Apparatus and Method for Stereo Filing in Multichannel Coding

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

This invention improves the decoding of multichannel audio signals, particularly for systems with three or more audio channels (such as surround sound or 3D audio). It introduces an apparatus and method that identify and fill 'spectral holes'—frequency bands that have been quantized to zero during encoding—by generating and inserting noise derived intelligently from previous audio output channels instead of random noise. This approach, called 'stereo filling,' leverages the redundancy and relationships between channels, adapting dynamically to changing channel combinations to maintain audio quality, especially at low bitrates.

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

• Home theater or cinema surround sound systems to provide higher quality audio at lower data rates.
• Streaming services or digital broadcasting that need to compress multichannel audio efficiently without degrading sound quality.
• Virtual reality (VR) and augmented reality (AR) environments that use immersive audio with many spatial channels.
• Hearing aids or assistive listening devices that transmit or process multiple channels of sound efficiently.
• Professional audio production and mastering tools that encode and decode high-fidelity multichannel audio for music, film, or gaming.

BenefitsContent extracted from patent full text and abstract with AI.

• Reduces undesirable artifacts ('spectral holes') and improves the perceived quality of decoded audio, even at low bitrates.
• Allows for more efficient compression of multichannel audio without sacrificing sound quality.
• Adapts dynamically to different and changing channel configurations, supporting modern flexible audio setups (e.g., 7.1.4, 22.2).
• Maintains better spatial fidelity and tonal balance by using information from correlated channels rather than injecting purely random noise.
• Ensures backward compatibility with existing decoders when implemented carefully, facilitating deployment in current infrastructures.
• Reduces computational complexity by using an efficient selection of previous channels for noise filling.

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Patent Abstract

An apparatus for decoding an encoded multichannel signal of a current frame to obtain three or more current audio output channels is provided. A multichannel processor is adapted to select two decoded channels from three or more decoded channels depending on first multichannel parameters. Moreover, the multichannel processor is adapted to generate a first group of two or more processed channels based on said selected channels. A noise filling module is adapted to identify for at least one of the selected channels, one or more frequency bands, within which all spectral lines are quantized to zero, and to generate a mixing channel using, depending on side information, a proper subset of three or more previous audio output channels that have been decoded, and to fill the spectral lines of frequency bands, within which all spectral lines are quantized to zero, with noise generated using spectral lines of the mixing channel.