thanks !
for now there is no sound : I plan to add a headset with microphone like "real" coaches
and certainly see to add sound effects also.
I'm now working on live broadcasting. I fight with latency, my last tests gave me about 3seconds of delay, and with quality.
I'm also trying to use VLC to input the best quality I can (640x480, 30fps) in the live streaming, instead of the 25fps 320x200 I just can obtain for now using the basic web browser based applications live streaming offers for linux users (I can use their win/mac dedicated broadcasting softwares).