Scalable Audio Coding Frame Loss Compensation
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Solution Overview
Problem
In scalable speech coding, quality deterioration of decoded signals occurs in subsequent frames due to inconsistent state data after concealing frame loss in lower layers, particularly with CELP coding, where adaptive codebook data and LPC synthesis filter state data differ between the transmitting and receiving sides.
Innovation Solution
A scalable coding apparatus with a lower layer and higher layer configuration, including a loss concealing section, a first higher layer coding section for correcting speech quality deterioration, and a selecting section to choose between general and deterioration correction coded data for transmission, ensuring consistent state data and reduced quality degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If loss concealment is performed using past coded data when lower layer coded data is lost, then decoding can continue without complete interruption, but state data becomes inconsistent between transmitting and receiving sides causing quality deterioration in subsequent frames
Solution Approach 1:
The transmitting side performs preliminary loss concealment processing and generates corrected state data before transmission. This preliminary action ensures that when the receiving side experiences frame loss, the transmitted corrected coded data already contains the necessary compensation information, allowing the receiving side to restore consistent state data without quality deterioration in subsequent frames
Solution Approach 2:
The system implements feedback by having the transmitting side detect frame loss conditions and generate corrected coded data based on the actual loss situation. This feedback loop ensures that the transmitted data adapts to the receiving side's state, maintaining consistency and preventing quality deterioration in subsequent frames
2Reliability
If coded data of lower layers is transmitted with higher reliability to control frame loss, then robustness to frame loss improves, but transmission bandwidth consumption increases
Solution Approach 1:
The invention applies different quality levels to different parts of the coded data. Critical lower layer coded data that requires loss concealment is transmitted with higher reliability (duplicated or protected), while non-critical enhancement layer data uses standard transmission. This selective approach improves frame loss robustness where needed without unnecessarily consuming bandwidth across all data
Solution Approach 2:
The system dynamically changes transmission parameters based on frame loss conditions. When frame loss is detected, the transmitting side switches to loss concealment mode and transmits corrected coded data with adjusted parameters. This parameter adaptation allows the system to maintain reliability only when necessary, optimizing bandwidth consumption
Data Source
AI summary
A scalable coding apparatus is provided to suppress deterioration of a quality of a coded signal in a normal frame next to a frame compensated for the occurrence of a data loss. The scalable coding apparatus is provided with a core-layer coding section (11) to carry out core-layer coding for the n-th frame input audio signal, an ordinary coding section (121) to generate expanding-layer ordinary-coding layer L2(n) by carrying out ordinary-coding of an expanding layer for the input audio signal, a deterioration-compensation coding section (123) to generate an expanding-layer-deterioration coding data L2′(n) by carrying out compensation for quality deterioration of coded audio in a current frame due to a past frame loss, a judging section (125) to determine whether either the expanding-layer ordinary-coding data L2(n) or the expanding-layer deterioration-coding data L2′(n) should be output from the expanding-layer coding section (12) as expanding-layer coding data of the current frame.