CELP Audio Coding Using Look-Ahead Side Information for Packet Loss
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing audio encoding technologies face challenges in maintaining audio quality during packet loss in communication networks, particularly in CELP encoding, where packet loss leads to adaptive codebook synchronization issues and increased algorithmic delay, degrading 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
1Device complexity
If packet loss concealment is performed without using side information by copying decoded audio signal, then implementation complexity is reduced, but concealment accuracy 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 preliminary detection enables the decoder to select more appropriate concealment strategies that adapt to the actual audio characteristics, rather than using fixed copying methods.
Solution Approach 2:
The patent introduces side information as an intermediary element that carries characteristics of the audio signal (such as pitch lag, gain, or other parameters) from the encoder to the decoder. This side information acts as a mediator that enables the decoder to reconstruct lost packets with higher accuracy by providing reference data about the original signal properties.
2Measurement precision
If waiting for next packet arrival before decoding is performed to enable packet loss concealment, then concealment accuracy is improved, but algorithmic delay increases
Solution Approach 1:
The encoder performs preliminary encoding of side information that can be used for concealment. The decoder can then immediately use this pre-prepared side information when packet loss is detected, without needing to wait for subsequent packets to arrive for analysis, thus reducing delay while maintaining accuracy.
Solution Approach 2:
The system enables the decoder to perform self-service concealment by using locally available side information and previously decoded data when packet loss occurs. This eliminates the need to wait for external packet arrivals to perform concealment operations, reducing algorithmic delay while maintaining concealment functionality.
3Measurement precision
If adaptive codebook is updated using excitation signal from lost packet at encoder, then encoding accuracy is improved, but synchronization with decoder deteriorates due to packet loss
Solution Approach 1:
The patent implements feedback mechanisms where the encoder and decoder exchange information about their respective adaptive codebook states and excitation signals. When packet loss is detected, the system uses feedback from previously synchronized states and side information to maintain consistency between encoder and decoder adaptive codebooks, preventing synchronization divergence.
Solution Approach 2:
The system prepares compensatory measures in advance by encoding and transmitting side information that can cushion against the effects of packet loss. When packet loss occurs, this pre-prepared information allows the decoder to reconstruct the excitation signal and update its adaptive codebook in a way that maintains synchronization with the encoder, preventing drift.
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.