Enhancement, implementation and evaluation of an RTCP-based centralized Inter-Destination Multimedia Synchronization (IDMS) approach

Abstract

El objetivo de este Trabajo Final de Grado (TFG) era mejorar e implementar una solución preliminar de Sincronización Multimedia Inter-Destinatario (IDMS), basada en el uso y extensión de los protocolos RTP/RTCP, en la plataforma plataforma de simulación NS-2, con tal de posibilitar su evaluación en multitud de escenarios y bajo diversas condiciones de red. Asimismo, el módulo de simulación diseñado debía implementar de manera completa y fidedigna las funcionalidades de los protocolos RTP/RTCP (especificados en la RFC 3550) con tal de facilitar la medida y evaluación de métricas de QoS en sistemas multimedia típicos (p.ej. aplicaciones de video streaming distribuidas). Newer distributed multimedia applications, such as Social TV or networked multi-player games, enable independent groups (or clusters) of users to interact between them and share services within the context of simultaneous media content consumption. In such scenarios, concurrently synchronized playout points must be ensured so as not to degrade the user experience on such interaction. We refer to this process as Inter-Destination Multimedia Synchronization (IDMS). This work presents the design, implementation and evaluation of an evolved version of an RTCP-based Centralized Inter-Destination Multimedia Synchronization (IDMS) approach, including an Adaptive Media Playout (AMP) scheme, that aims to dynamically and smoothly adjust the playout timing of each one of the geographically distributed consumers in a specific cluster if an allowable asynchrony threshold between their playout states is exceeded. For that purpose, we had also to previously develop a full implementation of RTP/RTCP protocols for NS-2. Simulation results prove the feasibility of such IDMS and AMP proposals, by adopting several dynamic master selection policies, to maintain an overall synchronization status (within allowable limits) in each cluster of participants, while minimizing the occurrence of long-term playout discontinuities (such as skips/pauses) which are subjectively more annoying to users than small variations in the media playout rate.