NZ777923B2 - Backward-compatible integration of harmonic transposer for high frequency reconstruction of audio signals - Google Patents

Backward-compatible integration of harmonic transposer for high frequency reconstruction of audio signals

Info

Publication number
NZ777923B2
NZ777923B2 NZ777923A NZ77792318A NZ777923B2 NZ 777923 B2 NZ777923 B2 NZ 777923B2 NZ 777923 A NZ777923 A NZ 777923A NZ 77792318 A NZ77792318 A NZ 77792318A NZ 777923 B2 NZ777923 B2 NZ 777923B2
Authority
NZ
New Zealand
Prior art keywords
audio signal
lowband
high frequency
audio
frequency reconstruction
Prior art date
Application number
NZ777923A
Other versions
NZ777923A (en
Inventor
Per Ekstrand
Heiko Purnhagen
Lars Villemoes
Original Assignee
Dolby International Ab
Filing date
Publication date
Application filed by Dolby International Ab filed Critical Dolby International Ab
Priority to NZ787837A priority Critical patent/NZ787837A/en
Priority to NZ794714A priority patent/NZ794714A/en
Priority to NZ794707A priority patent/NZ794707A/en
Priority to NZ794713A priority patent/NZ794713A/en
Priority to NZ787839A priority patent/NZ787839B2/en
Priority to NZ793664A priority patent/NZ793664A/en
Priority claimed from NZ759800A external-priority patent/NZ759800A/en
Publication of NZ777923A publication Critical patent/NZ777923A/en
Publication of NZ777923B2 publication Critical patent/NZ777923B2/en

Links

Classifications

    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F17/00—Digital computing or data processing equipment or methods, specially adapted for specific functions
    • G06F17/10—Complex mathematical operations
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10L—SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING
    • G10L19/00—Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals, using source filter models or psychoacoustic analysis
    • G10L19/008—Multichannel audio signal coding or decoding using interchannel correlation to reduce redundancy, e.g. joint-stereo, intensity-coding or matrixing
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10L—SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING
    • G10L19/00—Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals, using source filter models or psychoacoustic analysis
    • G10L19/02—Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals, using source filter models or psychoacoustic analysis using spectral analysis, e.g. transform vocoders or subband vocoders
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10L—SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING
    • G10L19/00—Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals, using source filter models or psychoacoustic analysis
    • G10L19/04—Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals, using source filter models or psychoacoustic analysis using predictive techniques
    • G10L19/16—Vocoder architecture
    • G10L19/18—Vocoders using multiple modes
    • G10L19/22—Mode decision, i.e. based on audio signal content versus external parameters
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10L—SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING
    • G10L19/00—Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals, using source filter models or psychoacoustic analysis
    • G10L19/04—Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals, using source filter models or psychoacoustic analysis using predictive techniques
    • G10L19/16—Vocoder architecture
    • G10L19/18—Vocoders using multiple modes
    • G10L19/24—Variable rate codecs, e.g. for generating different qualities using a scalable representation such as hierarchical encoding or layered encoding
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10L—SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING
    • G10L19/00—Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals, using source filter models or psychoacoustic analysis
    • G10L19/04—Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals, using source filter models or psychoacoustic analysis using predictive techniques
    • G10L19/26—Pre-filtering or post-filtering
    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10L—SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING
    • G10L21/00—Speech or voice signal processing techniques to produce another audible or non-audible signal, e.g. visual or tactile, in order to modify its quality or its intelligibility
    • G10L21/02—Speech enhancement, e.g. noise reduction or echo cancellation
    • G10L21/038—Speech enhancement, e.g. noise reduction or echo cancellation using band spreading techniques

Abstract

method for decoding an encoded audio bitstream is disclosed. The method includes receiving the encoded audio bitstream and decoding the audio data to generate a decoded lowband audio signal. The method further includes extracting high frequency reconstruction metadata and filtering the decoded lowband audio signal with an analysis filterbank to generate a filtered lowband audio signal. The method also includes extracting a flag indicating whether either spectral translation or harmonic transposition is to be performed on the audio data and regenerating a highband portion of the audio signal using the filtered lowband audio signal and the high frequency reconstruction metadata in accordance with the flag.

