US 12,094,480 B2
Backward-compatible integration of harmonic transposer for high frequency reconstruction of audio signals
Lars Villemoes, Järfälla (SE); Heiko Purnhagen, Sundbyberg (SE); and Per Ekstrand, Saltsjobaden (SE)
Assigned to DOLBY INTERNATIONAL AB, Dublin (IE)
Filed by DOLBY INTERNATIONAL AB, Dublin (IE)
Filed on Jul. 31, 2023, as Appl. No. 18/228,109.
Application 17/078,113 is a division of application No. 16/484,077, granted, now 10,818,306, issued on Oct. 27, 2020, previously published as PCT/US2018/023183, filed on Mar. 19, 2018.
Application 18/228,109 is a continuation of application No. 17/963,582, filed on Oct. 11, 2022, granted, now 11,763,830.
Application 17/963,582 is a continuation of application No. 17/078,113, filed on Oct. 23, 2020, granted, now 11,626,123, issued on Apr. 11, 2023.
Claims priority of provisional application 62/475,619, filed on Mar. 23, 2017.
Prior Publication US 2023/0377589 A1, Nov. 23, 2023
This patent is subject to a terminal disclaimer.
Int. Cl. G10L 19/00 (2013.01); G10L 19/008 (2013.01); G10L 19/24 (2013.01); G10L 19/26 (2013.01)
CPC G10L 19/26 (2013.01) [G10L 19/008 (2013.01); G10L 19/24 (2013.01)] 6 Claims
OG exemplary drawing
 
1. A method for decoding an encoded audio bitstream, the method comprising:
receiving the encoded audio bitstream, the encoded audio bitstream including audio data representing a lowband portion of an audio signal, wherein the encoded audio bitstream further includes a fill element with an identifier indicating a start of the fill element and fill data after the identifier, and wherein the fill data includes an extension payload, the extension payload includes spectral band replication extension data, and the extension payload is identified with a four bit unsigned integer transmitted most significant bit first and having a value of ‘1101’ or ‘1110’, wherein the identifier is a three bit unsigned integer transmitted most significant bit first and having a value of 0x6;
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 parameters for a high frequency reconstruction process that linearly translates a consecutive number of subbands from a lowband portion of the audio signal to a highband portion of the audio signal;
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, wherein the fill data includes the flag; 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,
wherein the analysis filterbank includes analysis filters, hk(n), that are modulated versions of a prototype filter, p0(n), according to:

OG Complex Work Unit Math
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.