Stereo Signal Processing Device for Restoring High-Frequency Components
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Solution Overview
Problem
Compression-encoded audio signals suffer from deteriorated characteristics, particularly lacking high-frequency components and middle- to high-frequency spectra in left-and-right difference signals, leading to muffled sounds and reduced sound field and atmospheric feelings during playback.
Innovation Solution
A signal processing device with a prediction error calculating unit, adders, and a gain adjusting unit that computes and adds error signals to restore the original characteristics of the audio signal, specifically the left-and-right difference signal, by predicting and adjusting the error signals between input signals, thereby recovering the missing high-frequency components and enhancing the sound field and atmospheric feelings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If compression encoding (AAC or MP3) is applied to save storage capacity or communication bandwidth, then storage efficiency and transmission efficiency are improved, but the audio signal characteristics deteriorate causing muffled sound and loss of sound field feeling
Solution Approach 1:
The prediction error calculating unit pre-calculates the error signal between the left signal and the prediction signal predicted from the right signal before the final signal reconstruction. This preliminary calculation of the prediction error allows the system to recover high-frequency components that were lost during compression encoding, thereby resolving the contradiction between compression efficiency and audio quality preservation
2Productivity
If compression encoding is applied to save storage capacity or communication bandwidth, then storage efficiency and transmission efficiency are improved, but the characteristics of the left-and-right difference signal deteriorate causing loss of sound field and atmospheric feeling
Solution Approach 1:
The system uses feedback by calculating the prediction error between the actual left signal and the predicted left signal (generated from the right signal). This error signal contains the missing high-frequency components and difference signal characteristics. By adding this error signal back to the decoded signals, the system restores the left-and-right difference signal characteristics that were lost during compression, thereby recovering the sound field and atmospheric feeling
3Loss of information
If the prediction error calculating unit computes the error signal and adders add the error signal to restore original characteristics, then the sound field feeling and atmospheric feeling are recovered, but the device complexity increases
Solution Approach 1:
The prediction error calculating unit acts as an intermediary component that bridges the compressed decoded signal and the original high-quality signal. Instead of attempting to directly reconstruct the entire original signal, the system uses this intermediary unit to generate only the essential missing components (prediction error signal), which are then added to the decoded signal. This intermediary approach recovers the sound field feeling and atmospheric feeling while keeping the added complexity minimal and focused only on the necessary error calculation and addition operations
Data Source
AI summary
A signal processing device is provided, including a prediction error calculating unit that calculates an error signal between a left signal l(n) and a prediction signal of the left signal l (n) predicted from a right signal r(n), a gain adjusting unit that makes a gain adjustment and outputs an error signal, a first adder that adds the left signal l(n) and the error signal and outputs, and a second adder that adds the right signal r(n) and the error signal in opposite phase and outputs.