Elaboration de nouveaux signaux d'ancrage pour l'évaluation des codeurs.

Listening tests are the most reliable ways to assess subjective quality of codecs. Reference conditions are needed to allow comparison of results coming from different tests. New coding techniques are developed for which Modulated Noise Reference Unit (MNRU) is no more appropriate. The goal of this paper is to propose a reference system related to the degradations produced by the new coding schemes. An ACR (Absolute Category Rating) test helps in the selection of 20 codecs of similar quality but showing different degradations. The results of dissimilarity tests conducted on signals created using those 20 codecs enter a multidimensional analysis. From the perceptive attributes characterizing the four dimensions of the perceptive space, reference signals have been built. Three of the perceptive attributes have been validated through a second analysis using part of the previous coded signals and the reference signals.