1,721,195 research outputs found
DCT-based watermarking for video
No full text[[abstract]]In this paper, an MPEG-based technique for embedding digital "watermarks" into digital video is proposed. Watermarking technique has been proposed as a method to hide secret information into the signals so as to discourage unauthorized copying or attest the origin of the media. In the proposed method, we take advantage of prediction types of MPEG bitstreams to embed watermarks into both intraframe and non-intraframe with different residual masks. The experimental results show that the proposed watermarking technique results almost invisible difference between the watermarked frames and the original frames, and also robust to cropping operations and MPEG compression.[[note]]SC
Real-time PC-based software implementation of H.261 video codec
No full text[[abstract]]The complexity of a video codec has made it seems impossible to accomplish an audio-visual application without using application specific integrated circuits (ASICs). However, recent advancing of computing power for microprocessors has made the development of software-based multimedia applications more feasible. More and more complicated tasks with heavy computation load can be realized on the basis of the general purpose CPU. In this paper, a PC-based software H.261 video codec, which is most strictly related to the real-time constraint applications such as video-phone and video-conference, is presented. The whole video codec system works will on Pentium-133.[[note]]SC
A lightweight genetic block-matching algorithm for video coding
No full text[[abstract]]In this paper, a lightweight genetic search algorithm (LGSA) is proposed. Different evolution schemes are investigated, such that the control overheads are largely reduced. It is also shown that the proposed LGSA can be viewed as a novel expansion of the three-step search algorithm (TSS), It can be seen from the simulation results that the performance of LGSA is very similar to that of FSA, and the computational complexity is much lower than that of FSA and other previously proposed genetic motion estimation algorithms.[[note]]SC
A refined fast 2-D discrete cosine transform algorithm with regular butterfly structure
No full text[[abstract]]In this paper, a fast computation algorithm for the two-dimensional discrete cosine transform (2-D DCT) is derived based on index permutation. As a result, only the computation of N N-point 1-D DCT's and some post-additions are required for the computation of an (NxN)-point 2-D DCT. Furthermore, as compared with [7], the derivation of the refined algorithm is more succinct, and the associated post-addition stage possesses a more regular butterfly structure. The regular structure of the proposed algorithm makes it more suitable for VLSI and parallel implementations.[[note]]SC
Content-based rate control scheme for very low bit-rate video coding
No full text[[abstract]]In the applications of very low bit-rate video coding, the quality of the encoded pictures always suffers from serious degradation due to limited bandwidth. The quantization levels, in typical video coding systems, are adjusted depending only on the fullness of the output buffer while the content of the video is not taken into account. This explains why the picture quality varies saliently in very low bit-rate applications. In this paper, a content-based bit-rate control scheme is proposed. In this approach, the content of the coded picture is first analyzed to find the main attributes of each macroblock. The attributes of the macroblocks are then consulted while adjusting the quantization levels. In other words, the quantization levels are adjusted not only depending on the fullness of the output buffer but also on the content of the coded material. Simulation results show that the perceptual quality of the coded pictures, by using the proposed method, is better while comparing with the traditional non-content-based approach.[[note]]SC
DSRA: A block matching algorithm for near-real-time video encoding
No full text[[abstract]]The correlations of motion vectors between neighboring image blocks have long been applied to improve the efficiency of block matching algorithms. In this paper, a block matching algorithm with a dynamic search range is presented. The search range is adjusted based on the correlations of the motion vectors between neighboring blocks. It is shown by simulation results that the proposed method can speed an MPEG-1 encoding system up to a ratio of 13.3 and increases the bit-rate only of 0.025 bpp, in average. It is therefore beneficial to embed the proposed method into a motion-based encoding system.[[note]]SC
Normal bases expansion of the discrete cosine transform
No full text[[abstract]]In this correspondence, we show that the discrete cosine transform (DCT) can be obtained by projecting the discrete Fourier transform from the extension field to the basefield, Applying the framework of projection operator, a fast fully recursive algorithm For computing the DCT is also presented.[[note]]SC
Synthesis and Properties of New Dialkoxyphenylene Quinoxaline-Based Donor-Acceptor Conjugated Polymers and Their Applications on Thin Film Transistors and Solar Cells
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