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Promotions-Vortrag Multi Channel Audio Processing: Enhancement, Compression and Evaluation of Quality
Dipl.-Ing. Magnus Schäfer
28. April 2014
11:15 Uhr
Hörsaal 4G IKS
The demand for high definition audio and video services is rapidly increasing. Efficient techniques are required for enhancement and compression of multi channel audio signals. For both tasks, novel signal processing and coding algorithms are developed and theoretical bounds are derived. Additionally, a new instrumental quality measure for the evaluation of multi channel signal processing algorithms is derived.
The enhancement schemes include a near field filter-and-sum beamformer which achieves a target directivity characteristic at the recording side and an efficient postfilter for the reproduction side which increases speech intelligibility.
The main part of this work covers multi channel predictive compression of audio signals. A new coding system is proposed which uses both inter and intra channel prediction. Performance bounds are derived and two methods for adaptive bit rate distribution are devised. Multi channel noise shaping concepts are introduced. The performance of the compression system is quantified by instrumental measures.
A novel instrumental quality measure is introduced for the evaluation of multi channel signal enhancement and compression. It combines a proven single channel quality measure with a binaural auditory model and a mathematical model of cognitive behavior. The inclusion of spatial information into the instrumental quality measurement leads to a consistently high correlation between the instrumental measure and human perception.
