By-Pass Audio Object Rendering With Informed Loudness Compensation
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Solution Overview
Problem
Current audio rendering technologies face challenges in maintaining consistent loudness across different audio programs and channels, leading to annoying volume differences during switching, as existing solutions fail to accurately estimate and compensate for loudness changes in real-time without delay.
Innovation Solution
A decoder and encoder system that uses loudness information and rendering information to determine a loudness compensation value, allowing for the generation of audio output channels that maintain consistent loudness by adjusting the loudness of audio object signals based on their energy contributions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If audio rendering is conducted on the decoder side to allow flexible manipulation of audio objects, then adaptability and ease of operation are improved, but the total loudness of the received audio signal changes, causing volume differences between programs and channels
Solution Approach 1:
The encoder pre-calculates and transmits loudness information (such as ITU-R BS.1770 loudness values) for different rendering scenarios along with the audio objects. This preliminary action allows the decoder to predict the total loudness before rendering occurs, enabling proactive loudness compensation to maintain consistency across different programs and channels while preserving decoder-side rendering flexibility
Solution Approach 2:
The system implements a feedback mechanism where the decoder uses the transmitted loudness information to monitor and adjust the rendered output loudness. By comparing the predicted loudness with a reference level, the decoder can apply compensation gains to ensure that volume differences between programs are minimized, thus maintaining loudness consistency while allowing flexible rendering
2Measurement precision
If traditional loudness estimation methods are used, then device complexity is reduced, but measurement precision and reliability of loudness estimation are insufficient, leading to delayed and inaccurate loudness compensation
Solution Approach 1:
The encoder performs preliminary loudness estimation using accurate methods (such as ITU-R BS.1770) and transmits the results as side information. This shifts the computational complexity to the encoding stage, allowing the decoder to use the pre-calculated values for immediate and accurate loudness compensation without implementing complex estimation algorithms, thus improving measurement precision while managing device complexity
Solution Approach 2:
The patent introduces loudness information as an intermediary element that mediates between the audio objects and the rendering process. This side information acts as a carrier of accurate loudness characteristics, enabling the decoder to achieve precise loudness estimation and compensation without directly implementing complex estimation algorithms, thereby improving accuracy while keeping the decoder relatively simple
Data Source
AI summary
A decoder for generating an audio output signal having one or more audio output channels is provided, having a receiving interface for receiving an audio input signal having a plurality of audio object signals, for receiving loudness information on the audio object signals, and for receiving rendering information indicating whether one or more of the audio object signals shall be amplified or attenuated, further having a signal processor for generating the one or more audio output channels of the audio output signal, configured to determine a loudness compensation value depending on the loudness information and depending on the rendering information, and configured to generate the one or more audio output channels of the audio output signal from the audio input signal depending on the rendering information and depending on the loudness compensation value. One or more by-pass audio object signals are employed for generating the audio output signal. Moreover, an encoder is provided.