Parametric Audio Decoding With Reversible Dynamic Range Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing adaptive distribution formats for audiovisual media struggle with bandwidth efficiency, computational efficiency, error resilience, and noticeable bitrate switching events, particularly when legacy decoders are used alongside newer equipment, and dynamic range control techniques are not compatible with adaptive bitrate coding methods.
Innovation Solution
A coding format that allows for seamless bitrate transitions by including pre-processing and post-processing dynamic range control parameters in the bitstream, enabling decoders to restore the original dynamic range and adjust playback accordingly, ensuring consistent dialogue levels across different equipment types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If adaptive bitrate coding methods are used to improve bandwidth efficiency and handle network variations, then bandwidth efficiency is improved, but dynamic range inconsistencies and noticeable bitrate switching events occur
Solution Approach 1:
The encoder pre-calculates and embeds DRC parameters in the bitstream before decoding, enabling the decoder to proactively adjust dynamic range before playback. This preliminary preparation ensures that when bitrate switching occurs, the dynamic range is already compensated, preventing inconsistencies and making switching events imperceptible to users.
2Ease of operation
If legacy decoders are used to maintain backward compatibility, then ease of operation is improved, but computational efficiency and error resilience deteriorate
Solution Approach 1:
The patent designs a universal coding format where legacy decoders can process the bitstream using existing algorithms while newer decoders can utilize additional DRC parameters for enhanced performance. The bitstream structure accommodates both old and new decoder capabilities, allowing legacy equipment to function with basic decoding while advanced equipment achieves superior computational efficiency and error resilience through the embedded DRC information.
3Device complexity
If simple DRC implementation with metadata gain factor is used to improve ease of manufacture, then device complexity is reduced, but adaptability to adaptive bitrate coding deteriorates
Solution Approach 1:
The DRC functionality is segmented into distinct components: a simple metadata field for gain factor that all decoders can process, and additional DRC parameters that provide enhanced control. This segmentation allows basic implementations to use only the simple gain factor metadata while maintaining compatibility, whereas advanced implementations can utilize the full set of DRC parameters for superior adaptability to adaptive bitrate coding scenarios.
Data Source
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 (a) 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.