183 research outputs found
Virtual RTCP: A Case Study of Monitoring and Repair for UDP-based IPTV Systems
IPTV systems have seen widespread deployment, but often lack robust mechanisms for monitoring the quality of experience. This makes it difficult for network operators to ensure that their services match the quality of traditional broadcast TV systems, leading to consumer dissatisfaction. We present a case study of virtual RTCP, a new framework for reception quality monitoring and reporting for UDP-encapsulated MPEG video delivered over IP multicast. We show that this allows incremental deployment of reporting infrastructure, coupled with effective retransmission-based packet loss repair
Building self-optimized communication systems based on applicative cross-layer information
This article proposes the Implicit Packet Meta Header(IPMH) as a standard method to compute and represent common QoS properties of the Application Data Units (ADU) of multimedia streams using legacy and proprietary streamsâ headers (e.g. Real-time Transport Protocol headers). The use of IPMH by mechanisms located at different layers of the communication architecture will allow implementing fine per-packet selfoptimization of communication services regarding the actual application requirements. A case study showing how IPMH is used by error control mechanisms in the context of wireless networks is presented in order to demonstrate the feasibility and advantages of this approach
Format-independent media delivery, applied to RTP, MP4, and Ogg
The current multimedia landscape is characterized by a significant heterogeneity in terms of coding and delivery formats, usage environments, and user preferences. This paper introduces a transparent multimedia content adaptation and delivery approach, i.e., model-driven content adaptation and delivery. It is based on a model that takes into account the structural metadata, semantic metadata, and scalability information of media bitstreams. Further, a format-independent multimedia packaging method is proposed based on this model for media bitstreams and MPEG-B BSDL. Thus, multimedia packaging is obtained by encapsulating the selected and adapted structural metadata within a specific delivery format. This packaging process is implemented using XML transformation filters and MPEG-B BSDL. To illustrate this format-independent packaging technique, we apply it to three packaging formats: RTP, MP4, and Ogg
Linux-Box: DVB and VoD streaming over local area networks
Aquest treball tracta sobre un projecte comĂș anomenat Linux-Box portat a terme per diferents persones al departament de Telecomunicacions (IET) de la Universitat de Pisa. Linux-Box Ă©s un sistema dotat amb targetes TDT (DVB-T) i de televisiĂł per satĂšl·lit (DVB-S) que permet transmetre aquests senyals fins a un Ă mbit domĂšstic. MĂ©s endavant podria ser utilitzat en Ă mbits privats com les cases de clients o en institucions pĂșbliques com escoles, universitats, biblioteques i tambĂ© seria possible en Ă mbits empresarials. El projecte estĂ dividit en 4 apartats:
1. Ubuntu 6.06 LTS. Explica perquĂš sâutilitza Ubuntu en el projecte. A mĂ©s
tambĂ© sâexplica de forma breu que Ă©s Linux i les distribucions mĂ©s utilitzades.
2. Multimedia Network Protocols: sâexpliquen els diferents protocols desde la capa de xarxa fins la capa dâaplicaciĂł que sâutilitzen en el projecte Linux-Box.
Aquests protocols sĂłn utilitzats tant en streaming, com en anunciaciĂł,
unicast/multicast, encapsulat de vĂdeo i codecs. Els diversos temes tractats aquĂ
es fan amb el propĂČsit de comparar i no nomĂ©s com a recerca teĂČrica. A la fi es
veuen els programes utilitzats en el projecte per analitzar el trĂ fic de la xarxa.
3. Linux-Box: sâexplica el funcionament i els objectius globals del projecte. Es
dedica un sub-apartat a âVideoLan - VLCâ part important a nivell de sofware. MĂ©s
endavant es parla de les caracterĂstiques de la Linux-Box de forma acurada:
streaming de VoD i senyals de TV i sâanalitzen els problemes coneguts i les
seves solucions proposades. A la fi sâenumeren els llenguatges de programaciĂł
utilitzats al projecte i en quina part sâutilitzen. Observarem que Ă©s una aplicaciĂł
on diversos llenguatges de programaciĂł estan contĂnuament solapats.
4. Developed Part: es posa en prĂ ctica la teoria estudiada a la resta del treball.
EstĂ dividida en 4 seccions:
Desenvolupar una aplicaciĂł en codi C per convertir la llista de Canals
(tant terrestre com de satÚl·lit) en format XML.
