Parametric Audio DRC Compensation for Bitrate Switching
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Solution Overview
Problem
Existing adaptive distribution formats for audiovisual media struggle with maintaining backward compatibility and often result in dynamic range inconsistencies during bitrate switching, especially in legacy equipment.
Innovation Solution
A coding format that includes pre-processing and post-processing dynamic range control (DRC) parameters, allowing for seamless dynamic range adjustment and restoration, enabling consistent dialogue levels across different bitrates and equipment types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If adaptive bitrate switching is implemented to handle network variations, then bandwidth efficiency is improved, but dynamic range inconsistencies occur during bitrate switching
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing compensation values for dynamic range control parameters before bitrate switching occurs. The system prepares multiple sets of DRC parameters corresponding to different bitrate scenarios, allowing seamless transition without dynamic range inconsistencies when switching between bitrates.
Solution Approach 2:
The patent implements parameter changes by dynamically adjusting dynamic range control parameters based on the current bitrate mode. When switching between high and low bitrates, the system modifies DRC parameters to compensate for potential dynamic range variations, ensuring consistent playback characteristics across different transmission conditions.
2Ease of operation
If legacy decoder compatibility is maintained, then ease of operation is improved, but dynamic range control precision deteriorates
Solution Approach 1:
The patent introduces an intermediary layer that translates between legacy decoder expectations and modern dynamic range control requirements. The system embeds DRC parameters in a format compatible with legacy decoders while enabling precise dynamic range control for advanced equipment, acting as a mediator between old and new technologies.
Solution Approach 2:
The patent achieves universality by designing a dual-mode DRC system that can operate in both legacy-compatible mode and enhanced precision mode. The same decoder architecture can serve both backward compatibility requirements and high-precision dynamic range control needs, depending on the capabilities of the connected playback equipment.
3Loss of information
If parametric coding is used to reduce bitrate, then loss of information is reduced, but computational complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the audio signal processing into distinct parametric analysis and synthesis stages. The encoder separates the audio signal into core components that can be efficiently transmitted at lower bitrates, while the decoder reconstructs the full-quality signal through parametric synthesis, reducing overall computational complexity compared to full-bandwidth processing.
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 (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.