[FFmpeg-user] formula for transcoding to ogv, shrinking an mkv

[James Miller]

I do some screencasting, that involves both video and audio capture, using 
ffmpeg's x11grab. At the same time, I have upload limits at the site where 
I wish to host these screencasts. On doing some reading and making a few 
consultations, I decided I should record my screencasts in a lossless 
format, then convert and shrink the resulting files prior to uploading. I 
came across a good incantation for converting and shrinking to flv: the 
resulting files are actually about one tenth the size of the original, 
lossless ones--just about the ideal proportion. Now, though, I'd like to 
try and develop a similar formula for converting and shrinking to ogv. The 
following incantation, which I developed by trial and error, gives a 
result 
close to what I need:

ffmpeg -i infile.mkv -acodec libvorbis -ab 48k -ac 2 -vcodec libtheora 
-preset slow -wpredp 0 -crf 22 -threads 0 outfile.ogv

But that results in a file about one-sixth the size of the lossless 
original, while I'd like to make the outfile size more like one tenth. Can 
anyone offer suggestions on yet further shrinking the resulting ogv file? 
Also, please feel free to offer any corrections to the incantation I've 
come up with: I (as may be clear) have a rather poor understanding of 
ffmpeg.

Thanks,
James