A layered multicast packet video system

Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to [email protected], referencing the URI of the item.Includes bibliographical references.Issued also on microfiche from Lange Micrographics.Software based desktop videoconferencing tools are developed to demonstrate techniques necessary for video delivery in heterogeneous packet networks. Using the current network infrastructure and no network resource reservation, a one-to-many implementation is designed around a two-layer pyramidal video coder. During periods of congestion, the network routers give priority to the base layer, which by itself allows reconstruction of reasonable quality video. Receiver feedback is used to lower the output rate of the encoder's low priority pyramidal layer when all receivers are suffering high packet loss. Each of the two layers is transmitted on a separate multicast channel. Under persistent congestion, an individual receiver will discard the low priority pyramidal layer, which allows the network to prune the multicast tree 'd congestion. A new scheme is examined where if the other receivers back and avoi are agreeable, the source will respond to a receiver pruning its pyramidal layer by lowering its rate and allowing the receiver to quickly rejoin the pyramidal layer at a quality level higher than what the high priority base layer can provide by itself. Another new scheme is described where an agent on the receiver's local router provides spare capacity information to assist the receiver in its decision to rejoin the pyramidal layer

Low-complexity video coding for receiver-driven layered multicast

In recent years, the “Internet Multicast Backbone,” or MBone, has risen from a small, research curiosity to a large- scale and widely used communications infrastructure. A driving force behind this growth was the development of multipoint audio, video, and shared whiteboard conferencing applications. Because these real-time media are transmitted at a uniform rate to all of the receivers in the network, a source must either run at the bottleneck rate or overload portions of its multicast distribution tree. We overcome this limitation by moving the burden of rate adaptation from the source to the receivers with a scheme we call receiver-driven layered multicast, or RLM. In RLM, a source distributes a hierarchical signal by striping the different layers across multiple multicast groups, and receivers adjust their reception rate by simply joining and leaving multicast groups. In this paper, we describe a layered video compression algorithm which, when combined with RLM, provides a comprehensive solution for scalable multicast video transmission in heterogeneous networks. In addition to a layered representation, our coder has low complexity (admitting an effi- cient software implementation) and high loss resilience (admitting robust operation in loosely controlled environments like the Inter- net). Even with these constraints, our hybrid DCT/wavelet-based coder exhibits good compression performance. It outperforms all publicly available Internet video codecs while maintaining comparable run-time performance. We have implemented our coder in a “real” application—the UCB/LBL videoconferencing tool vic. Unlike previous work on layered video compression and transmission, we have built a fully operational system that is currently being deployed on a very large scale over the MBone

Distributed multimedia systems

A distributed multimedia system (DMS) is an integrated communication, computing, and information system that enables the processing, management, delivery, and presentation of synchronized multimedia information with quality-of-service guarantees. Multimedia information may include discrete media data, such as text, data, and images, and continuous media data, such as video and audio. Such a system enhances human communications by exploiting both visual and aural senses and provides the ultimate flexibility in work and entertainment, allowing one to collaborate with remote participants, view movies on demand, access on-line digital libraries from the desktop, and so forth. In this paper, we present a technical survey of a DMS. We give an overview of distributed multimedia systems, examine the fundamental concept of digital media, identify the applications, and survey the important enabling technologies.published_or_final_versio

Sistemas de comunicação e multimédia com integração de vídeo: evolução, situação actual e boas práticas

Mestrado em Gestão da InformaçãoA presente dissertação pretende reflectir a evolução, o papel, a aplicação e a integração de vídeo em sistemas de comunicação unidireccionais e bidireccionais. Versando fortemente o universo digital, o trabalho é composto pela contextualização do vídeo em cenários multimédia, o desenho de uma taxonomia vídeo (apresentando exemplos práticos para cada uma das categorias) e a avaliação de uma sessão de videoconferência. Para finalizar, são propostas boas práticas para a produção, integração e distribuição de vídeo em multimédia.The present work describes the progress, functions, application, and integration of video in unidireccional and bidirectional communication systems. Focusing mainly the digital domain, it addresses different matters, namely: (1) video contextualization in multimedia settings, (2) the framework for a video taxonomy, having covered examples for each case, (3) the evaluation of a videoconference session, and finally (4) the itemization of good practices for the production, integration and distribution of video in multimedia systems

CPA\u27s guide to the Internet

https://egrove.olemiss.edu/aicpa_guides/1966/thumbnail.jp

CPA\u27s guide to the Internet

https://egrove.olemiss.edu/aicpa_guides/1967/thumbnail.jp

Layer-based coding, smoothing, and scheduling of low-bit-rate video for teleconferencing over tactical ATM networks

This work investigates issues related to distribution of low bit rate video within the context of a teleconferencing application deployed over a tactical ATM network. The main objective is to develop mechanisms that support transmission of low bit rate video streams as a series of scalable layers that progressively improve quality. The hierarchical nature of the layered video stream is actively exploited along the transmission path from the sender to the recipients to facilitate transmission. A new layered coder design tailored to video teleconferencing in the tactical environment is proposed. Macroblocks selected due to scene motion are layered via subband decomposition using the fast Haar transform. A generalized layering scheme groups the subbands to form an arbitrary number of layers. As a layering scheme suitable for low motion video is unsuitable for static slides, the coder adapts the layering scheme to the video content. A suboptimal rate control mechanism that reduces the kappa dimensional rate distortion problem resulting from the use of multiple quantizers tailored to each layer to a 1 dimensional problem by creating a single rate distortion curve for the coder in terms of a suboptimal set of kappa dimensional quantizer vectors is investigated. Rate control is thus simplified into a table lookup of a codebook containing the suboptimal quantizer vectors. The rate controller is ideal for real time video and limits fluctuations in the bit stream with no corresponding visible fluctuations in perceptual quality. A traffic smoother prior to network entry is developed to increase queuing and scheduler efficiency. Three levels of smoothing are studied: frame, layer, and cell interarrival. Frame level smoothing occurs via rate control at the application. Interleaving and cell interarrival smoothing are accomplished using a leaky bucket mechanism inserted prior to the adaptation layer or within the adaptation layerhttp://www.archive.org/details/layerbasedcoding00parkLieutenant Commander, United States NavyApproved for public release; distribution is unlimited