Recent Patents in Signal Processing (June 2017) – Audio Coding

For our June 2017 issue, we cover recent patents dealing with audio coding. In accordance with an embodiment pf patent no 9,646,616, a method of generating an encoded audio signal, the method includes estimating a time-frequency energy of an input audio signal from a time-frequency filter bank, computing a global variance of the time-frequency energy, determining a post-processing method according to the global variance, and transmitting an encoded representation of the input audio signal along with an indication of the determined post-processing method. According to patent no. 9,576,586 an audio coding device includes a memory; and a processor configured to execute a plurality of instructions stored in the memory, the instructions comprising: selecting a main lobe among a plurality of lobes detected from a frequency signal configuring an audio signal on a basis of bandwidth and power of the lobes; and coding the audio signal in such a manner that a first amount of bits per a unit frequency domain allocated to coding of the frequency signal of the main lobe is larger than a second amount of bits per the unit frequency domain allocated to the coding of the frequency signal of a side lobe as a lobe other than the main lobe. Patent no. 9,564,143 introduces an audio signal transmission device for encoding an audio signal includes an audio encoding unit that encodes an audio signal and a side information encoding unit that calculates and encodes side information from a look-ahead signal. An audio signal receiving device for decoding an audio code and outputting an audio signal includes: an audio code buffer that detects packet loss based on a received state of an audio packet, an audio parameter decoding unit that decodes an audio code when an audio packet is correctly received, a side information decoding unit that decodes a side information code when an audio packet is correctly received, a side information accumulation unit that accumulates side information obtained by decoding a side information code, an audio parameter missing processing unit that outputs an audio parameter upon detection of audio packet loss, and an audio synthesis unit that synthesizes decoded audio from the audio parameter. In patent no. 9,558,785 embodiments of systems and methods are described for generating layered audio such that computing devices can request a variable amount of data based on criteria such as their available bandwidth, device capability, or user selection. A base layer and one or more enhancement layers that incrementally enhance the previous layers may be generated. A computing device may retrieve the base layer and/or one or more enhancement layers, adjusting, in real-time or near real-time, which layers are retrieved based on fluctuations in the available bandwidth among other possible criteria. In the invention no. 9,536,533 linear prediction based audio coding is improved by coding a spectrum composed of a plurality of spectral components using a probability distribution estimation determined for each of the plurality of spectral components from linear prediction coefficient information. The linear prediction coefficient information is available anyway. Accordingly, it may be used for determining the probability distribution estimation at both encoding and decoding side. The latter determination may be implemented in a computationally simple manner by using, for example, an appropriate parameterization for the probability distribution estimation at the plurality of spectral components. The coding efficiency as provided by the entropy coding is compatible with probability distribution estimations as achieved using context selection, but its derivation is less complex. The derivation may be purely analytically and/or does not require any information on attributes of neighboring spectral lines such as previously coded/decoded spectral values of neighboring spectral lines as is the case in spatial context selection. Following patent no. 9,524,724, noise filling in perceptual transform audio codecs is improved by performing the noise filling with a spectrally global tilt, rather than in a spectrally flat manner. In patent no. 9,524,722, frame elements which shall be made available for skipping are transmitted more efficiently by arranging that a default payload length information is transmitted separately within a configuration block, with the length information within the frame elements, in turn, being subdivided into a default payload length flag followed, if the default payload length flag is not set, by a payload length value explicitly coding the payload length of the respective frame element. However, if the default payload length flag is set, an explicit transmission of the payload length may be avoided. Rather, any frame element, the default extension payload length flag of which is set, has the default payload length and any frame element, the default extension payload length flag of which is not set, has a payload length corresponding to the payload length value. By this measure, transmission effectiveness is increased. The invention no. 9,508,352 introduces an audio coding device that performs predictive coding on a third-channel signal included in a plurality of channels in an audio signal according to a first-channel signal and a second-channel signal, which are included in the plurality of channels, and to a plurality of channel prediction coefficients included in a coding book, the device includes a processor; and a memory which stores a plurality of instructions, which when executed by the processor, cause the processor to execute, selecting channel prediction coefficients corresponding to the first-channel signal and the