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49th IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP)

作者： Hold, Christoph McCormack, Leo Politis, Archontis Pulkki, Ville Aalto Univ Dept Informat & Communicat Eng Acoust Lab Espoo Finland Tampere Univ Fac Informat Technol & Commun Sci Tampere Finland

ISBN: (纸本)9798350344868;9798350344851

Scene-based spatial audio formats, such as Ambisonics, are playback system agnostic and may therefore be favoured for delivering immersive audio experiences to a wide range of (potentially unknown) devices. The number of channels required to deliver high spatial resolution Ambisonic audio, however, can be prohibitive for low-bandwidth applications. Therefore, this paper proposes a compression codec, which is based upon the parametric higher-order Directional audio coding (HO-DirAC) model. The encoder downmixes the higher-order Ambisonic (HOA) input audio into a reduced number of signals, which are accompanied by perceptually-motivated scene parameters. The downmixed audio is coded using a perceptual audio coder, whereas the parameters are grouped into perceptual bands, quantized, and downsampled. On the decoder side, low Ambisonic orders are fully recovered. Not fully recoverable HOA components are synthesized according to the parameters. The results of a listening test indicate that the proposed parametric spatial audio codec can improve the adopted perceptual audio coder, especially at low to medium-high bitrates, when applied to fifth-order HOA signals.

关键词： spatial audio coding Ambisonics Parametric spatial audio audio compression

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APPLICATIONS OF SHORT SPACE-TIME FOURIER ANALYSIS IN DIGITAL ACOUSTICS

APPLICATIONS OF SHORT SPACE-TIME FOURIER ANALYSIS IN DIGITAL...

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IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP)

作者： Pinto, Francisco Vetterli, Martin Ecole Polytech Fed Lausanne EPFL IC LCAV CH-1015 Lausanne Switzerland

ISBN: (纸本)9781457705397

This paper presents a signal processing tool for analyzing and manipulating digitized acoustic wave fields, based on a spatio-temporal extension of the time-frequency representation space. The emphasis is on wave fields acquired with a 1-D linear array of equidistant microphones (representing the spatial samples), but the basic formulation is valid for the three dimensions of space. We start by defining a spatio-temporal extension of the short time Fourier transform, in both continuous and discrete space and time, and then focus on applications of the proposed representation. In particular, we show that acoustic scenes with multiple sources can benefit from the use of space-frequency analysis in applications such as source separation (spatial filtering) and spatial audio coding (wave field coding). The experiments suggest that there is a spatial window size for which the performance of filtering and coding is optimal.

关键词： Time-frequency analysis space-frequency analysis source separation spatial audio coding

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MULTICHANNEL audio UPMIXING BASED ON NON-NEGATIVE TENSOR FACTORIZATION REPRESENTATION

MULTICHANNEL AUDIO UPMIXING BASED ON NON-NEGATIVE TENSOR FAC...

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IEEE Workshop on Applications of Signal Processing to audio and Acoustics (WASPAA)

作者： Nikunen, J. Virtanen, T. Vilermo, M. Tampere Univ Technol Korkeakoulunkatu 1 Tampere 33720 Finland Nokia Res Ctr Tampere 33720 Finland

ISBN: (纸本)9781457706936

This paper proposes a new spatial audio coding (SAC) method that is based on parametrization of multichannel audio by sound objects using non-negative tensor factorization (NTF). The spatial parameters are estimated using perceptually motivated NTF model and are used for upmixing a downmixed and encoded mixture signal. The performance of the proposed coding is evaluated using listening tests, which prove the coding performance being on a par with conventional SAC methods. The novelty of the proposed coding is that it enables controlling the upmix content by meaningful objects.

关键词： spatial audio coding Object-based audio coding Non-negative tensor factorization

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RESOLVING spatial SAMPLING EFFECTS IN PARAMETRIC DIRECTIONAL FILTERING

RESOLVING SPATIAL SAMPLING EFFECTS IN PARAMETRIC DIRECTIONAL...

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IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP)

作者： Kallinger, Markus Buerger, Michael Thiergart, Oliver Kuech, Fabian Mahne, Dirk Fraunhofer Inst Integrated Circuits IIS D-91058 Erlangen Germany

ISBN: (纸本)9781457705397

Directional audio coding (DirAC) represents an efficient scheme to analyze and reproduce spatial sound;the coded stream consists of a single-channel audio signal and few parameters. Estimation of these parameters ideally relies on figure-of-eight microphones and one omnidirectional microphone. The figure-of-eight directivity can be efficiently approximated by first-order differential microphone arrays. However, due to spatial sampling, there are considerable deviations from the required directivity at high frequencies. These deviations lead to incorrect spatial parameter estimates;especially, the instantaneous direction-of-arrival (DOA) becomes biased and - beyond a certain aliasing frequency - ambiguous. Parameters like the DOA drive subsequent processing units, e. g., for spatial filtering. In this paper we propose a novel strategy to compensate bias and ambiguity not directly w. r. t. the DOA but the output parameters of a spatial filtering processing unit. Simulation results confirm the benefits of the novel method, which does not involve additional computational load at run-time.