Una secciĂł dedicada al streaming de Canals de TV a la pĂ gina web principal.
Un anĂ lisis profund dels paquets creats per la Linux-Box i la seva activitat a la xarxa.
Finalment sâanalitzen els diferents scripts i les seves configuracions.
Alguns sĂłn Ăștils per a un futur desenvolupament i dâaltres sâutilitzen en
seccions prĂšvies.
5. Conclusions: contĂ© les conclusions i lĂnies futures. El projecte compta amb
diverses opcions que encara poden ser implementades i estudiades. AquĂ
exposem les nostres interpretacions i possibles lĂnies futures dâestudi
Reflections on security options for the real-time transport protocol framework
The Real-time Transport Protocol (RTP) supports a range of video conferencing, telephony, and streaming video ap- plications, but offers few native security features. We discuss the problem of securing RTP, considering the range of applications. We outline why this makes RTP a difficult protocol to secure, and describe the approach we have recently proposed in the IETF to provide security for RTP applications. This approach treats RTP as a framework with a set of extensible security building blocks, and prescribes mandatory-to-implement security at the level of different application classes, rather than at the level of the media transport protocol
Linux-Box: DVB and VoD streaming over local area networks
Aquest treball tracta sobre un projecte comĂș anomenat Linux-Box portat a terme per diferents persones al departament de Telecomunicacions (IET) de la Universitat de Pisa. Linux-Box Ă©s un sistema dotat amb targetes TDT (DVB-T) i de televisiĂł per satĂšl·lit (DVB-S) que permet transmetre aquests senyals fins a un Ă mbit domĂšstic. MĂ©s endavant podria ser utilitzat en Ă mbits privats com les cases de clients o en institucions pĂșbliques com escoles, universitats, biblioteques i tambĂ© seria possible en Ă mbits empresarials. El projecte estĂ dividit en 4 apartats:
1. Ubuntu 6.06 LTS. Explica perquĂš sâutilitza Ubuntu en el projecte. A mĂ©s
tambĂ© sâexplica de forma breu que Ă©s Linux i les distribucions mĂ©s utilitzades.
2. Multimedia Network Protocols: sâexpliquen els diferents protocols desde la capa de xarxa fins la capa dâaplicaciĂł que sâutilitzen en el projecte Linux-Box.
Aquests protocols sĂłn utilitzats tant en streaming, com en anunciaciĂł,
unicast/multicast, encapsulat de vĂdeo i codecs. Els diversos temes tractats aquĂ
es fan amb el propĂČsit de comparar i no nomĂ©s com a recerca teĂČrica. A la fi es
veuen els programes utilitzats en el projecte per analitzar el trĂ fic de la xarxa.
3. Linux-Box: sâexplica el funcionament i els objectius globals del projecte. Es
dedica un sub-apartat a âVideoLan - VLCâ part important a nivell de sofware. MĂ©s
endavant es parla de les caracterĂstiques de la Linux-Box de forma acurada:
streaming de VoD i senyals de TV i sâanalitzen els problemes coneguts i les
seves solucions proposades. A la fi sâenumeren els llenguatges de programaciĂł
utilitzats al projecte i en quina part sâutilitzen. Observarem que Ă©s una aplicaciĂł
on diversos llenguatges de programaciĂł estan contĂnuament solapats.
4. Developed Part: es posa en prĂ ctica la teoria estudiada a la resta del treball.
EstĂ dividida en 4 seccions:
ï· Desenvolupar una aplicaciĂł en codi C per convertir la llista de Canals
(tant terrestre com de satÚl·lit) en format XML.
ï· Una secciĂł dedicada al streaming de Canals de TV a la pĂ gina web principal.
ï· Un anĂ lisis profund dels paquets creats per la Linux-Box i la seva activitat a la xarxa.
ï· Finalment sâanalitzen els diferents scripts i les seves configuracions.
Alguns sĂłn Ăștils per a un futur desenvolupament i dâaltres sâutilitzen en
seccions prĂšvies.
