Luca Celetto

Polyphase spatial subsampling multiple description coding of video streams with H264

In this work, we propose a multiple description (MD) coding system for video streams. In particular, our scheme originates four descriptions from the spatially downsampled polyphase components of the original frames. Each description is compressed independently with the recent H264/AVC video coding standard, it is packetized and sent over an error prone network. In case of errors in one or more descriptions, appropriate concealing is applied at the receiver, before insertion of the corrected frames into the corresponding receiver frame buffers. We propose and compare different concealment solutions and a post processing stage to attenuate visual effects related to MD coding. We analyze the trade off between robustness to channel errors and coding efficiency, comparing the proposed technique with single description (SD) video coding with H264/AVC. Experimental results validate the effectiveness of the proposed scheme.

Peer-to-peer streaming of scalable video in future Internet applications

Scalable video delivery over peer-to-peer networks appears to be key for efficient streaming in emerging and future Internet applications. Contrasting the conventional server-client approach, here, video is delivered to a user in a fully distributed fashion. This is, for instance, beneficial in cases where a high demand for a particular video content is imposed, as different users can receive the same data from different peers. Furthermore, due to the heterogeneous nature of Internet connectivity, the content needs to be delivered to a user through networks with highly varying bandwidths. Moreover, content needs to be displayed on a variety of devices featuring different sizes, resolutions, and computational capabilities. If video is encoded in a scalable way, it can be adapted to any required spatio-temporal resolution and quality in the compressed domain, according to a peer bandwidth and other peers¿ context requirements. This enables efficient low-complexity content adaptation and interoperability for improved peer-to-peer streaming in future Internet applications. An efficient piece picking and peer selection policy enables high quality of service in such a streaming system.

An Accurate Low-Complexity Rate Control Algorithm Based on

The standard H.264/AVC defines an efficient coding architecture both for coding applications where bandwidth or storage capacity is limited (e.g., video telephony or video conferencing over mobile channels and devices) and for applications that require high reconstruction quality and bit rate (e.g., HDTV). Since its main applications concern video communication over time-varying bandwidth channels, the bit rate has to be controlled with scalable algorithms that can be implemented on low resource devices. The paper describes a rate control algorithm that needs reduced memory area and complexity compared to other ones. The number of coded bits for each frame is accurately predicted through the percentage of null quantized transform coefficients, which is related to the quantization step via the energy of the quantized signal. It is possible to design a rate control algorithm based on this model that provides a good compression performance at a low computational cost.

(\rho, E_{q})

H.264 is an emerging video coding standard, providing significant improvements with respect to its ancestors, like MPEG-2 and MPEG-4. In this paper, we present an evaluation of the most important H.264 coding tools in terms of visual quality and compression efficiency

-Domain

This paper describes an ultra-low power, cache based, and programmable motion estimator with memory reduction for MPEG-4 video encoding. It exploits a low complexity motion estimation algorithm, achieving a quality comparable to the full search approach with only 1% of the computation and the power consumption.

Detailed rate-distortion analysis of H.264 video coding standard and comparison to MPEG2/4

Peer-to-peer (P2P) streaming systems grow in numbers and potential and several commercial products are already competing. Internet home users - through the diffusion of xDSL connections - represent the potential market of IPTV channels that Content Generators may distribute at reduced costs. This work describes the state of the art of P2P streaming clients and poses some questions about the end-user perspective in heterogeneous networks. To this aim, a representative set of experiments has been performed on a popular P2P system. The client offers live streaming content from some European broadcasters, start-up delay is a few seconds and the user satisfaction rank is good. The trend moves toward solutions that try to optimize the whole network stack, pursuing flexibility in terms of user needs and system requirements. This work is aimed at focusing on the key-drives in the design of P2P streaming clients.

An innovative, programmable architecture for ultra-low power motion estimation in reduced memory MPEG-4 encoder

This paper provides a performance analysis of adaptation approaches designed for scalable media resources. In particular, we investigate the streaming of media resources compliant to the scalable video coding (SVC) extensions of advanced video coding (AVC) within heterogeneous environments, i.e., terminals and networks with different capabilities. Therefore, we have developed a test-bed in order to analyze two different approaches for the adaptation of scalable media resources, namely a generic approach that is applicable independently of the actual scalable coding format used and a specific approach especially built for SVC. The results show that if adaptation is required the generic approach clearly outperforms the approach specifically built for SVC.

Survey on P2P Overlay Streaming Clients

Coding techniques are progressively succeeding in finding a beneficial use throughout all the components of advanced multimedia streaming networks, including peer-to-peer (P2P) content distribution strategies. In fact, although P2P algorithms are regarded as an important technology that will be part of future commercial Internet protocol television (IPTV) platforms, it has been shown that their ability to efficiently distribute multimedia streams within strict time constraints, and their robustness to high churn rates, can still improve when putting to good use source and network coding algorithms. For this reason, in the past few years a wealth of research has been undertaken aiming at jointly optimizing both coding and streaming schemes. In this article, we analyze the progress made by the latest scientific research in the field of jointly using coding and P2P streaming strategies, and we offer a set of experimental results performed on a real planet-wide P2P streaming test-bed, using Digital Fountains (DFs). Surprisingly, our testbed study reveals that utilizing DF techniques is not always beneficial to the distribution of streaming data using a P2P distribution strategy. In fact, our results show that only when the network scales beyond a certain size, it is possible to appreciate the advantages introduced by the use of DFs, showing that coding techniques should always be carefully deployed and their advantages well understood. For this reason, we believe this work can provide a useful aid in better appreciating the critical aspects of jointly utilizing multimedia streaming and DF coding techniques for IPTV.

Performance Analysis of Scalable Video Adaptation: Generic versus Specific Approach

Widespread and affordable mobile broadband access opens up opportunities for delivery of new streaming services everywhere and anytime. However, what is expected to fundamentally change the way how people use the network is the ability to produce, and seamlessly deliver and share their own multimedia content. In this paper we describe the content distribution and adaptation architecture that we have implemented and tested, the results utilising new coding formats of video coding (e.g. SVC, MVC) and new methods for increasing the robustness of video delivery.

Using digital fountains in future IPTV streaming platforms: a future perspective

The Internet is incontrovertibly a great success that has changed our social and economic world. Today, over one billion users access the Internet on regular basis, more than 100 million users have downloaded at least one (multi) media file, and over 47 million of them do so regularly, searching in more than 160 exabytes of content. The content is expected to rise to more than 990 exabytes before 2012, fueled mainly by the users themselves [1]. It is envisaged that in the near- to mid-term future, mobile Internet will provide the means to share and distribute (new) multimedia content and services with superior quality and striking flexibility, in a trusted and personalized way, improving citizens? quality of life, working conditions, edutainment, and safety.