To guarantee the real-time transmission of a video stream, based on the stochastic optimal control method, a frame layer adaptive rate control algorithm for the wireless transcoder is proposed, which is capable of dyn...To guarantee the real-time transmission of a video stream, based on the stochastic optimal control method, a frame layer adaptive rate control algorithm for the wireless transcoder is proposed, which is capable of dynamically determining the transcoder＇s objective bit rate, according to the bandwidth variation of the wireless channel and the buffer occupancy. Then the transient performance, steady performance, and computational complexity of the algorithm are analyzed. Finally, the experiment results demonstrate that the algorithm can improve the synthetic performance of rate control through the compromise between the end-to-end delay and the playout quality.展开更多
The new H.264 video coding standard achieves significantly higher compression performance than MPEG-2. As the MPEG-2 is popular in digital TV, DVD, etc., bandwidth or memory space can be saved by transcoding those str...The new H.264 video coding standard achieves significantly higher compression performance than MPEG-2. As the MPEG-2 is popular in digital TV, DVD, etc., bandwidth or memory space can be saved by transcoding those streams into H.264 in these applications. Unfortunately, the huge complexity keeps transcoding from being widely used in practical applications. This paper proposes an efficient transcoding architecture with a smart downscaling decoder and a fast mode decision algorithm. Using the proposed architecture, huge buffering memory space is saved and the transcoding complexity is reduced. Performance of the proposed fast mode decision algorithm is validated by experiments.展开更多
A new scheme combining a scalable transcoder with space time block codes （STBC） for an orthogonal frequency division multiplexing （OFDM） system is proposed for robust video transmission in dispersive fading channe...A new scheme combining a scalable transcoder with space time block codes （STBC） for an orthogonal frequency division multiplexing （OFDM） system is proposed for robust video transmission in dispersive fading channels. The target application for such a scalable transcoder is to provide successful access to the pre-encoded high quality video MPEG-2 from mobile wireless terminals. In the scalable transcoder, besides outputting the MPEG-4 fine granular scalability （FGS） bitstream, both the size of video frames and the bit rate are reduced. And an array processing algorithm of layer interference suppression is used at the receiver which makes the system structure provide different levels of protection to different layers. Furthermore, by considering the important level of scalable bitstream, the different bitstreams can be given different level protection by the system structure and channel coding. With the proposed system, the concurrent large diversity gain characteristic of STBC and alleviation of the frequency-selective fading effect of OFDM can be achieved. The simulation results show that the proposed schemes integrating scalable transcoding can provide a basic quality of video transmission and outperform the conventional single layer transcoding transmitted under the random and bursty error channel conditions.展开更多
为应对未来移动网络所面临的巨大挑战,业界提出了自适应比特流(adaptive bit rate,ABR)技术和移动边缘计算(mobile edge computing,MEC),旨在为用户提供高体验质量、低时延、高带宽和多样化的服务。联合ABR和MEC来优化视频内容分发,对...为应对未来移动网络所面临的巨大挑战,业界提出了自适应比特流(adaptive bit rate,ABR)技术和移动边缘计算(mobile edge computing,MEC),旨在为用户提供高体验质量、低时延、高带宽和多样化的服务。联合ABR和MEC来优化视频内容分发,对于提高网络性能和用户体验质量具有重要意义。其中,各项网络资源的联合优化是重要的研究课题。首先对MEC进行了概述,然后基于面向自适应流的MEC缓存转码联合优化问题,对业界已有工作进行了分析和对比,并对未来面临的挑战和研究难点进行了归纳和展望。展开更多
基金the National High Technology Research and Development Program (2007AA1Z24002003AA1Z2210).
文摘To guarantee the real-time transmission of a video stream, based on the stochastic optimal control method, a frame layer adaptive rate control algorithm for the wireless transcoder is proposed, which is capable of dynamically determining the transcoder＇s objective bit rate, according to the bandwidth variation of the wireless channel and the buffer occupancy. Then the transient performance, steady performance, and computational complexity of the algorithm are analyzed. Finally, the experiment results demonstrate that the algorithm can improve the synthetic performance of rate control through the compromise between the end-to-end delay and the playout quality.
基金Project (No. CNGI-04-15-2A) supported by the China Next Gen-eration Internet (CNGI)
文摘The new H.264 video coding standard achieves significantly higher compression performance than MPEG-2. As the MPEG-2 is popular in digital TV, DVD, etc., bandwidth or memory space can be saved by transcoding those streams into H.264 in these applications. Unfortunately, the huge complexity keeps transcoding from being widely used in practical applications. This paper proposes an efficient transcoding architecture with a smart downscaling decoder and a fast mode decision algorithm. Using the proposed architecture, huge buffering memory space is saved and the transcoding complexity is reduced. Performance of the proposed fast mode decision algorithm is validated by experiments.
文摘A new scheme combining a scalable transcoder with space time block codes （STBC） for an orthogonal frequency division multiplexing （OFDM） system is proposed for robust video transmission in dispersive fading channels. The target application for such a scalable transcoder is to provide successful access to the pre-encoded high quality video MPEG-2 from mobile wireless terminals. In the scalable transcoder, besides outputting the MPEG-4 fine granular scalability （FGS） bitstream, both the size of video frames and the bit rate are reduced. And an array processing algorithm of layer interference suppression is used at the receiver which makes the system structure provide different levels of protection to different layers. Furthermore, by considering the important level of scalable bitstream, the different bitstreams can be given different level protection by the system structure and channel coding. With the proposed system, the concurrent large diversity gain characteristic of STBC and alleviation of the frequency-selective fading effect of OFDM can be achieved. The simulation results show that the proposed schemes integrating scalable transcoding can provide a basic quality of video transmission and outperform the conventional single layer transcoding transmitted under the random and bursty error channel conditions.
文摘为应对未来移动网络所面临的巨大挑战,业界提出了自适应比特流(adaptive bit rate,ABR)技术和移动边缘计算(mobile edge computing,MEC),旨在为用户提供高体验质量、低时延、高带宽和多样化的服务。联合ABR和MEC来优化视频内容分发,对于提高网络性能和用户体验质量具有重要意义。其中,各项网络资源的联合优化是重要的研究课题。首先对MEC进行了概述,然后基于面向自适应流的MEC缓存转码联合优化问题,对业界已有工作进行了分析和对比,并对未来面临的挑战和研究难点进行了归纳和展望。
