Audio DSP Preset Switching for Low-Overhead Equalizer Control
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Solution Overview
Problem
Existing digital signal processors for audio systems require significant data transmission between the microcomputer and DSP during audio reproduction, which can lead to interruptions in data transmission for spectrum analysis and increased overhead, especially with interfaces like I2C, affecting the display of correct frequency spectra.
Innovation Solution
A digital signal processor configuration that stores all preset setting data during startup and transmits only selection data during audio reproduction, using an interface circuit and coefficient setting circuit to manage multi-band equalizers and delay circuits, reducing data transmission and supporting presets for reverberation and acoustic adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If all preset setting data is transmitted during audio reproduction, then the DSP can maintain accurate frequency spectra, but data transmission overhead increases and causes interruptions
Solution Approach 1:
The patent applies preliminary action by transmitting and storing all preset setting data in the DSP during system startup before audio reproduction begins. This allows the DSP to have all necessary coefficient data readily available in its memory during audio playback, eliminating the need for continuous data transmission interruptions. The microcomputer sends complete preset data sets (multiple coefficient groups) upfront, and the DSP switches between them during reproduction without requiring additional transmission interruptions.
2Adaptability or versatility
If preset data is transmitted during audio reproduction, then frequency correction can be adjusted, but data transmission amount and overhead increase
Solution Approach 1:
The patent transmits multiple complete preset data sets during startup rather than transmitting individual adjustment parameters during reproduction. This preliminary transmission of all possible preset data reduces the need for repeated large data transmissions during audio playback, as the DSP can simply switch between pre-loaded coefficient groups using small selection signals.
Solution Approach 2:
The patent segments the frequency correction functionality into multiple independent preset data sets, each containing complete coefficient information for all filters. This segmentation allows the system to transmit comprehensive data once at startup and then make adjustments by selecting between segments rather than transmitting incremental changes, reducing overall data transmission during reproduction.
3Device complexity
If using I2C interface for data transmission, then device complexity is reduced, but transmission overhead and interruptions increase
Solution Approach 1:
The patent maximizes the use of the simple I2C interface by performing all substantial data transmissions during startup when no audio reproduction is occurring. This preliminary action allows the I2C interface to transmit large amounts of preset data without causing interruptions during critical audio playback periods, thereby maintaining the simplicity of the interface while achieving high transmission efficiency during reproduction.
Data Source
AI summary
A digital signal processor for audio includes: an interface circuit communicating with an microcomputer; a multi-band equalizer including digital filters corresponding respectively to bands, wherein the frequency characteristic of each digital filter is changed according to coefficient group; a memory; and a coefficient setting circuit setting the coefficient group of each digital filter, wherein the frequency characteristic of the multi-band equalizer is selected from presets, wherein, when the digital signal processor start, the interface circuit receives setting data corresponding to the presets from the microcomputer and stores the received setting data in the memory, and wherein, at the time of audio reproduction, the interface circuit receives selection data to designate one of the plurality of presets and the coefficient setting circuit sets the coefficient group of each digital filter according to one of the setting data stored in the memory, the one setting data corresponding to the selection data.