共查询到19条相似文献,搜索用时 369 毫秒
1.
2.
实时H.263+视频编码器的DSP实现 总被引:3,自引:0,他引:3
在多媒体处理芯片TM-1300的开发平台上,快速实现了H.263 视频编码器。首先,根据H.263 编码算法要求,介绍TM-1300适合视频通信开发的特点及其开发环境;然后,将编码算法移植到TM-1300平台并进行大量的优化,其中,重点讨论了位移估值的优化算法。由实验结果可知,使用本文给出的优化算法,可以在TM-1300上快速实现H.263 编码器,满足视频实时编解码的要求,且已应用于实际视频通信产品中。 相似文献
3.
4.
文章针对H.263 编码器算法原理和Philips公司多媒体处理芯片PNX1500的结构特点,设计了适应实时信号处理的高性能H.263 编码器。实验结果表明,该编码器能实现对各种运动幅度视频数据的快速编码,可满足对不同运动级别视频信号的实时处理。 相似文献
5.
从实时应用角度出发,参考H.263编码标准,对H.264视频编码器进行精简,并对耗时较大的算法进行改进.仿真结果表明,简化后的H.264编码器编码速度达到20f/s(帧/秒),达到实时编码要求,且编码性能优于H.263编码标准的编码器. 相似文献
6.
MMX技术在视频压缩中的应用 总被引:2,自引:0,他引:2
在视频压缩中,实时性与高压缩率对编码运算的速度提出了严格要求;以ITU-T的H.263编码器为例,详细讨论了采用MMXTM汇编技术;取得了通过指令级的优化提高视频编码器的执行速度所取得的显著效果. 相似文献
7.
8.
9.
10.
11.
本文主要介绍了用TMS320C6201实现低比特率视频压缩编码标准H.263的编译码系统。本文对H.263实现算法进行了研究,并针对DSP的结构特点,提出了多种改进措施以适应实时图像编译码与误码信道传输的要求,本文还给出硬件设计与软件的优化处理方法。 相似文献
12.
13.
本文对H.263编码算法的现有实现方法作了深入的分析,首先发现变换部分存在大量无效运算,提出了在变换前加判决的前变换判决的编码方案,以压缩无效的变换运算;其次发现运动估计部分由于忽略了图像场景的分级运动而存在一定的无效搜索运算,提出了基于分级运动的可变搜索域法来压缩无效的搜索运算;最后将前变换判决方案与运动估计的可变搜索域法有机地结合在一起,提出了全局判决编码方案,从而比较全面地改进了现有实现方法,因而能大幅度地提高编码器的编码速度. 相似文献
14.
15.
We propose and evaluate a multi-frame extension to block motion compensation (BMC) coding of videoconferencing-type video signals for wireless channels. The multi-frame BMC (MF-BMC) coder makes use of the redundancy that exists across multiple frames in typical videoconferencing sequences to achieve additional compression over that obtained by using the single frame BMC (SF-BMC) approach, such as in the base-level H.263 codec. The MF-BMC approach also has an inherent ability of overcoming some transmission errors and is thus more robust when compared to the SF-BMC approach. We model the error propagation process in MF-BMC coding as a multiple Markov chain and use Markov chain analysis to infer that the use of multiple frames in motion compensation increases robustness. The Markov chain analysis is also used to devise a simple scheme which randomizes the selection of the frame (amongst the multiple previous frames) used in BMC to achieve additional robustness. The MF-BMC coders proposed are a multi-frame extension of the base level H.263 coder and are found to be more robust than the base level H.263 coder when subjected to simulated errors commonly encountered on wireless channels. 相似文献
16.
Rate control feedback mechanism for packet video networks 总被引:1,自引:0,他引:1
The authors incorporate a newly proposed rate control feedback mechanism (RCFM) in an H.263 video coder. RCFM adapts to network conditions to locally drop video packets and then discard corresponding macroblocks (MBs) from any further prediction process. The proposed RCFM regulates the output bitrate of an H.263 codec while keeping all encoder parameters fixed and maintaining a good QoS 相似文献
17.
Kossentini F. Yuen-Wen Lee Smith M.J.T. Ward R.K. 《Selected Areas in Communications, IEEE Journal on》1997,15(9):1752-1763
Predictive rate-distortion (RD) optimized motion estimation techniques are studied and developed for very low bit-rate video coding. Four types of predictors are studied: mean, weighted mean, median, and statistical mean. The weighted mean is obtained using conventional linear prediction techniques. The statistical mean is obtained using a finite-state machine modeling method based on dynamic vector quantization. By employing prediction, the motion vector search can then be constrained to a small area. The effective search area is reduced further by varying its size based on the local statistics of the motion field, through using a Lagrangian as the search matching measure and imposing probabilistic models during the search process. The proposed motion estimation techniques are analyzed within a simple DCT-based video coding framework, where an RD criterion is used for alternating among three coding modes for each 8×8 block: motion only, motion-compensated prediction and DCT, and intra-DCT. Experimental results indicate that our techniques yield very good computation-performance tradeoffs. When such techniques are applied to an RD optimized H.263 framework at very low bit rates, the resulting H.263 compliant video coder is shown to outperform the H.263 TMN5 coder in terms of compression performance and computations simultaneously 相似文献
18.
介绍了一种在局域网上利用RTP技术实时传输H.263图像数据的方法,并对其性能进行了测试,给出了C语言编程实例。通过RTP及RTCP提供的信息对编码端进行码率调整等方法,成功地实现了基于局域网的图像监控系统中的H.263图像数据的实时传送。 相似文献
19.
An error detection and recovery algorithm for compressed videosignal using source level redundancy 总被引:1,自引:0,他引:1
The motion compensation-discrete cosine transform (MC-DCT) coding is an efficient compression technique for a digital video sequence. However, the compressed video signal is vulnerable to transmission errors over noisy channels. In this paper, we propose a robust video transmission algorithm, which protects the compressed video signal by inserting redundant information at the source level. The proposed algorithm encodes every lth frame in the semi-intra frame (S-frame) mode, in which the redundant parity-check DC coefficients (PDCs) are systematically inserted into the compressed bitstream. Then, the decoder is capable of recovering very severe transmission errors, such as loss of an entire frame, in addition to detecting the errors effectively without requesting any information from external devices. The proposed algorithm is implemented based on the H.263 coder, and tested intensively in realistic error prone environment. It is shown that the proposed algorithm provides much better objective and subjective performances than the conventional H.263 coder in the error prone environment. 相似文献