Parametric Audio DRC Reversal for Consistent Bitrate Switching
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Solution Overview
Problem
Existing adaptive distribution formats for audiovisual media struggle with bandwidth efficiency, computational efficiency, error resilience, and noticeable bitrate switching events, particularly due to incompatibility with dynamic range control techniques, which can cause dynamic range inconsistencies in legacy equipment during bitrate switching.
Innovation Solution
A coding format that allows for adaptive bitrate switching without sharp dialogue level changes by incorporating pre-processing and post-processing dynamic range control parameters, enabling dynamic range restoration and adjustment to maintain consistent dialogue levels across different equipment types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If adaptive bitrate switching is implemented in legacy equipment, then bandwidth efficiency is improved, but dynamic range inconsistencies occur causing noticeable dialogue level changes
Solution Approach 1:
The patent applies preliminary action by pre-calculating and embedding compensation values in the bitstream that anticipate dynamic range adjustments needed during bitrate switching. These pre-computed compensation parameters enable legacy decoders to proactively adjust dialogue levels before switching occurs, preventing noticeable level changes while maintaining bandwidth efficiency through adaptive bitrate selection.
2Reliability
If dynamic range control parameters are transmitted in bitstream, then dialogue level consistency is improved, but bandwidth consumption increases
Solution Approach 1:
The patent employs parameter changes by transmitting dynamic range control information in a compressed and optimized format within the bitstream. Rather than transmitting full dynamic range control sequences, the system encodes essential compensation parameters that can be efficiently decoded and applied, thereby maintaining dialogue level consistency across bitrate transitions while minimizing the additional bandwidth required for parameter transmission.
3Ease of operation
If legacy decoders maintain compatibility with new format, then ease of operation is improved, but computational efficiency deteriorates
Solution Approach 1:
The patent introduces an intermediary layer of compensation parameters that act as a bridge between legacy decoder architecture and modern adaptive bitrate requirements. These intermediate parameters enable legacy decoders to interpret and process adaptive bitrate information using existing computational pathways, thereby maintaining backward compatibility without imposing excessive computational burdens on legacy hardware while still achieving dynamic range consistency.
Data Source
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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.