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3D video, which consists of a sequence of 3D mesh models, can provide detailed 3D information both in spatial and temporal domain. In this paper, a key frame extraction method has been developed to summarize 3D video by rate-distortion optimization. For this purpose, we introduce an effective feature vector extraction algorithm from 3D video. Prior to key frame extraction, shot detection is performed...
With the standardization of H.264/AVC by ITU-T and ISO/IEC and the adaptatation into new hardware, the necessity of transcoding between existing standards and H.264 will arise to achieve interoperability between hardware devices. Because of the many new prediction parameters as well as the pixel-based deblocking filter and the new transform of H.264 this is a difficult task to perform. In our work...
This paper proposes error resilient video transcoding structures based on the multiple description (MD) scheme. Two structures are proposed for different use, namely low complexity simple MD transcoding structure (simple MD) and adaptive MD transcoding structure (adaptive MD). Simple MD structure always converts and splits the given bit stream into two descriptions regardless of channel condition...
In this paper, we introduce and evaluate a low complexity macroblock partition mode decision algorithm for inter-frame prediction in MPEG-2 to H.264 transcoder. The proposed tools are used to compute an optimal MB coding mode decision with significantly reduced computational complexity. Specifically, we achieve the computational savings by using the following MB information coming from MPEG-2: the...
Bit rate adaptation is one of the most important types of video transcoding. With H.264 becoming the predominant video codec of choice in video coding and streaming, prudent rate-adaptation techniques should be developed. In this paper, we investigate certain critical points in the spectrum of rate shaping requests. We show that the selection of quantization step sizes may not have monotonic effects...
Motion-compensated temporal filtering (MCTF) is an innovative prediction scheme for video coding and the core technology of scalable extension of H.264/AVC. The first MCTF and ME hardware work is in this paper. The proposed hardware not only can support the various coding schemes in JSVM and H.264 but also can adapt itself to provide rate-distortion-computation scalability. With the frame-level searching...
This paper points out some defects in the techniques used in H.264 rate control and presents two new techniques to improve them. The improved scheme has the following main features: 1) the bits allocated to each P-frame is proportional to the local motion in it, i.e., more bits are allocated to a frame if the local motion in it is stronger; 2) the quantization parameter (QP) calculation is based on...
The rate-distortion optimal mode decision as well as motion estimation adopted in H.264 brings a big challenge to real-time encoding and transcoding due to the high computation complexity. In this paper, we propose a hierarchical motion description model to present the motion data of each macroblock (MB) from coarsely to finely. A preprocessing approach is developed to estimate the motion data for...
Nearly all block-based transform schemes for image and video coding developed so far choose the 2-D discrete cosine transform (DCT) of a square block shape. With almost no exception, this conventional DCT is implemented separately through two 1-D transforms, one along the vertical direction and another along the horizontal direction. In this paper, we develop a new block-based DCT framework in which...
We examine the bit rate variability-distortion (VD) curve of I, P, and B frames of MPEG-4 VBR encoded video sequences. We show that the concave VD curve shape at high compression ratios or large quantization scales, is influenced by both the texture and the motion information. We use linear and quadratic models for the texture and motion bits statistics and devise accurate VD curve models. The model...
In this paper we explore use of a new rate-distortion metric for optimizing real-time Internet video streaming with the transmission control protocol (TCP). The basic idea is to combat packet delays caused by TCP retransmissions that are essentially interpreted as errors by the streaming application. To this aim, we develop an analytical model of the expected video distortion at the decoder with respect...
In this paper, an efficient cost function for mode decision in H.264/AVC is proposed. The proposed cost function is based on integer transform coefficients, where the rate and the distortion are jointly modeled by the number of nonzero quantized coefficients, the sum of absolute integer transformed differences (SAITD) and sum of squared integer transformed differences (SSITD). Comparing to the high-complexity...
The multiple bit-rate (MBR) representation of video sequences offers an effective solution to video streaming services over the Internet. To facilitate such MBR-based streaming services, a mechanism is required to support seamless switching among multiple bit-streams when a bandwidth change is detected. The SP-frames developed in H.264 provide such a mechanism at each pre-selected switching point...
In this paper we propose a rate-distortion optimized motion estimation algorithm that is built upon a quadtree structure. Each node of the quadtree represents a block in the current frame together with its motion vector, and the block size decreases from the root to the leaves. In the first step, the quadtree is pruned according to a rate-distortion criterion in order to obtain blocks of variable...
A joint rate-distortion-complexity H.264 motion search framework is proposed to balance the encoder's coding efficiency and complexity in an embedded system environment. Under our framework, the complexity of H.264 motion search is primarily measured by the execution time of the sum of absolute differences (SAD) calculation. Two Lagrange parameters are used to terminate the complexity-inefficient...
In a multi-source video streaming system, premature draining of low-power nodes can cause sudden failures of peer connections and degrade streaming performance. To solve this problem, we propose an energy-aware scheduling (EAS) scheme to better distribute the streaming load among different peers by jointly considering network conditions and node energy levels. We model the proposed scheme using a...
This paper focuses on the mode decision and motion selection problem when H.264/AVC video streams are transcoded in spatial resolution. A fast downsizing transcoding scheme is developed in which a new rate-distortion (R-D) optimal mode decision mechanism is presented for high speed transcoding as well as high coding efficiency. A model for estimating relative prediction errors is applied in this paper,...
We propose a new real-time packet scheduling algorithm for streaming scalable H.264. Our algorithm makes use of a packet importance measure, which we define, that takes into consideration transmission history, channel conditions, and the unique decoding dependencies due to the temporal wavelet encoding. Our algorithm utilizes this importance measure to minimize the expected reconstruction distortion...
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