共查询到19条相似文献,搜索用时 426 毫秒
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提出了一个基于MPEG4的快速高效存储的DCT视频编码器,用他把一个H.261视频数据流转换为一个低比特率、低空间分辨率的MPEG4流,并进行无线视频处理。和现有编码器相比,他不仅能够大大地节省实际需要存储空间,计算复杂度也降低了许多,实验结果表明设计的编码器得到的视频质量与象素领域方法得到的视频质量相当。 相似文献
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在基于对象的视频编码中,视频对象的分割是重要的任务.本文研究一种利用位移帧差(DFD)的高阶统计特性和数学形态学算子的视频对象自动分割方法.这种方法首先根据一组转移帧差的高阶矩来得到一个大体覆盖运动对象的区域(模板),接着用形态学的腐蚀算子从模板的边沿向内腐蚀,直到对象的边沿.提出一种简单而高效的基于查找人头肩像轮廓最大转折点的头肩分离算法.在分割的基础上,用软件实现了一种基于MPEG-4的视频编码系统.提出一种面向对象分配带宽(OOBA——object-oriented bandwidth allocation)的极低比特率视频编码器.该编码器与传统基于帧的视频编码器相比,在低比特率环境下,PSNR略为下降,但图像的主观视觉质量得到提高. 相似文献
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为实现近距离无线视频传输,提出了一种基于MPEG-4编码的近距离无线视频传输方案.由CMOS摄像头OV7620采集到的数据,通过专用MPEG-4编码器,ML86410得到速率低于2 Mbit·s-1的MPEG-4数据流,在FPGA控制器的控制下,通过nRF24L01无线发送;接收端利用同系列芯片nRF24LU1接收无线... 相似文献
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本对MPEG-4视频编码的功能与特点进行了描述。对基于VOP的视频编码器的原理与结构进行了分析,并将MPEG-4与其他视频编码标准做了对比。 相似文献
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简要介绍了MPEG-4视频编码器的实现原理,详细分析了基于实时操作系统DSP/BIOS的RF5框架,将MPEG-4视频编码器和解码器在VC下合成并仿真成功,提取合成编解码器中的编码模块和解码模块分两种方式移植到DM642上,一种是在一个任务中完成视频的采集、编解码处理和显示功能,另一种是分别由3个任务来完成视频的采集、编解码处理和显示功能,最终成功地实现了两种方式下的编解码器,在DM642上能完成视频的连续采集、编解码处理和显示. 相似文献
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双核DSP BF-561上XGA视频编码的实现 总被引:2,自引:0,他引:2
主要介绍在双核BF-561处理器上通过一种并行算法实现XGA分辨力的MPEG-4视频编码器.首先介绍了BF-561双核之间的通信与同步的实现.然后介绍了XGA分辨力MPEG-4算法的实现和优化.最后说明了MPEG-4编码器在双核上的任务分配,调整了数据传输和内存分配,并通过多项优化,实现了XGA图像的实时编码,编码速度达18f/s(帧,秒). 相似文献
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本文提出一种新的低功率分层运动估值器的VLSI结构,它支持低比特视频编码器的高级预测模式,如H.263和MPEG-4。为减少芯片尺寸及功率消耗,在所有搜索层中使用同一个基本的搜索单元 (BSU)。另外,通过对数据流的有效控制,使其在高级预测模式下,在获得宏块运动矢量的同时,也获得每个宏块中的4个88子块的运动矢量。实验结果表明,这种结构采用较少的门电路,有效降低了功率消耗,并且实现了与全搜索块匹配算法(FSBMA)相似的编码效果,可广泛应用于无线视频通信所需的低功率视频编码器中。 相似文献
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Martinez J.L. Weerakkody W.A.R.J. Fernando W.A.C. Quiles F. Kondoz A.M. 《Electronics letters》2008,44(15):899-900
A transform domain distributed video coding (DVC) codec is proposed using turbo trellis coded modulation (TTCM). TTCM symbols are generated at the DVC decoder using the side information and the parity bits received from the DVC encoder. These generated symbols are used at the TTCM-based DVC decoder to decode the bit stream. Simulation results show that a significant rate-distortion performance gain can be achieved using the proposed codec compared to the best state-of-the-art transform domain DVC codecs discussed in the literature. 相似文献
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Jo Yew Tham Ranganath S. Kassim A.A. 《Selected Areas in Communications, IEEE Journal on》1998,16(1):12-27
We introduce a highly scalable video compression system for very low bit-rate videoconferencing and telephony applications around 10-30 kbits/s. The video codec first performs a motion-compensated three-dimensional (3-D) wavelet (packet) decomposition of a group of video frames, and then encodes the important wavelet coefficients using a new data structure called tri-zerotrees (TRI-ZTR). Together, the proposed video coding framework forms an extension of the original zero tree idea of Shapiro (1992) for still image compression. In addition, we also incorporate a high degree of video scalability into the codec by combining the layered/progressive coding strategy with the concept of embedded resolution block coding. With scalable algorithms, only one original compressed video bit stream is generated. Different subsets of the bit stream can then be selected at the decoder to support a multitude of display