CELP Audio Coding With Look-Ahead Side Information for Packet Loss
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Solution Overview
Problem
Existing audio encoding technologies face challenges in maintaining audio quality during packet loss in communication networks, particularly in CELP encoding, due to inconsistencies in adaptive codebooks and increased algorithmic delay, which degrades voice communication quality.
Innovation Solution
An audio coding system that includes an audio encoding device and method for encoding audio signals using side information calculated from a look-ahead signal, which is encoded and transmitted to facilitate accurate packet loss concealment at the decoding end, reducing adaptive codebook inconsistencies and algorithmic delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If packet loss concealment is performed using traditional methods (copying past audio signal), then implementation simplicity is maintained, but audio quality deteriorates when audio properties change suddenly
Solution Approach 1:
The encoder performs preliminary analysis of the audio signal to detect sudden changes in audio properties (such as pitch, energy, or spectral characteristics) before packet loss occurs. This advance detection allows the system to prepare appropriate concealment strategies, switching from simple copying to more sophisticated methods when changes are detected, thereby maintaining audio quality without sacrificing implementation simplicity.
2Measurement precision
If side information is transmitted for packet loss concealment, then concealment accuracy is improved, but communication bandwidth consumption increases
Solution Approach 1:
Instead of transmitting side information for all audio frames, the system applies quality differentiation by transmitting detailed side information (such as pitch parameters, spectral characteristics) only for frames where sudden changes in audio properties are detected. For normal frames without significant changes, simpler concealment methods are used, reducing overall bandwidth consumption while maintaining high concealment accuracy when needed.
3Reliability
If adaptive codebook synchronization is implemented, then audio quality consistency is improved, but algorithmic delay increases
Solution Approach 1:
The system performs preliminary detection of packet loss conditions and proactively manages adaptive codebook synchronization by transmitting necessary synchronization information in advance or using previously received side information. This approach avoids the need for complex real-time synchronization procedures that would increase algorithmic delay, while still maintaining audio quality consistency through advance preparation.
Data Source
AI summary
An audio signal transmission device for encoding an audio signal includes an audio encoding unit that encodes an audio signal and a side information encoding unit that calculates and encodes side information from a look-ahead signal. An audio signal receiving device for decoding an audio code and outputting an audio signal includes: an audio code buffer that detects packet loss based on a received state of an audio packet, an audio parameter decoding unit that decodes an audio code when an audio packet is correctly received, a side information decoding unit that decodes a side information code when an audio packet is correctly received, a side information accumulation unit that accumulates side information obtained by decoding a side information code, an audio parameter missing processing unit that outputs an audio parameter upon detection of audio packet loss, and an audio synthesis unit that synthesizes decoded audio from the audio parameter.