Audio Receiver Loudness Equalization Across Broadcast Formats
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Solution Overview
Problem
The proliferation of different audio formats and equipment configurations leads to inconsistencies in loudness levels of audio signals, causing users to frequently adjust volume when switching channels or inputs, as the processing of audio signals varies across different pathways and devices.
Innovation Solution
A computer-implemented method and device for controlling audio receivers to equalize loudness levels by detecting and analyzing audio signals, adjusting their levels until they are perceived as equal, and saving these settings for future playback, using software stored on a processor to manage different audio formats such as MPEG-1 Layer II and Dolby Digital.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If different audio formats are used for digital broadcast to reduce frequency spectrum requirements, then data transmission efficiency is improved, but loudness consistency across different audio pathways deteriorates
Solution Approach 1:
The system performs preliminary loudness analysis on audio signals during the encoding stage. Loudness metadata is calculated and embedded in the audio bitstream before transmission, allowing the receiving device to pre-adjust playback levels without requiring post-processing analysis of the actual audio content.
Solution Approach 2:
The system implements a feedback mechanism where loudness metadata from multiple audio formats is analyzed and compared. The receiving device uses this feedback information to automatically adjust playback gain for each audio format, ensuring that loudness levels across different codecs (MPEG-1 Layer II, Dolby Digital, etc.) are equalized to a reference level.
2Adaptability or versatility
If multiple audio equipment configurations are supported to provide user choice, then adaptability is improved, but loudness level consistency deteriorates
Solution Approach 1:
The system implements a universal loudness equalization mechanism that works across all supported audio formats and equipment configurations. The loudness metadata processing and gain adjustment functionality is format-agnostic, allowing the same principle to apply whether the audio is encoded in MPEG-1 Layer II, Dolby Digital, or other formats, and regardless of the specific playback equipment used.
Solution Approach 2:
The system dynamically changes the playback gain parameter based on the detected audio format and its associated loudness metadata. The receiving device automatically adjusts the output level parameter for each audio pathway to compensate for format-specific differences, maintaining consistent perceived loudness across diverse equipment configurations without requiring manual user intervention.
3Reliability
If automatic loudness equalization is implemented across all audio formats, then loudness consistency is improved, but processing complexity increases
Solution Approach 1:
The system extracts loudness metadata from the audio bitstream during decoding, separating the loudness information from the actual audio content processing. This extracted metadata is then used to control the playback gain, allowing the complex task of loudness analysis to be performed once during encoding rather than continuously during playback processing.
Solution Approach 2:
The system replaces complex real-time audio analysis with a simpler metadata-driven approach. Instead of continuously analyzing the actual audio signal characteristics during playback, the system uses pre-calculated loudness metadata and simple gain adjustment operations, substituting complex mechanical/audio processing with lighter computational operations.
Data Source
AI summary
The application discusses a computer implemented method and apparatus for performing audio equalization in an audio receiver device, such as an integrated receiver/decoder or set top box, or integrated TV, connected to one or more audio playback devices, such as a television unit, computer screen and speakers, amplifier or home theater equipment. The method and apparatus use an equalization process which compares audio signals received in different audio formats (e.g. MPEG-1 Layer II, AC-3 2.0, AC-3 5.1 and HE-AAC) with one another, allowing a correction gain factor to be determined for equalizing the perceived loudness of the signals when played-back at a connected playback device. The correction gain factor is then applied in the audio receiver device before output.