Wyner-Ziv video coding is committed to the compression of video with low computing resources. Since the encoding
may stop at any time for mobile devices with limited computing resources and bandwidth, it is also desirable to have the
scalable Wyner-Ziv video coding. The bit-plane coding is an inherent solution of scalable video coding. However, the
conventional bit-plane representation in hybrid video coding does not work well in the scenario of Wyner-Ziv coding.
Since the bit-plane representation is closely related to quantization, we propose a new bit-plane representation with
optimal quantization at any bit-plane in terms of Wyner-Ziv coding. In particular, for the DCT-domain Wyner-Ziv video
coding, the distribution of DCT coefficients and the conditional distribution given side information can be modeled with
symmetric Laplacian functions. Accordingly, a simplified adaptive bit-plane representation is proposed without pre-knowing
the Laplacian distribution parameters. A DCT-domain scalable Wyner-Ziv video coding scheme is then
developed, in which the encoding can stop at any bit-plane and the bit-stream can also be flexibly truncated. The testing
has shown that there is no performance penalty due to the unpredicted bit-plane truncation.
In this paper, we propose a joint power-distortion optimization scheme for real-time H.264 video encoding under the
power constraint. Firstly, the power constraint is translated to the complexity constraint based on DVS technology.
Secondly, a computation allocation model (CAM) with virtual buffers is proposed to facilitate the optimal allocation of
constrained computational resource for each frame. Thirdly, the complexity adjustable encoder based on optimal motion
estimation and mode decision is proposed to meet the allocated resource. The proposed scheme takes the advantage of
some new features of H.264/AVC video coding tools such as early termination strategy in fast ME. Moreover, it can
avoid suffering from the high overhead of the parametric power control algorithms and achieve fine complexity
scalability in a wide range with stable rate-distortion performance. The proposed scheme also shows the potential of a
further reduction of computation and power consumption in the decoding without any change on the existing decoders.
In this paper, we present a new image compression scheme, which is specially designed for computer generated compound color images. First we classify the image content into two kinds: text/graphic content and picture content. Then two different compression schemes are applied blocks of different types. We propose a two stage segmentation scheme which combines thresholding block features and rate-distortion optimization. The text/graphics blocks compression scheme consists of two parts: color quantization and lossless coding of quantized images. The input images will first be color quantized and converted to codebooks and labels, introducing constraint distortion to the color quantization images. Then generated labels and codebooks are lossless compressed respectively. We proposed a rate-distortion optimized color quantization algorithm for text/graphic content, which introduces distortion to text content and minimizes the bit rate produced by the following lossless entropy compression algorithm. The picture content is compressed using conventional image algorithms like JPEG. The results show that the proposed scheme achieves better coding performance than other images compression algorithms such as JPEG2000 and DjVu.
The free viewpoint switching is one of the most important features of multi-view video streaming. The key problem lies in how to achieve the best performance when the camera processing capability and the network bandwidth are limited. In this paper, we propose a novel free viewpoint switching scheme for multi-view video scenario, in which the distributed video coding technique is employed. In this scheme, the multi-camera video sources are encoded separately with the traditional hybrid video coding scheme, and meanwhile an alternative bitstream is produced for every frame based on the Wyner-Ziv coding method for the purpose of error correction when the viewpoint switching occurs. When switching happens, the Wyner-Ziv bits corresponding to the actual reference frame at the switching point is transmitted and used to recover the true reference. Instead of completely removing the mismatch, the proposed switching scheme tries to reduce the mismatch to an acceptable level so as to save the bits for the switching frame. A wavelet transform domain Wyner-Ziv coding method is proposed to produce the Wyner-Ziv bits for the switching frame. Conclusively, with the proposed scheme, the inter-camera communication can be avoided and the drifting error can be controlled efficiently when the viewpoint switching occurs.
There are mainly two key points which can affect the efficiency of multi-view video capture and transmission system largely: communication between cameras and computing complexity of encoder. In this paper, we propose a practical framework of distributed multi-view video coding, in which inter-camera communication is avoided and the large computing complexity is moved from encoder to decoder. In this scheme, multi-camera video sources are encoded separately and decoded dependently, and the traditional inter frame is replaced by Wyner-Ziv frame. To reach this goal, Wyner-Ziv theory on source coding with side information is employed as the basic coding principle. A Wyner-Ziv coding method based on wavelet transform and turbo codes is used as the core of the scheme. To further improve the coding performance, we also consider exploiting the large redundancy between adjacent views. A more flexible prediction method that can jointly use temporal and view correlations is proposed to generate the side information at the decoder. The experimental results show that the coding performance of proposed DMVC scheme is very promising compared to the traditional intra coding.