Assessing brain wave activity is a viable strategy for monitoring fatigue when performing tasks such as driving, and numerous studies have been conducted in this area. However, results of a systematic review on changes in brain wave activity associated with fatigue have revealed equivocal findings. This study investigated brain wave activity associated with fatigue in 48 nonprofessional healthy drivers as they participated in a simulated driving task until they fatigued. The results showed that as a person fatigues, slow wave activity increased over the entire cortex, in theta and in alpha 1 and 2 bands, while no significant changes were found in delta wave activity. Substantial increases also occurred in fast wave activity, though mostly in frontal sites. The results suggest that as a person fatigues, the brain loses capacity and slows its activity, and that attempts to maintain vigilance levels lead to increased beta activity.

Regional brain wave activity changes associated with fatigue.

In 2004 the ISO/MPEG Audio standardization group started a new work item on efficient and backward-compatible coding of high-quality multichannel sound using parametric coding techniques. Finalized in the fall of 2006, the resulting MPEG Surround specification allows the transmission of surround sound at bit rates that have been commonly used for coding of mono or stereo sound. The results of the standardization process are summarized by describing the underlying ideas and providing an overview of the MPEG Surround technology. The performance of the scheme is characterized by the results of recent verification tests. These tests include several operation modes as they would be used in typical application scenarios to introduce multichannel audio into existing audio services.

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MPEG Surround – the ISO/MPEG Standard for Efficient and Compatible Multi-Channel Audio Coding

Provided are an audio encoding method and apparatus and an audio decoding method and apparatus in which audio signals can be encoded or decoded so that sound images can be localized at any desired position for each object audio signal. The audio decoding method generating a third downmix signal by combining a first downmix signal extracted from a first audio signal and a second downmix signal extracted from a second audio signal; generating third object-based side information by combining first object-based side information extracted from the first audio signal and second object-based side information extracted from the second audio signal; converting the third object-based side information into channel-based side information; and generating a multi-channel audio signal using the third downmix signal and the channel-based side information.

Methods and apparatuses for encoding and decoding object-based audio signals

The present invention teaches a new audio coding system that can code both general audio and speech signals well at low bit rates. A proposed audio coding system comprises linear prediction unit for filtering an input signal based on an adaptive filter; a transformation unit for transforming a frame of the filtered input signal into a transform domain; and a quantization unit for quantizing the transform domain signal. The quantization unit decides, based on input signal characteristics, to encode the transform domain signal with a model-based quantizer or a non-model-based quantizer. Preferably, the decision is based on the frame size applied by the transformation unit.

Audio encoder and decoder

An audio encoder (109) has a hierarchical encoding structure and generates a data stream comprising one or more audio channels as well as parametric audio encoding data. The encoder (109) comprises an encoding structure processor (305) which inserts decoder tree structure data into the data stream. The decoder tree structure data comprises at least one data value indicative of a channel split characteristic for an audio channel at a hierarchical layer of the hierarchical decoder structure and may specifically specify the decoder tree structures to be applied by a decoder. A decoder (115) comprises a receiver (401) which receives the data stream and a decoder structure processor (405) for generating the hierarchical decoder structure in response to the decoder tree structure data. A decode processor (403) then generates output audio channels from the data stream using the hierarchical decoder structure.

Audio encoding and decoding

Reference LCAV-CONF-2005-029 URL: www.aes.org Record created on 2005-10-07, modified on 2017-05-12

MPEG Spatial Audio Coding / MPEG Surround: Overview and Current Status

An overview of the recently finalized ISO/MPEG standard for multichannel audio compression MPEG Surround is provided. This audio compression scheme enables backwardcompatible multichannel audio coding and transmission at unsurpassed coding efficiency. This is achieved by generating a mono, stereo, or matrixed-surround compatible down mix, which can be transmitted using any existing mono or stereo service, extended with a small amount of parametric side information that describes the perceptually relevant spatial properties of the original multichannel content. The concepts behind spatial parameterization are outlined, and the architecture of the MPEG Surround system is explained. Results of subjective evaluations are included to demonstrate its efficiency.

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Background, concept, and architecture for the recent MPEG surround standard on multichannel audio compression

A Multi-channel synthesiser for generating at least three output channels (110, 111, 112) using an input signal having at least one base channel, the base channel being derived from the original multi-channel signal (101, 102, 103), the input signal further including at least two different up-mixing parameters, and an up-mixer mode indication (1005) indicating, in a first state that a first up-mixing rule is to be performed, and, indicating, in a second state, that a different second up-mixing rule is to be performed, uses an up-mixer for up-mixing the at least one base channel using the at least two different up-mixing parameters based on the first or the second up-mixing rule in response to the up-mixer mode indication (1005) so that the at least three output channels (110, 111, 112) are obtained.

Multi parametrisation based multi-channel reconstruction

The emerging MPEG Surround specification allows coding of high-quality multi-channel audio at bit rates comparable to rates currently used for coding of mono or stereo sound. This paper describes the underlying concept and provides an overview of this technology, including its rich feature set such as compatibility to traditional matrixed surround, the ability of employing manually produced (‘artistic’) downmix signals, and the provisions for binauralized decoding.

MPEG Surround: The Forthcoming ISO Standard for Spatial Audio Coding

A selected channel of a multi-channel signal which is represented by frames composed from sampling values having a high time resolution can be encoded with higher quality when a wave form parameter representation representing a wave form of an intermediate resolution representation of the selected channel is derived, the wave form parameter representation including a sequence of intermediate wave form parameters having a time resolution lower than the high time resolution of the sampling values and higher than a time resolution defined by a frame repetition rate. The wave form parameter representation with the intermediate resolution can be used to shape a reconstructed channel to retrieve a channel having a signal envelope close to that one of the selected original channel. The time scale on which the shaping is performed is shorter than the time scale of a framewise processing, thus enhancing the quality of the reconstructed channel. On the other hand, the shaping time scale is larger than the time scale of the sampling values, significantly reducing the amount of data needed by the wave form parameter representation.

Gerard Hotho

Papers

MPEG Spatial Audio Coding / MPEG Surround: Overview and Current Status

Background, concept, and architecture for the recent MPEG surround standard on multichannel audio compression

Multi parametrisation based multi-channel reconstruction

MPEG Surround: The Forthcoming ISO Standard for Spatial Audio Coding

Temporal and spatial shaping of multi-channel audio signals