Improving Medium-Sized Media Clip Distribution Through Transparent Tail Synchronization

Information excerpted from the extended abstract:

• Poster A. Striegel, D. Salyers, D. Moore, Y. Jiang, A. Blaich, "Improving Medium-Sized Media Clip Distribution Through Transparent Tail Synchronization," poster at IEEE BroadNets, pp. 294-295, Raleigh, NC, Sept. 2007. DOI IEEE Xplore

Abstract

The emergence of popular video sharing sites such as YouTube has created a tremendous content shift towards timely, medium-sized media together with placing significant demands on the network. While techniques such as Application Layer Multicast and P2P streaming offer the potential to reduce the impact of general streaming content, the difficulty in imposing synchronization and the heavy asymmetry of clients nullify the majority of the respective benefits of the techniques. In this paper, we propose a method, transparent tail synchronization, that discovers latent opportunities for synchronization from the tail of the content to take advantage of efficient distribution techniques. Our approach maximizes savings at the content provider while operating in a straightforward and easily deployable manner. We describe how tail synchronized media distribution can offer savings across a wide range of asymmetry at the end clients.

Introduction

With the proliferation of high-speed network access to the home user, the scale of content has gravitated towards richer media interactions. For traditional broadcast media from live sources, numerous solutions ranging from IP multicast to Application Layer Multicast (ALM) to Peer to Peer (P2P) streaming have emerged to efficiently deliver content. For each of these respective solutions, a critical characteristic of the content is the natural synchronization of users due to the live broadcast nature of the content. The memory-less property of live content (i.e. future clients joining do not need previous content) allows for a de facto synchronization that is simply not present in all media.

In contrast, the emergence of rich media sites such as YouTube introduce a significantly different type of transfer. This medium-scale media dwarfs the requirements of typical content-laden web pages but yet pales in comparison to an average full length movie (DVD, HD-DVD, BluRay, etc.). We posit that this "medium-scale'' content introduces interesting properties that complicate distribution of such media over previously dominant content. To start, content often arrives in a reliable manner via TCP due to both the simplicity of using TCP as well as the ability of TCP to easily navigate firewall/NAT mechanisms. Furthermore, the magnitude of the available content choices in terms of both choices and size creates numerous issues regarding the ability to effectively remotely cache content. These constraints are only exacerbated by the expectation of near immediate playback, i.e. show me the rich clip now, not two hours from now.

The paper posits a relatively simple question: is it possible to extract synchronization without imposing significant restrictions on the existing transfer mechanisms, i.e. is there latent potential for synchronization that can be exploited transparently? To that end, we propose the concept of tail synchronization that virtually subdivides existing static media objects into zones for the purposes of coalescing, streaming, and completion. The root of tail synchronization emerges from how objects are synchronously streamed from the tail to minimize the impact of the unreliable aspects of streaming content on playback but conversely to maximize the amount of time available to stream content through the highly asymmetric pipes. Tail synchronization is not a replacement for distribution mechanisms but rather provides amenable content that can take advantage of such mechanisms (ALM, IP Multicast, Small Group Multicast, P2P, etc.). We believe tail synchronization is an extremely lightweight approach that can bring reasonable efficiency gains in an immediate timescale.