before first slice).
 * ffmpeg: use indeo v3 decoder (untested).
 * stream_ouput.c,libvlc.h : take care of:
 --sout-acodec,--sout-vcodec : use transcoding. (You can specify bitrate
using --sout-abitrate and --sout-vbitrate in kilobits/s).
 --sout-display: to display while streaming.
(Btw there is a problem with vout and display, it leads to a ref count = -1)