Scalable Video Coding provides important functionalities, such as the spatial, temporal, and SNR (quality) scalability, thereby significantly improving coding efficiency over prior standards such as the H.264/AVC and enabling the power adaptation. In turn, these functionalities lead to the enhancement of the video streaming over Peer-to-Peer networks, thereby providing a powerful platform for a variety of multimedia streaming applications, such as video-on-demand, video conferencing, live broadcasting, and many others. P2P systems are considered to be extremely cost-effective, since they utilize resources of the peer machines (e.g., CPU resources, memory resources, and bandwidth). However, since bandwidth is usually not constant and also since Peer-to-Peer networks suffer from the packet loss, there is no guarantee for the end-user video presentation quality. In addition, due to different server and end-user hardware configurations, it will be useful to specify the quality of the media (e.g., the bit-rate, spatial/temporal resolution, and the like). As a result, the Scalable Video Coding approach is an excellent choice, since the media streaming can be adjusted to a suitable stream to fit a particular Peer-to-Peer network and particular end-user requirements.
TopIntroduction
This chapter comprehensively covers the topic of the Peer-to-Peer (P2P) media streaming by using Scalable Video Coding (SVC), which is the extension of the H.264/AVC, while making a special emphasis on the Peer-To-Peer video streaming in a wireless environment, which is currently a very important issue due to the recent technological achievements in the mobile device field and due to the recent worldwide trends.
The advent of cheaper and more powerful mobile devices having the ability to play, create, and transmit video content, thereby maximizing a number of multimedia content distributions on various mobile networks, such as peer-to-peer wireless networks, has placed unprecedented demands for the high capacity, low-latency, and low-loss communications paths. The reduction of cost of digital video cameras along with the development of user-generated video sites (e.g., iTunes™, Google™ Video and YouTube™) have stimulated the new user-generated content sector. The growing premium content coupled with advanced video technologies, such as the Mobile TV, will mainly replace in the near future the conventional technologies (e.g., the cable or satellite TV). In this context, high-definition, highly interactive networked media applications pose challenges to network operators.
The variety of end-user devices with different capabilities, ranging from cell phones with small screens and restricted processing power to high-end PCs with high-definition displays, have stimulated a significant interest in effective technologies for video adaptation for spatial formats, consuming the power and bit rate. As a result, much of the attention in the field of video adaptation is currently directed to the Scalable Video Coding (SVC), which was standardized in 2007 as an extension of H.264/AVC (Schwarz et al., 2007; Wiegand et al., 2006), since the bit-stream scalability for video is currently a very desirable feature for many multimedia applications to be used on heterogeneous devices (Grois & Hadar, 2011a; Grois & Hadar, 2011b). Figure 1 presents, for example, the usage of the SVC Region-of-Interest (ROI) scalability for end-user devices having different spatial resolutions (e.g., QCIF, CIF, and SD).
Figure 1. Example of the region-of-interest dynamic adjustment and scalability (e.g., for mobile devices with different spatial resolution)
The need for the scalability arises from the need for spatial formats, bit rates and power (Wiegand & Sullivan, 2003; Grois et al., 2010a; Grois et al., 2010b). To fulfill these requirements, it would be beneficial to simultaneously transmit or store video in variety of spatial/temporal resolutions and qualities, leading to the video bit-stream scalability. The major requirement for the Scalable Video Coding is to enable encoding of a high-quality video bitstream that contains one or more subset bitstreams, each of which can be transmitted and decoded to provide video services with lower temporal or spatial resolutions, or to provide reduced reliability, while retaining reconstruction quality that is highly relative to the rate of the subset bitstreams.
As a result, the SVC provides important functionalities, such as the spatial, temporal and SNR (quality) scalability, thereby enabling the power adaptation (Schwarz et al., 2007; Wiegand et al., 2006). Also, the SVC has achieved significant improvements in coding efficiency compared to the scalable profiles of prior video coding standards. In turn, these functionalities and improvements lead to enhancements of video streaming, and particularly Peer-to-Peer (P2P) media streaming.
In the following sections, we review in detail the recent advances in P2P media streaming by using SVC. Particularly, in the following sections, we discuss in detail: