Based on the emerging ISO/IEC MPEG-DASH standard we have developed a prototype application which is fully integrated into the well known VLC media player and supporting a seamless and interoperable session transfer. The system could be deployed without modification on any existing device which is capable of VLC. Due to the flexible design of the software it is also possible to integrate it on a wide range of other devices with less modification.
In general session mobility is defined as the transfer of a running streaming session from one device to another where it may need to be consumed in an adaptive way. The two main challenges for such a system are:
(1) Taking into account the new context of the device e.g. bandwidth conditions, resolution and codec capabilities, to which the session is transferred.
(2) Performing the transfer in a seamless and interoperable way.
In anticipation of the results we can conclude that interoperability is achieved adopting existing standards while the performance of the system does not depend on these standards. Furthermore the system also adjusts seamlessly to the modified bandwidth conditions and capabilities of the target device.
Architecture
The session mobility architecture used for our system is depicted in Figure below. In this scenario, the user decides during the DASH session to switch to another device i.e. from the laptop to the mobile device. As a consequence the client on the laptop has to save the current state of the session e.g. media playtime, user preferences etc. Due to this fact we have adopted the MPEG-21 Context Digital Item (CDI) which is based on XML and designed for such purposes.
User Interface
Figure 2 shows the user interface of the session mobility which is seamlessly integrated into VLC. As mentioned before our implementation is fully integrated into VLC. The Figure beneath depicts the user interface that enables the interaction with the session transfer engine.
Show Case
The following video shows two clients connected through a TCP/IP network which are performing the session transfer as described above.
