[vdr] xineliboutput config "video-buffer"

[Bellina Informatica]

i've tried to play smooth HD channels on 919 (ita), but afer 2 min i get
scatters (1 -2 secs)

digging on 
/etc/vdr/setup.conf 
/home/.../.xine/config_xineliboutput

i've discover that when the "block" (1 - 2 secs) happen the config
option --video-buffer RESET TO 250 (sound impossible for HD content)

I've double check that vdr (runvdr) and the front-end where not running.

The strange is that if i use the --buffer=800 in the vdr-sxfe,
config_xineliboutput don't change, and "scatters" are quite rare.

Why ?

Atom, ION 1.6 (Giaga)
vdr 1.7.14
ffmpeg (cvs -less than 1 month)
xine-lib (cvs - less than 1 month)

cpu is max 25%, the first CPU-thread (bin vdr) bounce from 5,10%
(SD-channels) up to (60-90% HD), 

dmesg report 4 CPU's
top -total CPU usage -> max 25% (HD content)