Residual Encoding for Object-Based Audio Upmix Artifact Reduction
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Solution Overview
Problem
Existing audio compression methods face challenges in efficiently transmitting and upmixing downmixed multi-channel audio signals, particularly in object-based systems, due to high bandwidth requirements and the presence of artifacts when using lossy compression.
Innovation Solution
A method involving lossy compression of a residual signal and a total mix signal, along with at least one compressed audio object, to reduce bit-rate requirements while minimizing upmix artifacts, allowing for backward compatibility and efficient transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lossy compression is applied to downmixed multi-channel audio signals, then bandwidth requirements are reduced, but upmix artifacts increase
Solution Approach 1:
The audio signal is segmented into multiple independent audio objects, each representing a discrete sound source. This segmentation allows the encoder to process and compress each object separately, preserving important spatial and temporal characteristics while reducing overall bit-rate requirements. The decoder can then reconstruct the downmixed signal and separate objects with minimal artifacts.
Solution Approach 2:
The patent introduces an intermediary encoding approach where audio objects are first encoded individually, then downmixed to create a compressed representation. This intermediary step allows the system to balance between lossless object preservation and lossy downmix compression, reducing artifacts during upmixing while maintaining backward compatibility.
2Measurement precision
If multiple audio objects are transmitted separately, then upmixing accuracy is improved, but bandwidth requirements increase
Solution Approach 1:
The patent merges multiple audio objects into a downmixed signal for transmission, reducing bandwidth requirements. The merge operation combines spatial and temporal information from multiple objects into a compact representation that can be efficiently transmitted. At the decoder, the downmixed signal is processed to separate and reconstruct the individual objects with high accuracy.
3Adaptability or versatility
If backward compatibility is maintained for legacy systems, then system versatility is improved, but compression efficiency decreases
Solution Approach 1:
The patent creates a universal encoding system that serves multiple functions: it provides backward compatibility with legacy monaural and stereo systems while simultaneously supporting advanced object-based audio reproduction. The same encoded bitstream can be decoded by simple legacy devices or by sophisticated object-based audio systems, achieving versatility without sacrificing compression efficiency.
Data Source
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AI summary
Lossy compression and transmission of a downmixed composite signal having multiple tracks and objects, including a downmixed signal, is accomplished in a manner that reduces the bit-rate requirement as compared to redundant transmission or lossless compression, while reducing upmix artifacts. A compressed residual signal is generated and transmitted along with a compressed total mix and at least one compressed audio objects. In the reception and upmix aspect the invention decompresses a downmixed signal and other compressed objects, calculates an approximate upmix signal, and corrects specific base signals derived from the upmix, by subtracting a decompressed residual signal. The invention thus allows lossy compression to be used in combination with downmixed audio signals for transmission through a communication channel (or for storage). Upon later reception and upmix, additional base signals are recoverable in capable systems providing multi-object capability (while legacy systems can easily decode a total mix without upmix).