5. Conclusions: contĂ© les conclusions i lĂnies futures. El projecte compta amb
diverses opcions que encara poden ser implementades i estudiades. AquĂ
exposem les nostres interpretacions i possibles lĂnies futures dâestudi
Understanding Timelines within MPEG Standards
(c) 2016 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.Nowadays, media content can be delivered via diverse broadband and broadcast technologies. Although these different technologies have somehow become rivals, their coordinated usage and convergence, by leveraging of their strengths and complementary characteristics, can bring many benefits to both operators and customers. For example, broadcast TV content can be augmented by on-demand broadband media content to provide enriched and personalized services, such as multi-view TV, audio language selection, and inclusion of real-time web feeds. A piece of evidence is the recent Hybrid Broadcast Broadband TV (HbbTV) standard, which aims at harmonizing the delivery and consumption of (hybrid) broadcast and broadband TV content. A key challenge in these emerging scenarios is the synchronization between the involved media streams, which can be originated by the same or different sources, and delivered via the same or different technologies. To enable synchronized (hybrid) media delivery services, some mechanisms providing timelines at the source side are necessary to accurately time align the involved media streams at the receiver-side. This paper provides a comprehensive review of how clock references (timing) and timestamps (time) are conveyed and interpreted when using the most widespread delivery technologies, such as DVB, RTP/RTCP and MPEG standards (e.g., MPEG-2, MPEG-4, MPEG-DASH, and MMT). It is particularly focused on the format, resolution, frequency, and the position within the bitstream of the fields conveying timing information, as well as on the involved components and packetization aspects. Finally, it provides a survey of proofs of concepts making use of these synchronization related mechanisms. This complete and thorough source of information can be very useful for scholars and practitioners interested in media services with synchronization demands.This work has been funded, partially, by the "Fondo Europeo de Desarrollo Regional" (FEDER) and the Spanish Ministry of Economy and Competitiveness, under its R&D&i Support Program in project with ref TEC2013-45492-R.Yuste, LB.; Boronat Segui, F.; Montagut Climent, MA.; Melvin, H. (2015). Understanding Timelines within MPEG Standards. Communications Surveys and Tutorials, IEEE Communications Society. 18(1):368-400. https://doi.org/10.1109/COMST.2015.2488483S36840018
Efficient Video Transport over Lossy Networks
Nowadays, packet video is an important application of the Internet. Unfortunately the capacity of the Internet is still very heterogeneous because it connects high bandwidth ATM networks as well as low bandwidth ISDN dial in lines. The MPEG-2 and MPEG-4 video compression standards provide efficient video encoding for high and low bandwidth media streams. In particular they include two paradigms which make those standards suitable for the transmission of video via heterogeneous networks. Both support layered video streams and MPEG-4 additionally allows the independent coding of video objects. In this paper we discuss those two paradigms, give an overview of the MPEG video compression standards and describe transport protocols for Real Time Media transport over lossy networks. Furthermore, we propose a real-time segmentation approach for extracting video objects in teleteaching scenarios
Seminario sullo Standard MPEG-4: utilizzo ed aspetti implementativi
Una delle tecnologie chiave che hanno permesso il grande sviluppo della televisione digitale Ăš la compressione video. La tecnologia di codifica video nota come MPEG-2, sviluppata nei primi anni novanta, Ăš diventata lo standard di trasmissione DTV (Digital TV) sia satellitare sia terrestre in quasi tutti i paesi del mondo. Da allora la velocitĂ dei microprocessori e le capacitĂ di memoria dei dispositivi hardware per la codifica e la decodifica sono migliorate significativamente rendendo possibile lo sviluppo e
lâimplementazione di algoritmi di codifica innovativi in grado di abbattere significativamente i limiti di compressione dello standard MPEG-2. Tali innovazioni, sfociate nel 2003 nello standard MPEG-4 AVC (Advanced Video Coding), non hanno permesso di mantenere la compatibilitĂ allâindietro con lâMPEG-2, e questo ha inizialmente costituito un limite alla loro introduzione nei sistemi di trasmissione DTV. Tuttavia, negli ultimi anni la codifica MPEG-4 AVC si Ăš diffusa rapidamente, Ăš stata adottata dal progetto DVB, recentemente dallâATSC, ed Ăš lo standard di codifica nellâIPTV.
Lâobiettivo di questo seminario, che si articola in due giornate, Ăš quello di presentare lo standard di codifica MPEG-4 AVC con particolare attenzione agli aspetti implementativi del livello di codifica video.2008-11-18Sardegna Ricerche, Edificio 2, LocalitĂ Piscinamanna 09010 Pula (CA) - ItaliaSeminario sullo Standard MPEG-4: utilizzo ed aspetti implementativ
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