Adaptive Transform Coding Using LMS-like Principal Component Tracking (original) (raw)

Linear Predictive Coding With Backward Adaptation and Noise Shaping

2014

In linear predictive coding, the benefit of backward adaptation in comparison to forward adaptation of the prediction coefficients is that it allows to save bit rate since no prediction coefficients need to be transmitted from the encoder to the decoder. Also, backward adaptation yields very low complexity and algorithmic delay. Unfortunately, noise shaping techniques which have proven to enable higher perceptual quality in speech and audio coding than approaches without noise shaping have been proposed only for forward adaptation. In order to overcome this shortcoming, in this paper we propose a novel scheme for noise shaping in linear predictive coding with backward sequential adaptation. The new concept is investigated involving two different methods for the adaptation of the prediction coefficients, the Gradient Adaptive Lattice (GAL) and the Normalized Least Mean Square (NLMS) algorithm. Measurements of the perceptual speech quality foradatabase ofspeech examples based on the w...

Optimization of Linear Multiresolution Transforms for Scene Adaptive Coding

1993

Scene adaptive coders are constituted by the cascade of a linear transform, scalar quantization, entropy coding and a huffer con- trolled by a feedback loop for hit rate regulation. The main contrihu- tion of this paper is to derive an analytical criterion evaluating the performances of any perfect reconstruction linear transform in the frame of scene adaptive coding. This criterion is, thereafter, used in order to optimize linear multiresolution transforms. The optimization adapts the filters parameters to the codec features and to the statistics of the 2-D sources; so, we call these tranforms adapted multiresolution transforms (AMT's). The transforms under study are implemented by a cascade of separable perfect-reconstruction (PR) FIR two-band filter hanks that can change at each resolution level. Two types of filter banks are envisaged: the PR orthogonal quadrature mirror filter (QMF) bank, which allows to implement the orthogonal AMT and the PR linear-phase filter (LPF) bank...