Browsing by Author "Nunes, M. S."
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- Evaluation of the H.264 scalable video coding in error prone IP networksPublication . Monteiro, J. M.; Calafate, C. T.; Nunes, M. S.The Joint Video Team, composed by the ISO/IEC Moving Picture Experts Group (MPEG) and the ITU-T Video Coding Experts Group (VCEG), has standardized a scalable extension of the H.264/AVC video coding standard called Scalable Video Coding (SVC). H.264/SVC provides scalable video streams which are composed by a base layer and one or more enhancement layers. Enhancement layers may improve the temporal, the spatial or the signal-to-noise ratio resolutions of the content represented by the lower layers. One of the applications, of this standard is related to video transmission in both wired and wireless communication systems, and it is therefore important to analyze in which way packet losses contribute to the degradation of quality, and which mechanisms could be used to improve that quality. This paper provides an analysis and evaluation of H.264/SVC in error prone environments, quantifying the degradation caused by packet losses in the decoded video. It also proposes and analyzes the consequences of QoS-based discarding of packets through different marking solutions.
- Peer-to-peer video streamingPublication . Monteiro, J. M.; Cruz, R. S.; Patrikakis, C. Z.; Papaoulakis, N. C.; Calafate, C. T.; Nunes, M. S.The Internet as a video distribution medium has seen a tremendous growth in recent years. Currently, the transmission of major live events and TV channels over the Internet can easily reach hundreds or millions of users trying to receive the same content using very distinct receiver terminals, placing both scalability and heterogeneity challenges to content and network providers. In private and well-managed Internet Protocol (IP) networks these types of distributions are supported by specially designed architectures, complemented with IP Multicast protocols and Quality of Service (QoS) solutions. However, the Best-Effort and Unicast nature of the Internet requires the introduction of a new set of protocols and related architectures to support the distribution of these contents. In the field of file and non-real time content distributions this has led to the creation and development of several Peer-to-Peer protocols that have experienced great success in recent years. This chapter presents the current research and developments in Peer-to-Peer video streaming over the Internet. A special focus is made on peer protocols, associated architectures and video coding techniques. The authors also review and describe current Peer-to-Peer streaming solutions. © 2013, IGI Global.
- Rate adaptation for wireless video streaming based on error statisticsPublication . Monteiro, J. M.; Vaz, R. N.; Grilo, A. M.; Nunes, M. S.This paper presents a new rate-control algorithm for live video streaming over wireless IP networks, which is based on selective frame discarding. In the proposed mechanism excess 'P' frames are dropped from the output queue at the sender using a congestion estimate based on packet loss statistics obtained from RTCP feedback and from the Data Link (DL) layer. The performance of the algorithm is evaluated through computer simulation. This paper also presents a characterisation of packet losses owing to transmission errors and congestion, which can help in choosing appropriate strategies to maximise the video quality experienced by the end user. Copyright © 2007 Inderscience Enterprises Ltd.
- Robust multipoint and multi-layered transmission of H.264/SVC with Raptor codesPublication . Monteiro, J. M.; Calafate, C. T.; Nunes, M. S.The scalable extension of the H.264 Advanced Video Coding (AVC) standard called Scalable Video Coding (SVC), or H.264/SVC, provides scalable video streams which are composed by a base layer and one or more enhancement layers. Enhancement layers may improve the temporal, the spatial or the signal-to-noise ratio resolutions of the content represented by the lower layers. One of the applications of this video coding standard is related to point-to-multipoint video distributions in both wired and wireless communication systems, where packet losses contribute to the degradation of the user's Quality of Experience. Designed for the transmission of data over Binary Erasure Channels (BEC), Raptor codes are a Forward Error Correction (FEC) mechanism that is gaining popularity for Internet Protocol Television (IPTV) applications due to their small decoding complexity and reduced overhead. This paper evaluates the quality enhancements introduced by the integration of several H.264/SVC layers with a Raptor coding protection scheme. Our goal is to improve the distribution of video over loss prone networks in terms of rate-distortion performance by assessing several alternative packetization options and protection schemes.