Audio Decoder Gain Sequencing for Clipping-Free Dynamic Range Control
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Solution Overview
Problem
Existing audio encoding/decoding systems face challenges in managing dynamic range control and clipping prevention, with decoder-side peak limiters causing additional look-ahead delay and computational complexity, and lacking encoder-side control over clipping prevention.
Innovation Solution
The system separates dynamic range control and guided clipping prevention metadata, allowing encoder-side control and transmission of gain sequences to the decoder, enabling flexible scaling and mapping based on decoder configuration and playback scenarios, thereby reducing or eliminating the need for decoder-side peak limiters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a decoder-side peak limiter is used for clipping prevention, then clipping is prevented, but additional look-ahead delay and computational complexity are introduced
Solution Approach 1:
The patent applies preliminary action by performing clipping prevention processing at the encoder side before audio encoding, rather than at the decoder side. The encoder calculates clipping prevention gain sequences in advance based on the audio signal characteristics, and these pre-calculated gains are transmitted to the decoder. This eliminates the need for complex real-time peak limiting at the decoder, reducing both delay and computational complexity while maintaining reliable clipping prevention.
Solution Approach 2:
The patent extracts the clipping prevention function from the decoder side and relocates it to the encoder side. By separating the clipping prevention processing from the decoding process and implementing it independently at the encoding stage, the patent removes the source of decoder complexity and delay while preserving the essential clipping prevention capability.
2Adaptability or versatility
If dynamic range control and clipping prevention are handled separately, then each function can be optimized independently, but the system complexity increases
Solution Approach 1:
The patent merges dynamic range control and clipping prevention into a unified processing framework at the encoder side. Both functions operate on the same audio signal and use a common gain sequence calculation mechanism. The encoder simultaneously determines both dynamic range control gains and clipping prevention gains, which are then transmitted together to the decoder. This integration reduces system complexity while preserving the ability to independently optimize each function through separate parameter control.
Data Source
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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 comprises an audio processing chain configured to receive a decoded audio signal derived from the audio bitstream and to adjust characteristics of the audio signal in order to produce an audio output signal, the audio adjustment chain comprising 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.