Statistical, DCT and vector quantisation-based video codec (original) (raw)

Multiresolution, perceptual and vector quantization based video codec

Multimedia Tools and Applications, 2012

This paper presents a novel Multiresolution, Perceptual and Vector Quantization (MPVQ) based video coding scheme. In the intra-frame mode of operation, a wavelet transform is applied to the input frame and decorrelates it into its frequency subbands. The coefficients in each detail subband are pixel quantized using a uniform quantization factor divided by the perceptual weighting factor of that subband. The quantized coefficients are finally coded using a quadtree-coding algorithm. Perceptual weights are specifically calculated for the centre of each detail subband. In the inter-frame mode of operation, a Displaced Frame Difference (DFD) is first generated using an overlapped block motion estimation/compensation technique. A wavelet transform is then applied on the DFD and converts it into its frequency subbands. The detail subbands are finally vector quantized using an Adaptive Vector Quantization (AVQ) scheme. To evaluate the performance of the proposed codec, the proposed codec and the adaptive subband vector quantization coding scheme (ASVQ), which has been shown to outperform H.263 at all bitrates, were applied to six test sequences. Experimental results indicate that the proposed codec outperforms the ASVQ subjectively and objectively at all bit rates.

Multi-scale, Perceptual and Vector Quanitzation Based Video Codec

2007 Second International Conference on Digital Telecommunications (ICDT'07), 2007

This paper presents a novel hybrid Multi-scale, perceptual and vector quantization based video coding scheme. In intra mode of operation, a wavelet transform is applied to the input frame and decorrelate it into a number of subbands. The lowest frequency subband is losslessly coded. The coefficient of the high frequency subbands are pixel quantized using perceptual weights, which specifically designed for each high frequency subband. The quantized coefficients are then coded using quadtree-coding scheme. In the inter mode of operation, displaced frame difference is generated using overlapped block motion estimation / compensation to exploit the interframe redundancy. A wavelet transform is then applied to the displaced frame difference to decorrelate it into a number of subbands. The coefficients in the resulting subbands are coded using an adaptive vector quantization scheme.

Motion vector quantization for efficient low-bit-rate video coding

Visual Communications and Image Processing 2009, 2009

The most recent video coding standard H.264 achieves excellent compression performances at many different bit-rates. However, it has been noted that, at very high compression ratios, a large part of the available coding resources is only used to code motion vectors. This can lead to a suboptimal coding performance. This paper introduces a new coding mode for a H.264-based video coder, using quantized motion vector (QMV) to improve the management of the resource allocation between motion information and transform coefficients. Several problems have to be faced with in order to get an efficient implementation of QMV techniques, yet encouraging results are reported in preliminary tests, allowing to improve the performances of H.264 at low bit-rates over several sequences.

Improving H.264 performances by quantization of motion vectors

2009 Picture Coding Symposium, 2009

The coding resources used for motion vectors (MVs) can attain quite high ratios even in the case of efficient video coders like H.264, and this can easily lead to suboptimal rate-distortion performance. In a previous paper, we proposed a new coding mode for H.264 based on the quantization of motion vectors (QMV). We only considered the case of 16x16 partitions for motion estimation and compensation. That method allowed us to obtain an improved trade-off in the resource allocation between vectors and coefficients, and to achieve better rate-distortion performances with respect to H.264. In this paper, we build on the proposed QMV coding mode, extending it to the case of macroblock partition into smaller blocks. This issue requires solving some problems mainly related to the motion vector coding. We show how this task can be performed efficiently in our framework, obtaining further improvements over the standard coding technique.

Vector-quantization-based video codec for software-only playback on personal computers

Multimedia Systems, 1994

This paper discusses a video compression and decompression method based on vector quantization (VQ) for use on general purpose computer systems without specialized hardware. After describing basic VQ coding, we survey common VQ variations and discuss their impediments in light of the target application. We discuss how the proposed video codec was designed to reduce computational complexity in every principal task of the video codec process. We propose a classified VQ scheme that satisfies the data rate, image quality, decoding speed, and encoding speed objectives for software-only video playback. The functional components of the proposed VQ method are covered in detail. The method employs a pseudo-YUV color space and criteria to detect temporal redundancy and low spatial frequency regions. A treestructured-codebook generation algorithm is proposed to reduce encoding execution time while preserving image quality. Two separate vector codebooks, each generated with the treestructured search, are employed for detail and low spatial frequency blocks. Codebook updating and sharing are proposed to further improve encoder speed and compression.

Image Vector Quantization for Interframe Coding Applications

In this paper, an interframe image coding via vector quantization (VQ) is considered. Here, we identify the moving vectors in each frame using a block matching technique. A prediction is estimated by searching in the direction of minimum distortion in the previous reconstructed frame, then the differential vectors are quantized via a modified VQ to achieve high compression. Simulations have shown that an average PSNR=33 can be achieved at a bit rate R=0.15-0.25 bpp.

Multiresolution Vector Quantization for Video Coding

Multidimensional Filter Banks and Wavelets, 1997

Abstract. In this work, we propose a coding technique that is based on the generalized block prediction of the multiresolution subband decomposition of motion compensated difference image frames. A segmentation mask is used to distinguish between the regions where motion ...

A very low bit rate video coder based on vector quantization

IEEE Transactions on Image Processing, 1996

Describes a video coder based on a hybrid DPCM-vector quantization algorithm that is suited for bit rates ranging from 8-16 kb/s. The proposed approach involves segmenting difference images into variable-size and variable-shape blocks and performing segmentation and motion compensation simultaneously. The purpose of obtaining motion vectors for variable-size and variable-shape blocks is to improve the quality of motion estimation, particularly in those areas where the edges of moving objects are situated. For the larger blocks, decimation takes place in order to simplify vector quantization. For very active blocks, which are always of small dimension, a specific vector quantizer has been applied, the fuzzy classified vector quantizer (FCVQ). The coding algorithm described displays good performance in the compression of test sequences at the rates of 8 and 16 kb/s; the signal-to-noise ratios obtained are good in both cases. The complexity of the coder implementation is comparable to that of conventional hybrid coders, while the decoder is much simpler in this proposal

64 kbit/s Video coding algorithm using adaptive gain/shape vector quantization

Signal Processing: Image Communication, 1989

A hybrid coding algorithm, consisting of motion compensated interframe prediction and adaptive gain/shape vector quantization, is proposed for low bit rate video coding. A video coding system using the proposed coding algorithm and its coding characteristics are also described. Motion compensated interframe prediction is an efficient technique for reducing temporal redundancy contained in moving pictures. In the proposed scheme, constant amplitude blocks ("gra) level blocks") are also included in search vectors in order to increase coding efficiency for quick object movement or scene change. Adaptive gain/shape vector quantization with a tree search codebook is employed to encode motion compensated interframe difference signals. It can respond to changes in source statistics because its codebook is independent of the gain components of the input vectors. The proposed coding algorithm has been evaluated by computer simulations and shown to be effective for low bit rate video transmission. A 64 kbit/s video coding system based on this coding algorithm has been implemented. The developed coding system can transmit multiplexed video, audio and digital data at the basic ISDN rate, and can be applied to videophone as well as videoconferencing .