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

Claim 8:
9. An audio processing unit for performing high frequency reconstruction of an audio signal, the audio processing unit comprising:
an input interface for 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;
a core audio decoder for decoding the audio data to generate a decoded lowband audio signal;
a deformatter for 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;
an analysis filterbank for filtering the decoded lowband audio signal to generate a filtered lowband audio signal; and
a high frequency regenerator for reconstructing a highband portion of the audio signal using the filtered lowband audio signal and the high frequency reconstruction metadata, wherein the reconstructing includes a spectral translation if the patching mode parameter is the first value and the reconstructing includes harmonic transposition by phase-vocoder frequency spreading if the patching mode parameter is the second value,
wherein the analysis filterbank, high frequency regenerator, and synthesis filterbank are performed in a post-processor 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.