关键词： spatial filters beamforming spatial audio coding spatial aliasing

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OPTIMIZING HIGHER-ORDER DIRECTIONAL audio coding WITH ADAPTIVE MIXING AND ENERGY MATCHING FOR AMBISONIC COMPRESSION AND UPMIXING

OPTIMIZING HIGHER-ORDER DIRECTIONAL AUDIO CODING WITH ADAPTI...

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IEEE Workshop on Applications of Signal Processing to audio and Acoustics (WASPAA)

作者： Hold, Christoph McCormack, Leo Politis, Archontis Pulkki, Ville Aalto Univ Dept Signal Proc & Acoust Espoo Finland Tampere Univ Fac Informat Technol & Commun Sci Tampere Finland

ISBN: (纸本)9798350323726

In order to transmit sound-scenes encoded into the higher-order Ambisonics (HOA) format to low-bandwidth devices, transmission codecs are needed to reduce data requirements. Recently, the model-based higher-order directional audio coding (HO-DirAC) method was formulated for HOA input to HOA output. Compression is achieved by reducing the number of audio transport channels through spatial discretization. These transport channels are then used to reconstruct the scene on the receiving end based on accompanying spatial metadata. This reconstructed scene may also be optionally upmixed to a higher-order;leading to an enhancement in spatial-resolution. In this paper, the authors analyze certain sound-scenes that were especially challenging for the previously proposed HO-DirAC framework, which the authors postulate could be attributed to the lower-order reconstruction of diffuse sound-field components. Three optimizations for HO-DirAC are proposed, which all employ optimal adaptive mixing and/or energy matching of Ambisonic components based on spatial covariance matrices. The methods are formulated such that they are applied directly in the reconstruction of HOA from the spatially discrete transport audio signals. Notably, a dedicated low-complexity solution without additional side-information is derived. Instrumental evaluations confirm a reduced reconstruction error when using either of the proposed optimizations. These improvements were also demonstrated via a perceptual evaluation, whereby four, six, and twelve transport channels were used to reconstruct (and upmix to) fifth-order reference sound-scenes. The evaluation highlighted the high perceptual performance of the proposed optimizations, including the low-complexity version, thereby improving parametric spatial audio coding and reproduction.

关键词： spatial audio coding higher order ambisonics spherical harmonic domain

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Enhanced direction estimation using microphone arrays for Directional audio coding

Enhanced direction estimation using microphone arrays for Di...

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Workshop on Hands-Free Speech Communication and Microphone Arrays

作者： Kallinger, Markus Kuech, Fabian Schultz-Amling, Richard Del Galdo, Giovanni Ahonen, Jukka Pulkki, Ville Fraunhofer Inst Integrated Circuit IIS Erlangen Germany Aalto Univ Lab Acoust & Audio Sig Proc Helsinki Finland

ISBN: (纸本)9781424423378

Modem home entertainment systems offer surround sound audio playback. This progress over known mono and stereo devices is also intended for high quality hands-free telephony to enhance intelligibility of speech in group conversation. Directional audio coding (DirAC) provides an efficient and well-established way to record and encode spatial sound and to render it at an arbitrary loudspeaker setup. On the recording site, DirAC is based on B-format microphone signals. These signals can be obtained by one omnidirectional and three figure-of-eight microphones pointing along the axes of a three-dimensional Cartesian coordinate system. However, a grid of omnidirectional microphones is more appropriate for consumer applications due to economic reasons. Arrays can provide the required figure-of-eight directionality only for a certain frequency range. However, in this contribution we show that a straightforward direction estimator is biased. After formulating the bias analytically we propose an unbiased estimator and derive the theoretical limits for unique direction estimation. The results are illustrated by means of simulations and measurements.

关键词： spatial audio coding microphone array spatial filters audio coding planar arrays

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Experimental Study of MPEG Surround for Stereo audio Transmission 5

Experimental Study of MPEG Surround for Stereo Audio Transmi...

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5th International Conference on Information Technology Systems and Innovation (ICITSI)

作者： Luthfi, Amirul Permana, Al Kautsar Saputra, Oki Elfitri, Ikhwana Univ Andalas Dept Elect Engn Padang Indonesia Univ Jambi Dept Elect Engn Jambi Indonesia Inst Teknol Bandung Sch Elect Engn & Informat Bandung Indonesia

ISBN: (纸本)9781538656938

MPEG Surround (MPS) has been well-known for years as a standard for encoding multichannel audio signals based on the concept of spatial audio coding. It is normally used for 5.1 audio channels or even higher number of audio channels. However, as a modular encoding system, it is also possible to employ MPS for encoding lower number of audio channels such as for stereo audio signals. In this study, MPEG Surround is operated for encoding stereo audio signals at low bitrates. The reverse one-to-two (R-OTT), a module applied in the MPEG Surround to down-mix two channels as a single channel, is employed as a single block to process stereo audio signal. Using a single R-OTT module in the encoder and a single OTT module in the decoder, performance of MPS to compress stereo audio can be analyzed. The objective results show that employing single block R-OTT, MPEG Surround can outperform HE-AAC+ Parametric Stereo (PS) at very low bitrate 24 kb/s. At the same time, it also provides good performance over HE-AAC at bitrate 32 - 64 kb/s.

