Audio Packet Loss Concealment for Stable Spatial Reconstruction
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Solution Overview
Problem
Existing audio codecs like IVAS face issues with packet loss concealment for metadata, leading to incorrect spatial reconstruction and audible artifacts due to the loss of spatial reconstruction parameters.
Innovation Solution
A method for processing audio signals that involves generating a reconstructed audio signal based on received signals and reconstruction parameters, including upmixing audio channels, fading to a predefined spatial configuration, and gradually muting the signal in case of packet loss, while utilizing time-differential coding to estimate missing parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If packet loss concealment is applied to audio signals, then audio continuity is maintained, but spatial reconstruction accuracy deteriorates due to loss of metadata
Solution Approach 1:
The patent segments the audio data into two distinct parts: audio signal data and metadata (reconstruction parameters). Different concealment strategies are applied to each segment - audio signals use standard PLC while metadata uses estimation based on previously decoded frames, thereby maintaining both audio continuity and spatial accuracy
Solution Approach 2:
The patent stores previously decoded metadata frames in advance, so that when packet loss occurs, the stored metadata can be immediately used for estimation and reconstruction without interruption, maintaining both continuity and accuracy
2Device complexity
If standard packet loss concealment is used for metadata, then processing simplicity is maintained, but spatial artifacts increase due to incorrect reconstruction
Solution Approach 1:
The patent uses feedback from previously successfully decoded metadata frames to estimate and reconstruct lost metadata. This feedback mechanism ensures that spatial parameters are accurately recovered without requiring complex processing, avoiding spatial artifacts while maintaining simplicity
3Stability of the object's composition
If reconstruction parameters are estimated from previous frames, then spatial consistency is improved, but time delay increases due to additional processing
Solution Approach 1:
The patent pre-stores decoded metadata frames in a buffer before they are needed for reconstruction. This preliminary action eliminates the need for real-time processing during packet loss events, maintaining spatial consistency while avoiding additional time delays
Data Source
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AI summary
Described are methods of processing an audio signal for packet loss concealment. The audio signal comprises a sequence of frames, each frame containing representations of a plurality of audio channels and reconstruction parameters for upmixing the plurality of audio channels to a predetermined channel format. One method includes: receiving the audio signal; and generating a reconstructed audio signal in the predefined channel format based on the received audio signal. Generating the reconstructed audio signal comprises: determining whether at least one frame of the audio signal has been lost; and if a number of consecutively lost frames exceeds a first threshold, fading the reconstructed audio signal to a predefined spatial configuration. Also described is a method of encoding an audio signal. Yet further described are apparatus for carrying out the methods, as well as corresponding programs and computer-readable storage media.