Encoding to x264 using ffmpeg

[Marcelo Magno T. Sales]

Hello,

When I was running Karmic, I would encode a video to x264 running ffmpeg 
as follows:
ffmpeg -i inputfile.ext -vcodec libx264 -acodec libfaac -sameq -s 
854x480 -aspect 1.78 outputfile.mp4

It used to work great. However, when I use this very same command line 
in lucid, I get this error message:

[libx264 @ 0xc28200]broken ffmpeg default settings detected
[libx264 @ 0xc28200]use an encoding preset (vpre)
Error while opening codec for output stream #0.0 - maybe incorrect 
parameters such as bit_rate, rate, width or height

I found some preset files in /usr/share/ffmpeg. If I use one of them 
with the -vpre switch, ffmpeg runs without complaining, but with none of 
these preset files I get results comparable with what I was used to in 
Karmic. For example, if I run ffmpeg with -vpre default, I get a very 
tiny file with horrible quality. If I use -vpre lossless_slower, I get a 
file with good quality, but with a size 7 to 10 times the original (in 
Karmic, I would get a file smaller than the original). And so on.
I've read some ffmpeg encoding tutorials, but so far I'm still unable to 
generate video files with acceptable quality and sizes.

Any suggestions?

Thanks,

Marcelo