Patent ID: 11908486
Assignee: DOLBY INTERNATIONAL AB
Field: Computer technology (Electrical engineering)
Classification: CPC G | IPC G

Claim 0:
1. A method for performing high frequency reconstruction of an audio signal, the method comprising:
receiving an encoded audio bitstream, the encoded audio bitstream including audio data representing a lowband portion of the audio signal and high frequency reconstruction metadata;
decoding the audio data to generate a decoded lowband audio signal;
extracting from the encoded audio bitstream the high frequency reconstruction metadata, the high frequency reconstruction metadata including operating parameters for a high frequency reconstruction process, the operating parameters including a patching mode parameter located in a backward-compatible extension container of the encoded audio bitstream, wherein a first value of the patching mode parameter indicates spectral translation and a second value of the patching mode parameter indicates harmonic transposition by phase-vocoder frequency spreading;
filtering the decoded lowband audio signal to generate a filtered lowband audio signal; and
regenerating a highband portion of the audio signal using the filtered lowband audio signal and the high frequency reconstruction metadata, wherein the regenerating includes spectral translation if the patching mode parameter is the first value and the regenerating includes harmonic transposition by phase-vocoder frequency spreading if the patching mode parameter is the second value,
wherein the filtering, regenerating, and combining are performed as a post-processing operation with a delay of 3010 samples per audio channel and wherein the spectral translation comprises maintaining a ratio between tonal and noise-like components by adaptive inverse filtering.