Downmixer and Method for Downmixing at Least Two Channels and Multichannel Encoder and Multichannel Decoder

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

This patent introduces a downmixer system and method for audio signals with two or more channels (like stereo or surround sound). Unlike traditional systems which simply sum the channels and may suffer from audio quality issues (such as signal dropouts or distortions when channels are out of phase), this invention adds a "complementary signal" to compensate for these losses. This complementary signal is calculated from the original channels but is different from their direct sum. The result is a more robust and stable downmix, with improved audio quality across a wide range of input conditions.

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

• Audio streaming services or file formats that need to reduce multichannel audio (e.g., 5.1 surround) to stereo or mono for playback on less advanced systems.
• Hearing aids or assistive listening devices that need to deliver complex audio environments through limited channels.
• Consumer electronics, such as TVs, smartphones, tablets, or Bluetooth speakers, that play multichannel content on hardware with fewer audio outputs.
• Audio codecs and compression schemes that must efficiently transmit multichannel signals at low bit rates with minimal quality loss.
• Professional audio post-production and broadcasting, where multichannel soundtracks must be downmixed for different platforms or legacy systems.

BenefitsContent extracted from patent full text and abstract with AI.

• Minimizes signal cancellation, coloration, and instability compared to conventional downmixing, thus providing higher audio quality in downmixed signals.
• Provides controlled and adaptive energy equalization, so output signal levels remain consistent and natural, avoiding abrupt changes or artifacts.
• Reduces or eliminates the risk of singularities (situations where the downmix output collapses to zero) that can occur with standard methods when input channels are out of phase.
• Flexible and low-complexity implementation suitable for software or hardware, allowing integration into a wide range of consumer and professional audio equipment.
• Improves listener experience regardless of playback device's channel limitations, helping content creators and platform providers maintain artistic intent.

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Patent Abstract

A downmixer for downmixing at least two channels of a multichannel signal (12) having the two or more channels, comprises: a processor (10) for calculating a partial downmix signal (14) from the at least two channels; a complementary signal calculator (20) for calculating a complementary signal from the multichannel signal (12), the complementary signal (22) being different from the partial downmix signal (14); and an adder (30) for adding the partial downmix signal (14) and the complementary signal (22) to obtain a downmix signal (40) of the multichannel signal.