ugly artifacts around subtitles

[numerodix]

When I encode dvds with mencoder and rescale them, I get these ugly artifacts around the subtitles that I'd like to get rid of.

I'm using -vf spp,scale=xxx:yyy,hqdn3d

Here's what happens (look at the right hand side of the question mark in the first line)
http://img171.imageshack.us/img171/876/00000080om5.th.png (http://img171.imageshack.us/my.php?image=00000080om5.png)

I saw a suggestion to use
expand=::::1
as the first filter, but that only made it worse, giving some kind of 3d effect of the text *with* said artifacts.

The noise already appears when just playing the movie in mplayer, but when I encode it with x264 it "expands" from a few white pixels here and there to these lines/shapes.

[rvm]

I've just tested your options in MPlayer 1.0rc1 (linux) and I don't get those artifacts at all.

http://img444.imageshack.us/img444/2616/atlantisoj0.th.jpg (http://img444.imageshack.us/my.php?image=atlantisoj0.jpg)

[numerodix]

Have you looked closely? They don't appear in every frame, just about every other subtitle has them, though.

[rvm]

I've been playing a video for some minutes with those options and I can't see anything strange.

Options I used: -vf spp,scale=512:288,hqdn3d
Other options in mplayer config:

font = /home/ricardo/.fonts/arialbd.ttf
subfont-autoscale = 1
subfont-text-scale = 5
subcp = latin1
spuaa = 4
ffactor = 1