Buffer size in dvdplayer?

Can anyone explain how/where the buffer size is set when playing an internet stream in dvdplayer? From a quick test (on Windows), the System:Cache settings don't seem to have an effect. I don't see anywhere obvious in the dvdplayer code that deals with it... however I've probably overlooked something.

I'd like to improve the rtmp playback:
1) currently the XBOX codestream doesn't have any pre-caching at all, so an rtmp stream starts playback then rebuffers after a few seconds. The linuxport code has a pre-buffer dialog but the size doesn't seem to be configurable.
2) the DvdInputStreamRTMP code doesn't correctly declare it's buffer size to the rtmp server, which makes playback unnecessarily slow to start (data is only sent at the playback rate, if it knew our buffer size that much data would be sent as fast as possible).

Congrats, you've found one of several current mysteries in XBMC ports.

You are probably right, the cache options has no effect, they do have an effect on Mplayer on XBOX though.

Why is it so then ? Noone has gotten around to fix it it yet

I also want to reduce the buffer size. I am playing live webcam streaming from the Mediatomb AV media server. But the delay is pretty much and is up to 15 seconds. I have reduced the Mediatomb's buffer size but could not get any way to reduce the player's buffer.