Abstract

This paper investigates the influence of GSM speech coding on text independent speaker recognition performance. The three existing GSM speech coder standards were considered. The whole TIMIT database was passed through these coders, obtaining three transcoded databases. In a first experiment, it was found that the use of GSM coding degrades significantly the identification and verification performance (performance in correspondence with the perceptual speech quality of each coder). In a second experiment, the features for the speaker recognition system were calculated directly from the information available in the encoded bit stream. It was found that a low LPC order in GSM coding is responsible for most performance degradations. By extracting the features directly from the encoded bit-stream, we also managed to obtain a speaker recognition system equivalent in performance to the original one which decodes and reanalyzes speech before performing recognition.0-7803-6293-4/00/$10.00 02000 IEEE.

Abstract. In this paper we introduce a low complexity and accurate technique for target image search and retrieval. This method, which operates directly in the compressed JPEG domain, addresses two of the CBIR challenges stated by The Benchathlon Network regarding the search of a specific image: finding out if an exact same image exists in a database, and identifying this occurrence even when the database image has been compressed with a different coding bit-rate. The proposed technique can be applied in feature-containing or featureless image collections, and thus it is also suitable to search for image copies that might exist on the Web for law enforcement of copyrighted material. The reported method exploits the fact that the phase of the Discrete Cosine Transform coefficients contains a significant amount of information of a transformed image. By processing only the phase part of these coefficients, a simple, fast, and accurate target image search and retrieval technique is achieved.

Low power consumption is a requirement for any battery powered p ortable equipment. When designing ASICs for image and video c ompression, emphasis has been placed mainly on building circuits that are fast enough to satisfy the high data throughput associated with image and video p r ocessing. The imminent development of portable systems featuring full multimedia applications, adds the low-power constraint to the design of VLSI circuits for this kind of applications. Several techniques as lowering the supply voltage, architectural parallelization, pipelining etc., have been proposed in the literature to achieve low-power consumption. In this paper we report a VLSI circuit featuring a power management user-controllable technique that trades image quality for power consumption in a transform-based algorithm.

Line Spectrum Pair (LSP) representation of Linear Predictive Coding (LPC) parameters is widely used in speech coding applications. An efficient method for LPC to LSP conversion is Kabal's method. In this method the LSPs are the roots of two polynomials P' p (x) and Q' p (x), and are found by a zero crossing search followed by successive bisections and interpolation. The precision of the obtained LSPs is higher than required by most applications, but the number of bisections cannot be decreased without compromising the zero crossing search. In this paper, it is shown that, in the case of 10 th -order LPC, five intervals containing each only one zero crossing of P' 10 (x) and one zero crossing of Q' 10 (x) can be calculated, avoiding the zero crossing search. This allows a trade-off between LSP precision and computational complexity resulting in considerable computational saving.