Audio Gain Metadata Transcoding for Clipping-Resistant DRC
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Solution Overview
Problem
The challenge lies in transcoding audio metadata between different audio coding schemes, such as HE AAC, Dolby E, and Dolby Digital, to ensure that metadata is not deteriorated during the process, maintaining the original audio quality and compatibility across various playback environments.
Innovation Solution
A method for transcoding audio gain metadata involves selecting gain values based on the gain values of the source metadata, using a time interval defined by an upper and lower limit, and applying appropriate interpolation curves to maintain the dynamic range control and prevent clipping, ensuring the transcoded metadata is resistant to gain overshoots and compatible with different coding schemes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gain values are directly mapped between different audio coding schemes, then the transcoding process is simple, but gain overshoots and clipping occur causing audio quality deterioration
Solution Approach 1:
The patent applies preliminary action by selecting the minimum gain value from the first gain metadata before applying it to the second audio coding scheme. This proactive selection prevents gain overshoots and clipping from occurring in the first place, rather than correcting them after they occur. The method examines the time interval around each gain value and proactively chooses the minimum value to ensure audio quality is maintained throughout the transcoding process.
2Reliability
If the transcoding method uses minimum gain value selection within time intervals, then audio quality is maintained and clipping is prevented, but the processing complexity increases
Solution Approach 1:
The patent applies self-service by using the gain values that are already present in the first gain metadata to determine the minimum gain value for the second gain metadata. The system serves itself by selecting from its own existing data rather than requiring external intervention or complex external processing. This approach maintains metadata integrity while keeping the processing relatively simple, as it leverages the available data structure efficiently.
3Adaptability or versatility
If different coding schemes are used for production and broadcasting, then compatibility with various systems is achieved, but metadata deterioration occurs during transcoding
Solution Approach 1:
The patent applies parameter changes by modifying the gain values parameter during the transcoding process from the first audio coding scheme to the second. Specifically, it changes the gain parameter selection criterion to always choose the minimum value within the time interval, which preserves the essential dynamic range control information while adapting to the different coding scheme requirements. This maintains metadata quality despite the format transformation.
Data Source
AI summary
The invention relates to the field of audio encoding. In particular, it relates to the transcoding of audio metadata between different audio coding schemes. It describes a method and a system for transcoding audio gain metadata related to dynamic range control from first gain metadata of a first audio coding scheme to second gain metadata of a second audio coding scheme, wherein the first and second audio coding schemes use coding blocks and wherein each coding block has at least one associated gain value. The method and the system select a gain value of the second gain metadata based on the gain values of the first gain metadata such that within a time interval around the time instance associated with the gain value of the second gain metadata, the minimum gain value of the first gain metadata is selected.