Inter-channel Bandwidth Extension Audio Coding

The patent applies preliminary action by performing temporal alignment and phase correction on audio channels before the stereo encoding process. The encoder determines temporal shift values and applies corrections to align left and right channels, ensuring that coding gains and redundancy are calculated based on properly synchronized signals. This preliminary synchronization resolves the contradiction by eliminating temporal mismatches that would otherwise compromise the reliability of coding parameters while maintaining the efficiency benefits of mid-side and parametric stereo coding.

The patent applies the taking out principle by removing the ICBWE gain mapping parameters from the extraction and transmission process. Instead of extracting these parameters from the frequency-domain channels and including them in the bitstream, the encoder omits this step entirely. The decoder then generates the necessary gain mapping parameters independently using the received stereo parameters (such as inter-channel level differences and phase differences). This approach maintains audio quality by preserving the essential stereo information while significantly reducing coding complexity and transmission bandwidth requirements.

The patent applies the copying principle by having the decoder generate ICBWE gain mapping parameters as a copy or derivation of the received stereo parameters rather than receiving them directly. The decoder uses the transmitted inter-channel level differences and phase differences to reconstruct the gain mapping parameters locally. This approach achieves reconstruction accuracy comparable to direct transmission while reducing transmission bandwidth, as the decoder recreates the necessary parameters from the essential stereo cues already present in the compressed bitstream.