Download Low bit-rate audio coding with hybrid representations
We present a general audio coder based on a structural decomposition : the signal is expanded into three features : its harmonic part, the transients and the remaining part (referred as the noise). The rst two of these layers can be very eciently encoded in a wellchosen basis. The noise is by construction modelized as a gaussian (colored) random noise. Furthermore, this decomposition allows a good time-frequency psycoacoustic modeling, as it dircetly provides us with the tonal and nontonal part of the signal.
Download Wavelet based Method for audio-video synchronization in broadcasting applications
The difference between standards used for films and for video generates problems when a conversion from one format to another is required : Since all the images are displayed, the change of frame rate induces a pitch change on the sound. To avoid this problem, the whole soundtrack has to be processed during the duplication. In this paper, we address the corresponding sound transformation problem, namely the dilation of the sound spectrum without changing its duration. For broadcasting applications, the ratio of transposition is within the range 24/25-25/24. The wide variety of sounds (music, speech, noise…) used in movies led us to first construct a database of representative sounds containing both transient, noisy and quasiperiodic sounds. This database has been used to compare the performances of different approaches. The reviewing of the most well known methods clearly shows significant disparities between them according to the class of the signal. This led us to reconsider the problem and to propose methods based on wavelet transforms.