2007/4

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    Content Adaptive True Motion Estimator for H.264 Video Compression
    (Společnost pro radioelektronické inženýrství, 2007-12) Huska, Jozef; Kulla, Peter
    Content adaptive true motion estimator for H.264 video coding is a fast block-based matching estimator with implemented multi-stage approach to estimate motion fields between two image frames. It considers the theory of 3D scene objects projection into 2D image plane for selection of motion vector candidates from the higher stages. The stages of the algorithm and its hierarchy are defined upon motion estimation reliability measurement (image blocks including two different directions of spatial gradient, blocks with one dominant spatial gradient and blocks including minimal spatial gradient). Parameters of the image classification into stages are set adaptively upon image structure. Due to search strategy are the estimated motion fields more corresponding to a true motion in an image sequence as in the case of conventional motion estimation algorithms that use fixed sets of motion vector candidates from tight neighborhood.
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    New Methods of Stereo Encoding for FM Radio Broadcasting Based on Digital Technology
    (Společnost pro radioelektronické inženýrství, 2007-12) Stranak, Pavel
    The article describes new methods of stereo encoding for FM radio broadcasting. Digital signal processing makes possible to construct an encoder with properties that are not attainable using conventional analog solutions. The article describes the mathematical model of the encoder, on the basis of which a specific program code for DSP was developed. The article further deals with a new method of composite clipping which does not cause impurities in the output spectrum, and at the same time preserves high separation between the left and right audio channels. The application of the new method is useful mainly where there are unwanted signal overshoots on the input of the stereo encoder, e.g., in case of signal transmission from the studio to the transmitter site through a route with psychoacoustic lossy compression of data rate.
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    On the Relationship between Integer Lifting and Rounding Transform
    (Společnost pro radioelektronické inženýrství, 2007-12) Prochaska, Jan; Vargic, Radoslav
    In this paper we analyze the relationship between integer Lifting scheme and Rounding transform as means to compute the wavelet transform in signal processing area. We bring some new results which better describe relationship, reversibility and equivalence of integer lifting scheme and rounding transform concept.
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    Evaluation of Measurement Performance in Averaging Quantization System with Noise
    (Společnost pro radioelektronické inženýrství, 2007-12) Kamensky, Miroslav; Kovac, Karol; Kralikova, Eva; Krammer, Anton
    Statistical description of quantization process is common in the theory of quantization. For the case of nonsubtractive dither theoretical analyses of the dithered quantizer have been confronted with experimental results. As a quantization system one-chip microcomputer with the analog-to-digital converter on a chip has been used. Generally valid criteria for dithered system performance have been practically applied for Gaussian dither. Interaction of natural noise present in the signal with an added Gaussian noise of several different disperses and influence of differential nonlinearity of the converter has been observed.
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    Blind Source Separation Using Time-Frequency Masking
    (Společnost pro radioelektronické inženýrství, 2007-12) Mohammed, Abbas; Ballal, Tarig; Grbic, Nedelko
    In blind source separation (BSS), multiple mixtures acquired by an array of sensors are processed in order to recover the initial multiple source signals. While a variety of Independent Component Analysis (ICA)-based techniques are being used, in this paper we used a newly proposed method: The Degenerate Unmixing and Estimation Technique (DUET). The method applies when sources are W-disjoint orthogonal; that is, when the time-frequency representations, of any two signals in the mixtures are disjoint sets. The method uses an online algorithm to perform gradient search for the mixing parameters, and simultaneously construct binary time-frequency masks that are used to partition one of the mixtures to recover the original source signals. Previous studies have demonstrated the robustness of the method. However, the investigation in this paper reveals significant drawbacks associated with the technique which should be addressed in the future.