Object-Based Audio Loudness Compensation Using By-Pass Signals
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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 provide accurate and immediate loudness estimation and compensation on the decoder side without delay.
Innovation Solution
A decoder and encoder system that receives audio object signals, loudness information, and rendering instructions to generate audio output channels with precise loudness compensation, using downmix signals and loudness values to ensure consistent loudness across audio scenes, even when rendering settings change.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If audio rendering is conducted on the decoder side to enable flexible audio object manipulation, then adaptability and ease of operation are improved, but loudness consistency deteriorates due to significant effects on overall/total loudness
Solution Approach 1:
The encoder performs preliminary loudness estimation and calculates compensation values before audio rendering. The decoder receives pre-computed loudness information and compensation values, enabling it to maintain loudness consistency while performing flexible rendering operations without real-time computational delays.
Solution Approach 2:
The system implements a feedback mechanism where loudness information is transmitted from encoder to decoder, and the decoder uses this feedback to adjust rendering parameters and apply loudness compensation, ensuring the output loudness matches the reference loudness level.
2Device complexity
If traditional loudness estimation methods are used without by-pass audio object signals, then device complexity is reduced, but measurement precision deteriorates due to inaccurate loudness estimation
Solution Approach 1:
The audio signal is segmented into downmix components and by-pass audio object signals. The loudness estimation is performed separately for each component and then combined, improving accuracy by accounting for both the mixed and unmixed audio objects without requiring complete signal reconstruction.
Solution Approach 2:
Loudness information acts as an intermediary carrier that conveys precise loudness characteristics from the encoder to the decoder. This intermediary data structure enables accurate loudness estimation without requiring the decoder to perform complex real-time analysis of all audio components.
3Measurement precision
If temporal integration is applied for loudness measurement, then measurement precision is improved, but loss of time increases due to integration delays
Solution Approach 1:
The encoder performs temporal integration and calculates precise average loudness values before encoding. The pre-computed loudness information is transmitted to the decoder, eliminating the need for the decoder to perform time-consuming integration operations and removing temporal delays from the decoding process.
4Device complexity
If all audio object signals are mixed into downmix channels, then device complexity is reduced, but loss of information increases due to exclusion of by-pass audio objects from loudness estimation
Solution Approach 1:
The audio object signals are segmented into two groups: those mixed into downmix channels and by-pass audio objects that remain separate. The loudness estimation process is segmented to estimate loudness for both groups independently, then combine the results to achieve complete and accurate loudness measurement.
Solution Approach 2:
The loudness estimation mechanism is designed to handle multiple signal types universally - it can process both downmix channel signals and by-pass audio object signals through the same estimation algorithm, ensuring no information is lost regardless of the signal path.
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.