Post-processor, Pre-Processor, Audio Encoder, Audio Decoder and Related Methods for Enhancing Transient Processing

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

This patent discloses a system and methods for improving the processing of audio signals containing frequent and dense transient events, such as applause or raindrops, which are traditionally very challenging for audio compression formats (codecs) at low bitrates. The technology, known as High Resolution Envelope Processing (HREP), uses a pre-processor to analyze and attenuate high-frequency transients before audio encoding, generating side information that describes the changes applied. After decoding, a post-processor uses this side information to restore the original transient characteristics, thus preserving perceptual audio quality while reducing the bitrate required for accurate encoding.

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

• Streaming and broadcasting of live events with significant background noise or applause (e.g., concerts, sports) where preserving audio quality is critical.
• Compression and storage of audio recordings with many transient noises or percussive sounds, such as rain, fireworks, or handclaps.
• Audio codecs in consumer applications (e.g., online music streaming, video conferencing) to improve quality at lower bitrates.
• Multi-channel or 3D audio systems (object-based or spatial audio) requiring efficient handling of transient-heavy content.
• Applications in hearing aids or professional audio editing where audio clarity during transient-rich passages is needed.

BenefitsContent extracted from patent full text and abstract with AI.

• Significantly improves perceived audio quality for signals that contain dense transient events, especially at low and medium bitrates.
• Reduces the bitrate required for high-quality coding of difficult signals like applause or rain without introducing pre-echo artifacts or blurring transients.
• Ensures that non-transient (regular) audio signals are not degraded, maintaining general audio transparency.
• Adds minimal computational and implementation complexity, making it suitable for real-time and low-power devices.
• Provides flexible, per-channel/object processing applicable to mono, stereo, multi-channel, and 3D audio formats, including support for parametric spatial coding.
• Subjective listening tests show substantial gains in perceptual quality scores with no notable degradation in other content types.

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Patent Abstract

An audio post-processor (100) for post-processing an audio signal (102) having a time-variable high frequency gain information (104) as side information comprises: a band extractor (110) for extracting a high frequency band (112) of the audio signal (102) and a low frequency band (114) of the audio signal (102); a high band processor (120) for performing a time-variable modification of the high frequency band (112) in accordance with the time-variable high frequency gain information (104) to obtain a processed high frequency band (122); and a combiner (130) for combining the processed high frequency band (122) and the low frequency band (114). Furthermore, a pre-processor for analyzing an audio signal to determine a time-variable high frequency gain information, perform modification of an high frequency band, and output a signal comprising the pre-processed audio signal and the high frequency gain information.