specifications such as bit rate, quality level, spatial resolution, frame rate, decoding hardware complexity, and end-to-end coding delay. The proposed video codec also allows precise bit rate control at both the encoder and decoder, and this can be achieved independently of the other video scaling parameters. Such a scheme is very useful for both constant and variable bit rate transmission over mobile communication channels, as well as video distribution over heterogeneous multicast networks. Finally, our simulations demonstrated comparable objective and subjective performance when compared to the ITU-T H.263 video coding standard, while providing both multirate and multiresolution video scalability 相似文献
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1 IntroductionWiththerapidlydevelopmentofmultimediacommunicationtechnology ,theH .2 6 1 ,MPEG 1andMPEG 2recommendationshavebeenestab lishedbytherelevantorganizationsofITU TorISOinthepastyears.Thesestandardsprovidethetoolsforimagestoreortransmissionatthehigher… 相似文献
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Xiaopeng Fan Oscar C. Au Yan Chen Jiantao Zhou Mengyao Ma Peter H.W. Wong 《Journal of Visual Communication and Image Representation》2009,20(6):365-376
In this paper, we propose a novel Wyner–Ziv-based video compression scheme which supports encoding a new type of inter frame called ‘M-frame’. Different from traditional multi-hypothesis inter frames, the M-frame is specially compressed with its two neighbor frames as reference at the encoder, but can be identically reconstructed by using any one of them as prediction at the decoder. Based on this, the proposed Wyner–Ziv-based bidirectionally decodable video compression scheme supports decoding the frames in a video stream in both temporal order and reverse order. Unlike the other schemes which support reverse playback, our scheme achieves the reversibility with low extra cost of storage and bandwidth. In error-resilient test, our scheme outperforms H.264 based schemes up to 3.5 dB at same bit rate. The proposed scheme also provides more flexibility for stream switching. 相似文献
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Sassan Pejhan Tihao Chiang Ya-Qin Zhang 《Circuits, Systems, and Signal Processing》2001,20(3-4):361-373
A mechanism for varying the frame rate of pre-encoded video clips online is described. The mechanism relies on two different encoders. An offline encoder creates a high-quality bit stream encoded at 30 fps, as well as separate files containing motion vectors for the same clip at lower frame rates. An online encoder decodes the bit stream (if necessary) and re-encodes it at lower frame rates in real time using the precomputed, stored motion information. Online frame rate control, used in conjunction with dynamic bit rate control, allows clients to solve the rate mismatch between the bandwidth available to them and the bit rate of the pre-encoded bit stream. Clients can therefore choose the amount of trade-off between temporal and spatial quality while resolving the rate mismatch problem. Moreover, online frame rate control provides a natural means for implementing a VCR-like fast forward control for video streaming applications, without increasing bandwidth consumption.An earlier version of this paper appeared in Proceedings of ACM Multimedia, 1999, pp. 141–144. 相似文献
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实现网络视频首先要在发送端对连续的图像图形进行压缩编码,其次要将编码的比特流分层表示,第三要解决图像在网上传输时出现的包丢失问题。本文从上述三个方面出发,对MPEG-4分层编码算法进行改进,并用改进的算法实现基于物体的编码和比特流的分层表达;采用传输解码缓存模型实现图象传输的连续性,用优先重传技术解决包丢失问题,实验结果表明,上述理论是实现网络视频的较为优选的方案。 相似文献