Iraj Sodagar

A zerotree wavelet video coder

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.

Scalable wavelet coding for synthetic/natural hybrid images

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.

A new error resilience technique for image compression using arithmetic coding

Arithmetic coding is commonly used for entropy coding in image compression. It has been shown that arithmetic coding has a higher coding efficiency than other entropy coding schemes. However, it has a severe drawback when used in an error prone environment. Since arithmetic coding makes it impossible to precisely locate an error, a large portion of a bitstream must be discarded when an error occurs. In traditional packetization techniques, the bitstream is segmented to packets and the arithmetic encoder is reset at the beginning of each packet. However, the re-initialization will significantly reduce the coding efficiency of the arithmetic coder. We propose a novel technique to improve the error resilience of arithmetic coding. This new technique adds segment markers in the coded bitstream without the re-initialization of the arithmetic coder, which helps retain the correctly decoded segments within the bitstream improving the quality of the reconstructed image. Segment markers have been adopted in both MPEG-4 and JPEG 2000. Experimental results show that THE segment marker significantly improves the quality of reconstructed image with minor increase in bitstream size.

Zerotree entropy coding of wavelet coefficients for very low bit rate video

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.

Multi-scale zerotree entropy coding

This paper describes the visual texture compression scheme adopted for MPEG-4 international standard. The scheme is based on the concept of multiscale zerotree wavelet entropy coding (MZTE) technique that provides different levels of scalability layer in terms of either spatial resolutions or picture quality. MZTE provides much improved compression efficiency and fine-gradual scalabilities. The MZTE scheme is adopted as the baseline technique for the visual texture coding profile in both MPEG4 video group and SNHC group.

Demonstration of the MPEG-2, MPEG-4 and H.263 video coding standards

In this demonstration session, we will demonstrate several examples of the state-of-the-art video compression standards MPEG-2, MPEG-4 and H.263. These demonstrations captured some of the recent work developed in the Digital Video Communications group at Sarnoff. For the MPEG-2 demonstration, the compression process uses standards compliant syntax with Sarnoffs proprietary algorithms to select the encoding parameters. For the MPEG-4 demonstration, we show the encoding results of the Verification Model including Sarnoffs contribution in scalable rate control and texture coding mode. In addition, we show the encoding results of a video streaming technology using H.263 and Sarnoffs proprietary technologies.