Phrase Waveform Data Selection for Realistic Ethnic Instrument Accompaniment
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Solution Overview
Problem
Conventional automatic accompaniment apparatuses face challenges in generating realistic accompaniment for ethnic instruments with peculiar scales and struggle to maintain sound quality when changing the tempo of phrase waveform data, often resulting in deterioration of waveform concatenation due to reliance on MIDI or time stretching.
Innovation Solution
An accompaniment data generating apparatus that stores phrase waveform data for various chords and reference notes, allowing for selection and reading of data based on calculated performance speed and tone pitch adjustments, combined with time stretching to maintain sound quality during tempo changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If time stretching is used to adjust the length of waveform data on the time axis, then the tempo can be changed, but sound quality deteriorates due to waveform concatenation issues
Solution Approach 1:
The waveform data is divided into multiple partial waveforms corresponding to different phrases. By segmenting the accompaniment data into manageable units (first partial waveform, second partial waveform, etc.), the system can selectively concatenate pre-adjusted segments rather than stretching the entire waveform, thereby maintaining sound quality while achieving tempo adjustment.
Solution Approach 2:
The waveform data is pre-processed by dividing it into partial waveforms and storing them separately before actual playback. This preliminary segmentation allows the system to efficiently concatenate pre-adjusted segments during performance, avoiding real-time stretching operations that degrade sound quality.
2Extent of automation
If MIDI data is used for automatic accompaniment, then the accompaniment can be generated automatically, but it is difficult to achieve realistic performance for ethnic instruments with peculiar scales
Solution Approach 1:
Instead of generating accompaniment tones synthetically via MIDI, the system records and stores actual waveform data from real instrument performances. By copying and reproducing authentic recorded performances, the system maintains the natural characteristics and realism of ethnic instruments while still providing automatic accompaniment functionality.
3Adaptability or versatility
If phrase waveform data is stored for multiple reference notes, then the adaptability to different chords increases, but the device complexity increases
Solution Approach 1:
The system stores a limited set of phrase waveform data corresponding to different reference notes (e.g., C, F, G), and through pitch shifting and concatenation operations, makes these stored phrases serve multiple chords. This multi-functional approach allows the same stored data to accompany various chords, reducing the need to store separate data for every possible chord while maintaining high adaptability.
Data Source
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AI summary
An accompaniment data generating apparatus has phrase waveform data storing means (8,15) for storing sets of phrase waveform data (PW) each indicative of a phrase of accompaniment tones performed at a reference tempo and each corresponding to a different reference note. By program processing, the accompaniment data generating apparatus obtains a reproduction tempo (SA2), obtains the first reference note (SB2, SB3, SB5), selects a set of phrase waveform data corresponding to the second reference note whose tone pitch is different from a tone pitch of the first reference note (SB5 to SB7, SB9, SB10, SB13, SB14), and reads out the selected phrase waveform data set at a speed by which the tone pitch of the second reference note of the selected phrase waveform data set agrees with the tone pitch of the first reference note of a case where a set of phrase waveform data corresponding to the first reference note is reproduced at the reference note (SB5 to SB7, SB11, SB12, SB16).