Broadcast Audio Loudness Normalization Using Partial Frame Decoding
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Solution Overview
Problem
In digital multimedia broadcasts, variations in audio loudness levels between program segments and channels cause viewer discomfort due to the need for frequent volume adjustments, as dialnorm values are not consistently maintained across different content sources.
Innovation Solution
Implementing a system that partially decodes audio frames, calculates average energy levels, compares them to a nominal level, and adjusts the dialnorm setting to maintain consistent audio levels, using psychoacoustic models to account for human hearing sensitivity and excluding silent periods from measurements, with optional look-ahead algorithms to reduce lag in volume adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If dialnorm values are calculated by special purpose equipment for entire video program files, then audio loudness indication is provided, but variations in audio loudness levels between program segments and channels cause viewer discomfort
Solution Approach 1:
The patent applies segmentation by processing audio frames in segments rather than requiring complete file processing. The system calculates dialnorm values for individual audio frames or groups of frames, allowing incremental processing and earlier availability of loudness information. This enables the system to provide loudness indication without waiting for entire program files to be processed, thereby reducing viewer discomfort from loudness variations.
Solution Approach 2:
The patent implements preliminary action by calculating dialnorm values ahead of time during audio encoding or pre-processing stages. The system computes loudness metrics for audio frames before they are played back to the viewer, allowing advance adjustment of audio levels. This preliminary calculation enables consistent audio loudness across different program segments and channels, eliminating the need for viewers to frequently adjust volume.
2Measurement precision
If audio frames are fully decoded to calculate average energy level, then accurate loudness measurement is achieved, but processing time and computational resources increase
Solution Approach 1:
The patent applies partial action by performing only the necessary portion of audio decoding required for loudness measurement. Instead of fully decoding audio frames to raw audio data, the system partially decodes frames to extract the information needed for energy level calculation. This approach achieves sufficient measurement accuracy while significantly reducing processing time and computational resource requirements compared to complete decoding.
Solution Approach 2:
The patent implements extraction by directly extracting energy level information from encoded audio frames without complete decoding. The system extracts relevant audio parameters and energy metrics from the compressed format, obtaining accurate enough loudness measurements without the computational overhead of full decoding. This extraction approach maintains measurement precision while improving processing efficiency.
Data Source
AI summary
Systems and methods of this disclosure can operate to provide audio level normalization in multimedia streams. In some implementations, audio level normalization can include partially decoding audio frames included in a multimedia stream, calculating an average energy level of the partially decoded frames, comparing the average energy level of the partially decoded frames to a nominal energy level, modifying a dialnorm setting associated with the multimedia stream, and reencoding the partially decoded audio frames for inclusion as a modified audio stream corresponding to the video stream.