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Abstract-This paper describes a hybrid motion-compensated wavelet transform coder designed for encoding video at very low bit rates. The coder and its components have been submitted to MPEG-4 to support the functionalities of compression efficiency and scalability. Novel features of this coder are the use of overlapping block motion compensation in combination with a discrete wavelet transform followed by adaptive quantization and zerotree entropy coding, plus rate control. The coder outperforms the VM of MPEG-4 for coding of I-frames and matches the performance of the VM for P-frames while providing a path to spatial scalability, object scalability, and bitstream scalability.

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This paper describes the texture representation scheme adopted for MPEG-4 synthetic/natural hybrid coding (SNHC) of texture maps and images. The scheme is based on the concept of multiscale zerotree wavelet entropy (MZTE) coding technique, which provides many levels of scalability layers in terms of either spatial resolutions or picture quality. MZTE, with three different modes (single-Q, multi-Q, and bilevel), provides much improved compression efficiency and fine-gradual scalabilities, which are ideal for hybrid coding of texture maps and natural images. The MZTE scheme is adopted as the baseline technique for the visual texture coding profile in both the MPEG-4 video group and SNHC group. The test results are presented in comparison with those coded by the baseline JPEG scheme for different types of input images. MZTE was also rated as one of the top five schemes in terms of compression efficiency in the JPEG2000 November 1997 evaluation, among 27 submitted proposals.Index Terms-Compression, image and video coding, JPEG-2000, MPEG-4, texture coding, wavelet.

This paper introduces ZeroTree Entropy (ZTE) coding for wavelet transform coefficients of video I-frames and motion-compensated video residuals. ZTE coding is based on but differs significantly from the Embedded Zerotree Wavelet (EZW) algorithm. As in EZW, the new ZTE coding algorithm exploits the self-similarity inherent in the wavelet transform to predict the location of information across wavelet scales. The new ZTE coder does not produce an embedded bitstream as EZW does, but by sacrificing the embedding property, ZTE achieves substantial improvement in coding efficiency and provides greater flexibility and other advantages over EZW.