QStream
QStream (Quality Adaptive Media Streaming) is an experimental media streaming system. The goal of QStream is to develop a better software infrastructure for media streaming over the Internet, based on an encode once, stream anywhere approach. QStream was designed as a NATURAL consequence of several years of academic research (still ongoing) into systems and networking support for multimedia. The development efforts on QStream have so far have been directed to support internal research experiments and demonstrations. As such, the software is still quite rough around the edges. The main designer of QStream is Dr. Charles 'Buck' Krasic, who is currently associated with the Computer Science Department at The University of British Columbia. However, many other persons have also contributed to the design and development of QStream. The complete list of all the contributors can be found here: 1.
QStream is currently not ready for end-users yet, but in the long run, the designers intend to make it so. Currently, QStream runs over most of the major Operating System distributions like Linux and Microsoft Windows. A preliminary port on Mac OS X has also been completed though it is not well tested and some of the features of QStream may not be fully available. Qstream also supports streaming from a webcam and video conferencing. However, this support is still in its experimental stage. In future, the developers intend to make it a fully grown video conferencing, media streaming system.
Supported Media Formats
QStream uses its own specific SPEG media format (Scalable MPEG). This makes QStream extremely adaptive and scalable to large bandwidth variations without significant loss of quality. Conversion from common media formats to QStream recognizable SPEG format is a two stage process; first conversion to SPEG AVI stream and then from that to QStream recognizable .db format media. However, QStream already includes some sample scripts that facilitate this process and its website has an elaborate writeup on this conversion technique.
Adaptation Techniques
There are two kinds adaptations supported, spacial and temporal. Temporal adaptation corresponds to dropping of frames in a video playback when the resoures are limited. Spacial adaptation corresponds to reduction in quality of played video. The SPEG codec supports 8 layers of spacial adaptation. The relative importance of both kinds of adaptations can be adjusted by the user and is also dynamically adapted to meet with the constrained resources available.
Licencing
QStream is open source free software released under GNU General Licence Agreement.