Gaussian mixture model based vector quantization (GMM-VQ) is a powerful technique for structured vector quantization. This thesis describes the implementation and evaluation of a perceptual audio coder using GMM-VQ. It is combined with a perceptual transform using psychoacoustic preand post-filtering. The coder was tested for low rate mono audio coding (64 kbps) and the results were compared to...

A novel technique for speaker verification over a communication network is proposed. The technique employs cepstral coefficients (LPCCs) derived from G.729 and G.723.1 coder parameters as feature vectors. Based on the LP coefficients derived from the coder parameters, LP residuals are reconstructed, and the verification performance is improved by taking account of the additional speaker-depende...

This paper presents an embedded joint source-channel coding scheme of speech. The source coder is an embedded variable bit rate perceptually based sub-band coder producing bits with different error sensitivities. The channel encoder is a Rate Compatible Punctured Trellis code (RCPT) which permits rate variability and unequal error protection by puncturing symbols. Furthermore, RCPT code design ...

Traditional parametric coding of speech facilitates low rate but provides poor reconstruction quality because of the inadequacy of the model used. We describe how a WaveNet generative speech model can be used to generate high quality speech from the bit stream of a standard parametric coder operating at 2.4 kb/s. We compare this parametric coder with a waveform coder based on the same generativ...

This paper presents an improved Mixed Excitation Linear Prediction (MELP) coder. The MELP is the linearprediction-based speech coder that was recently chosen as the new 2400 bps U.S. Federal Standard. Even though the MELP is quite good, there are still some perceivable distortions, particularly around non-stationary speech segments and for some low-pitch male speakers. The key features of our n...

We present an embedded image coder based on a statistical characterization of natural images in the wavelet transform domain. We describe the joint distribution between pairs of coefficients at adjacent spatial locations, orientations, and scales. Although the raw coefficients are nearly uncorrelated, their magnitudes are highly correlated. A linear magnitude predictor, coupled with both multip...

In this paper, we present a 6.8-32 kbit/s scalable speech and audio coder using a modified-discrete-cosine-transform (MDCT)-based bandwidth extension on top of a 6.8 kbit/s code-excited-linear-prediction (CELP) coder. The proposed coder comprises a 6.8 kbit/s narrowband CELP as its corelayer and eight enhancement layers with the bitrates of 0.8, 1.2, 3.2, or 4.0 kbit/s. After encoding of a narr...

Among progressive 3D mesh compression algorithms, the kd-tree-based algorithm proposed by Gandoin and Devillers [1] is one of the state-of-the-art algorithms. Based on the observation that this geometry coder has a large amount of overhead at high kd-tree levels, we propose an octree-based geometry coder that demands a less amount of coding bits at high octree levels by applying selective cell ...

This paper describes an 8 kbit/s ACELP speech coder with high performance for both speech and non-speech signals such as background noise. While the traditional waveform matching LPAS structure employed in many existing speech coders provides high quality for speech signals, it has significant performance limitations for e.g. background noise. The coder presented here employs a novel adaptive g...

In this paper, a low delay 16 kb/s wideband speech coder with a buffering delay of 1.25 ms is introduced. This coder is basically inspired from the G.728 LD-CELP standard for narrowband speech signals. Our main goal is to reduce the implementation complexity of our wideband G728 – like coder, which is mainly due to the search of the optimal excitation (gain-shape) in codebook. For this reason a...