The Internet's growing transport layer diversity makes it increasingly difficult for application programmers to choose the right mechanism. I believe that guidelines are needed; these guidelines should rely on a qualitative evaluation of mechanisms at the application (or user) level.
The "Adaptive Video Communication System" (AVCS) is an open source tool for MS Windows which realizes very obvious quality adaptation on top of TCP-friendly congestion control by changing the video resolution (or compression factor in the case of MJPEG, which is also supported). The implemented TCP-friendly mechanisms are RAP (fully functional) and TFRC (still buggy); they are based on the original ns-2 code.
Screenshots: main window, options screen
Download - note that the "RTX" versions require the RTX realtime extension from VenturCom
AVCS was developed by Gerhard Stummer for his diploma thesis
under my supervision; the thesis is the only available documentation, and it
Gerhard Stummer maintains pages about his thesis and AVCS at his personal homepage (under "Informatic").
We made some user tests with AVCS; check out the questionnaire if you are interested in example video sequences The results were published in this paper:
Michael Welzl: "User-Centric Evaluation of TCP-friendly
Congestion Control for Real-Time Video Transmission", e&i "Elektrotechnik
und Informationstechnik" 06/2005. Invited paper.