Variable Crossfade Tone Synthesis for Smooth Dynamics

Solution Overview

Problem

Conventional tone synthesis apparatuses fail to dynamically adjust waveform switching times based on input dynamics and pitch bend information, leading to undesired tone color variations that can be either delayed or stepwise, affecting the quality of synthesized tones.

Innovation Solution

A tone synthesis apparatus that acquires dynamics and pitch values over time, selects appropriate waveforms, and dynamically sets waveform switching times based on the variation amounts, ensuring smooth and responsive tone color changes through crossfade synthesis.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a fixed crossfade time period is used for waveform switching, then the tone color variation reflects a balanced crossfade time, but the waveform switching cannot respond optimally to sudden dynamics variations

Engineering Contradiction:

Improvetone color variation responsivenessVSAvoidwaveform switching delay

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent applies dynamics by making the crossfade time period variable rather than fixed. The determination section calculates the variation amount of dynamics values over time and uses this to dynamically adjust the crossfade time period. When dynamics vary rapidly (sudden attacks), the crossfade time is shortened to reduce delay. When dynamics vary slowly, the crossfade time is extended to maintain smooth transitions, thus optimizing waveform switching response to actual performance dynamics.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent implements feedback by continuously monitoring the dynamics values over time and using this information to adjust the crossfade time period. The determination section refers to past dynamics values (acquired at predetermined time intervals) to calculate variation amounts, which then feed back into controlling the crossfade synthesis process. This closed-loop control ensures the waveform switching adapts to the actual temporal characteristics of the performance.

Inventive Principle:

Principle #23Feedback

2Stability of the object's composition

If a fixed crossfade time period is used for waveform switching, then the tone color variation is balanced, but stepwise tone color changes occur when dynamics vary slowly

Engineering Contradiction:

Improvetone color smoothnessVSAvoidtone color variation precision

Core Design Contradiction:

Stability of the object's compositionVSManufacturing precision

Solution Approach 1:

The patent applies dynamics by making the crossfade time period variable rather than fixed. The determination section calculates the variation amount of dynamics values over time and uses this to dynamically adjust the crossfade time period. When dynamics vary rapidly (sudden attacks), the crossfade time is shortened to reduce delay. When dynamics vary slowly, the crossfade time is extended to maintain smooth transitions, thus optimizing waveform switching response to actual performance dynamics.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the parameter of crossfade time period from a fixed value to a variable parameter that adapts to performance characteristics. By modifying this temporal parameter based on the calculated variation amount of dynamics values, the system achieves both responsive waveform switching and smooth tone color transitions, eliminating stepwise changes while maintaining precision in following the performer's intentions.

Inventive Principle:

Principle #35Parameter changes

3Speed

If waveform switching is accelerated to follow sudden dynamics changes, then responsiveness improves, but tone color smoothness deteriorates

Engineering Contradiction:

Improvewaveform switching speedVSAvoidtone color smoothness

Core Design Contradiction:

SpeedVSStability of the object's composition

Solution Approach 1:

The patent applies dynamics by making the crossfade time period variable rather than fixed. The determination section calculates the variation amount of dynamics values over time and uses this to dynamically adjust the crossfade time period. When dynamics vary rapidly (sudden attacks), the crossfade time is shortened to reduce delay. When dynamics vary slowly, the crossfade time is extended to maintain smooth transitions, thus optimizing waveform switching response to actual performance dynamics.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS7432435B2Tone synthesis apparatus and method

Publication Date: 2008.10.07 YAMAHA CORP

AI summary

Dynamics value is acquired intermittently at predetermined time periods, and a waveform data set for a sustain tone, corresponding to the acquired dynamics value, is specified from among waveform data sets stored in a memory. To generate a tone waveform while switching to the specified waveform, a waveform switching time is used which is modified suitably in accordance with a dynamics value variation amount from a predetermined time earlier than the current dynamics value acquisition time to the current dynamics value acquisition time. Such arrangements not only can variably control a tone, having a tone-color-variation realizing characteristic, in accordance with the input dynamics value but also permits a tone color variation with an enhanced responsiveness without causing the tone color variation to impart a feeing of undesired step-like unsmoothness, thereby synthesizing a tone with a high quality faithfully reproducing a desired tone color variation.