume to zero;
- generating a second note using the oscillator;
- and
- during a transition of stopping the generation of the first note, fitting a spline function between the volume of the first note at a beginning of the transition and the volume of zero, wherein the spline function is a smoothly changing value of the volume of the first note.
Dependencies are inferred from the claim text.