Apparatus and Method for Post-Processing an Audio Signal Using Prediction Based Shaping

Simple SummaryContent extracted from patent full text and abstract with AI.

This invention provides an apparatus and method for post-processing audio signals to improve quality by addressing issues like pre-echo and transient blurring caused by audio compression. It works by converting audio into a frequency domain (spectral representation), uses prediction-based filters to precisely shape and enhance transient (sharp or sudden) parts of the audio (like drum hits or consonant sounds), and then converts the modified signal back to standard audio. The process can effectively clean up compression artifacts and sharpen attacks in audio, especially after it has been coded for storage or transmission.

Use CasesContent extracted from patent full text and abstract with AI.

• Restoring and enhancing audio quality in music or speech that has been compressed with perceptual audio codecs (e.g., MP3, AAC) and suffered from artifacts like pre-echo and attack blurring.
• Post-processing in consumer and professional audio playback devices (e.g., music players, smartphones, streaming devices) to improve perceived audio quality of legacy or low-bitrate content.
• Audio restoration for archives or broadcast, enabling existing collections of compressed audio material to sound clearer and more natural without access to the original files.
• Enhancement in digital audio workstations and plug-ins for music production/mastering, allowing producers to recover or enhance transients lost during prior processing or compression.
• Integration into hearing aids or audio assistive devices to improve attack sharpness and clarity for better speech and music intelligibility.

BenefitsContent extracted from patent full text and abstract with AI.

• Removes or significantly mitigates pre-echo and transient blurring artifacts that are common in compressed audio, improving perceived sound quality.
• Operates as a post-processing step, making it applicable to any previously coded (compressed) audio without the need for original source data or changes to existing codecs.
• Automatically detects and enhances transients without requiring external guidance or side-channel information, enabling easy deployment and processing of large audio libraries.
• Preserves the integrity of tonal and non-transient content, avoiding unwanted distortion or unnaturalness in music and speech.
• Can be implemented efficiently in software or hardware, and flexibly inserted into various audio processing chains or consumer devices.

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Patent Abstract

Apparatus for post-processing (20) an audio signal, comprising: a time-spectrum-converter (700) for converting the audio signal into a spectral representation comprising a sequence of spectral frames; a prediction analyzer (720) for calculating prediction filter data for a prediction over frequency within a spectral frame; a shaping filter (740) controlled by the prediction filter data for shaping the spectral frame to enhance a transient portion within the spectral frame; and a spectrum-time-converter (760) for converting a sequence of spectral frames comprising a shaped spectral frame into a time domain.