Frequency-Domain Error Concealment via Spectral Copying
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Solution Overview
Problem
Existing error concealment techniques for audio and video data in codecs are inadequate under adverse channel conditions, as they either introduce artifacts, require excessive complexity, or incur unacceptable delays, especially when dealing with packet losses and corrupted data.
Innovation Solution
A frequency-domain error concealment technique that exploits coding coefficient correlation in both time and frequency domains, allowing for the estimation and replacement of erroneous coefficients using intra-frame and inter-frame correlations, with optional phase and amplitude prediction based on group delay matching and energy matching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple description coding is used to bridge packet losses, then reliability is improved, but device complexity and data rate increase
Solution Approach 1:
The patent uses spectral copying by estimating missing spectral coefficients based on corresponding coefficients from previously received frames. Instead of creating multiple independent descriptions, the system copies and adapts spectral information from past frames to reconstruct lost data, reducing complexity while maintaining reliability
Solution Approach 2:
The patent performs preliminary spectral analysis and stores spectral coefficients from previous frames before transmission. When packet loss occurs, these pre-computed spectral representations are used to rapidly conceal errors, avoiding the need for complex real-time multiple description coding
2Reliability
If multiple description coding is used to bridge packet losses, then reliability is improved, but loss of time increases
Solution Approach 1:
Spectral coefficients from previous frames are pre-computed and stored in buffer memory before transmission. When packet loss occurs, these pre-available spectral representations enable immediate error concealment without waiting for retransmission or complex real-time processing, thus reducing delay
Solution Approach 2:
The system copies spectral information from previously received frames to reconstruct lost packets. This copying approach provides immediate replacement data without requiring waiting for multiple descriptions or retransmission, thereby minimizing loss of time
3Device complexity
If rudimentary error concealment techniques are used, then device complexity is reduced, but manufacturing precision deteriorates
Solution Approach 1:
The patent employs spectral copying where missing spectral coefficients are estimated by copying and adapting corresponding coefficients from previous frames. This approach achieves high reconstruction quality by leveraging the temporal redundancy and self-similarity of spectral information, far surpassing rudimentary techniques like muting or zero-filling
Solution Approach 2:
The patent replaces complex time-domain signal processing with frequency-domain spectral analysis and copying. By working in the spectral domain, the system achieves more accurate error concealment with simpler operations, substituting mechanical time-domain filtering with elegant frequency-domain coefficient copying
Data Source
AI summary
The invention concerns a frequency-domain error concealment technique for information that is represented, on a frame-by-frame basis, by coding coefficients. The basic idea is to conceal an erroneous coding coefficient by exploiting coding coefficient correlation in both time and frequency. The technique is applicable to any information, such as audio, video and image data, that is compressed into coding coefficients and transmitted under adverse channel conditions. The error concealment technique proposed by the invention has the clear advantage of exploiting the redundancy of the original information signal in time as well as frequency. For example, this offers the possibility to exploit redundancy between frames (inter-frame) as well as within frames (intra-frame). The use of coding coefficients from the same frame as the erroneous coding coefficient is sometimes referred to as intra-frame coefficient correlation and it is a special case of the more general frequency correlation.