second-channel signal so that an error, which is determined by a difference between the third-channel signal before predictive coding and the third-channel signal after predictive coding, is minimized; and controlling the first-channel signal or the second-channel signal so that the error is further reduced. The invention no. 9,495,970 provides a layered audio coding format with a monophonic layer and at least one sound field layer. A plurality of audio signals is decomposed, in accordance with decomposition parameters controlling the quantitative properties of an orthogonal energy-compacting transform, into rotated audio signals. Further, a time-variable gain profile specifying constructively how the rotated audio signals may be processed to attenuate undesired audio content is derived. The monophonic layer may comprise one of the rotated signals and the gain profile. The sound field layer may comprise the rotated signals and the decomposition parameters. In one embodiment, the gain profile comprises a cleaning gain profile with the main purpose of eliminating non-speech components and/or noise. The gain profile may also comprise mutually independent broadband gains. Because signals in the audio coding format can be mixed with a limited computational effort, the invention may advantageously be applied in a tele-conferencing application. In patent no. 9,484,038 an apparatus for generating a merged audio data stream is provided. The apparatus includes a demultiplexer for obtaining a plurality of single-layer audio data streams, wherein each input audio data stream includes one or more layers, wherein the demultiplexer is adapted to demultiplex each one of one or more input audio data streams having one or more layers into two or more demultiplexed audio data streams having exactly one layer. Furthermore, the apparatus includes a merging module for generating the merged audio data stream based on the plurality of single-layer audio data streams. Each layer of the input data audio streams, of the demultiplexed audio data streams, of the single-layer data streams and of the merged audio data stream includes a pressure value of a pressure signal, a position value and a diffuseness value as audio data. If you have an interesting patent to share when we next feature patents related to audio coding, or if you are especially interested in a signal processing research field that you would want to be highlighted in this section, please send email to Csaba Benedek (benedek.csaba AT sztaki DOT mta DOT hu).   References Number: 9,646,616 Title: System and method for audio coding and decoding Inventors:  Virette; David (Munich, DE), Gao; Yang (Mission Viejo, CA), Xiao; Wei (Munich, DE) Issued: May 9, 2017 Assignee: Huawei Technologies Co., Ltd. (Shenzhen, CN) Number: 9,576,586 Title: Audio coding device, audio coding method, and audio codec device Inventors: Kishi; Yohei (Kawasaki, JP), Kamano; Akira (Kawasaki, JP), Otani; Takeshi (Kawasaki, JP) Issued: February 21, 2017 Assignee: Fujitsu Limited (Kawasaki, JP) Number: 9,564,143 Title: Audio coding device, audio coding method, audio coding program, audio decoding device, audio decoding method, and audio decoding program Inventors: Tsutsumi; Kimitaka (Tokyo, JP), Kikuiri; Kei (Tokyo, JP), Yamaguchi; Atsushi (Tokyo, JP) Issued: February 7, 2017 Assignee: NTT DOCOMO, INC. (Tokyo, JP) Number: 9,558,785 Title: Layered audio coding and transmission Inventors: Johnson; Mark Rogers (Pasadena, CA), Maness; Phillip L. (Thousand Oaks, CA) Issued: January 31, 2017 Assignee: DTS, Inc. (Calabasas, CA) Number: 9,536,533 Title: Linear prediction based audio coding using improved probability distribution estimation Inventors: Baeckstroem; Tom (Nuremberg, DE), Helmrich; Christian (Erlangen, DE), Fuchs; Guillaume (Erlangen, DE), Multrus; Markus (Nuremberg, DE), Dietz; Martin (Nuremberg, DE) Issued: January 3, 2017 Assignee: Fraunhofer-Gesellschaft zur Foerderung der angewandten Forschung e.V. (Munich, DE) Number: 9,524,724 Title: Noise filling in perceptual transform audio coding Inventors: Disch; Sascha (Fuerth, DE), Gayer; Marc (Erlangen, DE), Helmrich; Christian (Erlangen, DE), Markovic; Goran (Nuremberg, DE), Luis Valero; Maria (Nuremberg, DE) Issued: December 20, 2016 Assignee: Fraunhofer-Gesellschaft zur Foerderung der angewandten Forschung e.V. (Munich, DE) Number: 9,524,722 Title: Frame element length transmission in audio coding Inventors: Neuendorf; Max (Nuremberg, DE), Multrus; Markus (Nuremberg, DE), Doehla; Stefan (Erlangen, DE), Purnhagen; Heiko (Sundbyberg, SE), De Bont; Frans (Riethoven, NL) Issued: December 20, 2016 Assignee: Fraunhofer-Gesellschaft zur Foerderung der angewandten Forschung e.V. (Munich, DE) Number: 9,508,352 Title: Audio coding device and method Inventors:  Takeuchi; Shunsuke (Kawasaki, JP), Kishi; Yohei (Kawasaki, JP), Suzuki; Masanao (Yokohama, JP), Kamano; Akira (Kawasaki, JP), Shirakawa; Miyuki (Fukuoka, JP) Issued: November 29, 2016 Assignee: Fujitsu Limited (Kawasaki, JP) Number: 9,495,970 Title: Audio coding with gain profile extraction and transmission for speech enhancement at the decoder Inventors: Dickins; Glenn (Como, AU), Purnhagen; Heiko (Sundbyberg, SE), Samuelsson; Leif Jonas (Sundbyberg, SE) Issued: November 15, 2016 Assignee: Dolby Laboratories Licensing Corporation (San Francisco, CA) Number: 9,484,038 Title: Apparatus and method for merging geometry-based spatial audio coding streams Inventors: Del Galdo; Giovanni (Heroldsberg, DE), Thiergart; Oliver (Forchheim, DE), Herre; Juergen (Buckenhof, DE), Kuech; Fabian (Erlangen, DE), Habets; Emanuel (Spardorf, DE), Craciun; Alexandra (Erlangen, DE), Kuntz; Achim (Hemhofen, DE) Issued: Fraunhofer-Gesellschaft zur Foerderung der angewandten Forschung e.V. (Munich, DE) Assignee: November 1, 2016