Audio Decoder Metadata-Guided Gain Control for Clipping Prevention
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Solution Overview
Problem
Conventional audio decoding technologies face challenges in effectively managing dynamic range compression and preventing clipping, particularly due to the lack of encoder-side control over clipping prevention, leading to increased computational complexity and additional delays at the decoder side.
Innovation Solution
The implementation of an audio encoder that produces a metadata bitstream containing dynamic range control gain sequences and guided clipping prevention gain sequences, allowing for encoder-side control of dynamic range compression and clipping prevention, which are then applied at the decoder side to adjust the audio output, thereby reducing the need for a peak limiter and minimizing computational complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dynamic range compression and clipping prevention are performed at the decoder side, then audio quality can be maintained, but computational complexity and processing delay increase
Solution Approach 1:
The encoder performs preliminary clipping prevention processing by generating a first clipping prevention gain sequence and applying it to the audio signal before encoding. This preliminary action transfers part of the clipping prevention burden from the decoder to the encoder, reducing the computational complexity at the decoder side while maintaining audio quality.
Solution Approach 2:
The patent introduces an intermediary mechanism where the encoder provides clipping prevention gain sequences as side information to the decoder. This intermediary approach allows the decoder to apply pre-computed gain sequences rather than performing complex real-time clipping detection and prevention, thereby reducing computational load while preserving audio fidelity.
2Reliability
If a peak limiter is added to the decoder, then clipping can be prevented, but processing delay increases
Solution Approach 1:
The encoder performs preliminary clipping prevention by computing and applying gain sequences before encoding. This shifts the clipping prevention action to the encoding stage, eliminating the need for real-time peak limiting at the decoder and thus avoiding additional processing delay.
Solution Approach 2:
The encoder creates a copy of the audio signal processed with clipping prevention gain sequences and transmits this pre-processed version to the decoder. The decoder simply applies the provided gain sequences without performing complex peak detection and limiting operations, thereby minimizing processing delay.
3Device complexity
If clipping prevention is performed without encoder-side control, then decoder complexity increases, but if encoder-side control is implemented, then metadata transmission overhead increases
Solution Approach 1:
The encoder performs preliminary computation of clipping prevention gain sequences and transmits them as compact metadata to the decoder. This preliminary action at the encoder side enables the decoder to simply apply the provided gain sequences without performing complex computations, thereby reducing decoder complexity despite the metadata transmission overhead.
Solution Approach 2:
The patent changes the parameter representation by encoding clipping prevention gain sequences in a compressed format that balances metadata size with decoding simplicity. The gain sequences are transmitted with sufficient precision to ensure clipping prevention effectiveness while maintaining reasonable metadata overhead, optimizing the trade-off between information loss and decoder complexity reduction.
Data Source
AI summary
The invention provides a concept for combined dynamic range compression and guided clipping prevention for audio devices. An audio decoder for decoding an audio bitstream and a metadata bitstream related to the audio bitstream according to the concept includes an audio processing chain including a plurality of adjustment stages including a dynamic range control stage for adjusting a dynamic range of the audio output signal and a guided clipping prevention stage for preventing clipping of the audio output signal; and a metadata decoder configured to receive the metadata bitstream and to extract dynamic range control gain sequences and guided clipping prevention gain sequences from the metadata bitstream, at least a part of the dynamic range control gain sequences being supplied to the dynamic range control stage, and at least a part of the guided clipping prevention gain sequences being supplied to the guided clipping prevention stage.