Stefan Schandl

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This paper describes the scalable coder - G.729.1 - which has been recently standardized by ITU-T for wideband telephony and voice over IP (VoIP) applications. G.729.1 can operate at 12 different bit rates from 32 down to 8 kbit/s with wideband quality starting at 14 kbit/s. This coder is a bitstream interoperable extension of ITU-T G.729 based on three(More)
Recommendation G.729.1 is a new ITU-T standard which was approved in May 2006. This recommendation describes a hierarchical speech and audio coding algorithm built on top of a narrowband core codec. One challenge in the codec design is the generation of a wideband signal with a very limited additional bit rate (less than 2 kb/s). In this paper, we describe(More)
We present a technique to extend narrowband (NB) speech communication systems, using e.g. the GSM enhanced full rate (EFR) codec, with wideband (WB, 50-7000 Hz) capability. The limited acoustic bandwidth of narrowband speech coding is extended using a fairly coarse description of the missing high frequency band (3.4-7 kHz) in terms of temporal and spectral(More)
We report an outbreak of gastroenteritis due to Salmonella Enteritidis PT 21 associated with attending an annual traditional fair in a small Austrian village on 4 May 2005. The outbreak lasted from 4 to 8 May. Descriptive and analytical epidemiological investigations were conducted in order to determine the extent of the outbreak and to identify outbreak(More)
We present a technique to enhance the perceived speech quality in narrowband (NB, cutoff frequency fc = 3.4 kHz) speech communication systems, e.g., implementing the ITU-T G.729A codec [1]. Therefore, wideband (WB, fc = 7 kHz) capability is introduced. The limited acoustic bandwidth of NB speech coding is extended using a fairly coarse description of the(More)
We present an embedded and hierarchical 8-32 kbit/s speech and audio coding algorithm that has been successfully submitted to the ITU-T as a candidate for ITU-T Rec. G.729.1 (ex G.729EV). The submitting consortium consisted of Siemens AG, Matsushita Electric Industrial Co. Ltd., and Mindspeed Technologies Inc. This contribution gives a comprehensive(More)
This paper presents an enhancement layer coming on top of G.729 Annex A codec. This enhancement layer consists of an optimization of the algebraic fixed codebook pulses that were selected by the Annex A codec during the fixed codebook search. The pulses selected by the ACELP codec have all the same absolute amplitude. Our method optimizes each of these(More)
Silence compression scheme is essential for efficient voice communication systems. It allows a significant reduction of transmission bandwidth during silence period where only parametric descriptions of the background noise are transmitted. A silence compression scheme includes a voice activity detection (VAD), a discontinuous transmission (DTX), a silence(More)
Supersoft X-ray sources are characterized by the radiation of a white dwarf with a temperature of some 105 K. The compact star is surrounded by an irradiated accretion diskwhich provides the high optical luminosity. For CAL 87 (Schandl et al. 1996a, 1996b) it could be shown, that this disk has an elevated rim at the outer edge. The impact of the accretion(More)
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