Audio Pre-Distortion for Codec-Induced Dialogue Intelligibility Loss
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Solution Overview
Problem
Existing audio systems in TV shows and movies suffer from distortion during transmission, particularly affecting dialogue intelligibility due to high dynamic range and compression, which is exacerbated by perceptual codecs, making it difficult for both average viewers and the hearing impaired to understand dialogue.
Innovation Solution
A system and method that pre-distorts audio data before transmission using neural network models to neutralize distortion, employing techniques like frequency response adjustment and glottal impulse response to enhance speech intelligibility, ensuring the dialogue is more understandable post-transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If compression rate is increased for transmission, then transmission efficiency is improved, but speech intelligibility deteriorates due to deletion or degradation of phonetic information by the codec
Solution Approach 1:
The system applies pre-distortion processing to the audio signal before encoding, which proactively compensates for the phonetic information loss that will occur during compression. By预先 modifying the signal characteristics, the system counteracts the codec's tendency to delete or degrade phonetic information, thereby maintaining speech intelligibility even at higher compression rates
Solution Approach 2:
The pre-distortion technique applies an opposite transformation to the audio signal before encoding, specifically designed to counteract the distortion introduced by the codec. This preliminary anti-action ensures that when the codec processes the signal, the net effect preserves phonetic information rather than degrading it
2Reliability
If dynamic range with surround sound effects is maintained, then audio quality is improved, but dialogue intelligibility deteriorates due to mixing of speech, music, and sound effects
Solution Approach 1:
The system applies different processing characteristics to different frequency ranges and time segments of the audio signal. By identifying and selectively enhancing frequency bands containing speech information while allowing other bands to maintain surround sound effects, the system preserves dialogue intelligibility without sacrificing overall audio quality
Solution Approach 2:
The audio signal is divided into multiple frequency bands or time segments, allowing independent processing of speech-containing portions versus music and sound effect portions. This segmentation enables targeted enhancement of dialogue regions while maintaining the integrity of other audio elements
Data Source
AI summary
A system and process for pre-distorting TV shows and/or movie media enables digital transmission of the media via MPEG4/AC3 (or AAC) or MPEG4/AC4 codec for broadcast or streaming over the Internet with enhanced speech intelligibility. Processing of the entire media file is performed using pre-distortion techniques and algorithms including NN models (which includes DNN, RNN, CNN, and similar NN models) that are trained on perceptual codec induced noise, quantization noise, dynamic power level adjustment, frequency response adjustment, pitch and glottal impulse response adjustment, and other techniques. The pre-distortion process is iterative, and all combinations of pre-distortions to combat perceptual codec noise are attempted, and the result scored by an automatic speech recognition engine. The best speech recognition results and highest intelligibility scores are considered to indicate the best pre-distortion to be applied. Once the best pre-distortion is applied, a single media file is then encoded for transmission.