Video Compression Algorithms and Related Transport Protocols for Real Time, Unicast and Multicast Video over internet

互联网上实时、单播和组播视频的视频压缩算法和相关传输协议

• 批准号: 9905799
• 负责人: Avideh Zakhor
• 金额: $ 42万
• 依托单位: University of California-Berkeley
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-09-15 至 2003-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9905799&HistoricalAwards=false
• 关键词: Video; Compression; Algorithms; Related; Transport

Supporting low latency video communication over the Internet is an important yet challenging task. A few possible applications include video conferencing, tele-medicine, and interactive access to pre-recorded videos stored in remote databases. There are two main requirements for internet video communication: (1) bandwidth scalability; (2) error-resilient. Lack of bandwidth scalability results in non-adaptive streams with two sets of disadvantages. First, it leads to congestion collapse when the aggregate bandwidthof the video traffic exceeds network capacity. Second, it competes unfairly with other adaptive traffic, such as TCP, which reduces transmission rate in face of network congestion. Lack of error resilience results in error propagation, and hence widely varying video quality as a function of time. Current approaches to mitigate the effects of error propagation include error control mechanisms at the transport level. This typically takes the form of retransmissions or forward error correction (FEC). Retransmission based error control methods often fail to be real-time, particularly when round-trip propagation delay is large.FEC schemes on the other hand, are often ineffective when losses are bursty.The main goal of this proposal is to investigate video compression techniques and transport protocols needed for real time delivery of unicast and multicast video over best effort networks such as the internet. Our approach for the unicast case is to combine a novel compression method that is error resilient and bandwidth scalable with a low-delay TCP-friendly transport protocol. Specifically, compressed video is packetized into individually decodable packets of equal expected visual importance. Consequently, relatively constant video quality can be achieved at the receiver under lossy conditions. Furthermore, the packets can be truncated to instantaneously meet the time varying bandwidth imposed by a TCP-friendly transport protocol. As a result,adaptive flows that are friendly to other Internet traffic are produced. Actual Internet experiments together with simulations are used to evaluate the performance of the compression, transport, and the combined schemes.Our approach to multicast video transmission is to combine bandwidth scalable video compression scheme with hierarchical FEC. By hierarchical FEC, we mean the production of embedded FEC or redundancystreams, each of which belongs to a different multicast group. This way, subscribing to more groups corresponds to higher level of protection, but larger delays. There are two advantages to this approach. First, each receiver can independently adjust the desired level of protection based on past reception statistics and loss characteristics. This receiver-driven approach to FEC is more flexible than most existing FEC schemes for multicast where the source determines a set of redundancy packets which are then multicast to every recipient. Second, each receiver will subscribe to only as many redundancy layers as necessary, reducing overall bandwidth utilization. Furthermore, the hierarchical nature of the FEC layers ensuresminimum network utilization through sharing of common redundancy streams. Actual internet experiments will be done to examine the effectiveness of our approach.

支持互联网上的低延迟视频通信是一项重要但具有挑战性的任务。 一些可能的应用包括视频会议、远程医疗和交互式访问存储在远程数据库中的预先录制的视频。 互联网视频通信有两个主要要求：（1）带宽可扩展性;（2）容错性。 带宽可伸缩性的缺乏导致具有两组缺点的非自适应流。 首先，当视频流量的总带宽超过网络容量时，它会导致拥塞崩溃。 其次，它与其他自适应流量（如TCP）进行不公平竞争，这会在网络拥塞时降低传输速率。 错误恢复能力的缺乏导致错误传播，并因此导致视频质量随时间的变化。 目前的方法，以减轻错误传播的影响，包括在传输级的错误控制机制。 这通常采取重传或前向纠错（FEC）的形式。 基于重传的差错控制方法往往不能实时，特别是当往返传播延迟是大的。另一方面，FEC方案，往往是无效的，当损失是bursty.The主要目标的建议是调查视频压缩技术和传输协议所需的真实的时间交付的单播和组播视频在尽力而为的网络，如互联网。我们的单播情况下的方法是结合联合收割机一种新的压缩方法，是错误的弹性和带宽可扩展的低延迟TCP友好的传输协议。 具体来说，压缩视频被打包成具有相等预期视觉重要性的可单独解码的数据包。 因此，在有损条件下可以在接收器处实现相对恒定的视频质量。 此外，分组可以被截断以即时满足TCP友好传输协议所施加的时变带宽。 因此，产生了对其他互联网流量友好的自适应流。 通过实际的网络实验和仿真，对压缩、传输和组合方案的性能进行了评估。我们的多播视频传输方案是将联合收割机带宽可伸缩的视频压缩方案与分级FEC相结合。 通过分层FEC，我们指的是嵌入式FEC或冗余流的产生，每个流属于不同的多播组。 这样，订阅更多的组对应于更高的保护级别，但延迟更大。 这种方法有两个优点。 首先，每个接收器可以基于过去的接收统计和丢失特性独立地调整期望的保护级别。 这种接收器驱动的FEC方法比大多数现有的用于多播的FEC方案更灵活，其中源确定一组冗余分组，然后将其多播到每个接收器。 第二，每个接收器将仅订阅必要的冗余层，从而降低总体带宽利用率。 此外，FEC层的分层性质通过共享公共冗余流确保了最小的网络利用率。 实际的互联网实验将进行检查我们的方法的有效性。