关键词： spatial audio coding MPEG Surround Stereo audio

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R-TTT Module with Modified Residual Signal for Improving Multichannel audio Signal Accuracy

R-TTT Module with Modified Residual Signal for Improving Mul...

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International Conference on Automation, Cognitive Science, Optics, Micro Electro-Mechanical System, and Information Technology (ICACOMIT)

作者： Elfitri, Ikhwana Luthfi, Amirul Fitrilina Andalas Univ Fac Engn Dept Elect Engn Kampus UNAND Limau Manih Padang 25163 Sumatera Barat Indonesia

ISBN: (纸本)9781467374088

spatial audio coding is a technique that capable of representing multichannel audio signals as a lower number of audio channels accompanied by spatial parameters and residual signal which will be useful for recreating the original multichannel audio signals. Moving Picture Expert Group (MPEG) Surround, an international standard developed based on spatial audio coding, specifies Reverse Two-To-Three (R-TTT) module to extend stereo audio, consisted of left and right channels, into three audio channels: left, centre, and right channels based on Channel Prediction Coefficient (CPC) as spatial parameter and residual signal. In this paper, a modified residual signal is proposed to provide a better audio waveform reconstruction in the decoder side by minimising distortion caused by quantisation of CPC. Our experiments show that the waveform accuracy in terms of Signal-to-Noise Ratio (SNR) gets improved as high as 11 dB while the subjective test shows that the proposed method does not reduce perceptual quality, in terms of Subjective Difference Grade (SDG) score, of the reconstructed audio signals.

关键词： MPEG Surround spatial audio coding Multichannel audio Signals

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Relative Contribution of Frequency and Parameter Values to Selectivity for Interaural Correlation

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电脑学刊 2018年第2期29卷 21-33页

作者： Han Zhu Hui Zhang Song Wang Cong Zhang

With the advent of the digital age, 3D audio is confronted with an important issues that how to compress multi-channel audio signal effectively. It is a significant way to explore the perceptual mechanism of human ear by researching the relative contribution of frequency and parameter values to selectively for Interaural Correlation (IC). Five values of IC that corresponding to five special sound width are selected in accordance with qualitative analysis of perceptual characteristics for IC: 1, 0.98, 0.94, 0.87 and 0.77. The audible frequency range of the human ear is divided into 24 bands based. A self-adaption test method contained the traditional test methods such as 1 up/2 down and 2AFC is taken, the test sequences are chosen as Gaussian white noise, and the experimental data is analyzed mathematically by the linear interpolation method. The experiment results demonstrate that: JND changes more significantly with frequency, and the minimum value occurs at about 700Hz and 1170Hz while the maximum values correspond to both side bands and the JND increases as the IC of the standard increasing. The experimental data and conclusions can provide theoretical support for the efficient compression of 3D audio signals.

关键词： IC JND linear interpolation method self-adaption test method spatial audio coding

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R-TTT Module with Modified Residual Signal for Improving Multichannel audio Signal Accuracy

R-TTT Module with Modified Residual Signal for Improving Mul...

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International Conference on Automation, Cognitive Science, Optics, Micro Electro-Mechanical System, and Information Technology

作者： Ikhwana Elfitri Amirul Luthfi Fitrilina Department of Electrical Engineering Faculty of Engineering Andalas University

ISBN: (纸本)9781467374095

spatial audio coding is a technique that capable of representing multichannel audio signals as a lower number of audio channels accompanied by spatial parameters and residual signal which will be useful for recreating the original multi-channel audio signals. Moving Picture Expert Group (MPEG) Surround, an international standard developed based on spatial audio coding, specifies Reverse Two-To-Three (R-TTT) module to extend stereo audio, consisted of left and right channels, into three audio channels: left, centre, and right channels based on Channel Prediction Coefficient (CPC) as spatial parameter and residual signal. In this paper, a modified residual signal is proposed to provide a better audio waveform reconstruction in the decoder side by minimising distortion caused by quantisation of CPC. Our experiments show that the waveform accuracy in terms of Signal-to-Noise Ratio (SNR) gets improved as high as 11 dB while the subjective test shows that the proposed method does not reduce perceptual quality, in terms of Subjective Difference Grade (SDG) score, of the reconstructed audio signals.

关键词： MPEG Surround spatial audio coding Multichannel audio Signals residual signal audio coding audio signals audio channels Moving Pictures Experts Group Subjective testing Quantization

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