No abstract

No abstract

In this paper, an image sequence coding scheme for very low bit-rate video coding is presented. The new technique utilises windowed overlapped block matching motion compensation for the temporal coding scheme, and vector quantisation to reduce the spatial redundancy within the predicted image. There are many advantages associated with VQ, especially its capacity to operate in error-resilient coding systems and furthermore, VQ does not suffer from blocking effects that are visually disjointed and has therefore a major advantage over DCT based methods. We examine the performance of various codebooks to remove the spatial redundancy within the difference frame. When the codec is configured to operate at 10.1 kbit/s, average PSNR values in excess of 32.86dB and 25.6dB are achieved for the "Miss America" and "Carphone" sequences respectively.Keywords: Very low bit-rate, vector quantisation, windowed overlapped block matching motion compensation, and efficiency reversed ordering.

No abstract

A bandwidth efficient image codec is offered as a direct replacement of mobile radio speech codecs in second generation wireless systems, such as the Pan European GSM system. The image codec is contrived for Quarter Common Intermediate Format (QCIF) videophone sequences, and uses the 2-D orthogonal wavelet transform to decompose, the Displaced Frame Difference (DFD), into a four band structure using Quadrature Mirror Filters (QMF). The transformed coeflcients are then compressed using Classified Vector Quantisation (CVQ) and then multiplexed to a Time Division Multiple Access (TDMA) slot and modulated using Pilot Symbol Assisted Quadrature Amplitude Modulation (PSAQAM). The proposed image codec does not suffer from blocking effects that are visually disjointed and has therefore a major advantage over current Discrete Cosine Transform (DCT) methods. A further advantage of using wavelet based transforms is that they require less hardware and are simpler to implement on a DSP chip than Fourier based methods. The method proposed is suitable for implementation in VLSI technology.