Tools for Image and Video Transmission over Heterogeneous Network

大多数当前的数字视频系统只是用其更高效的数字对应物来取代现有的模拟视频传输模式。然而，随着诸如因特网的基于分组的网络开始成为通信基础设施的基本组件，以及通用计算机成为主要的通信终端，需要提供一组新的用于视频压缩和处理的算法，其针对端到端软件处理环境进行优化。然后，挑战是找到在基本上异步的传输/处理基础设施上嵌入视频数据的有效方法。为了应对这一挑战，本项目集中在两个主要领域：(I)计算/带宽可伸缩编码和(Ii)稳健的异步视频传输算法。无论是就其组件(主机、路由器)而言，还是就可用带宽和处理速度而言，互联网都是一个异质网络。因此，希望带宽/计算可伸缩算法能够以降低视频质量为代价来实现较不复杂的编码/解码。该项目正在开发一种可变复杂度、依赖于输入的编码/解码算法的设计方法，其目标是优化平均(而不是最差情况)的复杂度性能。此外，由于互联网提供的传输可靠性有限，还在开发健壮的异步视频传输算法。视频不仅对信息的丢失(例如，由于拥塞而丢弃的分组)敏感，而且对过度的延迟也很敏感。这项工作集中于用于异步视频传输的新的压缩技术，其中每个视频单元(帧的一部分)都有一个在此期间有用并且可以跨越多个帧时间间隔的“生命周期”。这一领域包括码率控制和图像域纠错/检测技术方面的新工作。

Most current digital video systems merely replace existing modes of analog video delivery with their more efficient digital counterparts. However, as packet-based networks, such as the Internet, start to be an essential component of the communications infrastructure and general purpose computers become the predominant communication terminal, there is a need to provide a new set of algorithms for video compression and processing, which are optimized for an endto- end software processing environment. The challenge is then to find efficient ways of embedding video data on a fundamentally asynchronous transmission/processing infrastructure. To address this challenge this project concentrates on two main areas: (i) computation/bandwidth scalable coding and (ii) robust asynchronous video transmission algorithms. The Internet is a heterogeneous network, both in terms of its components (hosts, routers) and in terms of available bandwidth and processing speed. Thus bandwidth/computation scalable algorithms are desirable to enable less complex encoding/decoding at the expense of a reduction in video quality. This project is developing a design methodology for variable complexity, input dependent coding/decoding algorithms where the goal is optimizing average (instead of "worst-case") complexity performance, robust asynchronous video transmission algorithms are also being developed, as motivated by the limited transmission reliability offered by the Internet. Video is sensitive not only to losses of information (e.g. packets being dropped due to congestion) but also to excessive delay. This work concentrates on new compression techniques for asynchronous video transmission where each video unit (a part of a frame) has a ``lifetime'' during which it is useful, and which can span more than a single frame time interval. This area includes novel work in both rate control and image domain error correction/detection techniques.