Development of an adaptive videoconferencing framework for collaborative telemedicine

In this paper, we propose a novel platform called VAGABOND (Video Adaptation framework, crossing security GAteways, Based ON transcoDing) which works, in a very efficient and original way; on TCP (Transmission Control Protocol). The advantage of this protocol is that it easily crosses firewalls and proxies (use of TCP ports 80 or 443). However, as TCP is a reliable transport protocol, we needed to design and to employ new intelligent adaptation strategies together with data transmission in order to cope with latency issues and sockets timeout. VAGABOND is composed of Adaptation Proxies (APs), which have been designed to take into consideration user preferences, device heterogeneities, and network dynamic bandwidth variations. VAGABOND is able to adapt itself at the user and network levels. Probabilities are calculated based on the number of retained video packets on all those received in a given lapse of time. Indeed, the binomial probability law is used to trigger user profile adaptations. A user profile corresponds to a medical expert videoconferencing needs. For instance, a dermatologist videoconferencing need maybe a video of higher resolution but with a lower frame rate. The choice of the TCP protocol for real-time data is backed by the fact that the User Datagram Protocol (UDP), which is classically recommended for real-time data, does not cross firewalls or proxies unless explicitly configured fixed ports are declared. Notwithstanding, these fixed ports are considered as a security breach and hence are banned in institutions like medical facilities.