Apparatus and Method for Mdct M/s Stereo with Global Ild with Improved Mid/side Decision

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

This patent relates to an advanced method and apparatus for encoding and decoding stereo audio signals, specifically by optimizing the decision between mid/side (M/S) stereo coding and left/right (L/R) (dual-mono) coding on a frequency band basis. The invention introduces a novel use of global Interaural Level Difference (ILD) parameters and normalization, allowing the encoding system to smartly decide, per frequency band, which stereo encoding mode is best for compression efficiency and audio quality. The approach leverages frequency domain noise shaping (FDNS), perceptual whitening, and intelligent bitrate allocation to achieve improved audio compression, especially for complex or "panned" stereo signals.

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

• Lossy audio codecs for music and speech streaming services (e.g., online music platforms, internet radio)
• Mobile communication codecs (e.g., for smartphones, VoIP applications)
• Professional audio compression for broadcasting or archiving (e.g., radio, TV, production studios)
• Embedded audio processing in consumer electronics (e.g., smart speakers, media players, gaming devices)
• Multi-channel and surround audio codecs used in home theater systems or virtual/augmented reality
• Efficient storage and transmission of stereo/multichannel audio files and streams

BenefitsContent extracted from patent full text and abstract with AI.

• Improved audio compression efficiency, leading to smaller file sizes or lower streaming bitrates for the same perceived quality
• Better audio quality, especially for stereo signals with complex spatial characteristics (e.g., sounds that are not centered)
• Adaptive encoding for each frequency band, providing optimal trade-off between compression and fidelity depending on the content
• Reduced computational complexity and resource usage compared to previous techniques, due to simplified decision-making and minimal side information
• Versatility to apply the method to both music and speech codecs, as well as multi-channel/surround scenarios
• Enhanced user experience by reducing artifacts and preserving stereo image even under strong compression

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Patent Abstract

Fig. illustrates an apparatus for encoding a first channel and a second channel of an audio input signal comprising two or more channels to obtain an encoded audio signal according to an embodiment. The apparatus comprises a normalizer (110) configured to determine a normalization value for the audio input signal depending on the first channel of the audio input signal and depending on the second channel of the audio input signal, wherein the normalizer (110) is configured to determine a first channel and a second channel of a normalized audio signal by modifying, depending on the normalization value, at least one of the first channel and the second channel of the audio input signal. Moreover, the apparatus comprises an encoding unit (120) being configured to generate a processed audio signal having a first channel and a second channel, such that one or more spectral bands of the first channel of the processed audio signal are one or more spectral bands of the first channel of the normalized audio signal, such that one or more spectral bands of the second channel of the processed audio signal are one or more spectral bands of the second channel of the normalized audio signal, such that at least one spectral band of the first channel of the processed audio signal is a spectral band of a mid signal depending on a spectral band of the first channel of the normalized audio signal and depending on a spectral band of the second channel of the normalized audio signal, and such that at least one spectral band of the second channel of the processed audio signal is a spectral band of a side signal depending on a spectral band of the first channel of the normalized audio signal and depending on a spectral band of the second channel of the normalized audio signal. The encoding unit (120) is configured to encode the processed audio signal to obtain the encoded audio signal.