Multichannel Audio Decoding With Dynamic Range Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing adaptive distribution formats and coding techniques for audiovisual media face limitations in bandwidth efficiency, computational efficiency, error resilience, and perceptibility of bitrate switching events, especially when maintaining backward compatibility with legacy decoders and equipment, which can result in dynamic range inconsistencies during bitrate switching.
Innovation Solution
A method and system for audio signal decoding that includes a decoding system capable of reconstructing an n-channel audio signal using a bitstream with pre-processing DRC parameters to cancel dynamic range limiting, allowing for consistent dialogue levels across different bitrates and equipment, using a parametric coding mode with multichannel coding parameters and post-processing DRC parameters to adjust dynamic range accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If adaptive bitrate switching is used to improve bandwidth efficiency, then bandwidth efficiency is improved, but dynamic range consistency deteriorates
Solution Approach 1:
The encoder applies dynamic range limiting to the core signal before parametric encoding, and transmits DRC parameters in the bitstream. This preliminary action ensures that when bitrate switching occurs, the dynamic range is already controlled and can be consistently reconstructed across different bitrates, preventing dialogue level fluctuations.
Solution Approach 2:
The system uses transmitted DRC parameters as feedback information that allows the decoder to adjust the reconstructed signal's dynamic range. This feedback mechanism ensures that regardless of bitrate changes, the output dynamic range remains consistent by compensating for encoder-side limiting based on the transmitted parameters.
2Ease of operation
If legacy decoder compatibility is maintained to improve ease of operation, then ease of operation is improved, but dynamic range control capability deteriorates
Solution Approach 1:
The bitstream is designed with dual functionality: it contains both the encoded audio signal and DRC parameters that can be used by legacy decoders for basic playback and by advanced decoders for enhanced dynamic range control. This universal design allows the same bitstream to serve both legacy and modern equipment effectively.
Solution Approach 2:
The DRC parameters act as an intermediary information layer between the encoded signal and the decoder. Legacy decoders can ignore these parameters and process the signal normally, while advanced decoders utilize these parameters to achieve precise dynamic range control, thus mediating between compatibility and capability requirements.
3Loss of energy
If parametric coding mode is used to improve bandwidth efficiency, then bandwidth efficiency is improved, but computational complexity deteriorates
Solution Approach 1:
Dynamic range limiting is applied to the core signal before parametric encoding, preparing the signal in advance. This preliminary processing simplifies the subsequent parametric decoding process by reducing the dynamic range variations that need to be handled during reconstruction, thereby managing computational complexity while maintaining bandwidth efficiency.
Data Source
Figure 1a~1b
Figure 2a~2c
Figure 3~5
AI summary
On the basis of a bitstream (P), an n-channel audio signal (X) is reconstructed by deriving an m-channel core signal (Y) and multichannel coding parameters (α) from the bitstream, where 1 ≤ m < n. Also derived from the bitstream are pre-processing dynamic range control, DRC, parameters (DRC2) quantifying an encoder-side dynamic range limiting of the core signal. The n-channel audio signal is obtained by parametric synthesis in accordance with the multichannel coding parameters and while cancelling any encoder-side dynamic range limiting based on the pre-processing DRC parameters. In particular embodiments, the reconstruction further includes use of compensated post-processing DRC parameters quantifying a potential decoder-side dynamic range compression. Cancellation of an encoder-side range limitation and range compression are preferably performed by different decoder-side components. Cancellation and compression may be coordinated by a DRC pre-processor.