Claims (7)

1. A method for decoding an encoded audio bitstream, the method comprising: 5 receiving the encoded audio bitstream, the encoded audio bitstream including audio data representing a lowband portion of an audio signal; decoding the audio data to generate a decoded lowband audio signal; extracting from the encoded audio bitstream high frequency reconstruction metadata, the high frequency reconstruction metadata including operating 10 parameters for a high frequency reconstruction that transposes a number of subbands from a lowband portion of the audio signal to a highband portion of the audio signal; extracting from the encoded audio bitstream a parameter indicating whether to use signal adaptive frequency domain oversampling; 15 filtering the decoded lowband audio signal with an analysis filterbank to generate a filtered lowband audio signal; extracting from the encoded audio bitstream a flag indicating whether either linear translation or harmonic transposition is to be performed on the audio data; regenerating a highband portion of the audio signal using the filtered lowband 20 audio signal and the high frequency reconstruction metadata in accordance with the flag; and combining the filtered lowband audio signal and the regenerated highband portion to form a wideband audio signal using synthesis filterbank, wherein the analysis filterbank includes analysis filters, hk(n), that are 25 modulated versions of a prototype filter, p0(n), according to: ? 1 ? h (? ) = ? (? ) exp {? (? + ) (? - )}, 0 = ? = ? ; 0 = ? < ? ? 2 2 where p0(n) is a real-valued symmetric or asymmetric prototype filter, M is a number of channels in the analysis filterbank and N is the prototype filter order and wherein the number of channels in the analysis filterbank is different from the 30 number of channels in the synthesis filterbank.
2. The method of claim 1, wherein the high frequency reconstruction metadata includes an operating parameter selected from the group consisting of envelope scale factors, noise floor scale factors, sinusoid addition information, time/frequency grid information, crossover frequency, and inverse filtering mode.
3. The method of claim 1, wherein the prototype filter, p (n), is derived from coefficients of Table 4 below.
4. The method of claim 3, wherein the prototype filter, p0(n), is derived from the 10 coefficients of Table 4 by one or more mathematical operations selected from the group consisting of rounding, subsampling, interpolation, or decimation.
5. The method of claim 1, wherein a phase shift is added to the filtered lowband audio signal after the filtering and compensated for before the combining.
6. A non-transitory computer readable medium containing instructions that when executed by a processor perform the method of claim 1.
7. A decoder for decoding an encoded audio bitstream, the decoder comprising: 20 an input interface for receiving the encoded audio bitstream, the encoded audio bitstream including audio data representing a lowband portion of an audio signal; a core decoder for decoding the audio data to generate a decoded lowband audio signal; 25 a deformatter for extracting from the encoded audio bitstream high frequency reconstruction metadata and a parameter indicating whether to use signal adaptive frequency domain oversampling, the high frequency reconstruction metadata including operating parameters for a high frequency reconstruction process that transposes a number of subbands from a lowband portion of the audio signal to a 30 highband portion of the audio signal; an analysis filterbank for filtering the decoded lowband audio signal to generate a filtered lowband audio signal; a deformatter for extracting from the encoded audio bitstream a flag indicating whether either linear translation or harmonic transposition is to be performed on the 35 audio data; a high frequency regenerator for regenerating a highband portion of the audio signal using the filtered lowband audio signal and the high frequency reconstruction metadata in accordance with the flag; and a synthesis filterbank for combining the filtered lowband audio signal and the 5 regenerated highband portion to form a wideband audio signal, wherein the analysis filterbank includes analysis filters, h (n), that are modulated versions of a prototype filter, p (n), according to: ? 1 ? ( ) ( ) { } h ? = ? ? exp ? (? + ) (? - ) , 0 = ? = ? ; 0 = ? < ? ? 2 2 where p (n) is a real-valued symmetric or asymmetric prototype filter, M is a number 10 of channels in the analysis filterbank and N is the prototype filter order, and wherein the number of channels in the analysis filterbank is different from the number of channels in the synthesis filterbank.
NZ777923A 2017-03-23 2018-03-19 Backward-compatible integration of harmonic transposer for high frequency reconstruction of audio signals NZ777923B2 (en)

Priority Applications (6)

Application Number Priority Date Filing Date Title
NZ787837A NZ787837A (en) 2017-03-23 2018-03-19 Backward-compatible integration of harmonic transposer for high frequency reconstruction of audio signals
NZ794714A NZ794714A (en) 2017-03-23 2018-03-19 Backward-compatible integration of harmonic transposer for high frequency reconstruction of audio signals
NZ794707A NZ794707A (en) 2017-03-23 2018-03-19 Backward-compatible integration of harmonic transposer for high frequency reconstruction of audio signals
NZ794713A NZ794713A (en) 2017-03-23 2018-03-19 Backward-compatible integration of harmonic transposer for high frequency reconstruction of audio signals
NZ787839A NZ787839B2 (en) 2018-03-19 Backward-compatible integration of harmonic transposer for high frequency reconstruction of audio signals
NZ793664A NZ793664A (en) 2017-03-23 2018-03-19 Backward-compatible integration of harmonic transposer for high frequency reconstruction of audio signals

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US201762475619P 2017-03-23 2017-03-23
NZ759800A NZ759800A (en) 2017-03-23 2018-03-19 Backward-compatible integration of harmonic transposer for high frequency reconstruction of audio signals

Publications (2)

Publication Number Publication Date
NZ777923A NZ777923A (en) 2023-12-22
NZ777923B2 true NZ777923B2 (en) 2024-03-26

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