We present vDelay, a tool for measuring the capture-to-display latency (CDL) and frame-rate of real-time video applications such as video chat and conferencing. vDelay allows measuring CDL and frame-rate without modifying the source code of these applications. Further, it does not require any specialized hardware. We have used vDelay to measure the CDL and frame-rate of popular video chat applications such as Skype, Windows Live Messenger, and GMail video chat. vDelay can also be used to measure the CDL and frame-rate of these applications in the presence of bandwidth variations.
Abstract-The SECE (Sense Everything, Control Everything) system allows users to create services that combine communication, calendaring, location and devices in the physical world. SECE is an event-driven system that uses a natural-English-like language to trigger action scripts. Presence updates, incoming calls, email, calendar and time events, sensor inputs and location updates can trigger rules. SECE retrieves all this information from multiple sources to personalize services and to adapt them to changes in the user's context and preferences. Actions can control the delivery of email, change the handling of phone calls, update social network status and set the state of actuators such as lights, thermostats and electrical appliances. We give an overview of the SECE language and system architecture.
We study the performance of four popular IM clients focusing our attention on video-chat. In particular, we analyze how Skype, Windows Live Messenger, Eyebeam and X-Lite react to changes in available bandwidth, presence of HTTP and bit-torrent traffic and random packet losses.
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