Audio Decoder Error Concealment by Bit Position and Signal Importance
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Solution Overview
Problem
Existing audio decoders often resort to full frame loss concealment upon detecting any bit-error, leading to annoying artefacts, especially when the signal is non-stationary, as they fail to differentiate between psychoacoustically important and less important signal data.
Innovation Solution
A decoder and encoder system that utilizes redundancy bits to detect corrupted bits within a bitstream payload, allowing selective application of full or partial frame loss concealment based on the position and characteristics of the corrupted bits and the signal's psychoacoustic importance, thereby improving audio quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If full frame loss concealment is applied upon detecting any bit-error, then audio quality is improved for stationary signals, but annoying artefacts occur for non-stationary signals
Solution Approach 1:
The patent applies different error concealment strategies to different parts of the audio signal based on their psychoacoustic importance. Critical signal components (such as low-frequency bands and tonal elements) receive different treatment than non-critical components. This is achieved by analyzing the signal characteristics and selectively applying concealment only where necessary, rather than uniformly across the entire frame, thereby avoiding artefacts in non-stationary signals while maintaining quality in stationary signals.
Solution Approach 2:
The patent dynamically adapts the error concealment strategy based on the detected signal characteristics. The system analyzes whether the signal is stationary or non-stationary, identifies critical frequency bands, and adjusts the concealment approach in real-time. This dynamic adaptation allows the system to switch between different concealment modes (e.g., full frame concealment for stationary signals, partial or no concealment for non-stationary signals) to optimize audio quality and minimize artefacts.
2Reliability
If full frame loss concealment is applied, then audio quality is improved, but the complexity of the decoding process increases
Solution Approach 1:
The patent segments the audio frame into different parts based on psychoacoustic importance, such as critical and non-critical frequency bands or time regions. By dividing the frame, the system can apply simplified concealment strategies to non-critical segments while using more sophisticated methods only where necessary. This segmentation reduces the overall computational complexity compared to applying full frame concealment uniformly, while still maintaining audio quality in critical regions.
Solution Approach 2:
The patent applies error concealment selectively rather than uniformly across the entire frame. Instead of performing full frame loss concealment in all cases, the system applies concealment only to the extent necessary based on the detected error impact and signal characteristics. This partial action approach reduces computational complexity by avoiding unnecessary processing in regions where errors are less critical or where the signal can tolerate some degradation.
3Object-affected harmful factors
If selective error concealment is applied based on bit position, then concealment artefacts are reduced, but the complexity of error detection and selection increases
Solution Approach 1:
The patent identifies specific bit positions or regions within the bitstream that are more critical to audio quality and applies different error detection and concealment strategies to these local regions. By focusing error detection efforts on critical bit positions (such as those encoding low-frequency bands or tonal elements), the system reduces concealment artefacts in important signal components while avoiding the need for complex analysis of the entire bitstream, thus managing complexity effectively.
Data Source
AI summary
A decoder for decoding a frame to reconstruct a signal portion of a signal is provided. The signal portion is encoded within the frame, wherein the frame includes a bitstream payload and two or more redundancy bits, wherein the bitstream payload includes a plurality of payload bits, wherein each of the payload bits exhibits a position within the bitstream payload. The decoder includes a channel decoding module, being configured to detect, depending on the two or more redundancy bits, whether the bitstream payload includes one or more corrupted bits being one or more of the payload bits that are distorted or that are likely to be distorted. Moreover, the decoder includes a source decoding module.